Eu:(Gd,Lu)2O3 transparent ceramics show exceptional promise for high-energy X-ray imaging due to their superior radiation resistance and high light yield. To overcome challenges in achieving high optical quality and optimized luminescence performance, this study establishes a synergistic calcination-sintering process: 5 at.% Eu:Gd0.6Lu1.3O3 nanopowders synthesized via co-precipitation were calcined at 1050 degrees C-1300 degrees C for 4 h, followed by vacuum pre-sintering at 1600 degrees C for 4 h, hot isostatic pressing (HIP) posttreatment at 1700 degrees C for 3 h under 200 MPa Ar, and annealing at different temperature (1100 degrees C-1500 degrees C). It is demonstrated that the calcination temperature critically exerts a critical influence on powder morphology and crystallinity, directly governing the final optical quality of ceramics. Crucially, 5 at.% Eu:Gd0.6Lu1.3O3 ceramics from 1100 degrees C-calcined powders exhibit optimal microstructure with uniform grains (16.1 & micro;m) and pore-free grain boundaries. This optimized microstructure endows the ceramics with excellent optical transparency, achieving an in-line transmittance of 79.8% at 800 nm and 78.2% at 611 nm (the characteristic emission peak of Eu3 +). The X-ray excited luminescence (XEL) intensity peaks at 1400 degrees C annealing, reaching approximately 10 times that of a Bi12GeO20 (BGO) crystal, but declines at higher temperatures due to scattering-induced light loss. Thermoluminescence analysis confirms progressive trap elimination with increasing annealing temperature. In addition, XEL spectra reveal intense emission, with a light yield about 10 times higher than that of Bi12GeO20 (BGO) single crystal, and a decay lifetime of 0.96 ms. These findings establish that both precise control of calcination temperature and optimized annealing temperature are essential for producing high-performance Eu:(Gd,Lu)2O3 transparent ceramics for advanced scintillation applications.

ABSTRACT Eu:(Gd,Lu) 2 O 3 transparent ceramics show exceptional promise for high‐energy X‐ray imaging due to their superior radiation resistance and high light yield. To overcome challenges in achieving high optical quality and optimized luminescence performance, this study establishes a synergistic calcination‐sintering process: 5 at.% Eu:Gd 0.6 Lu 1.3 O 3 nanopowders synthesized via co‐precipitation were calcined at 1050°C–1300°C for 4 h, followed by vacuum pre‐sintering at 1600°C for 4 h, hot isostatic pressing (HIP) posttreatment at 1700°C for 3 h under 200 MPa Ar, and annealing at different temperature (1100°C–1500°C). It is demonstrated that the calcination temperature critically exerts a critical influence on powder morphology and crystallinity, directly governing the final optical quality of ceramics. Crucially, 5 at.% Eu:Gd 0.6 Lu 1.3 O 3 ceramics from 1100°C‐calcined powders exhibit optimal microstructure with uniform grains (16.1 µm) and pore‐free grain boundaries. This optimized microstructure endows the ceramics with excellent optical transparency, achieving an in‐line transmittance of 79.8% at 800 nm and 78.2% at 611 nm (the characteristic emission peak of Eu 3 + ). The X‐ray excited luminescence (XEL) intensity peaks at 1400°C annealing, reaching approximately 10 times that of a Bi 12 GeO 20 (BGO) crystal, but declines at higher temperatures due to scattering‐induced light loss. Thermoluminescence analysis confirms progressive trap elimination with increasing annealing temperature. In addition, XEL spectra reveal intense emission, with a light yield about 10 times higher than that of Bi 12 GeO 20 (BGO) single crystal, and a decay lifetime of 0.96 ms. These findings establish that both precise control of calcination temperature and optimized annealing temperature are essential for producing high‐performance Eu:(Gd,Lu) 2 O 3 transparent ceramics for advanced scintillation applications.

