Yttrium-scandium oxide transparent ceramic nano-powder, transparent ceramic and preparation method of yttrium-scandium oxide transparent ceramic nano-powder

Abstract

The invention relates to yttrium-scandium oxide transparent ceramic nano-powder, transparent ceramic and a preparation method thereof, and the preparation method of the yttrium-scandium oxide transparent ceramic nano-powder comprises the following steps: synthesizing a yttrium-scandium composite precursor through a wet chemical coprecipitation method, and calcining to obtain high-activity nano-powder; carrying out ball milling on the nano powder and a dispersion medium to prepare slurry, and forming a uniform green body through a pressure-assisted slip casting technology; and carrying out vacuum sintering on the green body after glue discharging treatment, and finally annealing in an oxygen atmosphere to obtain the transparent ceramic. Compared with the prior art, a wet chemical process chain cooperation strategy without a sintering aid is adopted, a co-precipitation method is combined with pressure-assisted slip casting, the agglomeration defect and the dry pressing forming stress problem of traditional mechanical powder preparation are broken through, and intrinsic regulation and control of yttrium scandium oxide solid solution crystal lattices are achieved; the obtained transparent ceramic crystal boundary is clean and free of a second phase, the oxygen vacancy concentration is obviously reduced, and the transparent ceramic has high transmittance in a wide spectrum range.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic powder preparation and molding, and in particular to yttrium-scandium oxide transparent ceramic nanopowder, transparent ceramic and a preparation method thereof. Background Art

[0002] As solid-state laser technology continues to advance toward shorter pulses and higher energies, solid-state laser gain media are increasingly demanding higher thermal conductivity, lower phonon energy, and wider emission bandwidth. While traditional solid-state laser gain media, such as YAG, have been widely used in military, medical, and industrial fields, their inherent performance limitations make them incapable of fully meeting the demands of today's rapidly evolving laser technology. There is an urgent need to identify and develop gain medium materials with even higher performance.

[0003] Recent studies have shown that sesquioxides (Y2O3, Sc2O3, Lu2O3) are very suitable as host materials for ultrafast laser gain media due to their excellent physical and chemical properties, high thermal conductivity, low phonon energy and other intrinsic advantages. The presence of two different types of cation occupancy in sesquioxides (8 cations occupying the C2 site and 24 cations occupying the S6 site) results in the doped active ions being in different lattice environments, broadening the emission bandwidth. Figure 1 The crystal structure of Y2O3 shows that the cations occupy two different sites (C2 and S6).

[0004] The sintering aid dependence and molding process defects that are prevalent in the prior art have seriously restricted the further improvement of material properties. Document 1 (CN111087235A) discloses the preparation of YAG transparent ceramics by co-precipitation method, and reduces the sintering temperature by designing the yttrium / aid / aluminum triple core-shell structure. However, this method requires the introduction of sintering aids such as MgO and CaF2. Although it can promote densification, the incorporation of heterovalent ions leads to the formation of amorphous phases at the grain boundaries, triggering light scattering centers and limiting the improvement of optical transmittance. Document 2 (CN104557041A) uses Al2O3 as a sintering aid to prepare yttrium oxide transparent ceramics, but Al 3+ Doping can disrupt the integrity of the Y2O3 lattice, reduce the material's thermal conductivity, and increase the oxygen vacancy concentration, affecting the stability of laser performance. Furthermore, Reference 3 (CN112110485A) prepares yttrium-stabilized zirconia ceramics through coprecipitation combined with hot isostatic pressing. While achieving high densification, the introduction of ZrO2 results in a lattice distortion of 1.83%. Furthermore, the high cost of hot isostatic pressing equipment makes large-scale application difficult.

[0005] Another bottleneck in traditional preparation processes lies in the molding technology. Dry pressing is prone to causing internal stress gradients in the green body due to powder agglomeration, which can produce microcracks after sintering. Mechanical ball milling, on the other hand, produces coarse powder particles (>500nm) and insufficient activity, requiring high-temperature (>1800°C) or high-pressure sintering, which is energy-intensive and prone to introducing impurities. For example, comparative experiments have shown that when dry pressing is used for the same nanopowder, the green body density is only 45% of the theoretical density, and the transmittance of the final ceramic at 1100nm is 9.4% lower than that of wet pressing.

