Nd∶LuAG transparent ceramics, due to their excellent optical, mechanical, and thermodynamic properties, as well as their moderate saturation fluence, demonstrate greater development potential as a gain medium in high repetition rate high-energy solid-state lasers. The co-precipitation method for synthesizing nano-powders offers advantages such as high chemical homogeneity and low synthesis temperature. Nano-powders with high sintering activity can significantly reduce the densification temperature and time, as well as greatly decrease the grain size of ceramics. It is a commonly used and effective method for preparing garnet-based transparent ceramic powders. Using nitrate as raw material and ammonium bicarbonate as precipitant, 1at.% Nd:LuAG nano-powders were prepared via the co-precipitation method. The nano-powders exhibit a single LuAG phase with an average primary particle size of approximately 97nm. The 1at.% Nd:LuAG transparent ceramics were prepared by vacuum pre-sintering at 1450~1650℃ for 3h and HIP post-treated at 1500℃ for 3h under 200MPa. The effect of the vacuum pre-sintering temperature on the microstructure and optical transmittance was investigated. The experimental results indicate that when the vacuum pre-sintering temperature is 1550℃, the in-line transmittance of the 1.5mm thickness 1at.% Nd:LuAG transparent ceramics with an average grain size of 927nm is 83.6% at 1064nm. The successful preparation of fine-grained, high-optical-quality Nd:LuAG transparent ceramics is of great significance for enhancing the performance of high repetition rate nanosecond high-energy solid-state lasers.

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·m⁻¹·K⁻¹. A high lumen efficiency of 200.1 lm·W⁻¹ and a suitable correlated color temperature of 4608 K are achieved by the ceramics with 10 vol% AlN under 1.3 W·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.

Monophase Ce:Gd₃Al_5−xGa_xO₁₂ (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.

A slow scintillation component due to charge carrier capture at point defects is a serious issue in scintillator materials. Therefore, the fabrication of scintillators with a high proportion of fast components in the scintillation response is of great interest to material scientists. By applying the defect engineering strategy in advanced optical Lu₃Al₅O₁₂:Ce,Mg (LuAG:Ce,Mg) ceramics, an ultrahigh fast scintillation proportion can be achieved with a slight loss of fast scintillation light. Moreover, low-temperature thermoluminescence (TSL) investigations revealed that the intensities of all the TSL peaks decreased in the Mg²⁺-codoped samples. The slight loss of fast scintillation light observed was explained by density functional theory (DFT) calculations. The effect of {Ce³⁺–Mg²⁻} pairs on emission quenching was compared with that of {Ce³⁺–Ca²⁻} pairs. As a consequence, the 0.3 at% Mg²⁺-codoped ceramic sample has an LY_0.5µs/LY_10µs ratio of 99.8%, which is better than those reported for isostructural ceramics and single crystals. We conclude with a discussion of the role of Mg²⁺ co-doping and future research directions concerning other oxide scintillators.

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).

For high-repetition-rate nanosecond high-power solid-state lasers, it is essential to choose gain media with moderate saturation flux. Among these materials, Nd:Lu₃Al₅O₁₂ (LuAG) transparent ceramics have shown significant potential. The thermal effect limits their power density in the gain element, but increasing the size of the gain medium can help dissipate heat. However, a large aspect ratio can lead to high spontaneous fluorescence, causing amplified spontaneous emission (ASE) and parasitic oscillations (POs). A solution is to apply cladding layers to absorb stray radiation. Sm:LuAG transparent ceramics, with high absorption at 1064 nm, good transmittance at 808 nm, and a refractive index similar to that of Nd:LuAG, are ideal for cladding Nd:LuAG laser ceramics. In this work, highly transparent Sm:LuAG ceramics were successfully fabricated first through low-temperature vacuum pre-sintering combined with high-temperature hot isostatic pressing (HIP) post-treatment using the co-precipitated Sm:LuAG nano-powders. The influences of Sm³⁺ doping concentration on the microstructure and optical transmittance of Sm:LuAG ceramics were studied. The nano-powders calcined at 1100 °C for 4 h showed dendritic agglomerations but relatively small particle sizes and high uniformity. Sm:LuAG ceramics with different doping amounts were obtained by vacuum sintering at 1550 °C for 3 h followed by HIP post-treatment at 1550 °C in an argon atmosphere at 200 MPa for 3 h. The 3 at% Sm:LuAG transparent ceramics (1.5 mm in thickness) exhibited the highest in-line transmittance of 83.9% at 808 nm, a fine grain size of 909 nm, and an absorption coefficient of 2.44 cm⁻¹ at 1064 nm, indicating that it can effectively suppress ASE and PO.