Effects of Lu3+ admixture on photo-and radioluminescence, as well as on scintillation characteristics, were investigated in Gd3-xLuxAl3Ga2O12:Ce,Mg (x = 0.5, 1, 1.5, 2) scintillation ceramics fabricated via chemical co-precipitation and a combination of oxygen sintering, HIP post-treatment and annealing. The Ce3+ 5d1 -> 4f emission in photo-and radioluminescence bands was gradually blue shifted with increasing Lu content due to a decrease in the crystal field splitting of the 5d levels. Furthermore, the thermal ionization activation energy, determined from the temperature-dependent PL decay kinetics, increased with increasing Lu content, leading to higher thermal stability of the Ce3+ centers and increase of light yield value. The onset temperature at 362 K for luminescence quenching was determined from the temperature-dependent photoluminescence kinetics. The GdLu2Al3Ga2O12:Ce,Mg ceramic exhibited the highest light yield value of 11,400 photons/MeV at 662 keV gamma rays along with fast scintillation decay times of 26.5 ns (59%) + 58.2 ns (41%), and good time resolution of 249 ps.

As laser lighting advances toward kilowatt-level power, the thermal stability of phosphors has become a critical bottleneck limiting performance enhancement. To address the issue of luminescence degradation of YAG:Ce phosphors caused by a temperature rise under laser irradiation, we introduced highly thermally conductive AlN into the YAG:Ce matrix and successfully prepared AlN-YAG:Ce composite phosphor ceramics by powder-embedding nitrogen atmosphere sintering. The incorporation of AlN enhances lumen efficiency through increased scattering effects while improving thermal robustness via its inherent high thermal conductivity. The ceramic sample containing 50 vol% AlN exhibits a luminescence intensity comparable to that of YAG:Ce, yet its thermal conductivity is approximately three times higher, reaching 27.2 W & centerdot;m(-1)& centerdot;K-1. A high lumen efficiency of 200.1 lm & centerdot;W-1 and a suitable correlated color temperature of 4608 K are achieved by the ceramics with 10 vol% AlN under 1.3 W & centerdot;mm(-2) blue laser diode excitation. Moreover, a laser illumination prototype device incorporating ceramic samples containing 10 vol% AlN and a 10 W blue laser was constructed, emitting white light with an illumination range exceeding 500 m, demonstrating potential applications in laser-driven lighting.

Mo co-doped LuGd2Al3Ga2O12:Ce,Mo (Mo = 0, 300, 600 ppm) single crystals were grown by the micro-pulling down method. The optical absorption and X-ray excited luminescence spectra, temperature dependence of photoluminescence decay kinetics, afterglow and thermoluminescence (TL) intensity, and scintillation properties (light yield, LY, and decay time) were investigated. The quenching temperature of 355 K was determined from temperature-dependent photoluminescence decay kinetics in the temperature range of 77-487 K under excitation in the 4f-5d1 absorption band of the Ce3+ ions. Under excitation of 662 keV gamma rays, the LuGd2Al3Ga2O12:Ce, Mo600 sample showed high LY value of 32,900 photons/MeV, energy resolution of 7.6 %, and scintillation decay time of 119 ns (38 %) + 475 ns (62 %). The lower LY value together with higher contribution of slower scintillation decay component among the samples studied was observed for LuGd2Al3Ga2O12:Ce,Mo300 sample, consistently with its higher afterglow intensity and longer de-trapping time of the dominant TL glow peak at 356 K.

