Novel glass and glass ceramic compositions

Abstract

Novel glass and glass ceramic compositions are provided. A composition comprising: from 30 mol% to 60 mol% of SiO2; from 15 mol% to 35 mol% of Al2O3; from 5 mol% to 25 mol% of Y2O3; from 0 mol% to 20 mol% of TiO2; and from 0 mol% to 25 mol% of R2O, such that R2O is the sum of Na2O, K2O, Li2O, Rb2O, and Cs2O.

Description

[0001] This application is a divisional application of the invention patent application with application number 202110526582.7 and the invention title "Novel Glass and Glass-Ceramic Composition".

[0002] This application claims priority to U.S. Provisional Application No. 63 / 024,835, filed May 14, 2020, and Korean Patent Application No. 10-2020-0120241, filed September 18, 2020, pursuant to 35 USC §119, the contents of which form the basis of this document and are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to novel glass and glass-ceramic compositions. Background Technology

[0004] High-strength glass and glass-ceramic materials are essential for a wide range of applications, including handheld devices, memory disks, and optical fibers. For glass, sufficient mechanical properties can be achieved through compositions containing a high proportion of high field-strength oxides (e.g., MgO, Y₂O₃, La₂O₃, etc.). Glass-ceramics present more complex challenges. Designing mechanically advantageous glass-ceramics is more difficult to predict because the precursor glass composition does not necessarily indicate the behavior of the composite material (microcrystals and residual glass).

[0005] Therefore, as described herein, novel glass and glass-ceramic compositions with predictable and excellent mechanical properties are disclosed. Summary of the Invention

[0006] In some embodiments, a composition comprises: 30 mol% to 60 mol% SiO2; 15 mol% to 35 mol% Al2O3; 5 mol% to 25 mol% Y2O3; 0 mol% to 20 mol% TiO2; and 0 mol% to 25 mol% R2O, wherein R2O is the sum of Na2O, K2O, Li2O, Rb2O and Cs2O.

[0007] In one aspect that can be combined with any other aspect or embodiment, R2O is the sum of Na2O and Li2O. In one aspect that can be combined with any other aspect or embodiment, R2O consists of either Na2O or Li2O. In one aspect that can be combined with any other aspect or embodiment, R2O contains 0 mol% to 12.5 mol% Na2O. In one aspect that can be combined with any other aspect or embodiment, R2O contains 0 mol% to 12.5 mol% Li2O.

[0008] In one aspect that can be combined with any other aspect or embodiment, the composition further comprises 0 mol% to 2.5 mol% of B2O3. In one aspect that can be combined with any other aspect or embodiment, the composition further comprises 0 mol% to 4 mol% of ZrO2.

[0009] In one aspect, which may be combined with any other aspect or embodiment, the composition comprises: 30 mol% to 40 mol% SiO2; 25 mol% to 35 mol% Al2O3; 8 mol% to 14 mol% Y2O3; and 4 mol% to 18 mol% TiO2. In another aspect, which may be combined with any other aspect or embodiment, the composition comprises: 0 mol% to 12.5 mol% Li2O; 0 mol% to 10.5 mol% Na2O; and 0 mol% to 2.5 mol% B2O3.

[0010] In one aspect, which can be combined with any other aspect or embodiment, the composition comprises: 30 mol% to 50 mol% SiO2; 18 mol% to 30 mol% Al2O3; 10 mol% to 15 mol% Y2O3; and 4 mol% to 14 mol% TiO2. In one aspect, which can be combined with any other aspect or embodiment, the composition comprises: 0 mol% to 11.5 mol% Li2O; 0 mol% to 10.5 mol% Na2O; and 0 mol% to 4 mol% ZrO2.

[0011] In one aspect that can be combined with any other aspect or implementation, the ratio of R2O to Al2O3 is in the range of 0.1 to 1; or the ratio of Al2O3 to Y2O3 is in the range of 0.1 to 5; or the ratio of TiO2 to Y2O3 is in the range of 0.1 to 5; or the ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 1; or the ratio of TiO2 to SiO2 is in the range of 0.05 to 1.

[0012] In one aspect that can be combined with any other aspect or implementation method, the ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or the ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or the ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or the ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or the ratio of TiO2 to SiO2 is in the range of 0.05 to 0.75.

[0013] In one aspect that can be combined with any other aspect or embodiment, the composition is a glass composition. In another aspect that can be combined with any other aspect or embodiment, the composition is a glass-ceramic composition.

[0014] In some embodiments, the Young's modulus of the glass composition is in the range of 107 GPa to 126 GPa. In some embodiments, the Young's modulus of the glass-ceramic composition is in the range of 119 GPa to 177 GPa. Attached Figure Description

[0015] This disclosure can be more fully understood through the following specific embodiments, in conjunction with the accompanying drawings, wherein:

[0016] Figures 1A to 1I Backscattered scanning electron microscopy (SEM) images of Li-containing glass-ceramic microstructures are illustrated according to some embodiments.

[0017] Figure 2A and 2B Backscattered SEM images of Na-containing glass-ceramic microstructures are illustrated according to some embodiments.

[0018] Figure 3A and 3B Backscattered SEM images of glass-ceramic microstructures containing mixed alkali metals (e.g., containing Li and Na) are illustrated according to some embodiments.

[0019] Figure 4 Backscattered SEM images of glass-ceramic microstructures containing high SiO2, low Al2O3, and low ZrO2 are illustrated according to some embodiments. Detailed Implementation

[0020] In the following description, whenever a group is described as comprising at least one and a combination of a set of elements, it should be understood that the group may comprise any number of the listed elements in the form of individual elements or combinations thereof, or consist primarily of any number of the listed elements, or consist of any number of the listed elements. Similarly, whenever a group is described as consisting of at least one element or a combination thereof, it should be understood that the group may consist of any number of the listed elements in the form of individual elements or combinations thereof. Unless otherwise stated, the listed numerical ranges include both the upper and lower limits of the range, as well as any range between the upper and lower limits. It should also be understood that the various features disclosed in the specification and drawings can be used in any and all combinations thereof.