[0006] Based on this, there is an urgent need to develop a method for preparing yttrium-scandium oxide transparent ceramics that does not require sintering aids and has a simplified process to achieve a comprehensive improvement in the intrinsic performance of the material. Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a yttrium-scandium oxide transparent ceramic nanopowder, transparent ceramic and a preparation method thereof through the coordinated optimization of wet chemical powder synthesis and molding process.

[0008] In the process of conception, the present invention believes that the sesquioxide Y2O3 and Sc2O3 form (Y 1-x Sc x )2O3 solid solution will lead to structural disorder, further broaden the emission bandwidth, and by adjusting the Y / Sc ratio, the material properties can be adjusted to achieve tailoring of optical properties. 1-x Sc x )2O3 transparent ceramics have become a core challenge in the development of high-performance short-pulse lasers. ZrO2 as a sintering aid is used to prepare sesquioxide transparent ceramics, which have achieved extremely high optical transmittance. However, Zr 4+ As an alivalent element, it will cause lattice distortion and generate vacancies, resulting in a decrease in the thermal conductivity of the material, affecting the upconversion of activated ions, and ultimately deteriorating the laser performance of the ceramic.

[0009] During the conception process of this application, it was also believed that molding, as an intermediate step connecting powder preparation and sintering, plays a decisive role in the performance of the final sample. Traditional dry pressing is prone to agglomeration during the molding process, resulting in uneven distribution of powders, while wet molding particles can slide and rearrange with each other under liquid conditions, thereby improving the uniformity of the green body. Commonly used wet molding methods include slip casting, gelcasting, and tape casting. Among them, tape casting is usually used to prepare thin-layer ceramics or composite ceramics; gelcasting has advantages in near-net molding with high uniform green bodies with high density; pressure-assisted slip casting is used in this application, which can not only shorten the molding time but also improve the strength of the green body and eliminate gradient molding in the green body.

[0010] During the conception process of this application, it was also believed that: ceramic powder is the basis for obtaining high-quality transparent ceramics, and ideal ceramic powder has the characteristics of high purity, small particle size, good uniformity, and high sintering activity. The traditional mechanical ball milling method is not only easy to introduce impurities, but also the powder particle size is large and the sintering activity is poor. Wet chemical methods can overcome the inherent defects of mechanical methods. Wet chemical methods include co-precipitation method, sol-gel method, hydrothermal reaction method, combustion method, etc. Among these methods, the co-precipitation method has a simple process, low cost, and good uniformity of nanopowders. It is one of the preferred preparation methods for scientific researchers to prepare high-activity nanopowders.

[0011] The purpose of the present invention can be achieved by the following technical solutions:

[0012] A first aspect of the present invention provides a method for preparing a yttrium-scandium oxide transparent ceramic, comprising the following steps:

[0013] (1) Dissolve Y2O3 and Sc2O3 in nitric acid solution respectively to prepare Y(NO3)3 and Sc(NO3)3 solutions with the same concentration. 1-x Sc x )2O3 stoichiometric ratio to obtain a mother liquor;

[0014] (2) reacting the mother liquor obtained in step (1) with a precipitant solution containing a dispersant by titration, and aging, washing, and drying the reaction solution to obtain a precursor;

[0015] (3) calcining the precursor to obtain (Y 1-x Sc x )2O3 nanopowder;

[0016] (4) ball-milling the nanopowder and ethanol to prepare a slurry;

[0017] (5) vacuum degassing the obtained slurry and injecting it into a mold, maintaining the pressure at 0.5-1 MPa for 0.1-1 h to form the mold;

[0018] (6) After the formed green body is dried and debinded, it is pressurelessly sintered under vacuum conditions and finally annealed in an oxygen atmosphere to obtain a finished yttrium-scandium oxide transparent ceramic product.