Despite the success of using Al2O3 as a secondary phase in Ce:LuAG phosphor ceramics (PCs), there is still room for improvement in the compositional design of biphasic PCs, as well as in their luminescent and thermal performance. In this study, nanopowders with 40 wt.% Al2O3-0.4at.% Ce:LuAG stoichiometry were synthesized via a co-precipitation approach. Subsequently, a series of compositionally uniform PCs was successfully fabricated by adjusting the vacuum sintering temperature and dwelling time. The grain size distributions of the Al2O3 and LuAG phases, as well as the evolution of porosity and pore size, were systematically analyzed and correlated with the sintering conditions. The addition of Al2O3 has been demonstrated to enhance the thermal properties of ceramics. The thermal conductivity of the “1750 °C × 10 h” sample was 15.6 W·m−1·K−1 at room temperature. Concurrently, it exhibited excellent thermal quenching behavior, retaining 96% of its luminescence intensity upon heating to 450 K. Its fluorescence lifetime was determined to be 21.06 ns. Under 450 nm laser excitation, the optimized PC attained a luminous efficacy of 286 lm·W−1 at 1 W·mm−2. In addition, the luminous flux increased continuously with laser power from 1 to 20 W·mm−2 without any sign of saturation, reaching a maximum of 2500 lm. The findings indicate that biphasic 40 wt.% Al2O3-0.4at.% Ce:LuAG PCs have potential as high-flux, green-color converters for next-generation high-power laser lighting. Furthermore, a laser illumination prototype device incorporating 40 wt.% Al2O3-0.4at.% Ce:LuAG ceramic samples and a 10 W blue laser was constructed. This device emits white light with an illumination range exceeding 500 m, thereby demonstrating its potential applications in laser-driven lighting.

Monophase Ce:Y3Al5-xScxO12 (Ce:YSAG) with x = 0.5 −2.5 and 50 vol% Al2O3-containing composite phosphor ceramics (PCs) were prepared by reactive vacuum sintering. The effects of Sc3+ substitution on their microstructure, phase formation, and luminescence properties were systematically investigated. For the monophasic series, scandium was entirely concentrated in the octahedral crystallographic site (Al/Sc)2 (0, 0, 0) up to its complete occupation at x = 2, whereas subsequent increases in the nominal Sc content result only in enhanced formation of the Y4Al2O9-like additional phase. It was shown the limitations of reactive sintering technique that prevent obtaining Al2O3–Ce:YSAG with the nominal phase composition. For the composite series, the corundum phase participates in the formation of an additional amount of garnet, with Sc preferentially occupying the dodecahedral position (Y/Ce/Sc)3 (0.125, 0, 0.25). An increase in Sc content in the composites was accompanied by distortion of the absorption band shape at 460 nm (4 f→5d1) and a significant decrease in the absorption peak intensity at 340 nm (4 f→5d2). A different preference for Sc3+ substitution at the garnet sites was reflected in a red shift of the PL emission (5d→4 f) by Δλ= 12 nm. As a result, distortion of the crystal field around Ce3+ led to significant luminescence quenching and a decrease in the quantum efficiency (QE) of composite PCs. The effect became critical at x ≥ 1.0, as evidenced by the presence of a fast decay component τ1, a reduction in the average lifetime τ* from 39.2 to 18.5 ns, and an exponential drop in η(EQE) to 12%. Under the excitation of 450 nm laser diodes in a reflection mode, 0.4 mm-thick Ce:YSAG with x = 0.5 had an optimum luminous efficiency of 229 lm∙W−1, a correlated color temperature of 6245 K, and a color rendering index of 54.

(Gd,Y,Ce)3(Ga,Al)5O12 (Ce:GYGAG) is a promising scintillator for X-ray imaging owing to its high light yield, fast decay time and good radiation absorption capacity. Nevertheless, systematic investigations concerning Ce-concentration-dependent fabrication and scintillation performance of Ce:GYGAG ceramics remain insufficient. Herein, a series of x at.%Ce:Gd2Y1Ga3Al2O12 (x=0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0, 1.2) scintillation ceramics were fabricated of nanopowders via oxygen pre-sintering followed by hot isostatic pressing. The pure-phase Ce:GYGAG nanopowders, which were obtained by calcining co-precipitation-derived precursor in air, consisted of agglomerates based on worm-like primary particles. The resulting ceramics exhibited average grain size of 3.5–4.8 μm and in-line transmittance of 51–68% at 540nm. The optimal light yield reaches 52,100ph./MeV (1 μs shaping time) at 0.3at.% Ce, accompanied by fast and slow decay time of 46.5ns and 312.4ns, respectively. The thermally stimulated luminescence (TSL) fitting yielded distinct glow peaks at 90–114K, 246–265K and 320–362K, originating from multiple electron/hole trapping defects. Notably, increasing Ce content suppresses defect concentration, demonstrating that concentration quenching dominates the deterioration of light yield at elevated Ce doping. Overall, this work elucidates the influence of Ce doping concentration on the fabrication and scintillation properties of Ce:GYGAG ceramics, providing valuable insights for further optimization and practical application.