[0021] If a range of values ​​including upper and lower limits is listed herein, the range is intended to include the endpoints of the range as well as all integers and fractions within that range, unless otherwise specified in specific circumstances. The scope of the claims is not limited to the specific values ​​listed when defining the range. Furthermore, when quantities, concentrations, or other numerical values ​​or parameters are given in the form of ranges, one or more preferred ranges, or a list of preferred upper and lower limits, this should be understood as explicitly disclosing all ranges formed by any pairing of any upper or preferred value with any lower or preferred value, regardless of whether such pairings are disclosed individually. Finally, when the term “about” is used to describe the values ​​or endpoints of a range, it should be understood that this disclosure includes the specific value or endpoint referenced. When the values ​​or endpoints of a range are not listed using “about,” the values ​​or endpoints of the range are intended to include two embodiments: one modified by “about” and the other not modified by “about.”

[0022] In this document, glass and glass-ceramic compositions are expressed in molar percentages (based on oxides) of a particular component contained herein, unless otherwise stated. Any component having more than one oxidation state may be present in the glass or glass-ceramic composition in any oxidation state. However, the concentration of such a component is expressed in the oxide in which the component is in its lowest oxidation state, unless otherwise stated.

[0023] Unless otherwise stated, all components are expressed as mole percentages (mol%). Young's modulus, shear modulus, and Poisson's ratio were measured at the same time using resonant ultrasonic spectroscopy as described in ASTM E1875-00e1.

[0024] Glass and glass-ceramic compositions

[0025] The novel compositions disclosed herein include mechanically advantageous and ion-exchangeable precursor glasses, and robust, high Young's modulus, high hardness, and ion-exchangeable glass-ceramics. The precursor glasses are unique because they comprise extremely high Al₂O₃ and Y₂O₃ contents and low SiO₂ contents. The glass-ceramics possess novel phase compositions and microstructures (e.g., uniform nucleation and internal nucleation). Furthermore, in addition to their inherent strength, the disclosed glass and glass-ceramic compositions can be chemically strengthened, thereby further increasing their resistance to damage from surface defects.

[0026] As used herein, “composition” can refer to either “glass composition” or “glass-ceramic composition”. It is expected that the composition of the precursor glass and the glass-ceramic formed by heat-treating (ceramizing) the precursor glass will be substantially equivalent (explained below).

[0027] Silica (SiO2) is used as the main oxide component of the compositions in the embodiments and may be included to provide high-temperature stability and chemical durability. In some examples, the composition may contain 30 mol% to 60 mol% of SiO2. In some examples, the composition may contain 30 mol% to 50 mol% of SiO2. In some examples, the composition may contain 30 mol% to 35 mol% of SiO2, or 35 mol% to 40 mol% of SiO2, or 40 mol% to 45 mol% of SiO2, or 45 mol% to 50 mol% of SiO2, or 50 mol% to 55 mol% of SiO2, or 55 mol% to 60 mol% of SiO2, or 30 mol% to 40 mol% of SiO2, or 35 mol% to 50 mol% of SiO2, or 40 mol% to 50 mol% of SiO2, or any value or range disclosed herein. In some instances, the composition is substantially free of SiO2 or contains 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, 35 mol%, 36 mol%, 37 mol%, 38 mol%, 39 mol%, 40 mol%, 41 mol%, 42 mol%, 43 mol%, 44 mol%, 45 mol%, 46 mol%, 47 mol%, 48 mol%, 49 mol%, or 50 mol% of SiO2, or any range or value having the endpoints disclosed herein.

[0028] Network forming agents are the oxide components of glass that form the framework of the glass structure. Some examples include SiO2, Al2O3, P2O5, and B2O3. Alumina (Al2O3) can affect the structure of the composition and also lower the liquidus temperature and coefficient of thermal expansion, or raise the strain point. In addition to its role as a network forming agent, Al2O3 (and ZrO2) helps improve the chemical durability of silicate-based compositions without toxicity concerns.

[0029] Furthermore, alumina (Al₂O₃) advantageously promotes an increase in the mechanical strength of the composition. The compositions disclosed herein are unique due to their high Al₂O₃ content. Along with yttrium oxide, one of the most important effects of alumina is its increase in the elastic modulus E (GPa) of the glass or glass-ceramic composition. At least due to the concentration of alumina, glass and glass-ceramic compositions with high Young's modulus values ​​were obtained (Young's moduli of 107-126 GPa and 119-177 GPa, respectively). In addition, the glass-ceramic compositions also exhibit high fracture toughness (0.99-3.2 MPa*√m) and high Vickers hardness (868-1192 kgf / mm²). 2 ).

[0030] In some instances, the composition may contain 15 mol% to 35 mol% Al2O3. In some instances, the composition may contain 18 mol% to 31 mol% Al2O3. In some instances, the composition may comprise 15 mol% to 20 mol% of Al2O3, or 20 mol% to 25 mol% of Al2O3, or 25 mol% to 30 mol% of Al2O3, or 30 mol% to 35 mol% of Al2O3, or 18 mol% to 30 mol% of Al2O3, or 25 mol% to 31 mol% of Al2O3, or 18 mol% to 21 mol% of Al2O3, or 21 mol% to 24 mol% of Al2O3, or 24 mol% to 27 mol% of Al2O3, or 27 mol% to 30 mol% of Al2O3, or 30 mol% to 33 mol% of Al2O3, or 25 mol% to 35 mol% of Al2O3, or any value or range disclosed herein. In some instances, the composition comprises 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol%, 26 mol%, 27 mol%, 28 mol%, 29 mol%, 30 mol%, 31 mol%, 32 mol%, 33 mol%, 34 mol%, or 35 mol% of Al2O3, or any range or value having the endpoints disclosed herein.

[0031] Zirconia (ZrO2) acts as a nucleating agent, promoting internal nucleation, which is an important first step in crystallization. In some examples, the composition may contain 0 mol% to 10 mol% ZrO2. In some examples, the composition may contain 0 mol% to 5 mol% ZrO2. In some examples, the composition may contain 0 mol% to 4 mol% ZrO2, or 0.5 mol% to 3.5 mol% ZrO2, or 1 mol% to 3 mol% ZrO2, or any value or range disclosed herein. In some examples, the composition contains 0, >0, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, or 4 mol% ZrO2, or any range or value having the endpoints disclosed herein.