Transparent ceramic is a kind of ceramic which shows a good transparency in specific wavelength range. It is widely used in the fields of lasers, solid-state lighting, scintillator detectors, and magneto-optical isolators. Ever since the development of the first aluminum oxide translucent ceramics "Lucalox" in the 1950s by GE, researchers worldwide fabricated various kinds of transparent and translucent ceramics. There are various kinds of transparent ceramics, and each kind has its unique test methods. Optical windows and transparent armors are mainly used in the vehicle, personal and device protection, with major candidates of aluminum oxynitride and spinel, and test methods in considerations of optical, mechanical and thermal properties; high index ceramic lenses are mainly used in the fabrication of high performance optical parts, with major candidates of aluminum oxynitride, spinel, and yttrium aluminum garnet, and test methods in consideration including refractive index, transmittance, and chromatic dispersion properties; laser ceramics are used as a gain medium in the laser system, with major candidates of neodymium doped yttrium aluminum garnet, ytterbium doped yttrium aluminum garnet, neodymium doped sesquioxide, ytterbium doped sesquioxide and so on, and test methods in consideration including transmittance, absorption, optical homogeneity properties and so on; magneto-optical ceramics are the core part of the optical isolators, with major candidates of terbium aluminum garnet, terbium oxide, terbium gallium garnet, and yttrium iron garnet, and test methods in consideration including Verdet constant, optical and thermal properties, laser-damaged threshold, and so on; electro-optic ceramics are mainly used in the fields of optical modulator, optical storage, photoelectric sensor, spectral filter, optical switch, multicolor electrochromic display device, light valve, memory unit, and so on, with major candidates of lead lanthanum zirconate titanate, lead magnesium niobate-lead titanate, and potassium-sodium niobate based lead-free electro-optic ceramics, and test methods in consideration including ferroelectric, dielectric, and electric-induced light scattering properties; ceramic scintillators are mainly used in the field of high energy physics and medical imaging, with major candidates of cerium doped lutetium aluminum garnet, praseodymium doped lutetium aluminum garnet, cerium doped gadolinium gallium aluminum garnet, and cerium doped gadolinium yttrium gallium aluminum garnet and so on, test methods in consideration including γ-ray energy spectroscopy, scintillation decay profile, and afterglow; ceramic phosphors are used in the fields of lighting and display, with major candidates of cerium doped yttrium aluminum garnet and cerium doped lutetium aluminum garnet, test methods in consideration including luminous flux and lumen efficiency, chromaticity coordinate, correlated color temperature, color rendering index, and so on; persistent luminescent ceramics are mainly used in the fields of safety at night, fluorescence labeling, optical storage, optical anti-counterfeiting and so on, with major candidates of alkali-earth aluminate long persistence ceramics and sulfide long persistence ceramics, test methods in consideration including photoluminescence excitation and emission spectra, afterglow, and high temperature thermally stimulated luminescence properties. In this paper, we reviewed the test methods of the above mentioned eight kinds of transparent ceramics. The basic principles for the measurement, general test methods, application case studies, and the problems encountered during the test process were also mentioned.

Fluoride laser ceramics, which are employed as amplification media in solid-state lasers, have attracted considerable attention because of their excellent optical properties combined with other material parameters important for these applications, making them highly versatile materials. In this review, the fabrication and properties of fluoride laser ceramics, including CaF₂, SrF₂, and BaF₂ ceramics, are comprehensively investigated. As the state-of-art analysis shows, while some ceramic materials of this type have shown promising properties suitable for practical applications, most still require further research in the field of basic research. Specifically, this article reviews the state of research, identifies issues and prevailing challenges, and outlines development trends for fluoride ceramics for solid-state laser applications. The information gathered here is an important compendium of knowledge both for researchers seeking to work in this field of science and as a source of the latest information for experienced professionals who are already continuing preimplementation work in this area.

Owing to their rich color, excellent mechanical properties, and favorable biocompatibility, colored zirconia ceramics have been widely used in intelligent terminals, dental restoration, colored decorations, and other potential fields. This paper starts with the challenges faced by colored zirconia ceramics, followed by a summary of the application market of colored zirconia ceramics. Herein, we review various types of colorants and their mechanism of color development, summarize coloring methods, and analyze their advantages and disadvantages. Finally, the research progress on zirconia ceramics with red, blue, black, and other common colors is summarized, and future development directions are proposed in this review.

Terbium aluminum garnet (Tb₃Al₅O₁₂; TAG) ceramics are among the most promising magneto–optical materials owing to their outstanding comprehensive performance. Many works have focused on improving the optical quality of TAG ceramics. A key point for improving optical quality is ensuring the accuracy of the stoichiometric ratio and avoiding secondary phases. In this work, 0, 2, 4, or 6 wt% Sc₂O₃ was added to the TAG ceramics to increase the solid solubility. The effects of Sc substitution on the crystal structure, sintering process, microstructure, optical transmittance, and magneto–optical properties of (Tb_1−xSc_x)₃(Al_1−ySc_y)₂Al₃O₁₂ (TSAG) ceramics are studied in detail. 4 wt% Sc₂O₃:TAG ceramics with an in-line transmittance of 82.2% at 1064 nm and 81.2% at 633 nm were successfully fabricated, and the Verdet constant was 164.4 rad·T⁻¹·m⁻¹ at 633 nm. Anti-site defects (ADs) and Sc replacement in TAG are further studied via first-principles calculations to determine the working mechanism of Sc. Both the experimental and calculation results show that the introduction of Sc can effectively increase the solid solubility of TAG ceramics, suppress secondary phases, and hence improve the optical transmittance.