Monophase Ce:Gd3Al5u2212xGaxO12 (Ce:GAGG) with x = 0.5u20133.0 and 50 vol% Al2O3u2212containing composite phosphor ceramics (PCs) were prepared in a pure oxygen atmosphere. The effects of Ga3+ substitution on their phase formation, microstructure, and luminescence properties were systematically investigated. For Ce:GAGG series samples, no additional phases were identified, and the distribution of Ga between the octahedral (Al/Ga)2 (0, 0, 0) and tetrahedral (Al/Ga)3 (0.375, 0, 0.25) sites of the garnet phase was clarified. For Al2O3u2212Ce:GAGG composites, the exchange of Al and Ga elements between the phases of garnet Ga(Al,Ga)G and oxide (Al,Ga)2O3 was revealed, and the transformation of (Al,Ga)2O3 from the u03B1- to u03BA-phase (x u2265 2.0) with the formation of elongated grains and their partial melting (x = 3) is shown. This was also reflected in a less pronounced shift of the photoluminescence peak (PL) toward shorter wavelengths for the composite series in comparison with the monophase series: with an increase in x to 3.0, the shift in the position of the PL peak of intensity by 18 nm for Al2O3u2212Ce:GAGG was equivalent to that for Ce:GAGG at x = 1.5. A phosphorescence phenomenon was found at x = 2.5 and 3.0 for monophasic Ce:GAGG compositions. Under the excitation of 1 W 450 nm LDs in reflection mode, 0.4 mm-thick Al2O3u2212Ce:GAGG with x = 0.5u20131.5 had an optimum correlated color temperature of 5400u20136300 K, a luminous efficiency of 123u2013145 lmu2219Wu22121, and a color rendering index (Ra = 69u201364). The obtained PCs showed high application potential in solid-state laser lighting.

New efficient inorganic scintillation Ce:Gd3Al3Ga2O12 (Ce:GAGG) materials in ceramic form are of great interest for both fundamental and applied fields. An approach to producing Ce:GAGG by reactive spark plasma sintering (SPS) in argon without sintering additives was implemented. The effect of isothermal holding temperature (1300-1450°C / 30 min / 30 MPa) on the phase composition, microstructure, and material luminescent properties was studied. Using synchrotron radiation, it has been shown from the XRD spectra that peaks quantity corresponding to the GdAlO3 impurity phase and Gd–Al intermetallics tend to increase with rising SPS temperature, indicating slight GAGG decomposition and GAP reduction, respectively. The sample sintered at 1400 °C exhibited the densest polyhedral grain structure with an asymmetric size distribution (∼3.6 μm on average) well described by a lognormal function (R2 = 0.96). With a maximum absorptance ξ of 83%, the scintillation decay curve was fitted by two components: a fast component τ1 (I1) = 71.1 ns (94%) and slow component τ2 (I2) = 420.4 ns (6%).