[0032] Alkali metal oxides (R₂O, which is the sum of Na₂O, K₂O, Li₂O, Rb₂O, and / or Cs₂O) are used as auxiliaries to achieve low melting temperatures and low liquidus temperatures, and / or to contribute to improved bioactivity (if desired), and / or to influence the coefficient of thermal expansion, especially at low temperatures. In some examples, the composition may contain 0 mol% to 25 mol% of R₂O. In some examples, the composition may contain 0 mol% to 22 mol% of R₂O. In some examples, the composition may contain a combination of 0 mol% to 22 mol% of Na₂O and Li₂O. In some examples, the composition may contain 1 mol% to 20 mol%, or 3 mol% to 17 mol%, or 4 mol% to 16 mol%, or 4.5 mol% to 15.5 mol%, or 5 mol% to 15 mol%, or 0 mol% to 15 mol% of R₂O, or any values ​​or ranges disclosed herein. In some instances, the composition may contain 0 mol% to 15 mol% Na₂O, or 0 mol% to 12.5 mol% Na₂O, 0 mol% to 10.5 mol% Na₂O, or any values ​​or ranges disclosed herein. In some instances, the composition may contain 0 mol% to 15 mol% Li₂O, or 0 mol% to 12.5 mol% Li₂O, 0 mol% to 11.5 mol% Li₂O, or any values ​​or ranges disclosed herein. In some instances, the composition comprises 0, >0, 1 mol%, 2 mol%, 3 mol%, 4 mol%, 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, 25 mol% of R2O (e.g., Na2O, K2O, Li2O, Rb2O, Cs2O, or combinations thereof), or any range or value having the endpoints disclosed herein.

[0033] Yttrium oxide (Y₂O₃) advantageously promotes an increase in the mechanical strength of the composition. The compositions disclosed herein are unique due to their high Y₂O₃ content. Along with alumina, one of the most important effects of yttrium oxide is its increase in the elastic modulus E (GPa) of the glass or glass-ceramic composition. At least due to the concentration of yttrium oxide, glass and glass-ceramic compositions with high Young's modulus values ​​were obtained (Young's moduli of 107-126 GPa and 119-177 GPa, respectively). Furthermore, the glass-ceramic compositions also exhibit high fracture toughness (0.99-3.2 MPa*√m) and high Vickers hardness (868-1192 kgf / mm²). 2 ).

[0034] For glass compositions, these properties may be due to the high electric field strength of the network modifiers in these glasses. The high electric field strength results in a close-packed structure, leading to high modulus, as well as high density and refractive index. For glass-ceramic compositions, various crystalline phases increase the mechanical properties of the bulk material relative to their precursor glasses (e.g., as explained in Example 4 below). The phases that contribute most to this increase in mechanical properties are Y₂Ti₂O₇, Y₂Si₂O₇, and Y₃Al₅O₇. 12 (Yttrium aluminum garnet, YAG). The increase in Young's modulus is greatest in the Li-only compositions, but the increase in Young's modulus is still significant for Na-only glass ceramics.

[0035] In some instances, the composition may contain 5 mol% to 25 mol% Y₂O₃. In some instances, the composition may contain 8 mol% to 14 mol% Y₂O₃. In some instances, the composition may contain 10 mol% to 15 mol% Y₂O₃. In some instances, the composition may contain 7 mol% to 23 mol% or 10 mol% to 20 mol% Y₂O₃, or any value or range disclosed herein. In some instances, the composition contains 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol%, 21 mol%, 22 mol%, 23 mol%, 24 mol%, or 25 mol% Y₂O₃, or any range or value having the endpoints disclosed herein.

[0036] Boron trioxide (B₂O₃) helps lower the liquidus temperature and increase the amount of residual glass in the glass-ceramic composition. Currently, the liquidus temperatures of the compositions disclosed herein are significantly lower than those achieved by other glass-ceramics (e.g., enstatite glass-ceramics) with comparable high Young's moduli. In some examples, the compositions may contain 0 mol% to 5 mol% of B₂O₃. In some examples, the compositions may contain 0 mol% to 2.5 mol% of B₂O₃. In some examples, the compositions may contain 0 mol% to 1 mol% of B₂O₃. In some examples, the compositions may contain 0 mol% to 4 mol% of B₂O₃, or 0.5 mol% to 3.5 mol% of B₂O₃, or 1 mol% to 3 mol% of B₂O₃, or any values ​​or ranges disclosed herein. In some instances, the composition comprises 0, >0, 0.5 mol%, 1 mol%, 1.5 mol%, 2 mol%, 2.5 mol%, 3 mol%, 3.5 mol%, 4 mol%, 4.5 mol%, 5 mol% of B2O3, or any range or value having the endpoints disclosed herein.

[0037] Titanium dioxide (TiO2) acts as a nucleating agent, promoting internal nucleation, which is an important first step in crystallization. In some examples, the composition may contain 0 mol% to 20 mol% TiO2. In some examples, the composition may contain 5 mol% to 20 mol% TiO2. In some examples, the composition may contain 4 mol% to 14 mol% TiO2. In some examples, the composition may contain 4 mol% to 18 mol% TiO2, or 6 mol% to 18 mol% TiO2, or 6 mol% to 16 mol% TiO2, or 8 mol% to 16 mol% TiO2, or 8 mol% to 14 mol% TiO2, or any values ​​or ranges disclosed herein. In some instances, the composition comprises 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, 15 mol%, 16 mol%, 17 mol%, 18 mol%, 19 mol%, 20 mol% of TiO2, or any range or value having the endpoints disclosed herein.

[0038] Other compositions may include phosphorus pentoxide (P₂O₅), network modifiers such as alkaline earth metal oxides (MgO, CaO, SrO, and / or BaO), and zinc oxide (ZnO). Phosphorus pentoxide (P₂O₅) can also act as a network forming agent and help increase the viscosity of the composition, thereby widening the operating temperature range, which is advantageous for the manufacture and formation of glass and / or glass-ceramic compositions. Alkaline earth metal oxides can improve desired properties in materials, including increasing Young's modulus and coefficient of thermal expansion. In some instances, zinc oxide (ZnO) can act similarly to alkaline earth metal oxides (e.g., MgO).

