Polycrystalline materials comprising yttrium aluminum perovskite and methods of making the same

Abstract

This invention describes novel polycrystalline materials comprising yttrium aluminum perovskite (YAP) and yttrium zirconate (YZ). In one embodiment, the polycrystalline material (e.g., bulk or monolithic polycrystalline material) may comprise (a) at least 50 wt% of the yttrium aluminum perovskite (YAP) phase and (b) at least 0.1 wt% of the yttrium zirconate (YZ) phase. Such polycrystalline materials can achieve modified combinations of properties, such as modified combinations of two or more of the following: density, modulus of fracture (MOR), fracture toughness, dielectric strength, loss tangent, and plasma etch resistance.

Description

Polycrystalline Material Containing Yttrium Aluminum Calcium Titanate and Method for Manufacturing the Same As described in U.S. Patent Application Publication No. 2021 / 0221742, ceramic materials can be used to form structures that are transparent to electromagnetic radiation of various wavelengths. However, some ceramic materials may not have sufficient structural integrity when exposed to extreme forces or temperatures. Additionally, in cases where a ceramic material comprises multiple materials, a mismatch in the refractive index of each material can affect the transmittance and emissivity of the ceramic material. Broadly speaking, this patent application relates to novel polycrystalline materials containing yttrium aluminum calcium titanate (YAP) and yttrium zirconate (YZ) and methods for manufacturing the same. In one aspect, the polycrystalline material (e.g., a bulk or monolithic polycrystalline material) can comprise (a) at least 50 wt% of a yttrium aluminum calcium titanate (YAP) phase and (b) at least 0.1 wt% of a yttrium zirconate (YZ) phase. Such polycrystalline materials can achieve an improved combination of properties, such as an improved combination of two or more of the following: density, modulus of rupture (MOR), fracture toughness, dielectric strength, loss tangent, and plasma etch resistance, etc. Further details are provided below. i. Polycrystalline Material Composition As described above, the novel polycrystalline material generally comprises (a) at least 50 wt% of a yttrium aluminum calcium titanate (YAP) phase (YAlO 3 ) and (b) at least 0.1 wt% of a yttrium zirconate (YZ) phase (Y 4 ,Zr 3 O 12) (and may consist of or may consist essentially of). Since it is related to the YZ phase, in one embodiment, the novel polycrystalline material comprises at least 0.2 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 0.3 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 0.4 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 0.5 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 0.6 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 0.7 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 0.8 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 0.9 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 1.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 1.2 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 1.4 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 1.6 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 1.8 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 2.0 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 2.2 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 2.4 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 2.6 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises at least 2.8 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises at least 3.0 wt% of the YZ phase. In one embodiment, the novel polycrystalline material comprises not more than 10.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises not more than 9.0 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises not more than 8.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises not more than 7.0 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises not more than 6.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises not more than 5.0 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises not more than 4.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises not more than 3.0 wt% of the YZ phase. In yet another embodiment, the novel polycrystalline material comprises not more than 2.0 wt% of the YZ phase. In another embodiment, the novel polycrystalline material comprises not more than 1.0 wt% of the YZ phase. As described above, the novel polycrystalline material generally contains at least 50 wt% of the yttrium aluminum calcium titanate (YAP) phase. In one embodiment, the novel polycrystalline material contains at least 55 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 60 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 65 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 70 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 75 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 80 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 82 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 84 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 86 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 88 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 90 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 92 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 94 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 95 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 96 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 97 wt% of the YAP phase. In yet another embodiment, the novel polycrystalline material contains at least 98 wt% of the YAP phase. In another embodiment, the novel polycrystalline material contains at least 99 wt% of the YAP phase. These novel polycrystalline materials may contain limited amounts of other crystalline phases. For example, these novel polycrystalline materials may contain limited amounts of the yttrium aluminum garnet (YAG) phase, the yttrium aluminum monoclinic (YAM) phase, the yttrium oxide phase, and the aluminum oxide phase. Due to its similarity to the yttrium aluminum garnet (YAG) phase (Y 3 Al 5 O 12) is relevant. Thus, in one method, the novel polycrystalline material may comprise from 0.1 to 49.9 wt% of the YAG phase. In one embodiment, the novel polycrystalline material comprises at least 1 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 2 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 3 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 4 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 5 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 6 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 7 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 8 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 9 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 10 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 11 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 12 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 13 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 14 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 15 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 16 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 17 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 18 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 19 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 20 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 21 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 22 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises at least 23 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises at least 24 wt% of the YAG phase. In one embodiment, the novel polycrystalline material comprises no more than 45 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 40 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 38 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 36 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 34 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 32 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 