Monophase Ce:Gd3Al5−xGaxO12 (Ce:GAGG) with x = 0.5–3.0 and 50 vol% Al2O3−containing composite phosphor ceramics (PCs) were prepared in a pure oxygen atmosphere. The effects of Ga3+ substitution on their phase formation, microstructure, and luminescence properties were systematically investigated. For Ce:GAGG series samples, no additional phases were identified, and the distribution of Ga between the octahedral (Al/Ga)2 (0, 0, 0) and tetrahedral (Al/Ga)3 (0.375, 0, 0.25) sites of the garnet phase was clarified. For Al2O3−Ce:GAGG composites, the exchange of Al and Ga elements between the phases of garnet Ga(Al,Ga)G and oxide (Al,Ga)2O3 was revealed, and the transformation of (Al,Ga)2O3 from the α- to κ-phase (x ≥ 2.0) with the formation of elongated grains and their partial melting (x = 3) is shown. This was also reflected in a less pronounced shift of the photoluminescence peak (PL) toward shorter wavelengths for the composite series in comparison with the monophase series: with an increase in x to 3.0, the shift in the position of the PL peak of intensity by 18 nm for Al2O3−Ce:GAGG was equivalent to that for Ce:GAGG at x = 1.5. A phosphorescence phenomenon was found at x = 2.5 and 3.0 for monophasic Ce:GAGG compositions. Under the excitation of 1 W 450 nm LDs in reflection mode, 0.4 mm-thick Al2O3−Ce:GAGG with x = 0.5–1.5 had an optimum correlated color temperature of 5400–6300 K, a luminous efficiency of 123–145 lm∙W−1, and a color rendering index (Ra = 69–64). The obtained PCs showed high application potential in solid-state laser lighting.

Al2O3-YAG:Ce composite ceramic phosphors (CCPs) have attracted extensive attention for applications in solidstate lighting for excellent thermal performance, high light saturation thresholds, and high lumen efficiency, but the color rendering properties need to be further improved. In this work, a series of Al2O3-TbYAG:Ce CCPs with various Tb3 + contents were prepared by solid-state reaction sintering. Energy transfer from Tb3+ to Ce3+ confirmed in Al2O3-TbYAG:Ce ceramic system. As the Tb3+ content increases, the color rendering index (CRI) increases and the correlated color temperature (CCT) decreases due to the effective supplementation of the redlight component. Al2O3-Tb0.3Y0.7AG:Ce CCPs possess small thermal quenching (24.7 % loss in luminescence at 225 degrees C) and achieve an optimized CRI of up to 81.6 under LED excitation. Furthermore, these ceramic samples exhibit high lumen efficiency of 200-246 lm center dot W-1 and suitable CCT of 4949-5117 K under 18 W center dot mm-2 power density, which is of great significance for realizing high-brightness LED/LD lighting.

The coexistence of pores in composite phosphor ceramics (CPCs) for solid-state lighting is not necessarily a disadvantage, and it may be more conducive to enhancing luminous efficiency. In this work, x wt% BaAl2O4-LuAG:Ce CPCs (x = 1, 3, 5, 10) were fabricated via a solid-state reaction, which involves the coexistence of pores. BaAl2O4 can not only function as a sintering aid but also form secondary phases serving as scattering centers. The 3 wt% BaAl2O4-LuAG:Ce exhibits an intriguing microstructure, where large and small grains of LuAG:Ce coexist alongside pores and secondary phases, demonstrating better luminescent properties. Under 0.92 W laser excitation at 450 nm, 3 wt% BaAl2O4-LuAG:Ce exhibits an optimum luminous efficiency of 237 lm/W and a luminous flux of 218 lm. When the laser power reached 4.3 W, 3 wt% BaAl2O4-LuAG:Ce exhibited an optimal luminous flux of 1015 lm, which shows the potential for application in solid-state lighting (SSL).

Ce3+-doped (Lu,Y)3(Al,Ga)5O12 (Ce:LuYGAG) garnet ceramics hold promise as potential phosphor ceramics for lighting applications, yet their luminous properties remain unexplored. To address this issue, garnet nanopowders with compositions of Lu2YGaxAl5-xO12 (x=1.5, 2.0, 2.5, 3.0) doped with 0.2 at.% Ce were synthesized via a co-precipitation method. These nanopowders served as raw materials for fabricating highly dense ceramics through a combined process of pre-sintering in oxygen followed by hot isostatic pressing (HIP). With the increase of Ga content, the Ce3+ luminescence from the lowest 5d1 level was blue shifted from 507 nm to 498 nm, effectively bridging the "cyan light gap" in the emission spectrum. Furthermore, the full width at half maximum (FWHM) of the emission band broadened from 85 nm to 92 nm, pointing towards the possibility of achieving broadband luminescence. The Ce:Lu2YGa1.5Al3.5O12 demonstrated an impressive luminous efficacy up to 196 lm/W under excitation with 0.9 W laser diode (LD). Upon elevating the LD power to 4.3 W, this optimized ceramic achieved a high luminous flux of 758 lm. Overall, this research reports the luminous properties in Ce:Lu2YGaxAl5-xO12 ceramics through designed Ga3+ substitution, paving the way for the development of potential phosphors tailored for various illumination needs.

