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Numerical simulations of the evolution of mobile and immobile dislocations in ceramics under applied pressure in dry pressing at a relatively low temperature are performed in order to study the possibility of production of all-dislocation-ceramics of solid electrolytes, which are expected to have extremely high ionic conductivity without dendrite formation because the diameter of a dislocation pipe is considerably larger than the distance between neighboring dislocations. The present numerical simulations are only for the densification process by plastic deformation of grains under high pressure under the assumption that the compaction of particles by their rearrangement is completed beforehand. By the plastic deformation, new dislocations are generated inside the grains. The required total dislocation density of about 1017 m−2 seems to be achievable under some conditions of dry pressing according to the present numerical simulations. Very short ultrasound irradiation at the beginning of the dry pressing sometimes considerably increases the dislocation density, while for other cases, it even considerably decreases the dislocation density due to enhanced annihilation of mobile dislocations by ultrasound. [ABSTRACT FROM AUTHOR]

Lu 2 O 3 scintillation ceramics doped with different concentrations of Eu3+ were prepared by SPS in a vacuum environment. The microstructural properties of the prepared ceramics were analyzed using XRD, SEM and EDS in details. Excited by the 395 nm, the Eu3+-doped samples display a prominent emission peak at 612 nm, corresponding to the transition 5D 0 →7F 2. The PL spectra across various concentrations identified 3 at.% as the optimal doping concentration. The temperature-dependent PL spectra reveal the activation energy of approximately 0.266 eV for the 3 % Eu3+-doped Lu 2 O 3 ceramic. Under 395 nm excitation, the lifetimes of xEu:Lu 2 O 3 (x = 0.01, 0.03, 0.05 and 0.07) ceramics were fitted to be 1.07 ms, 1.02 ms, 0.99 ms and 0.92 ms, respectively. The XEL spectra of Eu3+-doped samples are consistent with their PL spectra, aligning well with the sensitivity range of the detector. These results demonstrate that Eu3+:Lu 2 O 3 scintillation ceramics are ideal materials for scintillation detectors. [ABSTRACT FROM AUTHOR]

Transparent Er-doped Y 2 O 3 ceramics were fabricated using the spark plasma sintering (SPS) technique without any sintering additives to achieve fine-grained mid-infrared laser ceramics. The average grain size of ceramics was typically 300 nm and their in-line optical transmittance in the 2.7 μm mid-infrared range reached approximately 99 % of the theoretical value. The fluorescence spectra and lifetimes confirmed that the ceramics fabricated using SPS exhibited emission characteristics nearly identical to those fabricated using other sintering techniques. Despite the numerous pores in the ceramics and considerably reduced transmittance at an excitation wavelength of 976 nm (approximately 90 % of the theoretical value), a successful laser oscillation at 2.7 μm in the mid-infrared region was achieved. To the best of our knowledge, this is the first report on mid-infrared laser operation for fine-grained ceramics having grain sizes below 500 nm. We believe that this study will contribute to further improvements in the optical properties and development of fine-grained transparent ceramics as new laser materials, particularly non-cubic materials. [ABSTRACT FROM AUTHOR]

Polycrystalline magnesium aluminate spinel (PMAS) ceramics is a kind of transparent oxide ceramic with the advantages of high hardness, high mechanical strength, thermal stability and chemical corrosion resistance. The optical transmittance and infrared absorption edge of PMAS ceramic are better than that of sapphire and ALON in the mid-infrared band with the wavelengths greater than 4.5 μm, which makes it as an ideal material for manufacturing the optics used in the fields of transparent armor protection, infrared optical window and infrared missile dome. However, the hardness of PMAS ceramics is close to that of sapphire, and the brittleness is greater than that of sapphire, which brings great challenges to ultra-precision ductile grinding. In this paper, the surface characteristics and damage mechanisms in ultra-precision grinding of PMAS ceramics were systematically researched based on AE signals monitoring. Firstly, the effects of grinding depth, feed speed and grain size on the surface characteristics were studied in detail. Secondly, the influences of grinding depth and feed speed on the damage characteristics of PMAS ceramics were researched based on energy spectrum analysis of AE signals. Thirdly, the evolution mechanisms of material removal modes and damage characteristics were revealed based on time-frequency analysis of AE signals. Then, the damage types on ductile surfaces and initiation mechanisms of damage crack were investigated. Ultimately, the crack-free ductile surfaces and surface roughness (Sa) of 3 nm were achieved through ultra-precision grinding. [ABSTRACT FROM AUTHOR]