30 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 28 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 26 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 24 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 22 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 20 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 18 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 16 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 14 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 12 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 10 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 8 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 6 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 5 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 4 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 3 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 2 wt% of the YAG phase. In yet another embodiment, the novel polycrystalline material comprises no more than 1 wt% of the YAG phase. In another embodiment, the novel polycrystalline material comprises no more than 0.5 wt% of the YAG phase. In one method, the YAG phase is included in the novel polycrystalline material only as an impurity. due to its association with the yttrium aluminum monoclinic (YAM) phase (Y 4 Al 2 O 9) is relevant. Thus, in one embodiment, the novel polycrystalline material comprises no more than 45 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 40 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 38 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 36 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 34 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 32 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 30 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 28 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 26 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 24 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 22 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 20 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 18 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 16 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 14 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 12 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 10 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 8 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 6 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 5 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 4 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 3 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 2 wt% of the YAM phase. In yet another embodiment, the novel polycrystalline material comprises no greater than 1 wt% of the YAM phase. In another embodiment, the novel polycrystalline material comprises no greater than 0.5 wt% of the YAM phase. In one method, the YAM phase is included in the novel polycrystalline material only as an impurity. As described above, the novel polycrystalline material may comprise a limited amount of yttrium oxide (Y 2 O 3) phase. In one embodiment, the novel polycrystalline material comprises no more than 10 wt% yttrium oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 8 wt% yttrium oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 6 wt% yttrium oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 5 wt% yttrium oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 4 wt% yttrium oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 3 wt% yttrium oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 2 wt% yttrium oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 1 wt% yttrium oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 0.5 wt% yttrium oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 0.25 wt% yttrium oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 0.1 wt% yttrium oxide phase. In one method, the yttrium oxide phase is included in the novel polycrystalline material only as an impurity. As described above, the novel polycrystalline material may comprise a limited amount of aluminum oxide (Al 2 O 3 ) phase. In one embodiment, the novel polycrystalline material comprises no more than 10 wt% aluminum oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 8 wt% aluminum oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 6 wt% aluminum oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 5 wt% aluminum oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 4 wt% aluminum oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 3 wt% aluminum oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 2 wt% aluminum oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 1 wt% aluminum oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 0.5 wt% aluminum oxide phase. In another embodiment, the novel polycrystalline material comprises no more than 0.25 wt% aluminum oxide phase. In yet another embodiment, the novel polycrystalline material comprises no more than 0.1 wt% aluminum oxide phase. In one method, the aluminum oxide is included in the novel polycrystalline material only as an impurity. ii. Microstructure As described above, the novel polycrystalline material can achieve an improved combination of properties, such as an improved combination of two or more of the following: density, modulus of rupture (MOR), fracture toughness, dielectric strength, loss tangent, and plasma etch resistance, etc. Such properties can be achieved due to, for example, the unique microstructure of the novel polycrystalline material. In one embodiment, the novel polycrystalline material achieves an average grain size of no greater than 30 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 28 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 26 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 24 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 22 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 20 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 18 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 16 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 14 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 12 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 10 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 8 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 6 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 5 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 4 microns. In another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 3 microns. In yet another embodiment, the novel polycrystalline material achieves an average grain size of no greater than 2 microns. In one embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 80 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 70 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 60 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 50 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 40 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 30 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 25 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 20 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 18 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 16 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 14 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 12 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 10 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 9 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 8 microns. In another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 7 microns. In yet another embodiment, the novel polycrystalline material achieves a maximum grain size of no greater than 6 microns. In one embodiment, the novel polycrystalline material includes at least some YZ phase precipitates at the grain boundaries. iii. Manufacturing method The novel polycrystalline material can be produced in a variety of ways, including by ceramic powder processing techniques. In one embodiment and with reference now to FIG. 1, method (10) may