Yb3+-doped (Lux,Sc1-x)2O3 materials demonstrate superior performance in generating short pulse lasers because of the broader emission spectra than single-component sesquioxide, making them a promising laser gain material for high-power ultrafast lasers. By adjusting the concentration of Lu/Sc, laser gain materials with different widths of emission spectra can be obtained. In this work, 5 at.% Yb:(LuxSc1-x)2O3 nano-powders with varying Lu concentrations (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9)were successfully synthesized by the co-precipitation method. Subsequently, Yb:(LuxSc1-x)2O3 transparent ceramics were produced through a combination of vacuum pre-sintering and hot isostatic pressing (HIP) post-treatment at 1700 degrees C. Influence of Lu content on densification process, microstructure changes and optical transmittance of Yb:(LuxSc1-x)2O3 ceramics was investigated in detail. The average grain sizes of ceramics pre-sintered at 1700 degrees C decrease from 3.42 mu m to 1.43 mu m, and all ceramics have a relatively uniform microstructure. After HIP post-treatment, the optimum in-line transmittance of Yb:(LuxSc1-x)2O3 ceramics reaches 77.6 % at 1100 nm when x value = 0.1. With the increase of Lu content, the emission wavelength experiences a gradual blueshift from 1041 nm to 1034 nm. Notably, the Yb:(Lu0.6Sc0.4)2O3 ceramics exhibited the broadest emission bandwidth of 18 nm, which is 1.5 times of the Yb: Sc2O3, suggesting their immense potential for applications in ultrashort pulse lasers.

The coexistence of pores in composite phosphor ceramics (CPCs) for solid-state lighting is not necessarily a disadvantage, and it may be more conducive to enhancing luminous efficiency. In this work, x wt% BaAl2O4u2013LuAG:Ce CPCs (x = 1, 3, 5, 10) were fabricated via a solid-state reaction, which involves the coexistence of pores. BaAl2O4 can not only function as a sintering aid but also form secondary phases serving as scattering centers. The 3 wt% BaAl2O4u2013LuAG:Ce exhibits an intriguing microstructure, where large and small grains of LuAG:Ce coexist alongside pores and secondary phases, demonstrating better luminescent properties. Under 0.92 W laser excitation at 450 nm, 3 wt% BaAl2O4u2013LuAG:Ce exhibits an optimum luminous efficiency of 237 lm/W and a luminous flux of 218 lm. When the laser power reached 4.3 W, 3 wt% BaAl2O4u2013LuAG:Ce exhibited an optimal luminous flux of 1015 lm, which shows the potential for application in solid-state lighting (SSL).

Solid-state lighting (SSL), particularly light-emitting diode (LED) and laser diode (LD)-based technologies, has revolutionized modern illumination due to its high efficiency and long lifespan. To further improve the color rendering index (CRI) of YAG:Ce ceramics for high-quality warm white SSL, we prepared YAG:Ce,Mn luminescent transparent ceramics with varying Mn2+-Si4+ co-doping concentrations via solid-state reactive sintering. Although partial oxidation of Mn2+ to Mn3+ occurs in the YAG:Ce,Mn ceramics, the experimental results demonstrate that Mn2+-Si4+ co-doping effectively broadens the emission spectrum by enhancing orange-red spectral components, thereby enabling warm white light emission. When the YAG:Ce,xMn (x = 2.0 at.%) transparent ceramic was combined with a blue LED chip, the CRI (Ra) increased from 76 to 83.4 compared with YAG:Ce,xMn (x = 0 at.%), with a correlated color temperature (CCT) of 4024-4371 K. Under 450 nm LD excitation, the YAG:Ce,xMn (x = 2.0 at.%) ceramic achieved a CRI (Ra) of 53.1, which is also higher than 26.5 of YAG:Ce,xMn (x = 0 at.%), with a CCT of 4010-4329 K, while the luminous efficiency decreased from 219 lm/W to 41 lm/W. Notably, the luminescence saturation threshold decreased from 14.1 to 4.5 W mm(-2) as the Mn2+-Si4+ co-doping concentration increases (x = 0-2.0 at.%). These results indicate that the optimized YAG:Ce,Mn transparent ceramics are promising for high color rendering warm white SSL applications in LEDs and LDs.