[0039] Additional components may be included in the composition to provide additional benefits, or may be included as contaminants commonly found in commercially prepared compositions. For example, additional components may be added as colorants or clarifying agents (e.g., to facilitate the removal of gaseous inclusions from the melt batch used to produce the composition) and / or for other purposes. In some instances, the composition may contain one or more compounds that act as ultraviolet radiation absorbers. In some instances, the composition may contain CeO, MnO, Nb₂O₅, MoO₃, Ta₂O₅, WO₃, SnO₂, Fe₂O₃, As₂O₃, Sb₂O₃, Cl, Br, or combinations thereof. According to some examples, the composition may also contain various contaminants associated with the batch material and / or introduced into the composition due to the melting, clarifying, and / or forming equipment used in the production of the composition. For example, in some embodiments, the composition may contain SnO₂ or Fe₂O₃, or combinations thereof.

[0040] In some examples, the composition comprises a combination of SiO2, Al2O3, Y2O3, and TiO2. For example, the composition comprises 30 mol% to 40 mol% SiO2, 25 mol% to 35 mol% Al2O3, 8 mol% to 14 mol% Y2O3, and 4 mol% to 18 mol% TiO2. In some examples, the composition further comprises Li2O, Na2O, and B2O3. For example, the composition comprises 0 mol% to 12.5 mol% Li2O, 0 mol% to 10.5 mol% Na2O, and 0 mol% to 2.5 mol% B2O3.

[0041] In some examples, the composition comprises a combination of SiO2, Al2O3, R2O, Y2O3, and TiO2. For example, the composition comprises 30 mol% to 50 mol% SiO2, 18 mol% to 30 mol% Al2O3, 0 mol% to 22 mol% R2O, 10 mol% to 15 mol% Y2O3, and 4 mol% to 14 mol% TiO2. In some examples, the composition further comprises ZrO2, wherein the R2O comprises Li2O and Na2O. For example, the composition comprises 0 mol% to 4 mol% ZrO2, 0 mol% to 11.5 mol% Li2O, and 0 mol% to 10.5 mol% Na2O.

[0042] Example

[0043] The implementation methods described herein are further illustrated by the following examples.

[0044] Example 1 – Formation of Precursor Glass Composition

[0045] Glasses with the oxide contents listed in Table 1 can be manufactured by conventional methods. In some instances, precursor glasses can be formed by thoroughly mixing the necessary batches (e.g., using a tubular mixer) to ensure a homogeneous melt, and then placing it in a silica and / or platinum crucible. The crucible can be placed in a furnace and the glass batch melted and held at a temperature of 1100°C to 1400°C for about 6 to 24 hours. The melt can then be poured into a steel mold to obtain glass preforms. These preforms can then be immediately transferred to an annealing furnace operating at about 400°C to 700°C, where the glass is held at the temperature for about 0.5 to 3 hours, followed by cooling overnight. In another non-limiting example, precursor glasses are prepared by dry mixing appropriate oxides and mineral sources for a time sufficient to thoroughly mix the components. The glass is melted in a platinum crucible at a temperature of about 1100°C to about 1400°C and held at the temperature for about 6 to 16 hours. The resulting glass melt is then poured onto a steel stage for cooling. The precursor glass is then annealed at an appropriate temperature.

[0046] The glass compositions used in specific embodiments can be ground into fine particles of 1-10 micrometers (μm) by air jet milling, or ground into short fibers. The glass frit can be crushed or ball-milled, with particle sizes varying from 1-100 μm. Furthermore, these glasses can be processed into short fibers, beads, sheets, or three-dimensional supports using various methods. Short fibers are manufactured via melt spinning or electrospinning; beads are produced by flowing glass particles through a vertical furnace or torch; sheets can be manufactured using thin rolling, float glass, or fusion drawing processes; and supports can be produced using rapid prototyping technology, polymer foam replication, and particle sintering.

[0047] Continuous fibers can be easily drawn from the claimed composition using processes known in the art. For example, fibers can be formed using a platinum sleeve with direct heating (through which current passes directly). Crushed glass is loaded into the sleeve and heated until the glass is molten. The temperature is set to achieve the desired glass viscosity (typically <1000 poise), allowing a droplet to form at an orifice in the sleeve (the sleeve size is selected to create limitations affecting the possible range of fiber diameters). The droplet is pulled by hand to begin fiber formation. Once fibers are formed, they are attached to a rotating drawing / collecting cylinder to continue the drawing process at a consistent speed. The fiber diameter can be manipulated using the cylinder speed (or revolutions per minute, RPM) and the glass viscosity—generally, the faster the drawing speed, the smaller the fiber diameter. Glass fibers with diameters in the range of 1–100 μm can be continuously drawn from the glass melt. Fibers can also be produced using an updrawing process. In this process, fibers are drawn from the surface of the glass melt located in a box furnace. By controlling the viscosity of the glass, a quartz rod is used to pull the glass from the surface of the melt to form fibers. The fibers can be continuously pulled upwards to increase their length. The speed at which the rod is pulled and the viscosity of the glass determine the fiber thickness.

[0048] Example 2 – Precursor Glass Composition

[0049] Table 1 lists non-limiting examples of the amount of oxides used to form the precursor glass.

[0050]

[0051] Table 1

[0052]

[0053] Table 1 (continued)

[0054] The ratios of TiO2 to Y2O3, TiO2 to the sum of Y2O3 and Al2O3, and TiO2 to SiO2 represent the ratios of the oxide component (TiO2) allocated to the nucleating crystallites to (A) another oxide (Y2O3) in the Ti-containing phase; (B) two components similarly coordinated in the precursor glass (Y2O3 and Al2O3); and (C) the glass network forming agent (SiO2). These ratios are important because they describe the equilibrium between the nucleating phase and other crystalline phases. It is assumed that all R... + First, balance the charge in Al. 3+ Therefore, the R2O to Al2O3 ratio is important for determining the charge balance of the precursor glass. In other words, the R2O to Al2O3 ratio is important for glass composition design because it represents the charge balance of the composition, which has a significant impact on the composition structure and therefore on the composition properties. The charge balance is also important for determining the ease of glass formation. The Al2O3 to Y2O3 ratio is important for determining the potential components that can be allocated to the yttrium aluminum garnet (YAG) phase, which is a phase that crystallizes.