include the steps of: producing a green body (100) from a powder comprising YAP (YAlO 3 ) and YZ (yttrium zirconate), and sintering the green body to thereby form a final product (200). The final product can achieve any of the compositions described above in the Polycrystalline material compositions section ( section i). Since it relates to step (100), i.e., producing a green body, this step may include any suitable green body manufacturing method, including (but not limited to) die pressing, isostatic pressing, slip casting, tape casting, extrusion, injection molding, and the like. In one embodiment, the producing step (100) is die pressing (e.g., dry pressing to form a solid compact). Since it relates to step (200), i.e., sintering the green body, this step may include heating the green body at any temperature or series of temperatures sufficient to produce a dense final product. In one embodiment, the sintering temperature is from 1200 °C to 1900 °C. In one embodiment, the sintering time is from 0.2 hours to 20 hours. In one embodiment, the sintering is pressureless sintering. In another embodiment, pressure may be applied during sintering. In one embodiment and now referring to FIG. 2, method (10') may include the steps of preparing a precursor powder (20) and then producing from the precursor powder a powder (50) comprising a YAP (YAlO 3 ) phase and a YZ (yttrium zirconate) phase. The powder comprising the YAP (YAlO 3 ) phase and the YZ (yttrium zirconate) phase may then be used to produce a green body as previously described. Since it relates to the step (20) of preparing the precursor powder, method (10') may include blending yttrium oxide and aluminum oxide to prepare a powder blend (22), and heating the powder blend (24) at a temperature and for a time sufficient to produce the precursor powder. Since it relates to the blending step (22), the powder blend may comprise 45 to 50 mole % of yttrium oxide and 50 to 55 mole % of aluminum oxide, although other amounts may be used. As shown in the examples herein, the amounts of yttrium oxide and aluminum oxide may be preselected to achieve a predetermined amount of the desired crystalline phases (e.g., a predetermined amount of YAP phase, YAG phase, YAM phase, YZ phase, yttrium oxide phase, and / or aluminum oxide phase). In one embodiment, the precursor powder comprises at least 55 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 60 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 65 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 70 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 75 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 80 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 82 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 84 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 86 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 88 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 90 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 92 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 94 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 95 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 96 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 97 wt% of the YAP phase. In yet another embodiment, the precursor powder comprises at least 98 wt% of the YAP phase. In another embodiment, the precursor powder comprises at least 99 wt% of the YAP phase. In one embodiment, the precursor powder comprises no more than 50 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 45 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 40 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 35 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 30 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 25 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 20 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 15 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 10 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 5 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 3 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 1 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 0.5 wt% of the YAG phase. In another embodiment, the precursor powder comprises no more than 0.25 wt% of the YAG phase. In yet another embodiment, the precursor powder comprises no more than 0.1 wt% of the YAG phase. In some embodiments, the precursor powder contains a specific targeted amount of YAG phase. For example, in one embodiment, the precursor powder may contain at least 0.5 wt% of YAG phase. In another embodiment, the precursor powder may contain at least 1 wt% of YAG phase. In one embodiment, the precursor powder contains no more than 50 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 45 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 40 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 35 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 30 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 25 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 20 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 15 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 10 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 5 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 3 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 1 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 0.5 wt% of YAM phase. In another embodiment, the precursor powder contains no more than 0.25 wt% of YAM phase. In yet another embodiment, the precursor powder contains no more than 0.1 wt% of YAM phase. In some embodiments, the precursor powder contains a specific targeted amount of YAM phase. For example, in one embodiment, the precursor powder may contain at least 0.5 wt% of YAM phase. In another embodiment, the precursor powder may contain at least 1 wt% of YAM phase. In one embodiment, the precursor powder contains no more than 10 wt% of yttrium oxide phase. In another embodiment, the precursor powder contains no more than 8 wt% of yttrium oxide phase. In yet another embodiment, the precursor powder contains no more than 6 wt% of yttrium oxide phase. In another embodiment, the precursor powder contains no more than 5 wt% of yttrium oxide phase. In yet another embodiment, the precursor powder contains no more than 4 wt% of yttrium oxide phase. In another embodiment, the precursor powder contains no more than 3 wt% of yttrium oxide phase. In yet another embodiment, the precursor powder contains no more than 2 wt% of yttrium oxide phase. In another embodiment, the precursor powder contains no more than 1 wt% of yttrium oxide phase. In yet another embodiment, the precursor powder contains no more than 0.5 wt% of yttrium oxide phase. In another embodiment, the precursor powder contains no more than 0.25 wt% of yttrium oxide phase. In yet another embodiment, the precursor powder contains no more than 0.1 wt% of yttrium oxide phase. In one embodiment, the precursor powder comprises no more than 10 wt% alumina phase. In another embodiment, the precursor powder comprises no more than 8 wt% alumina phase. In yet another embodiment, the precursor powder comprises no more than 6 wt% alumina phase. In another embodiment, the precursor powder comprises no more than 5 wt% alumina phase. In yet another embodiment, the precursor powder comprises no more than 4 wt% alumina phase. In another embodiment, the precursor powder comprises no more than 3 wt% alumina phase. In yet another embodiment, the precursor powder comprises no more than 2 wt% alumina phase. In another embodiment, the precursor powder comprises no more than 1 wt% alumina phase. In yet another embodiment, the precursor powder comprises no more than 0.5 wt% alumina phase. In another embodiment, the precursor powder comprises no more than 0.25 wt% alumina phase. In yet another embodiment, the precursor powder comprises no more than 0.1 wt% alumina phase. Referring back to FIG. 2, the step (20) of producing the precursor powder may include one or more additional powder processing steps such as any of the following: (a) milling the powder