In this paper, Eu3+ doped multi-component transparent aluminosilicate and oxyfluoride aluminosilicate glasses were fabricated by the melt-quenching procedure, and the glass-ceramics containing LiAlSi 2 O 6 microcrystals (LAS glass-ceramics) were produced by a two-step heat treatment process. The XRD, SEM, and EDS data demonstrate that spherical single-phase LiAlSi 2 O 6 microcrystals have precipitated from the glass matrices. The microhardness and flexural strength of the glass-ceramics vary in 6.27–6.66 GPa and 89.18–155.75 MPa, respectively. Phonon sideband analysis reveals that the phonon energies for both fluorine-containing and fluorine-free LAS glass-ceramics are approximately 971 cm−1, and the multiphonon relaxation rates (W mp / W 0) of the former are lower than those of the latter. Given its lower W mp / W 0 values, the fluorine-containing LAS glass-ceramic exhibits a higher emission intensity and a longer lifetime. Under 394 nm excitation, the fluorine-containing LAS glass-ceramic presents a warm and nearly pure red emission, characterized by a correlated color temperature of less than 3300 K and a color purity approaching 100 %. Time-resolved emission spectra support the photoluminescent stability of the Eu3+ ions. According to the Judd-Ofelt theory and spectral results, the fluorine-containing LAS glass-ceramic possesses lower Ω 2 / Ω 4 and asymmetry ratios, leading to a more symmetrical local environment for the Eu3+ ions. Benefiting from its enhanced red emission, the 5D 0 →7F 2 transition in the fluorine-containing LAS glass-ceramic exhibits a higher branching ratio (69.28 % > 50 %), emission cross-section (8.94 × 10−22 cm2), and gain bandwidth (12.12 × 10−28 cm3). Additionally, temperature-dependent photoluminescence spectra substantiate the excellent thermal stability of the Eu3+ doped fluorine-containing LAS glass-ceramic. Specifically, the intensity of the 5D 0 →7F 2 transition at 150 °C remains 80 % of the initial intensity. Therefore, the Eu3+ doped multi-component transparent oxyfluoride aluminosilicate glass-ceramic has a significant competitive advantage in the field of red lasers and trichromatic WLEDs. [ABSTRACT FROM AUTHOR]

A series of Tb3+–Yb3+co-doped transparent glass ceramics (GCs) containing NaBi(MoO4)2 were synthesized. Comparison of their X-ray diffraction (XRD) patterns with standard cards showed that the crystal phase in the glass ceramics was NaBi(MoO4)2. Optimal heat-treatment conditions for the GCs were obtained through differential scanning calorimetry-thermogravimetry (DSC-TG), light transmittance and scanning electron microscopy (SEM) analyses. At 980 nm, the upconversion luminescence intensity of the GCs doped with 0.8%Tb3+–0.6%Yb3+ was the strongest. Based on an increase in emission intensity with an increase in pump power, the mechanism of upconversion luminescence was studied. The color purity was calculated using upconversion emission spectra. The final results showed that the GCs have latent development and utilization value in the solar-energy-spectrum conversion of solar cells and optoelectronic communication devices. [ABSTRACT FROM AUTHOR]