[0055] The glass compositions disclosed herein can be in any form, such as particles, powders, microspheres, fibers, sheets, beads, scaffolds, or woven fibers.

[0056] Example 3 – Properties of the Precursor Glass Composition

[0057] Young's modulus, shear modulus, and Poisson's ratio were measured simultaneously using resonant ultrasonic spectroscopy, as described in ASTM E1875-00e1. Additionally, the ion-exchange properties of the glass were assessed at 450°C in 100% NaNO3. The ion-exchange process imparts a compressive stress layer to the glass material, increasing its resistance to damage from defects within this layer. These tests and conditions were conducted to demonstrate that these glass materials are ion-exchangeable.

[0058]

[0059] Table 2

[0060] The data in Table 2 illustrate that the precursor glass has an extremely high Young's modulus. In contrast, the Young's modulus of ordinary glass compositions is only about 75 GPa. The low weight change after ion exchange is one indication of successful ion exchange.

[0061] Example 4 – Properties of the Glass-Ceramic Composition

[0062] After the precursor glass as described in Examples 1-3 was formed and tested, the precursor glass was subjected to the following heat treatment (i.e., ceramization): (a) a first heating from room temperature (RT) to the nucleation step temperature at a rate of 5°C / min; (b) a first isothermal hold at the nucleation step temperature for a first predetermined time; (c) a second heating from the nucleation step temperature to the crystallization step temperature at a rate of 5°C / min; (d) a second isothermal hold at the crystallization step temperature for a second predetermined time; and (e) a final cooling from the crystallization step temperature to room temperature in a furnace at an inert cooling rate.

[0063] Table 3-6 shows the properties of the glass-ceramics formed due to the ceramization treatment. The glass-ceramics were characterized as described in Example 3 above—Young's modulus, shear modulus, Poisson's ratio, and ion exchange capacity. Fracture toughness was measured according to ASTM C1421-10 using methods known in the art, such as using V-grooves, short bars, grooved beams, etc. As described in this disclosure, the fracture toughness value (K... 1C The value refers to the value measured using the CNSB (Vickers indenter) method. Vickers hardness is measured using a Vickers indenter and a 200g load.

[0064]

[0065]

[0066] Table 3

[0067]

[0068]

[0069] Table 4

[0070]

[0071]

[0072] Table 5

[0073]

[0074]

[0075] Table 6

[0076] Example 5 – Backscatter Scanning Electron Microscopy

[0077] Figures 1A to 1I Backscattered scanning electron microscopy (SEM) images of Li-containing glass-ceramic microstructures are shown, summarized in Table 7 below.

[0078]

[0079]

[0080] Table 7

[0081] As the amount of nucleating agent (TiO2) in the bulk composition increases, nucleation and the resulting crystallization become more uniform (i.e., the crystallization—and the resulting microstructure—are consistent across the test area of ​​the sample material). For example... Figure 1B Better Figure 1C So uniform. For example, in the case of Figure 1A and Figure 1C When compared (both maintained at a nucleation temperature of 850℃ for 2 hours and a crystallization temperature of 950℃ for 4 hours), even though samples A and D have similar Young's modulus (A: 159.8 GPa; D: 157.3 GPa) and fracture toughness (A: 2.07 MPa*√m; D: 2.03 MPa*√m), their microstructures are unique and different. The large needle-like and spherical structures of sample A may contribute to its extremely high fracture toughness. Sample A contains half the amount of TiO2 nucleating agent as sample D. In other words, sample A ( Figure 1A The structure shown has many random, cross-shaded structures that grow rapidly and, given their random locations within the material, nucleate poorly. In contrast, sample D( Figure 1D The amount of TiO2 nucleating agent in sample A was twice that in sample A. Due to the increased nucleation, it exhibited a finer, more consistent, and uniform structure. In the study of... Figure 1B and Figure 1D Similar trends were observed when comparing the results (both maintained a nucleation temperature of 850°C for 2 hours and a crystallization temperature of 1050°C for 4 hours).

[0082] Figure 2A and 2B Backscattered SEM images of glass-ceramic microstructures containing only Na are shown, and are summarized in Table 8 below.

[0083]

[0084]

[0085] Table 8

[0086] The microstructure of sample E is unique compared to compositions containing only Li (e.g., those in Table 7). For glass-ceramic microstructures containing only Na, the microstructure differs due to the crystallization temperature from... Figure 2AThe structural difference resulting from adding 2B is not as significant as that of the Li-containing glass-ceramic microstructure. For example, the Young's modulus of the ceramization scheme with nucleation at 850°C for 2 hours and crystallization at 950°C for 4 hours is 119 GPa, compared to 134 GPa for ceramization with nucleation at 850°C for 2 hours and crystallization at 1050°C for 4 hours, representing an increase of only about 13%. This is likely due to the less strong two-phase crystallization and the weaker microstructure.

[0087] Figure 3A and 3B Backscattered SEM images of glass-ceramic microstructures containing mixed alkali metals (e.g., containing Li and Na) are shown, as summarized in Table 9 below. Figure 3A microstructure ratio Figure 3B The microstructure size is much smaller.

[0088]

[0089] Table 9

[0090] As expected, the measured strength properties fell between those of the Li-only and Na-only compositions: Young's modulus of sample D (Li-only): 157.3 GPa to 174 GPa; sample E (Na-only): 119 GPa to 134 GPa; and sample I (Li and Na-only): 142 GPa to 148 GPa. However, the microstructure differed significantly from either the Li-only or Na-only compositions.

[0091] Figure 4 Backscattered SEM images of a glass-ceramic microstructure containing high SiO2 (50.0 mol%), low Al2O3 (18.0 mol%), and low ZrO2 (4.0 mol%) are shown. Specifically, Figure 4 Sample J is shown, which underwent ceramization at a nucleation temperature of 850 °C for 2 hours and at a crystallization temperature of 950 °C for 4 hours. The microstructure of sample J is similar to... Figure 1A-3B The microstructure described in it is significantly different because it has a significantly greater number of spherical and needle-like structures.