Sc2O3, as a host for solid-state laser gain materials, has advantage of high thermal conductivity and easy matching with activating ions, which is promising in high-power laser applications. Currently, Yb-doped Sc2O3 ceramics have been fabricated at very high sintering temperatures, but their optical quality and sintering process still need further improvement. In this work, 5%Yb:Sc2O3 (in mass) nano-powders were obtained by co-precipitation, and then transparent ceramics were fabricated by vacuum pre-sintering and hot isostatic pressing (HIP) post-treatment. The cubic Yb:Sc2O3 nano-powders with good dispersity and an average crystallite of 29 nm were obtained. Influence of pre-sintering temperatures (1500-1700 degrees C) on densification process, microstructure changes, and optical transmittance of Yb:Sc2O3 ceramics was detected. Experimental data revealed that all samples have a uniform microstructure, while the average grain sizes increase with the increase of the sintering temperatures. Impressively, the optimum in-line transmittance of Yb:Sc2O3 ceramics, pre-sintered at 1550 degrees C after HIP post-treatment, reaches 78.1% (theoretical value of 80%) at 1100 nm. Spectroscopic properties of the Yb:Sc2O3 ceramics reveal that the minimum population inversion parameter beta 2 and the luminescence decay time of 5%Yb:Sc2O3 ceramics are 0.041 and 0.49 ms, respectively, which demonstrate that the optical quality of the Yb:Sc2O3 has been improved. Meanwhile, their best vacuum sintering temperature can be controlled down to a lower temperature (1550 degrees C ). In conclusion, Yb:Sc2O3 nano-powders are successfully synthesized by co-precipitation method, and good optical quality transparent ceramics are fabricated by vacuum pre-sintering at 1550 degrees C and HIP post-treatment.

Y3Al2Ga3O12:Ce3+,Cr3+(YAGG:Ce3+,Cr3+),as a persistent luminescent material,has advantages of high initial luminescence intensity and long persistent time,which is promising in persistent luminescent material applications.At present,YAGG:Ce3+,Cr3+powders exhibit good persistent performance,but their persistent performance of ceramics still needs to be further improved to meet the new requirements.In this work,(Y0.998Ce0.002)3(Al1-xCrx)2Ga3O12 ceramics with different Cr3+doping concentrations were prepared by solid-state reaction,including air pre-sintering,hot isostatic pressing(HIP)post-treatment and air annealing,to investigate the effects of Cr3+doping concentration on the microstructure,optical properties and persistent performance of the ceramics.The results showed that as the doping concentration of Cr3+increased from 0.025％to 0.2％(in atom),no significant effect of Cr3+concentration on the morphology of pre-sintered ceramics or HIP post-treatment ceramics was observed,but the in-line transmittance gradually increased while the persistent performance gradually decreased.Among them,YAGG:Ce3+,Cr3+ceramics doped with 0.025％Cr3+showed the strongest initial luminescence intensity exceeding 6055 mcd/m2 and a persistent time of 1030 min after air pre-sintering combined with HIP post-treatment and air annealing.By optimizing the Cr3+doping concentration and the fabrication process,the persistent luminescence(PersL)performance of the YAGG:Ce3+,Cr3+ceramics was obviously improved.