[0019] Steps (1) to (3) are performed by dissolving Y2O3 and Sc2O3 into a nitrate solution, using a precipitant such as ammonium bicarbonate to perform a co-precipitation reaction, generating a precursor, and then calcining to obtain a nanopowder. Typical wet chemical methods are used.

[0020] Steps (4) and (5) are to mix the nanopowder with ethanol and ball mill to prepare a slurry, which is then vacuum degassing and pressure casting (maintaining pressure of 0.5-1 MPa). The liquid slurry allows the particles to slide and rearrange, eliminating the agglomeration problem of dry pressing.

[0021] Furthermore, the precipitant in step (2) is one or more of ammonium bicarbonate, ammonia water, and urea, preferably ammonium bicarbonate, and the molar ratio of the precipitant to the rare earth element (Re=Y / Sc) is 2 to 5, preferably 3.

[0022] Furthermore, in step (2), the dispersant is ammonium sulfate or anhydrous ethanol.

[0023] Furthermore, in step (3), the calcination temperature is 1000-1200°C, preferably 1100°C.

[0024] Furthermore, in step (4), the mass ratio of the ball-milled powder, grinding balls, and ethanol is 1:(1-5):(0.2-1.5), preferably 1:(2-5):(0.8-1.5).

[0025] Furthermore, in step (6), the debinding is carried out in an oxygen atmosphere, the debinding temperature is 700-800° C., the heating rate is 1-2° C. / min, and the holding time is 2-4 h.

[0026] Furthermore, in step (6), the vacuum sintering adopts a gradient temperature rising process: heating to 1000°C at 10°C / min, then heating to 1400°C at 5°C / min, and finally heating to 1850°C at 2°C / min.

[0027] In existing technologies, sintering aids such as ZrO2 can introduce lattice distortion, affecting thermal conductivity and laser performance. The present preparation method uses no sintering aids throughout the entire process, relying on the high sintering activity of nanopowders (calcination temperature 1000-1200°C) and the uniformity of wet molding to achieve pressureless sintering (vacuum sintering to 1850°C).

[0028] Furthermore, in step (6), the annealing process includes: performing annealing in an oxygen atmosphere at 1200-1300° C. for 5-8 hours, and thinning and polishing the ceramic after annealing.

[0029] The second aspect of the present invention provides a yttrium-scandium oxide transparent ceramic nanopowder, the chemical formula of the yttrium-scandium oxide transparent ceramic nanopowder is (Y 1-x Sc x )2O3, where 0≤x≤1;

[0030] The yttrium-scandium oxide transparent ceramic nanopowder is prepared by adopting steps (1) to (3) in the above-mentioned preparation method.

[0031] More preferably, 0.2≤x≤0.3.

[0032] Most preferably, x=0.25.

[0033] A third aspect of the present invention provides a yttrium-scandium oxide transparent ceramic obtained by the preparation method described above.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1) In the invention, a wet chemical precipitation method is used to prepare a high sintering activity (Y 1-x Sc x )2O3 nanopowder, and innovatively combined with wet chemical molding method to prepare highly uniform ceramic green body, in the entire ceramic preparation stage to play the advantages of wet chemistry, without the use of sintering aids under the condition of pressureless sintering preparation (Y 1-x Sc x )2O3 transparent ceramics.

[0036] 2) The present invention uses a wet chemical co-precipitation method to prepare highly active nanopowders in coordination with pressure-assisted grouting molding, thus breaking through the dual bottlenecks of insufficient powder activity and poor molding uniformity in the preparation of traditional transparent ceramics. Nanopowders synthesized by wet chemical methods have excellent chemical uniformity and dispersibility, while the wet molding process promotes the full rearrangement of particles in the liquid medium, significantly improving the densification of the green body, thereby achieving high-density sintering without sintering aids. The combination of the two not only avoids the introduction of impurities in mechanical powder preparation and stress defects in dry pressing, but also ensures the high integrity of the intrinsic structure of the material through the full wet coordination of the process chain, ultimately obtaining transparent ceramics with high optical transmittance.