[0092] Therefore, as described herein, novel glass and glass-ceramic compositions with predictable and superior mechanical properties are disclosed. The mechanical and elastic properties of the glass compositions disclosed herein are superior to many commercially available glass compositions. For example, compositions commonly used in handheld devices, storage disks, and fiber applications have a Young's modulus of about 65 GPa to 75 GPa, while the Young's modulus range of the glass compositions disclosed herein is significantly higher, between 107 GPa and 126 GPa. These values ​​are high enough that the disclosed glass-ceramic precursor glass is competitive with many transparent glass-ceramics, a significant achievement for completely amorphous materials. In addition, the precursor glass compositions of this application can be chemically strengthened (as indicated by preliminary weight gain data) while also exhibiting high fracture toughness and hardness.

[0093] After heat treatment, the glass composition becomes opaque, forming a white glass-ceramic that is mechanically even more advantageous than the precursor glass (i.e., with a higher modulus value). Depending on the composition and ceramization scheme, the Young's modulus values ​​of the glass-ceramic range from 119 GPa to 177 GPa. Fracture toughness is generally proportional to Young's modulus, suggesting that these materials also have high fracture toughness, and therefore, improved strength for a given defect size compared to materials with lower fracture toughness values ​​(e.g., more common glass). Finally, these materials also have high hardness—Vickers hardness ranging from 868 kgf / mm². 2 Up to 1192 kgf / mm 2 In contrast, the Vickers hardness of ordinary glass is 550 kgf / mm². 2 Up to 700 kgf / mm 2 Within the range.

[0094] Furthermore, the glass-ceramics presented in this paper can be chemically strengthened, which increases the depth to which surface defects can penetrate before failure. At 450°C (a low temperature for glass-ceramics), the weight increase is 0.07%–0.29% to 0.09%–0.38% after only 4 and 8 hours. More ion exchange occurs at higher temperatures and longer times, resulting in even higher surface compressive stress and thus greater damage resistance. This damage resistance is crucial for handheld device applications using glass / glass-ceramic protective covers.

[0095] The term “and / or” as used herein, when used to list two or more items, means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B and / or C, then the composition may contain only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B and C.

[0096] The element locations mentioned herein (e.g., "top," "bottom," "above," "below," "first," "second," etc.) are used only to describe the orientation of the various elements in the accompanying drawings. It should be noted that the orientation of the various elements may vary depending on other exemplary embodiments, and such changes are intended to be covered within the scope of this disclosure. Furthermore, these relative terms are used only to distinguish one entity or action from another, and are not required to require or imply any actual such relationship or order between these entities or actions.

[0097] Modifications to this disclosure are possible for those skilled in the art and for those who have made or used this disclosure. Therefore, it should be understood that the embodiments shown in the drawings and described above are for illustrative purposes only and are not intended to limit the scope of this disclosure. As interpreted in accordance with the principles of patent law (including the doctrine of equivalents), the scope of this disclosure is defined by the appended claims.

[0098] Those skilled in the art will understand that the construction of the disclosure and other components is not limited to any particular material. Unless otherwise stated herein, other exemplary embodiments of this disclosure may be formed from a variety of materials.

[0099] As used herein, the terms “about,” “approximately,” “substantially,” and similar terms are intended to have a broad meaning consistent with usage generally acceptable to those skilled in the art to which the subject matter of this disclosure pertains. Those skilled in the art who review this disclosure will understand that these terms are intended to allow for the description of certain described and claimed features rather than limiting the scope of these features to the precise numerical ranges provided. Therefore, these terms should be interpreted as indicating that non-substantial or minor modifications or alterations to the described and claimed subject matter are considered to be within the scope of the invention as set forth in the appended claims. In other words, the terms “about,” “approximately,” etc., mean that quantities, dimensions, formulas, parameters, and other quantities and characteristics are not precise and do not need to be precise, but may be approximate and / or larger or smaller as required, such as reflecting tolerances, conversion factors, rounding, measurement errors, and other factors known to those skilled in the art.

[0100] Therefore, glass that is "free" or "substantially free" of a certain component means glass in which the component is not actively added or incorporated, but which may exist as a contaminant in very small amounts [e.g., 500 parts per million (500 ppm), 400 ppm, 300 ppm, 200 ppm or 100 ppm or less].

[0101] As used herein, terms such as “optional” or “optionally” are intended to indicate that an event or situation subsequently described may or may not occur, and the description includes instances where the event or situation occurs and instances where it does not occur. Unless otherwise stated, the modifiers “an”, “a”, and their corresponding modifiers “the” as used herein mean “at least one” or “one or more”.

[0102] For virtually any plural and / or singular terms used herein, those skilled in the art can appropriately convert them from plural to singular and / or from singular to plural forms, provided that it applies to the context and / or application. For clarity, various singular / plural permutations may be explicitly described herein.

[0103] Unless otherwise stated, all compositions are expressed as mole percentages (mol%) at the time of formulation. Those skilled in the art will understand that various molten components (e.g., silicon, alkali- or alkaline-earth metal-based components, boron, etc.) may be subject to varying degrees of volatilization during component melting (e.g., varying depending on vapor pressure, melting time, and / or melting temperature). Therefore, the mole percentage values ​​at the time of formulation relative to these components are intended to cover values ​​within ±0.5 wt% of these components in the final, melted article. For the above considerations, it is expected that the composition of the final article and the composition at the time of formulation are substantially equivalent. For example, it is expected that the composition of the precursor glass and the glass-ceramic after the heat treatment (ceramization) step are substantially equivalent.

[0104] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of the claimed subject matter. Therefore, the claimed subject matter is not limited to anything other than the appended claims and their equivalents.

Claims

1. A composition, based on an oxide, expressed in molar percentage of a specific component contained herein, said composition comprising: 30 mol% to 60 mol% SiO2; 15 mol% to 35 mol% Al2O3; 5 mol% to 25 mol% Y₂O₃; 0 mol% to 20 mol% TiO2; and 0 mol% to 25 mol% R2O, in, R2O is the sum of Na2O, K2O, Li2O, Rb2O, and Cs2O.