blend (e.g., attrition milling), (b) screening the powder blend, (c) preparing the powder blend for spray drying (e.g., using a suitable binder), and (d) spray drying the blended powder. The heating step (24) may be after the spray drying step. Continuing to refer to FIG. 2, the step (50) of producing a powder comprising a YAP (YAlO 3 ) phase and a YZ (yttrium zirconate) phase from the precursor powder may include any suitable powder processing steps such as any of the following: (a) milling the precursor powder (e.g., attrition milling), (b) screening the precursor powder, (c) preparing the precursor for spray drying (e.g., using a suitable binder), and (d) spray drying the precursor powder to produce a final powder comprising a YAP (YAlO 3 ) phase and a YZ (yttrium zirconate) phase. The final powder may then be used to produce a green body as described previously. In one method and now referring to FIG. 3, the method (10'') may include a step (52) of introducing zirconium to facilitate the production of the YZ phase in the final powder. Zirconium may be introduced at any suitable point in the process of producing the final powder. For example, zirconium may be introduced during the milling (54) of the precursor powder, such as by milling with a zirconium-containing grinding medium (e.g., zirconia grinding powder). In such embodiments, the zirconium-containing medium may be considered a transfer material. In some embodiments, zirconium can be introduced by adding a zirconium-containing material (56), such as zirconium powder, to the precursor powder. For example, zirconium powder (such as zirconia powder) can be blended with the precursor powder to facilitate the introduction of zirconium. Such blending can occur, for example, before, during, or after milling the precursor powder. In some embodiments, zirconium can be introduced by exposing the precursor powder to a liquid (58) containing zirconium. For example, the precursor powder can be contacted with an aqueous or organic solution containing zirconium (such as zirconium ions) or contacted by an aqueous or organic solution containing zirconium (such as zirconium ions). Such contact can occur, for example, in preparing the precursor powder for spray drying. The amount of zirconium introduced into the precursor powder can be selected based on the desired amount of the YZ phase in the final powder. In addition or alternatively, zirconium can be introduced during the production of the precursor powder. For example and with reference now to FIG. 2, zirconium can be introduced during (i) blending (22) yttrium oxide powder and alumina powder or (ii) milling yttrium oxide powder and alumina powder (such as by milling with a zirconium-containing grinding medium). In addition or alternatively, zirconium can be introduced in preparing the powder blend for spray drying, such as by contacting the powder blend with an aqueous or organic solution containing zirconium (such as zirconium ions). The amount of zirconium introduced into the powder blend can be selected based on the desired amount of the YZ phase in the final powder. iv. Properties As described above, the novel polycrystalline material can achieve an improved combination of properties, such as an improved combination of two or more of the following: density, modulus of rupture (MOR), fracture toughness, dielectric strength, loss tangent, and plasma etch resistance, etc. In one embodiment, the novel polycrystalline material achieves a density of at least 4.5 g / cm 3 In another embodiment, the novel polycrystalline material achieves a density of at least 4.6 g / cm 3 In yet another embodiment, the novel polycrystalline material achieves a density of at least 4.7 g / cm 3 In another embodiment, the novel polycrystalline material achieves a density of at least 4.8 g / cm 3 In yet another embodiment, the novel polycrystalline material achieves a density of at least 4.9 g / cm 3 In another embodiment, the novel polycrystalline material achieves a density of at least 5.0 g / cm 3 In yet another embodiment, the novel polycrystalline material achieves a density of at least 5.05 g / cm 3 of density. In another embodiment, the novel polycrystalline material achieves a density of at least 5.10 g / cm 3 of density. In yet another embodiment, the novel polycrystalline material achieves a density of at least 5.15 g / cm 3 of density. In another embodiment, the novel polycrystalline material achieves a density of at least 5.20 g / cm 3 of density. In yet another embodiment, the novel polycrystalline material achieves a density of at least 5.22 g / cm 3 of density. In another embodiment, the novel polycrystalline material achieves a density of at least 5.24 g / cm 3 of density. In yet another embodiment, the novel polycrystalline material achieves a density of at least 5.26 g / cm 3 of density. In another embodiment, the novel polycrystalline material achieves a density of at least 5.28 g / cm 3 of density. In yet another embodiment, the novel polycrystalline material achieves a density of at least 5.30 g / cm 3 of density. In one embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 200 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 210 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 220 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 230 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 240 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 250 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 260 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 270 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 280 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 290 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 300 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 310 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 320 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 330 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 340 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 350 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 360 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 370 MPa. In yet another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 380 MPa. In another embodiment, the novel polycrystalline material achieves a MOR (4-point) strength of at least 390 MPa. In one embodiment, the novel polycrystalline material achieves at least 2.0 MPa*m 1 / 2 of plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 2.2 MPa*m 1 / 2 of plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 2.4 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 2.6 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 2.8 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 3.0 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 3.2 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 3.4 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 3.6 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 3.8 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 4.0 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 4.2 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 4.4 MPa*m 1 / 2plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 4.5 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 4.6 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 4.7 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 4.8 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 4.9 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 5.0 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 5.1 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In yet another embodiment, the novel polycrystalline material achieves at least 5.2 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In another embodiment, the novel polycrystalline material achieves at least 5.3 MPa*m 1 / 2 plane strain (K IC ) fracture toughness. In one embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 12.0 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 12.2 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 12.4 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 12.6 