[0037] 3) The present invention's sintering aid-free strategy effectively preserves the intrinsic lattice properties of the yttrium-scandium oxide solid solution. By controlling the composition, it achieves controllable lattice distortion, significantly suppressing light scattering and optimizing phonon transmission pathways. Compared to conventional systems with sintering aids, the material's internal grain boundaries are clean and free of secondary phases, and the oxygen vacancy concentration is significantly reduced, resulting in a ceramic with uniformly high transmittance across a wide spectral range. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The crystal structure of Y2O3, the cation has two different occupancy sites (C2 and S6 sites)

[0039] Figure 2 The present invention is co-precipitated to prepare (Y 1-x Sc x )2O3 nanopowder process;

[0040] Figure 3 TEM characterization of nanopowders, (a) precursor; (b) nanoparticles after calcination;

[0041] Figure 4 is the DTA-TG curve of the precursor in the present invention;

[0042] Figure 5 This is a schematic diagram of the principle of pressure grouting molding of a ceramic body in the present invention;

[0043] Figure 6 The XRD spectra corresponding to the materials involved in the present invention are (a) precursor, nanopowder, and ceramic, and (b) precursor calcined at different temperatures;

[0044] Figure 7 The figure shows the actual image and transmittance results of the transparent ceramic sample in the present invention. DETAILED DESCRIPTION

[0045] In general, the purpose of the present invention is to prepare high-quality (Y 1-x Sc x )2O3 transparent ceramics with high sintering activity, low agglomeration and good uniformity are prepared by co-precipitation method 1-x Sc x To overcome the internal agglomeration problem caused by powder compaction, pressure-assisted slip casting was used to ensure that the powder particles could slide and rearrange during the molding process. By optimizing both the powder preparation and the green body molding process, the ceramic was sintered under vacuum and pressureless conditions to produce a transparent ceramic. Commercially available oxide powders were used to prepare a nitrate mother liquor, ammonium bicarbonate as a precipitant, and anhydrous ethanol as a dispersant. The nanoprecursor was prepared by forward titration.

[0046] The nanopowder obtained by calcination is refined by ball milling and then the slurry is pressure cast to prepare a green body. The process flow of the present invention is as follows: preparation of nitrate mother liquor, preparation of precursor by coprecipitation, calcination of precursor, slurry ball milling, pressure cast molding, binder removal, vacuum sintering, annealing, and post-processing.

[0047] When specifically implemented, in the present invention (Y 1-x Sc x ) A method for preparing 2O3 transparent ceramics, comprising:

[0048] Dissolve high-purity Y2O3 and Sc2O3 in high-temperature nitric acid solution to prepare (Y 1-x Sc x )2O3 mother liquor, a precursor is prepared by coprecipitation method, the obtained precursor is filtered and then dried, and calcined to obtain nano powder. The preparation process is shown in Figure 2 ;

[0049] The nanopowder is mixed with ethanol, and grinding balls are added thereto, and the mixture is ball-milled to obtain a ceramic slurry;

[0050] The ceramic slurry after degassing is used to prepare a ceramic green body through pressure injection molding, and the green body is prepared through debinding, vacuum sintering, annealing and post-processing (Y 1-x Sc x )2O3 transparent ceramics;

[0051] Among them, 0≤x≤1; the purity of high-purity Y2O3 and Sc2O3 is as high as 99.99%.

[0052] In specific implementation, the precipitant can be one or more of ammonium bicarbonate, ammonia water, urea, etc., preferably ammonium bicarbonate (NH4HCO3) is used as the precipitant, where n[NH4HCO3]:n[Re (Re=Y / Sc)]=R, R takes a value of (2~5), preferably R=3.

[0053] In specific implementation, the titration and sedimentation device is a 5L glass tank with built-in stirring.

[0054] The peristaltic pump regulates the titration rate to be controlled at 1-5 ml / min, preferably 2-3 ml / min, the stirring rate is controlled at 100-200 r / min, preferably 150 r / min, and the dispersant is selected from one or more of (NH4)2SO4 and anhydrous ethanol, preferably anhydrous ethanol, wherein the ratio of anhydrous ethanol to deionized water is (0:5; 1:4; 2:3; 1:1; 3:2; 4:1), preferably 2:3; 1:1; 3:2.