2. The composition of claim 1, wherein, R2O contains 0 mol% to 12.5 mol% Na2O.

3. The composition of claim 1, wherein, R2O contains 0 mol% to 12.5 mol% Li2O.

4. The composition of claim 1, further comprising 0 mol% to 2.5 mol% B2O3.

5. The composition of claim 1, further comprising 0 mol% to 4 mol% ZrO2.

6. The composition according to any one of claims 1-5, comprising: 30 mol% to 40 mol% SiO2; 25 mol% to 35 mol% Al2O3; 8 mol% to 14 mol% Y₂O₃; and 4 mol% to 18 mol% TiO2.

7. The composition of claim 6, comprising: 0 mol% to 12.5 mol% Li₂O; 0 mol% to 10.5 mol% Na₂O; and 0 mol% to 2.5 mol% B2O3.

8. The composition of claim 6, comprising: 8 mol% to 25 mol% Y₂O₃; and 4 mol% to 20 mol% TiO 2。 9. The composition according to any one of claims 1-5, comprising: 30 mol% to 50 mol% SiO2; 18 mol% to 30 mol% Al2O3; 10 mol% to 15 mol% Y₂O₃; and 4 mol% to 18 mol% TiO2.

10. The composition of claim 9, comprising: 0 mol% to 11.5 mol% Li₂O; 0 mol% to 10.5 mol% Na₂O; and 0 mol% to 4 mol% ZrO2.

11. The composition according to any one of claims 1-5, wherein: The molar ratio of R2O to Al2O3 is in the range of 0.1 to 1; or The molar ratio of Al2O3 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 1; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 1.

12. The composition of claim 10, wherein: The molar ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or The molar ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or The molar ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 0.

75.

13. The composition according to any one of claims 1-5, wherein, The composition is a glass composition having a Young's modulus greater than or equal to 107 GPa.

14. The composition according to any one of claims 1-5, wherein, The composition exhibits a fracture toughness ranging from 0.99 MPa*√m to 3.2 MPa*√m.

15. The composition according to any one of claims 1-5, wherein, The composition exhibits 868 kgf / mm². 2 Up to 1192 kgf / mm 2 Vickers hardness.

16. A glass-ceramic article comprising: The crystalline phase includes Y₂Ti₂O₇, Y₂Si₂O₇, or Y₃Al₅O₇. 12 One or more of them, in, The glass-ceramic product has a Young's modulus greater than or equal to 119 GPa.

17. The glass-ceramic article as described in claim 16, wherein, The crystalline phase comprises Y2Ti2O7.

18. The glass-ceramic article as described in claim 16, wherein, The crystalline phases comprise Y2Ti2O7 and LiAlSi2O6.

19. The glass-ceramic article as claimed in claim 16, wherein, The crystalline phases comprise Y2Ti2O7, LiAlSi2O6, Y2Si2O7, and LiAl5O8.

20. The glass-ceramic article as claimed in claim 16, wherein, The glass-ceramic articles exhibit a fracture toughness ranging from 0.99 MPa*√m to 3.2 MPa*√m.

21. The glass-ceramic article as claimed in claim 16, wherein, The glass-ceramic product exhibits 868 kgf / mm². 2 Up to 1192 kgf / mm 2 Vickers hardness.

22. The glass-ceramic article according to any one of claims 16-21, comprising a composition including: 8 mol% to 25 mol% Y₂O₃; and 4 mol% to 20 mol% TiO2.

23. The glass-ceramic article according to any one of claims 16-21, comprising a composition based on oxides, expressed in molar percentages of specific components contained therein, said composition comprising: 30 mol% to 60 mol% SiO2; 15 mol% to 35 mol% Al2O3; 5 mol% to 25 mol% Y₂O₃; and 4 mol% to 20 mol% TiO2; and 0 mol% to 25 mol% R2O, in, R2O is the sum of Na2O, K2O, Li2O, Rb2O, and Cs2O.

24. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 4 mol% to 18 mol% TiO2.

25. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 8 mol% to 18 mol% TiO2.

26. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 13.1 mol% to 18 mol% TiO2.

27. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 7 mol% to 23 mol% Y2O3.

28. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 8 mol% to 14 mol% Y2O3.

29. The glass-ceramic article as described in claim 23, wherein, The composition comprises: 10 mol% to 15 mol% Y2O3.

30. The glass-ceramic article as described in claim 23, wherein, R2O contains 0 mol% to 12.5 mol% Na2O.

31. The glass-ceramic article as described in claim 23, wherein, R2O contains 0 mol% to 12.5 mol% Li2O.

32. The glass-ceramic article as described in claim 23, wherein, The composition also contains 0 mol% to 2.5 mol% B2O3.

33. The glass-ceramic article as described in claim 23, wherein, The composition also contains 0 mol% to 4 mol% ZrO2.

34. The glass-ceramic article as described in claim 23, wherein, The composition comprises: The molar ratio of R2O to Al2O3 is in the range of 0.1 to 1; or The molar ratio of Al2O3 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 1; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 1.

35. The glass-ceramic article as described in claim 23, wherein, The composition comprises: The molar ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or The molar ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or The molar ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 0.

75.

36. A method for manufacturing glass-ceramic articles, the method comprising: Heating a glass article to form a glass-ceramic article, wherein the glass article comprises a composition, based on an oxide, expressed in molar percentages of specific components contained therein, the composition comprising: The molar ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or The molar ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or The molar ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 0.75; The heating includes: The glass article was heated for a first period of 0.3 to 3 hours at a nucleation temperature of 400°C to 850°C; then A second time period of heating at a crystallization temperature of 950℃ to 1400℃ for 4 to 16 hours; and The glass-ceramic product contains a crystalline phase, which includes Y2Ti2O7, Y2Si2O7, or Y3Al5O. 12 One or more of them.

37. The method of claim 36, further comprising chemically strengthening the glass-ceramic article.

38. The method of claim 37, wherein the chemical enhancement occurs after 4 to 8 hours.

39. The method of claim 38, wherein, Chemical fortification resulted in a weight gain of 0.07% to 0.38% by weight.

40. The method of claim 36, wherein, The composition comprises: 30 mol% to 60 mol% SiO2; 15 mol% to 35 mol% Al2O3; 5 mol% to 25 mol% Y₂O₃; 0 mol% to 20 mol% TiO2; and 0 mol% to 25 mol% R2O, R2O is the sum of Na2O, K2O, Li2O, Rb2O and Cs2O.