Multi‐mode luminescence tuning through in situ crystallization of topological glass holds significance for photonics applications. Here, NaAlSiO4:Eu2+‐based glass ceramics are presented as stable persistent luminescence (PersL) materials by controlling the phase transformation in Eu2+ doped Na2O‐Al2O3‐SiO2 from amorphous glass to crystalline nepheline phase. X‐ray and UV excited PersL colors from blue to yellow are realized by adjusting the crystallization duration time, and trap statuses reveal the dynamic PersL process with a trap redeployment from 0.83 to 1.09 eV during the transformation. Optical information storage model is constructed with a structure of stacked emitting layers to enhance storage capacity. X‐ray excited luminescence time‐lapse imaging is further demonstrated with optical memory longer than 5 days. These findings advance the development of superior stable PersL glass ceramics and offer optical manipulation tactics for multi‐mode optical information storage applications. [ABSTRACT FROM AUTHOR]

High entropy (Y 0.2 Gd 0.2 Lu 0.2 Sc 0.2 Tm 0.2) 2 O 3 transparent ceramics with a single phase of cubic structure were prepared for the first time via vacuum sintering using ZrO 2 as sintering aid. In addition, the content of ZrO 2 was optimized and the investigated systematically. The Zr4+ ions in sintering aid replaced RE3+ sites and produced interstitial oxygen, promoted densification of the ceramics, and inhibited growth of grains. The relative density was increased to 99.79 % from 96.91 %. The grain size reduced from 34.25 μm to 5.68 μm. Due to the higher relative density and smaller grain size, (Y 0.2 Gd 0.2 Lu 0.2 Sc 0.2 Tm 0.2) 2 O 3 transparent ceramics with 1 wt% ZrO 2 had better optical and mechanical properties. The transmittance is better than 75 % at the region of 2–7 μm and reached 80.9 % at 5.43 μm, and the hardness and fracture toughness were 9.179 ± 0.062 GPa and 0.805 ± 0.024 MPa m1/2, respectively. This high-entropy transparent ceramics has potential applications in medium wave atmospheric windows (3–5 μm). [ABSTRACT FROM AUTHOR]

Oxygen vacancy is the key contributing to the rapid bonding in flash joining. Prior to this study, the specific formation process of oxygen vacancy and its influencing factors have not been systematically investigated. In this work, the based materials yttrium oxide and Ti are phased observed during the incubation stage and the flash stage of flash joining. Three periods are summarized to reveal the whole process and variation in oxygen vacancy generation, electron binding, and metal filling. Following the stable stage, the factors impacting the oxygen vacancy are systematically studied and characterized to quantify their contribution. These factors include bonding temperature, current density, joining time, furnace atmosphere, and electric field direction. These findings have significant implications for precisely controlling the strength of the transparent/metal flash joint, meanwhile, may have reference value for universal flash joining. [ABSTRACT FROM AUTHOR]

The electrolytic cell is the main equipment for electrolytic aluminum production. The visual electrolytic cell can observe and study the production process and mechanism of aluminum electrolysis. The effects of Y2O3 addition and sample thickness on the densification behavior and transmittance of Magnesium-aluminate spinel (MAS) were studied. The relative density, porosity, phase composition, microstructure, Vickers hardness, and transmittance of the sintered samples were characterized using the Archimedes method, x-ray diffraction analysis, scanning electron microscopy, Vickers hardness tester, and UV-visible near-infrared diffuse reflection. The results show that the appropriate amount of Y2O3 can enhance the transmittance of MgAl2O4 and the optimum Y2O3 content is 2 wt.%. At this time, the relative density of Magnesium-aluminate spinel (MAS), the maximum hardness, and the maximum transmittance are 96.19%, 18.18 GPa, and 36.3%, respectively. Under the optimum conditions, when the mass of the sample is 0.2 g, the relative density and maximum hardness of the Magnesium-aluminate spinel (MAS) sample are 97.28% and 18.18 GPa, respectively. Although the transmittance is not the highest, it is only lower than the transmittance of 0.15 g sample. The optimum sintering additive content and sample thickness jointly promote the densification, hardness, and transmittance of Magnesium-aluminate spinel (MAS). [ABSTRACT FROM AUTHOR]