[0055] After the titration precipitation is completed, the stirring time is 12 to 24 hours, preferably 12 hours, and the sedimentation time is 12 to 24 hours, preferably 12 hours.

[0056] The precipitate is repeatedly washed with deionized water and anhydrous ethanol until the conductivity of the solution is lower than 1-3 ms / cm, preferably 1 ms / cm.

[0057] The precursor can be dried by blower oven drying and freeze drying, preferably freeze drying, with the drying condition being -51°C.

[0058] According to an embodiment of the present invention, the grinding balls are, for example, zirconia balls.

[0059] According to an embodiment of the present invention, in step (1), the mass ratio of the total amount of each reaction raw material: grinding balls: ethanol is 1: (1-5): (0.2-1.5).

[0060] According to step (4) of claim 1, the holding pressure is 0.5-1 MPa, preferably 0.5 MPa; the holding time is 0.1-1 h, preferably 0.5 h; the pressure can be provided by a rare gas cylinder or an air compressor.

[0061] According to an embodiment of the present invention, in step (5), the binder removal atmosphere is an oxygen atmosphere; the binder removal temperature is 600-900°C, preferably 700-800°C; the binder removal time is 1-5 hours, preferably 2-4 hours; and the heating rate during binder removal is 0.5-3°C / min, preferably 1-2°C / min.

[0062] According to an embodiment of the present invention, in step (5), the vacuum sintering temperature is 1700-1850°C, preferably 1800-1850°C. For example, the vacuum sintering is carried out at a temperature gradient, wherein the temperature gradient is 1000-1200°C, 1200-1400°C, and 1400-1850°C, for example, the temperature is increased to 1000°C at 10°C / min, then increased to 1400°C at 5°C / min, and then increased to 1850°C at 2°C / min.

[0063] In specific implementation, in step (5), the vacuum sintering time is 5-24 hours, preferably 8-15 hours.

[0064] In the specific implementation, in step (5), the vacuum degree of vacuum sintering is <1×10 -3 Pa.

[0065] In a specific implementation, in step (5), after sintering is completed, a cooling treatment is performed, for example, cooling to 800° C. at a rate of 5° C. / min, and then naturally cooling to room temperature.

[0066] In a specific implementation, in step (5), the annealing temperature is 1000-1400° C., preferably 1200-1300° C. The annealing time is 2-12 hours, preferably 5-8 hours. The annealing is performed in an oxygen atmosphere.

[0067] In specific implementation, in step (5), after annealing is completed, the product is subjected to thinning, polishing, and other treatments.

[0068] When specifically implemented, the preparation (Y 1-x Sc x )2O3 transparent ceramics method specifically includes:

[0069] (1) Dissolve high-purity Y2O3 and Sc2O3 in high-temperature nitric acid solution, prepare Y(NO)3 and Sc(NO)3 solutions of the same concentration, and prepare (Y2O3) according to the stoichiometric ratio. 1-x Sc x)2O3 mother liquor, ammonium bicarbonate (NH4HCO3) is selected as the precipitant, R=3, the titration rate is controlled at 3ml / min, the stirring rate is controlled at 150r / min, anhydrous ethanol is selected as the dispersant, and the ratio of anhydrous ethanol to deionized water is 1:1. After the titration precipitation is completed, stir for 12h, settle for 12h, and repeatedly wash the precipitate with deionized water and anhydrous ethanol until the solution conductivity is lower than 1ms / cm.

[0070] (2) The calcined nanopowder is used as a raw material, and the mass ratio of the total mass of the nanopowder: grinding balls: ethanol is 1: (2-5): (0.8-1.5).

[0071] (3) The defoamed ceramic slurry is used to prepare a high-density and high-uniform ceramic body through a pressure injection molding process.

[0072] (4) The green blank in step (3) was debinded in an oxygen atmosphere, and the debinded sample was placed in a vacuum furnace for sintering at a sintering temperature of 1700-1850°C and a vacuum degree of <1×10 -3 Pa, the sintered sample is annealed in an oxygen atmosphere at 1000-1400° C. to obtain the transparent porcelain.