41. The method of claim 40, wherein, The composition comprises: 8 mol% to 25 mol% Y₂O₃; and 4 mol% to 20 mol% TiO2.

42. The method of claim 40, wherein, The composition comprises: 4 mol% to 18 mol% TiO2.

43. The method of claim 40, wherein, The composition comprises: 13.1 mol% to 18 mol% TiO2.

44. The method of claim 40, wherein, The composition comprises: 7 mol% to 23 mol% Y2O3.

45. The method of claim 40, wherein, The composition comprises: 10 mol% to 15 mol% Y2O3.

46. ​​The method according to any one of claims 36-45, wherein, The glass-ceramic articles exhibit a fracture toughness ranging from 0.99 MPa*√m to 3.2 MPa*√m.

47. The method according to any one of claims 36-45, wherein, The glass-ceramic product exhibits 868 kgf / mm². 2 Up to 1192 kgf / mm 2 Vickers hardness.

48. A glass-ceramic article comprising: The crystalline phases include Y₂Ti₂O₇, LiAlSi₂O₆, Y₂Si₂O₇, and LiAl₅O₈; and A composition, based on an oxide, expressed in molar percentages of a specific component contained herein, the composition comprising: 30 mol% to 40 mol% SiO2; 25 mol% to 35 mol% Al2O3; 8 mol% to 14 mol% Y₂O₃; 4 mol% to 18 mol% TiO2; 0 mol% to 2.5 mol% B2O3; 0 mol% to 4 mol% ZrO2; and 0 mol% to 25 mol% R2O, in, R2O is the sum of Na2O, K2O, Li2O, Rb2O, and Cs2O. The composition comprises: The molar ratio of R2O to Al2O3 is in the range of 0.1 to 1; The molar ratio of Al2O3 to Y2O3 is in the range of 0.1 to 5; The molar ratio of TiO2 to Y2O3 is in the range of 0.1 to 5; The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 1; and The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 1; and The glass-ceramic product contains a Young's modulus greater than or equal to 119 GPa.

49. The glass-ceramic article as described in claim 48, wherein, The composition comprises: 33.6 mol% to 36 mol% SiO2; 26.2 mol% to 31 mol% Al2O3; 8.7 mol% to 12.9 mol% Y₂O₃; 13.1 mol% to 18 mol% TiO2; and 9.8 mol% to 12.9 mol% R2O.

50. The glass-ceramic article as described in claim 48, wherein: The molar ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or The molar ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or The molar ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 0.

75.

51. The glass-ceramic article as described in claim 48, wherein, The glass-ceramic articles exhibit a fracture toughness ranging from 0.99 MPa*√m to 3.2 MPa*√m.

52. The glass-ceramic article as described in claim 48, wherein, The glass-ceramic product exhibits 868 kgf / mm². 2 Up to 1192 kgf / mm 2 Vickers hardness.

53. The glass-ceramic article as described in any one of claims 48-52, wherein, The glass-ceramic product is chemically strengthened.

54. A handheld device comprising a protective cover, the protective cover comprising: A material having a composition, based on an oxide, expressed in molar percentages of a specific component contained therein, the composition comprising: 30 mol% to 60 mol% SiO2; 15 mol% to 35 mol% Al2O3; 5 mol% to 25 mol% Y₂O₃; 0 mol% to 20 mol% TiO2; and 0 mol% to 25 mol% R2O, Among them, R2O is the sum of Na2O, K2O, Li2O, Rb2O and Cs2O; The material is a glass-ceramic, which contains at least a Y₂Ti₂O₇ crystalline phase. The protective cover plate includes a compressive stress layer.

55. The handheld device as claimed in claim 54, wherein, The crystalline phases comprise Y2Ti2O7, LiAlSi2O6, Y2Si2O7, and LiAl5O8.

56. The handheld device as claimed in claim 54, wherein, The composition comprises: 8 mol% to 25 mol% Y₂O₃; and 4 mol% to 20 mol% TiO2.

57. The handheld device as claimed in claim 54, wherein, The composition further comprises: 0 mol% to 2.5 mol% B₂O₃; and 0 mol% to 4 mol% ZrO2.

58. The handheld device as claimed in claim 54, wherein, The composition comprises: 30 mol% to 40 mol% SiO2; 25 mol% to 35 mol% Al2O3; 8 mol% to 14 mol% Y₂O₃; 4 mol% to 18 mol% TiO2; 0 mol% to 2.5 mol% B2O3; 0 mol% to 4 mol% ZrO2; and 0 mol% to 25 mol% R2O.

59. The handheld device as claimed in any one of claims 54-58, wherein: The molar ratio of R2O to Al2O3 is in the range of 0.1 to 1; or The molar ratio of Al2O3 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to Y2O3 is in the range of 0.1 to 5; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 1; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 1.

60. The handheld device as claimed in any one of claims 54-58, wherein: The molar ratio of R2O to Al2O3 is in the range of 0.3 to 0.7; or The molar ratio of Al2O3 to Y2O3 is in the range of 1 to 4; or The molar ratio of TiO2 to Y2O3 is in the range of 0.25 to 1.75; or The molar ratio of TiO2 to the sum of Y2O3 and Al2O3 is in the range of 0.1 to 0.5; or The molar ratio of TiO2 to SiO2 is in the range of 0.05 to 0.

75.

61. The handheld device as claimed in any one of claims 54-58, wherein, The protective cover plate exhibits a fracture toughness ranging from 0.99 MPa*√m to 3.2 MPa*√m.

62. The handheld device as claimed in any one of claims 54-58, wherein, The protective cover plate exhibits a strength of 868 kgf / mm². 2 Up to 1192 kgf / mm 2 Vickers hardness.

63. The handheld device as claimed in any one of claims 54-58, wherein, The protective cover plate exhibits a Young's modulus ranging from 119 GPa to 177 GPa.

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