Pressureless sintering processing was adopted to fabricate transparent aluminum oxynitride (AlON) ceramics by using magnesium oxide (MgO) as a sintering additive into synthetic single phased aluminum oxynitride powder. Under the condition of adding 0.6 wt% magnesium oxide, the relative density of aluminum oxynitride ceramics increased from 98.67% with no addition to 99.9% after being held at 1800°C for 24 h, coupled by a reducing of average grain size from 190 µm to 130 µm. The optical linear transmittance of the AlON ceramic sample (thickness 1.2 mm) reached 84.2% at the wavelength of 1100 nm. The microstructural characterizations by energy dispersive spectroscopy and atom probe tomography indicated that the doping Mg element was uniformly dispersed inside aluminum oxynitride grains of as‐sintered ceramics. It was demonstrated that magnesium oxide played a key role in inhibiting the movement of grain boundaries, eliminating pores, leading to the fully densification of aluminum oxynitride ceramics. [ABSTRACT FROM AUTHOR]

Transparent alumina ceramics produced by pulsed electric current sintering (PECS) include black dots, which can be observed with the naked eye. These black dots have porous structures caused by the aggregates in the raw powder. In order to investigate the detailed mechanism of black dot formation, transparent alumina ceramics were prepared by sintering α-alumina granules to produce large pseudo-aggregates and introducing them into α-alumina powder for PECS. Macroscopic black dots were formed in the sample. Characteristic Raman peaks of graphite were detected in porous parts of these macroscopic black dots. Analysis of gas phases generated from graphite sheets for PECS suspected to be involved in carbon contamination showed CO and CO 2 generation. In thermodynamic calculations on carbon activity during PECS, gas phase including CO and CO 2 generated from the hot graphite mold/sheet permeates the porous part of the cold sample, and the carbon activity of gases including CO and CO 2 on the porous surface theoretically exceeds unity. Then, CO is adsorbed and decomposed on the porous surface, resulting in carbon contamination. The formation of macroscopic black dots is caused by carbon deposition in agglomerates of the raw powder from CO generated by graphite sheets during PECS. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is one of the most promising technologies for producing polycrystalline transparent ceramics. However, it has limitations regarding the complexity of the geometries that can be produced. This study addresses these limitations by combining additive manufacturing techniques with spark plasma sintering. Additionally, a Multiphysics sintering model based on the continuum theory of sintering is employed to predict the outcomes of the SPS process, particularly the microstructure of the densified parts. As a result, the geometrically complex Al 2 O 3 transparent parts manufactured in this study exhibit a uniform microstructure, high density (∼99 %), and a linear transmittance of 16 % at 490 μm. [ABSTRACT FROM AUTHOR]

Eu3+-doped Y2O3-based luminescent materials can be used as a scintillator for electron or high energy β-ray irradiation, which are essential for applications such as electron microscopy and nuclear batteries. Therefore, it is essential to understand their defect mechanisms and to develop materials with excellent properties. In this paper, Y2O3-based transparent ceramics with different Eu3+ doping concentrations were prepared by solid-state reactive vacuum sintering. This series of transparent ceramic samples exhibits strong red emission under electron beam excitation at the keV level. However, color change appears after the high-energy electron irradiation due to the capture of electrons by the traps in the Y2O3 lattice. Optical transmittance, laser-excited luminescence, X-ray photoelectron spectroscopy (XPS), and other analyses indicated that the traps, or the color change, mainly originate from the residual oxygen vacancies, which can be suppressed by high Eu doping. Seen from the cathodoluminescence (CL) spectra, higher doping concentrations of Eu3+ showed stronger resistance to electron irradiation damage, but also resulted in lower emissions due to concentration quenching. Therefore, 10% doping of Eu was selected in this work to keep the high emission intensity and strong radiation resistance both. This work helps to enhance the understanding of defect formation mechanisms in the Y2O3 matrix and will be of benefit for the modification of scintillation properties for functional materials systems. [ABSTRACT FROM AUTHOR]