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 12.8 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 13.0 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 13.2 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 13.4 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 13.6 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 13.8 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.0 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.2 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.3 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.4 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.5 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.6 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.7 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.8 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 14.9 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.0 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.1 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.2 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.3 kV / mm.In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.4 kV / mm. In yet another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.5 kV / mm. In another embodiment, the novel polycrystalline material achieves an AC dielectric strength (1 mm) of at least 15.6 kV / mm. In one embodiment, the novel polycrystalline material achieves a dielectric constant of at least 12.0 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 12.2 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 12.4 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 12.6 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 12.8 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 13.0 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 13.2 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 13.4 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 13.6 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 13.8 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.0 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.2 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.3 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.4 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.5 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.6 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.7 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.8 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 14.9 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.0 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.1 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.2 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.3 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.4 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.5 (4 GHz). In another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.6 (4 GHz). In yet another embodiment, the novel polycrystalline material achieves a dielectric constant of at least 15.7 (4 GHz). In one embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 5.0x10 -4 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 4.0x10 -4 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 3.0x10 -4 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 2.0x10 -4 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 1.0x10 -4 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 9.0x10 -5 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 8.0x10 -5 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 7.0x10 -5 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 6.0x10 -5 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 5.0x10 -5 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 4.0x10 -5 In another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 3.0x10 -5 In yet another embodiment, the novel polycrystalline material achieves a loss tangent (at 4 GHz) of no greater than 2.0x10 -5 of the loss tangent (at 4 GHz). In one method, the novel polycrystalline material achieves plasma etch resistance. In one embodiment, when according to this article When tested using the etching rate test procedure explained in the material characterization section, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.07 microns per hour. In another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.06 microns per hour. In yet another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.05 microns per hour. In another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.04 microns per hour. In yet another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.03 microns per hour. In another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.02 microns per hour. In yet another embodiment, the novel polycrystalline material achieves a bulk etching rate of no greater than 0.01 microns per hour. As shown in the examples, the novel material can achieve a unique color. In some embodiments, the polycrystalline material has a white color under as-sintered conditions. In some embodiments, the polycrystalline material is translucent under as-sintered conditions. Such color properties can provide improved aesthetics. v. Product Forms and Applications The novel polycrystalline material can have various product forms and can be used in various industrial applications. In one embodiment, the novel polycrystalline material is a bulk (single piece) polycrystalline material. In one embodiment, the novel polycrystalline material is used in semiconductor processing applications. In one embodiment, the novel polycrystalline material is in the form of a semiconductor component. In one embodiment, the semiconductor component is in the form of a nozzle blank or a nozzle. In one embodiment, the semiconductor component is structurally designed for use in a plasma environment. vi. Material Characterization As described above, X-ray diffraction (XRD) can be used to determine the amount of crystalline phase of the polycrystalline material described herein. The XRD instrument should be a Bruker D8 Discover (Bruker Corp., 40 Manning Rd, Billerica, MA 01821) or a comparable XRD instrument. The XRD radiation should be copper K-α radiation. The power should be 1.6 kW. The scanning range should be from 20º to 70º (2θ) (d = 4.5A to 1.35A). The following table provides the main and secondary peaks of the relevant crystalline phases for material characterization purposes. The following standards should be used to measure the material properties of the polycrystalline materials described herein. ● The density should be measured according to ASTM C373-18. ● The grain size should be measured according to ASTM E112-13(2021). ● The modulus of rupture (MOR) should be measured according to C1161-18, where the test bars are manufactured to have a "Type B configuration" with a bar thickness (A) of 4 mm and a bar width (B) of 3 mm. At least 5 bars are used for this test. ● The plane strain (K IC ) Fracture toughness should be measured using the "notched beam" method with a bar thickness (A) of 4 mm and a bar width (B) of 3 mm. At least 5 bars are used for this test. The test bars are notched to mid-thickness (T / 2) (2 mm depth in this configuration) using a diamond wafer blade, where the notch width is 0.010 + / - 0.002 inches wide. Each sample bar is positioned on a one-inch (1”) support span consisting of a ball and rod support system, where the notch is centered under a 0.125-inch (1 / 8”) load ball and the notch face is down (away from the load ball). The bar is loaded in an Instron test frame until fracture. The actual bar thickness and width are measured near fracture. The solid thickness at fracture is measured at three locations and averaged. The K IC fracture toughness value is calculated for each bar using the fracture load and geometric data. The average K IC fracture toughness for at least five specimens is used for the final reported K IC fracture toughness value. ● The dielectric constant and loss tangent tests should be performed by evaluating the dominant TE01 (transverse electric) resonance mode. Such evaluation methods are described, for