[0073] The present invention is described in detail below with reference to the accompanying drawings and specific examples. Any features, such as preparation methods, materials, structures, or composition ratios, not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art. Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0074] Example 1

[0075] (1) Dissolve high-purity Y2O3 and Sc2O3 in high-temperature nitric acid solution, prepare Y(NO)3 and Sc(NO)3 solutions of the same concentration, and prepare (Y2O3) according to the stoichiometric ratio. 0.75 Sc 0.25 )2O3 mother liquor, ammonium bicarbonate (NH4HCO3) was selected as the precipitant, R = 3, the titration rate was controlled at 3ml / min, the stirring rate was controlled at 150r / min, and anhydrous ethanol was selected as the dispersant, with a ratio of anhydrous ethanol to deionized water of 1:1. After the titration precipitation is completed, the mixture is stirred for 12 hours and allowed to settle for 12 hours. The precipitate was repeatedly washed with deionized water and anhydrous ethanol until the solution conductivity was less than 1ms / cm. The precipitate was filtered and then freeze-dried (freeze-drying temperature was -51°C) to obtain the precursor.

[0076] (2) The precursor obtained in (1) was calcined at 1100°C. The TEM characterization of the precursor and nanopowder before and after calcination was as follows: Figure 3 shown. Figure 4It is the DTA-TG curve of powder calcination. Figure 6 These are the XRD patterns of precursor, nanopowder and ceramic, as well as nanopowder at different calcination temperatures.

[0077] (3) The nanopowder obtained in (2) was ball-milled for 24 hours and then pressure-casted at a holding pressure of 0.5 MPa for 0.5 hours. The green body had a certain strength and did not crack when demolded. The green body after demolding was dried in a forced air oven at 80°C until the quality did not change.

[0078] (4) The ceramic blank obtained in (3) is subjected to debinding, cold isostatic pressing, sintering, and annealing to obtain (Y 0.75 Sc 0.25 )2O3 transparent ceramics, sample pictures and transmittance as shown Figure 7 As shown. Figure 7 The ceramic sample obtained by medium pressure grouting has a thickness of 3 mm and the transmittance at 600 nm and 1100 nm is 77.8@600 nm and 80.6@1100 nm, respectively.

[0079] Comparative Example 1

[0080] (1) Dissolve high-purity Y2O3 and Sc2O3 in high-temperature nitric acid solution, prepare Y(NO)3 and Sc(NO)3 solutions of the same concentration, and prepare (Y2O3) according to the stoichiometric ratio. 0.75 Sc 0.25 )2O3 mother liquor, ammonium bicarbonate (NH4HCO3) was selected as the precipitant, R = 3, the titration rate was controlled at 3ml / min, the stirring rate was controlled at 150r / min, and anhydrous ethanol was selected as the dispersant, with a ratio of anhydrous ethanol to deionized water of 1:1. After the titration precipitation is completed, the mixture is stirred for 12 hours and allowed to settle for 12 hours. The precipitate was repeatedly washed with deionized water and anhydrous ethanol until the solution conductivity was less than 1ms / cm. The precipitate was filtered and then freeze-dried (freeze-drying temperature was -51°C) to obtain the precursor.

[0081] (2) The precursor obtained in (1) was calcined at 1100°C.

[0082] (3) The nanopowder obtained in (2) was ball-milled for 24 h and then dry-pressed with a pre-pressing pressure of 5 MPa and a holding time of 1 min.

[0083] (4) The ceramic blank obtained in (3) is subjected to debinding, cold isostatic pressing, sintering, and annealing to obtain (Y 0.75 Sc 0.25 )2O3 transparent ceramics, sample pictures and transmittance as shown Figure 7 As shown. Figure 7 Ceramics produced by dry pressing are opaque in the visible light range. Although the nanopowders prepared by coprecipitation have excellent sintering activity, electrostatic and van der Waals forces between the powders cause powder agglomeration during the molding process, generating a pressure gradient within the ceramic body. This ultimately leads to agglomeration within the sintered ceramic sample, affecting the sample's optical properties. This also indirectly demonstrates the advantages of pressure slip casting.