Lanthanide-ion-doped red upconversion (UC) fluorescent materials with excellent signal-to-noise ratio, stability, and red-green luminous intensity ratio have proven of tremendous research importance for biomedical, three-dimensional (3D) displays, sensors, and other sectors. In this study, xYb, 1Er: Sr 5 (PO 4) 3 F (S-FAP) (x=0–5 at%) transparent ceramics with outstanding optical quality were fabricated by hot pressing the co-precipitation powder with high sintering activity. The energy dispersive X-ray (EDX) results showed that the trivalent lanthanide ions were evenly doped into the S-FAP ceramic lattice. Increased Yb3+ doping considerably restricted the growth of ceramic grain size, which should be attributable to a decrease in sintering activity under high Yb doping conditions. The co-doping of Yb3+ successfully resulted in a significant improvement in up/down conversion efficiency via effective energy transfer mechanisms and the optimization of the electron population at the energy level of red-green emission. Furthermore, single-band red upconversion luminescence with the greatest red-green upconversion luminescence integral intensity ratio of 125.74 was discovered under 980 nm laser pumping at room temperature. The energy transition process involved in the phenomenon of the up-conversion luminescence intensity shift of red-green emission has been thoroughly examined. Finally, the noncontact optical thermometric ability based on fluorescence intensity ratio (FIR) technology showed that the maximum absolute sensitivity (Sa) of the 5Yb1Er sample in the temperature range of 320–556 K is 1.1×10−3 K−1, implying the possible use of Yb/Er-doped S-FAP transparent ceramics in the field of optical thermometers. [ABSTRACT FROM AUTHOR]

High entropy or multi-principles component oxides as a new class of materials have been widely investigated for various applications due to their unique properties and multi-functionalities in recent years. In this study, a high entropy transparent ceramics ((Gd 0.2 Tb 0.2 Y 0.2 Lu 0.2 Yb 0.2) 3 Al 5 O 12) has been fabricated by spark plasma sintering (SPS) using co-precipitation synthesized powders. The powder preparation process was studied by TAG-DSC and FTIR. The phase structure, morphology, and element distribution of the obtained powder and ceramic samples are explored by XRD, SEM, and EDS mapping. It shows that the high entropy oxide (HEO) ceramic powder has a pure garnet phase, nanoparticle size, and homogenous elements distribution. The sintered ceramic exhibits the highest in-line transmittance in the visible and IR range of approximately 52 % at 700 nm and 74 % at 3.6 μm, respectively. In addition, characteristic optical properties of the final ceramics were demonstrated by photoluminescence spectroscopy. This work indicated that high-entropy garnet transparent ceramics with multi-wavelength emissions will provide more possibilities for multifunctional optical applications in the future. [ABSTRACT FROM AUTHOR]

The resent progress in the technology of transparent ceramics extends the application of CW and pulsed lasers. The parameters of the transparent ceramics are comparable with the single crystals both for active elements (Nd:YAG, Yb:YAG, etc.) and passive Q-switchers such as Cr4+:YAG. Despite the reaching of considerable progress, the sintering of Cr4+:YAG remains a challenge up to now. Up to the present the influence of the CaO, MgO and Cr 2 O 3 additives on the sintering process is poorly understander. Moreover, there is an absence of the unified model of Cr4+ ions formations in YAG ceramics. This factor limits the progress in the development of Cr4+:YAG ceramics. This review focused on the influence of the single additives and their combinations on the sintering trajectory of tetravalent chromium - doped YAG ceramics and the Cr4+ ions formation. [ABSTRACT FROM AUTHOR]