example, in the following NIST (National Institute of Standards and Technology) technical notes: ○ Janezic, Michael D., N. Paulter, and J. Blendell. "Dielectric and conductor loss characterization and measurement of electronic packaging materials" "materials)", NIST Technical Note 1520 (2001), available online at: https: / / doi.org / 10.6028 / NIST.TN.1520. ● The etching rate is to be measured by sequentially grinding the sample with diamond abrasives in decreasing stages, then polishing with diamond slurry on a Sn-composite polishing plate, and then performing carbon tetrafluoride (CF4) etching for 10 hours, where the gas rate ios is set to 50 sccm at 5.0 Pa, and the upper and lower plate RF powers are set to 135 W (13.56 MHz) and 10 W (13.56 MHz), respectively, resulting in an expected ion energy of less than 200 eV, and all samples are etched simultaneously when possible. The etching rate is calculated from the differential step height measurements taken between the plasma-exposed and masked portions of the sample surface via a diamond stylus profilometer. vii. Other These and other aspects, advantages, and novel features of this novel technology are partly stated in the description and drawings herein and will be apparent to those skilled in the art upon examination of the description and drawings herein, or may be learned by practicing one or more embodiments of the technology provided by the present invention. Among the benefits and improvements already disclosed, other objects and advantages of the present invention will be apparent from the description and drawings herein. Detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are only illustrative of the present invention, and the present invention may be embodied in various forms. In addition, each example given in connection with the various embodiments of the present invention is intended to be illustrative and not restrictive. Throughout this specification and the claims, unless the context clearly dictates otherwise, the following terms are used with the meanings specifically associated herein. The phrases "in one embodiment" and "in some embodiments" as used herein do not necessarily refer to the same embodiment, although they may. In addition, the phrases "in another embodiment" and "in some other embodiments" as used herein do not necessarily refer to different embodiments, although they may. Accordingly, the various embodiments of the present invention can be readily combined without departing from the scope or spirit of the present invention. Further, as used herein, unless the context clearly dictates otherwise, the term "or" is an inclusive "or" operator and is equivalent to the term "and / or". Unless the context clearly dictates otherwise, the term "based on" is not exclusive and allows for other factors not described. In addition, throughout this specification, unless the context clearly dictates otherwise, the meanings of "a", "an", and "the" include plural referents. Unless the context clearly dictates otherwise, the meaning of "in" includes "in" and "on". Although multiple embodiments of the present invention have been described, it should be understood that these embodiments are illustrative rather than restrictive, and many modifications will be apparent to those of ordinary skill in the art. Additionally, unless the context clearly requires otherwise, the various steps may be performed in any desired order, and any applicable steps may be added and / or eliminated. Cross - reference to related applications This patent application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 470,021, filed on May 31, 2023, entitled "Polycrystalline Materials Containing Yttrium Aluminum Calcium Titanate and Methods of Making the Same", which is incorporated herein by reference in its entirety. Examples 1 —— Formulation and calcination of starting materials High - purity yttrium oxide (Y 2 O 3 ) and aluminum oxide (Al 2 O 3 ) were blended to produce a series of powders having 45 to 50 mole % of yttrium oxide and 50 to 55 mole % of aluminum oxide. The formulated powders were then calcined for 6 hours at various temperatures. Subsequently, the crystalline phase composition of the calcined samples as a function of calcination time was determined using X - ray diffraction (XRD). (The material characterization methods are defined in Section of the Summary of this patent application in Part Table 1 : XRD 1 analysis of sample ( in weight percentage ) Table 2 : XRD 2 analysis of sample ( in weight percentage ) Table 3 : Samples 3 of the XRD analysis ( in weight percentage ) As shown, a customized amount of the YAP (YAlO 3 ) phase, the YAM (Y 4 Al 2 O 9 ) phase, the YAG (Y 3 Al 5 O 12 ) phase, the yttrium oxide phase, and the aluminum oxide phase can be produced using a pre-determined amount of yttrium oxide and aluminum oxide and pre-selected calcination conditions. Thus, a material with a pre-selected crystalline phase structure can be produced. For example, as shown in Table 1, to produce a material with a high weight fraction of the YAP phase (e.g., ≥ 95 wt% YAP), a yttrium oxide:aluminum oxide molar ratio of approximately 50:50 can be pre-selected and then calcined at a temperature of 1250 °C. As another example, a yttrium oxide:aluminum oxide molar ratio of approximately 45:50 can be pre-selected and then calcined at a temperature of 1250 °C to produce a bulk material with approximately 60 wt% YAP phase or approximately 38% YAG phase. As the data shows, many other combinations can be pre-selected and achieved. Example 2 —— Post-calcination processing and firing Several powders were produced according to Example 1. Those powders with a high weight fraction of the YAG phase were selected. Several powders (batches 1.1 to 1.4) were attrition milled using alumina as the grinding media loss while using zirconia (ZrO 2)Abrade several other powders (batches 2.1 to 2.6) as the abrasive medium loss. For batch number 2.4, additional zirconia particles (about 0.5 wt%) were added during abrasion to achieve the target zirconium content. Then, these powders were screened at 500 mesh, blended with a suitable organic binder and then spray-dried. Then, these powders were made into bulk components by filling a mold, followed by dry pressing to form a solid compact, and then sintered at about 1650 °C for 4 to 6 hours. After sintering, various properties of the bulk components were measured / characterized, and the results are shown in Tables 4 to 5 below. (The material characterization method is defined in the section of the invention content vi. ) Photographs of representative bulk components are shown in Figures 10a to 10b. Various figures illustrating the properties of the Example 1 material are provided in Figures 11a to 11f. For comparison purposes, bulk components were made from known pure yttrium oxide powder in substantially the same manner as described above. This bulk material is white, achieving a density of 4.95 g / cm 3 , an average grain size of 3.0 microns, a maximum grain size of about 15 microns, a MOR (4-point, MPa) of 130 MPa, a K 1 / 2 of 1.2 MPa m IC fracture toughness, a dielectric constant of 11.5 (4 GHz) and a loss tangent of 2.5x10 -5 (4 GHz). Table 4 : Example 2 bulk material XRD analysis ( in weight percentage ) Table 5 : Example 2 properties of bulk material After alumina abrasion of the powder and Via Zirconia grinding of the difference between powders As shown in Table 4, different phases can be achieved by using alumina or zirconia grinding media, or by adding zirconia particles to the powder. Products made from powders ground with alumina result in bulk products (1.1 to 1.4) consisting essentially of the YAP and YAG phases. Products made from powders ground with zirconia result in bulk products (2.1 to 2.6) having the YAP and YAG phases but also having a measurable amount of Y 4 Zr 3 O 12 (YZ) phase. The formation of the YZ phase is the result of zircon transfer to the formulation during the attrition grinding. As shown in batch / component number 2.4, the YZ phase can also be achieved by adding a zircon-containing