[0084] Example 2

[0085] (1) Dissolve high-purity Y2O3 and Sc2O3 in nitric acid solution respectively to prepare (Y 0.8 Sc 0.2 )2O3 mother liquor. Use ammonium bicarbonate (R = 2, n[NH4HCO3]:n[Re] = 2) at a titration rate of 1 ml / min, ammonium sulfate as the dispersant, and a 0:5 ratio of ethanol to deionized water. After precipitation, stir for 24 hours, let settle for 24 hours, and then rinse until the conductivity reaches 3 ms / cm.

[0086] (2) The precursor was calcined at 1000°C to obtain nanopowder (XRD confirmed phase purity, TEM showed particle size ~50 nm).

[0087] (3) Ball milling ratio 1:1:0.2 (powder: grinding ball: ethanol), pressure maintenance 0.5 MPa / 0.1h.

[0088] (4) Debinding parameters: 700℃ / 1℃ / min / 2h (oxygen atmosphere).

[0089] (5) Vacuum sintering gradient: 10°C / min→1000°C→5°C / min→1400°C→2°C / min→1850°C (total sintering time: 18 h).

[0090] (6) Annealing: 1200℃ oxygen / 5h. The final sample transmittance is 75% @ 600nm and 78% @ 1100nm.

[0091] Example 3

[0092] (1) Preparation (Y 0.7 Sc 0.3 )2O3 mother liquor, precipitant R=5, urea + ammonia water mixture, titration rate 5ml / min, dispersant is anhydrous ethanol (ethanol: water=4:1).

[0093] (2) Calcination at 1200℃, the powder particle size is ~80nm but the sintering activity is high.

[0094] (3) Ball milling ratio is 1:5:1.5, and the pressure is maintained at 1 MPa / 1h for molding.

[0095] (4) Debinding: 800℃ / 2℃ / min / 4h.

[0096] (5) Sintered with the same gradient and annealed at 1300℃ for 8h. The transmittance of the sample is 76% at 600nm and 79.5% at 1100nm.

[0097] Comparative Example 2

[0098] Mechanical powder making comparison, different from Example 1:

[0099] (1) Using solid phase mechanical mixing method: Y2O3 and Sc2O3 powders are mixed according to (Y 0.75 Sc 0.25 )2O3 were mixed in a certain ratio and ball milled for 48h (ethanol medium, powder: ball = 1:5).

[0100] (2) Direct dry pressing (5 MPa pressure maintenance for 1 min).

[0101] (3) Add 1wt% ZrO2 sintering aid and sinter at 1850℃ in vacuum.

[0102] Results: The ceramics were opaque (transmittance <50%@600nm), and SEM showed the presence of Zr aggregates at the grain boundaries.

[0103] In this comparative example, the powder was prepared by mechanical mixing and ZrO2 sintering aid was added. Although partial densification was achieved, the powder obtained by the mechanical method had a coarse particle size (SEM showed >500nm) and an uneven Y / Sc distribution (confirmed by EDS surface scanning), resulting in insufficient sintering driving force. 4 + Due to ionic radius and The difference is significant, with amorphous phases forming at the grain boundaries, creating light scattering centers. The final ceramic has a transmittance of only 46.2% at 600nm.

[0104] Comparative Example 3

[0105] Comparison of dry pressing molding, different from Example 1:

[0106] (1) Wet chemical preparation (Y) 0.75 Sc 0.25 )2O3 nanopowder.

[0107] (2) Dry pressing (5MPa pre-pressing + 200MPa cold isostatic pressing) is used.

[0108] (3) Vacuum sintering at 1850℃.

[0109] Results: The green body density was only 45% of the theoretical density, micro cracks existed after sintering, and the transmittance at 1200nm was 71.2%.