In this work, the plastic deformation of micro/nanoscale AlON ceramic pillars with different crystallographic orientations was investigated by in situ compression on scanning electron microscopy (SEM) system. The experimental results demonstrated a "smaller is stronger" size dependence of the yield strength of <100>-, <110>- and <111>-oriented AlON micro/nanopillars with scaling exponents of −0.19, −0.24 and −0.33, respectively. Transmission electron microscopy (TEM) illustrated that the Lomer-Cottrell dislocation reaction dominated the plastic deformation of <111>-oriented pillars. The plastic deformation of <110>-oriented AlON pillars was driven by rotation of the slip region, whereas the stress of <001>-oriented pillars were released through microcracks and plastic deformation. • In situ compression of micro/nanopillars. • Nanomechanical of AlON transparent ceramic. • The size dependent property of different crystallographic orientations AlON pillars. • The plastic deformation phenomenon of AlON micro/nanopillars at room temperature. • The variation of AlON plastic deformation mechanisms with different crystallographic orientations. [ABSTRACT FROM AUTHOR]

The large piezoelectric coefficient (d 33) and high mechanical quality factor (Q m) are essential for piezoelectric ceramics used in high-power devices. It is pity that the two parameters are usually opposite, with higher d 33 corresponding to lower Q m. In order to well-balance the d 33 and Q m , the rare-earth element Ce with multi-valence was introduced into the 0.06 Pb(Sc 1/2 Nb 1/2)O 3 -0.61 Pb(Mg 1/3 Nb 2/3)O 3 -0.33PbTiO 3 (x Ce-PSN-PMN-PT) ceramics in this work. The structure, electrical properties and optical properties of ceramics were systematically analyzed. Optimal electrical performances (d 33 = 719 pC/N, Q m = 256, and dielectric loss tan δ = 0.007) were obtained in 0.02Ce-PSN-PMN-PT ceramics. These excellent performances originate from the multiscale coordination effects among defect dipoles, local structural heterogeneity, domain structure, phase structure, and grain size. The x Ce-PSN-PMN-PT ceramics exhibit excellent photoluminescence properties in the blue wavelength range. Our research provides a new paradigm for deep-sea electro-optical communication. [ABSTRACT FROM AUTHOR]

In response to the limitations of current transparent window materials in γ-ray shielding scenarios, herein, high-lead equivalent (0.865 mmpb) Yb 2 Hf 2 O 7 transparent ceramics (YbHO-TCs) were prepared via a solid-state reaction and vacuum sintering. The fabricated YbHO-TC shows high transparency, where the in-line transmittance up to 78.9 % at 1200 nm, which is extremely close to their theoretical limit (79 %). Additionally, the linear absorption coefficient of YbHO-TC for γ-rays is 0.482, approximately twice that of the state-of-the-art lead glass materials widely employed in radiation-shielding windows. Remarkably, YbHO-TC displayed no discoloration, and its in-line transmittance exhibited little change even when exposed to a radiation dose as high as 800 kGy. The innovative developed YbHO-TC integrates high transparency and high-lead equivalent properties, not only rending them highly promising for deployment as γ-rays shielding windows but also inspiring the controllable design of high-performance optical windows tailored for use in radiation shielding applications. [ABSTRACT FROM AUTHOR]