material (such as zirconia) to the bulk powder. As described in further detail below, the addition of zircon can impart beneficial properties. Zircon can be introduced, for example, by using a zircon-containing grinding medium and / or by directly adding a zircon material (such as zirconia) to the powder blend to produce the YZ phase. Organic or aqueous solutions containing zircon can also be used to introduce zircon. Density As shown in Table 5, high density is achieved. Considering that the theoretical densities of the YAP and YAG phases have been reported as 5.35 and 4.55 g / cc, respectively, the measured density values are remarkably high. Microstructure and grain size As shown in Table 5, the average grain size is small and reproducible. The maximum grain size is similarly small. Figure 7 is a micrograph of bulk component number 1.4 (79.5 wt% YAP phase and 20.5 wt% YAG phase). As shown, the grain size is uniform and generally homogeneous. The absence of porosity is notable, confirming that the measured density is close to the theoretical maximum. There is also no intragranular porosity. The small amount of porosity that does exist appears to be intergranular - located along the grain boundaries. Thus, enhanced mechanical and / or corrosion resistance properties can be achieved. Figure 8 is a SEM micrograph of bulk component No. 2.1 (75 wt% YAP phase, 23.5 wt% YAG phase, and 1.5 wt% YZ phase). The weight ratio of YAP / YAG is similar to that of bulk component No. 1.4 shown in Figure 7, but with 1.5 wt% YZ phase. Without being bound by theory, it is believed that the presence of the YZ phase likely contributes to the reduced grain size and increased uniformity. At the sintering temperature (e.g., about 1650 °C), zirconium can be contained in solid solution with yttrium oxide. Upon cooling, the YZ phase precipitates at the grain boundaries, thereby depleting some yttrium oxide from the system and shifting the YAP / YAG ratio slightly closer to YAG. Figure 9 is a backscattered SEM micrograph of bulk component No. 2.1 (91 wt% YAP phase, 8 wt% YAG phase, and 1 wt% YZ phase), and illustrates the physical properties of the YZ precipitate phase. The dark phase is YAG, the gray phase is YAP, and the small white regions are YZ precipitates. MOR ( Modulus of Rupture ) and fracture toughness As shown in Table 5, the bulk components achieve significantly improved mechanical properties compared to the pure YAG phase and pure yttrium oxide phase. The four-point flexural strength (MOR) of the yttrium oxide phase and YAG phase is about 100 to 150 MPa, and both materials generally achieve low fracture toughness, typically about 1.2 MPa*m 1 / 2 , as confirmed by the comparative data of the bulk yttrium oxide products provided above. In contrast, the materials of the present invention achieve a high MOR (321 to 386 MPa), which is similar to the MOR of high-purity alumina (>300 MPa). The materials of the present invention also achieve an exceptionally high fracture toughness (4.5 to 5.3 MPa*m 1 / 2 ). In fact, bulk component No. 2.1 (91 wt% YAP phase, 8 wt% YAG phase, 1 wt% YZ phase) was measured to have a four-point flexural strength of 386 MPa and a fracture toughness of 5.3 MPa·m 1 / 2 . These mechanical property improvements provide significant advantages in component design and applications, as well as in processing that requires diamond grinding / machining procedures. Dielectric properties The materials of the present invention exhibit excellent dielectric properties. Pure yttrium oxide has dielectric constants of about 11.5 and 2x10 respectively, and -5The dielectric constant and loss tangent are confirmed by the comparative data of the bulk yttrium oxide products provided above. The materials of the present invention achieve a dielectric constant in the range of 14 to 16 and a loss tangent in the range of 3x10 -5 to 8x10 -5 . The pure YAP phase is reported to have a dielectric constant higher than 15, while the pure YAG phase is reported to have a dielectric constant of about 11.7. The dielectric constant variation shown by the composition of Example 2 is derived from the relative contents of the YAG phase and the YAP phase. Color Another interesting result is the color of the bulk products made from the zirconia-polished powders. As shown in Figure 10a, the color of the products made from the alumina-polished powders (Materials 1.1 to 1.4) is tan (light brown). However, surprisingly, the YZ-containing materials (2.1 to 2.6) achieve a bright white color. The YZ-containing materials are also translucent (Figure 10b). Thus, in addition to potentially providing enhanced physical properties, the YZ-containing materials can also provide products with enhanced visual appearance. Example 3 —— Evaluation of Plasma Etching Resistance Additional specimen blocks were made from the powder of Material 2.1 of Example 2. Comparative specimen blocks were made from alumina (99.5% and 99.8% purity) and yttrium oxide. Then, the samples were prepared for plasma etching tests by grinding with diamond abrasives in sequentially decreasing grit sizes and finally polished with diamond slurry on a Sn-composite grinding disk. After grinding, surface roughness measurements were performed on a 700x700 µm area using a Zeiss LSM 800 scanning laser confocal microscope, and areal surface texture calculations were performed in accordance with ISO 25178, and the results are provided in Table 6 below. Next, carbon tetrafluoride (CF 4 ) etching was performed for 10 hours. The gas rate was set at 50 sccm at 5.0 Pa. The upper and lower plate RF powers were set at 135 W (13.56 MHz) and 10 W (13.56 MHz), respectively, resulting in an expected ion energy of less than 200 eV. All material samples were etched simultaneously to minimize any possible differences in the etching conditions. The etching rate was calculated from the differential step height measurements taken between the plasma-exposed and masked portions of the sample surface using a diamond stylus profilometer. The etching rate results are also shown in Table 6 below. Table 6 : Example 3 Properties of Materials As shown, compared to the comparative material, Sample 2.1 from Example 2 achieves a lower surface roughness. Compared to the comparative material, Sample 2.1 from Example 2 also achieves a higher density and a lower grain size. Compared to the comparative alumina material, Sample 2.1 also achieves much better plasma etching resistance. Sample 2.1 achieves an etching rate comparable to that of the comparative yttrium oxide material, but has much better mechanical properties. Although various embodiments of the present invention have been described in detail, it is apparent that those skilled in the art will make modifications and adaptations to their embodiments. However, it should be clearly understood that such modifications and adaptations are within the spirit and scope of the present invention. 10: Method 10': Method 10": Method 20: Step 22: Step 24: Step 50: Step 52: Step 54: Step 56: Step 58: Step 100: Step 200: Step Figure 1 illustrates an embodiment of a method for producing a polycrystalline material having a customized amount of YAP phase and YZ phase. Figure 2 illustrates an embodiment of a method for producing a precursor powder. Figure 3 illustrates an embodiment for introducing zirconium into the precursor powder to facilitate the production of the final powder having the YZ phase. Figures 4 to 6 are graphs illustrating the crystalline phases of various Example 1 materials as a function of temperature. Figure 7 is a SEM micrograph of the YAP / YAG final product of Example 2. Figure 8 is a SEM micrograph of the YAP / YAG / YZ final product of Example 2. Figure 9 is a backscattered SEM micrograph of the YAP / YAG / YZ final product of Example 2. Figure 10a is a photograph illustrating the bulk (monolithic) final component of Example 2. Figure 10b is a photograph illustrating the white translucent final component of Example 2 having the YZ phase. Figures 11a to 11f are graphs illustrating various properties of the Example 1 alloy. 10: Method 100: Step 200: Step