[0110] Despite the use of a wet chemical method to prepare highly active nanopowders, van der Waals forces between the powders during dry pressing resulted in hard agglomeration (the compact density was only 45% TD). Although cold isostatic pressing was increased to 55% TD, insufficient particle rearrangement generated a stress gradient (residual stress > 200 MPa, as analyzed by XRD half-width analysis). This stress release during sintering formed a microcrack network. The final ceramic's transmittance in the near-infrared band (1100 nm) plummeted to 71.2%, a 9.4 percentage point decrease compared to Example 1, demonstrating the critical role of wet pressure slip casting in eliminating molding defects.

[0111] Comparative Example 4

[0112] Comparison with adding sintering aid, different from Example 1:

[0113] (1) Add 0.5 mol% ZrO2 during wet chemical preparation of powder.

[0114] (2) Wet pressure grouting molding as in Example 1.

[0115] (3) Vacuum sintering at 1850℃.

[0116] Results: The haze of the ceramic at 600nm was 15%.

[0117] After the introduction of 0.5 mol% ZrO2 into the wet chemical powder, although the sintering temperature was reduced by 50 °C (the Dilatometer curve showed densification at 1650 °C), the Zr4+ doping caused the lattice distortion to reach 1.83% (XRD calculation), and induced the oxygen vacancy concentration to rise to 10 18 cm -3 (The 450nm blue light emission peak in the PL spectrum is enhanced.) After annealing, a Zr segregation zone with a scale of 0.2-0.5μm still exists.

[0118] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing yttrium-scandium oxide transparent ceramics, characterized in that: The following steps are involved: (1) Dissolve Y2O3 and Sc2O3 in nitric acid solution respectively to prepare Y(NO3)3 and Sc(NO3)3 solutions with the same concentration. 1-x Sc x )2O3 stoichiometric ratio to obtain a mother liquor; (2) reacting the mother liquor obtained in step (1) with a precipitant solution containing a dispersant by titration, and aging, washing, and drying the reaction solution to obtain a precursor; (3) calcining the precursor to obtain (Y 1-x Sc x )2O3 nanopowder; (4) ball-milling the nanopowder and ethanol to prepare a slurry; (5) vacuum degassing the obtained slurry and injecting it into the mold, maintaining the pressure at 0.5-1 MPa for 0.1-1 h to form the mold; (6) After drying and debinding, the formed green body is pressurelessly sintered under vacuum conditions, and finally annealed in an oxygen atmosphere to obtain a finished yttrium-scandium oxide transparent ceramic product.

2. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: The precipitant in step (2) is one or more of ammonium bicarbonate, ammonia water, and urea, and the molar ratio of the precipitant to the rare earth element is 2 to 5.

3. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: In step (2), the dispersant is ammonium sulfate or anhydrous ethanol.

4. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: In step (3), the calcination temperature is 1000-1200°C.

5. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: In step (4), the mass ratio of the ball-milled powder, grinding balls, and ethanol is 1:(1-5):(0.2-1.5).

6. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: In step (6), the debinding is carried out in an oxygen atmosphere, the debinding temperature is 700-800° C., the heating rate is 1-2° C. / min, and the holding time is 2-4 h.

7. The method for preparing a yttrium-scandium oxide transparent ceramic according to claim 1, characterized in that: In step (6), the vacuum sintering adopts a gradient temperature rising process: heating to 1000°C at 10°C / min, then heating to 1400°C at 5°C / min, and finally heating to 1850°C at 2°C / min; The annealing process includes: performing annealing in an oxygen atmosphere at 1200-1300° C. for 5-8 hours, and performing thinning and polishing on the ceramic after annealing.

8. A yttrium-scandium oxide transparent ceramic nanopowder, characterized in that: The chemical formula of the yttrium scandium oxide oxygen transparent ceramic nanopowder is (Y 1-x Sc x )2O3, where 0≤x≤1; The yttrium-scandium oxide transparent ceramic nanopowder is prepared by steps (1) to (3) of the preparation method as claimed in claim 1.

9. The yttrium-scandium oxide transparent ceramic nanopowder according to claim 8, characterized in that: Where 0.2≤x≤0.

3.

10. A transparent yttrium-scandium oxide ceramic obtained by the preparation method according to any one of claims 1 to 7.

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