Claims

1. A polycrystalline material comprising: (a) at least 50% by weight of yttrium aluminum perovskite (YAP) phase; (b) at least 0.1% by weight of yttrium zirconate (YZ) phase; and (c) from 0.1% to 49.9% by weight of yttrium aluminum garnet (YAG) phase.

2. The polycrystalline material of claim 1 contains at least 0.5% by weight and no more than 5.0% by weight of YZ phase.

3. The polycrystalline material of claim 2, comprising at least 0.7% by weight and no more than 3.0% by weight of YZ phase.

4. The polycrystalline material of claim 1, which contains at least 60% by weight of YAP phase.

5. The polycrystalline material of claim 4, comprising at least 70% by weight of the YAP phase.

6. The polycrystalline material of claim 5, comprising at least 1% by weight and no more than 30% by weight of YAG phase.

7. The polycrystalline material of claim 6, comprising at least 5% by weight and no more than 26% by weight of YAG phase.

8. The polycrystalline material of claim 1 contains no more than 5% by weight of yttrium oxide phase.

9. The polycrystalline material of claim 1 contains no more than 5% by weight of alumina phase.

10. A polycrystalline material as claimed in any one of claims 1 to 9, wherein the polycrystalline material achieves a density of at least 5.0 g / cm3.

11. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material achieves an average grain size of not more than 5 micrometers.

12. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material achieves a maximum grain size of not more than 10 micrometers.

13. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material achieves a MOR (4-point) strength of at least 300 MPa.

14. A polycrystalline material as claimed in any one of claims 1 to 9, wherein the polycrystalline material achieves a plane strain (KIC) fracture toughness of at least 4.0 MPa*m1 / 2.

15. A polycrystalline material as claimed in any one of claims 1 to 9, wherein the polycrystalline material achieves an AC dielectric strength of at least 14.5 kV / mm (1 mm).

16. A polycrystalline material as claimed in any one of claims 1 to 9, wherein the polycrystalline material achieves a dielectric constant of at least 14.4 (4 GHz).

17. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material achieves a loss tangent of not more than 3.0 x 10⁻⁴ (4 GHz).

18. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material achieves a bulk etching rate of not more than 0.05 micrometers per hour.

19. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material is white in color under as-sintered conditions.

20. A polycrystalline material as claimed in any of claims 1 to 9, wherein the polycrystalline material is semi-transparent under sintering conditions.

21. The polycrystalline material of any one of claims 1 to 9, wherein the polycrystalline material is in the form of a semiconductor device.

22. The polycrystalline material of any one of claims 1 to 9, wherein the semiconductor component is in the form of a nozzle blank or a nozzle.

23. The polycrystalline material of claim 21, wherein the semiconductor component is structurally designed for use in a plasma environment.

24. A method for producing a polycrystalline material as claimed in any one of claims 1 to 23, comprising: (a) A green body is generated from a first powder containing the YAP (YAlO3) phase and the YZ (yttrium zirconate) phase; (b) The green blank is sintered at a temperature of 1200°C to 1900°C to form a final product, wherein the final product comprises a polycrystalline material as claimed in any one of claims 1 to 23.

25. The method of claim 24, comprising: Prior to the green body generation step, a precursor powder is prepared, wherein the precursor powder generation step comprises: (i) blending yttrium oxide and alumina to prepare a powder blend, wherein the powder blend comprises 45 to 50 moles of yttrium oxide and 50 to 55 moles of alumina; (ii) heating the powder blend at a temperature and time sufficient to generate the precursor powder, wherein the precursor powder comprises at least 50 wt% of a YAP phase, no more than 10 wt% of a yttrium oxide phase and no more than 10 wt% of an alumina phase; and generating the first powder from the precursor powder.

26. The method of claim 25, wherein the precursor powder comprises no more than 5% by weight of yttrium oxide phase.

27. The method of claim 25, wherein the precursor powder comprises no more than 5% by weight of an alumina phase.

28. The method of claim 25, wherein the precursor powder comprises at least 70% by weight of YAP phase.

29. The method of claim 25, wherein the precursor powder comprises no more than 5% by weight of YAM phase (Y4Al2O9).

30. The method of claim 29, wherein the precursor powder comprises 0.5% by weight to no more than 50% by weight of YAG phase (Y3Al5O12).

31. The method of claim 30, wherein the precursor powder comprises at least 1% by weight to no more than 30% by weight of YAG phase (Y3Al5O12).

32. The method of claim 25, wherein the sintering comprises pressureless sintering.

33. The method of any one of claims 25 to 32, wherein the step of generating the first powder from the precursor powder comprises: Zirconium is introduced into the precursor powder.

34. The method of claim 33, wherein the introduction step includes adding zirconium-containing powder to the precursor powder.

35. The method of claim 34, wherein the zirconium-containing powder comprises zirconium oxide.

36. The method of claim 33, wherein the introduction step includes transferring zirconium self-transfer material to the precursor powder.

37. The method of claim 36, wherein the transfer material is a zirconium-containing abrasive medium.

38. The method of claim 37, wherein the transfer step includes grinding the precursor powder with the transfer material.

39. The method of claim 33, wherein the introduction step includes exposing the precursor powder to a solution containing zirconium ions.

40. The method of claim 25, wherein the step of generating the first powder from the precursor powder includes one or more of the following: grinding the precursor powder, screening the precursor powder, and spray drying the precursor powder.

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