Optical ceramics with 50 at.% Sc in both dodecahedral ({Y 1·17 Er 0.03 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12 , {Y 1.2 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12) and octahedral ({Y 2·52 Er 0.03 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12 , {Y 2.55 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12) sites of the garnet structure were synthesized using the non-reactive vacuum sintering method. Analysis of the phase composition, thermal diffusivity, transmission in the visible and IR regions of the spectrum, as well as luminescent properties (Stokes and anti-Stokes luminescence, luminescence decay kinetics) revealed clear correlations with the chemical composition of ceramics. It has been determined that solid solutions in which Y3+ cations are partially replaced by Sc3+ cations, compared to solid solutions in which Al3+ cations in the octahedral site are partially replaced by Sc3+, are characterized by lower crystal lattice parameters (11.883 ± 0.004 Å and 12.153 ± 0.005 Å); lower thermal conductivity values (4.72 W/(m·K) and 5.9 W/(m·K)); higher characteristic vibration frequencies of structural groups; shorter lifetimes of excited states of Yb3+ (1.41 μs and 1.56 μs for YSAG:Yb; 0.42 μs and 0.65 μs for YSAG:Yb,Er) and Er3+ (8.6 μs and 9.2 μs) cations; higher efficiency of energy transfer from Yb3+ to Er3+. The results clearly indicate that solid solutions with high concentrations of Sc3+ cations in the dodecahedral site can also be effective matrices for Yb3+ and Er3+ cations compared to solid solutions with a predominant introduction of scandium in the octahedral site. [ABSTRACT FROM AUTHOR]

The lack of red light components in solid-state lighting technology urgently requires the development of new efficient red-emitting bulk phosphors. Herein, we successfully prepared a kind of red-emitting glass ceramics (GCs) (λ ex = 392 nm, λ em = 613 nm) containing Eu-doped strontium fluorophosphates (Sr 5 (PO 4) 3 F:Eu) nanocrystals via a melt-quenching method in SrF 2 –K 2 CO 3 –P 2 O 5 –H 3 BO 3 glass. The heat treatment temperature was found to significantly affect the grain size of the Sr 5 (PO 4) 3 F:Eu nanocrystals as well as the transmittance of the prepared GCs. After heat treatment at 600 °C for 2 h, the Sr 5 (PO 4) 3 F:Eu nanocrystals with grain size of about 18 nm were precipitated inside the GCs (GC600), which exhibited a high transmittance of 58–70 % in the range of 500–800 nm, with a stronger luminescence intensity than that of PG. Under excitation of 392 and 464 nm wavelengths, the CIE 1931 color coordinates of GC600 were around (0.626, 0.373) and (0.638, 0.362), respectively, both falling in red region. The present Sr 5 (PO 4) 3 F:Eu GCs are promising as red phosphors for UV-pumped white-light LEDs. [ABSTRACT FROM AUTHOR]

Advancements in laser glass compositions and manufacturing techniques has allowed the development of a new category of high-energy and high-power laser systems which are being used in various applications, such as for fundamental research, material processing and inertial confinement fusion (ICF) technologies research. A ceramic laser is a remarkable revolution in solid state lasers. It exhibits crystalline properties, high yields, better thermal conductivity, a uniformly broadened emission cross-section, and a higher mechanical constant. Polycrystalline ceramic lasers combine the properties of glasses and crystals, which offer the unique advantages of high thermal stability, excellent optical transparency, and the ability to incorporate active laser ions homogeneously. They are less expensive and have a similar fabrication process to glass lasers. Recent developments in these classes of lasers have led to improvements in their efficiency, beam quality, and wavelength versatility, making them suitable for a broad range of applications, such as scientific research requiring ultra-fast laser pulses, medical procedures like laser surgery and high-precision cutting and welding in industrial manufacturing. The future of ceramic lasers looks promising, with ongoing research focused on enhancing their performance, developing new doping materials and expanding their functional wavelengths. The ongoing progress in high-power ceramic lasers is continuously expanding the limits of laser technology, therefore allowing the development of more powerful and efficient systems for a wide range of advanced and complex applications. In this paper, we review the advances, limitations and future perspectives of ceramic lasers. [ABSTRACT FROM AUTHOR]

Yttrium oxide (Y2O3)$( {{{\mathrm{Y}}}_2{{\mathrm{O}}}_3} )$ has the potential to be used as a host material for creating polycrystalline transparent ceramics (PTCs). This paper presents an experimental study on opto‐electrical properties of Y2O3${{\mathrm{Y}}}_2{{\mathrm{O}}}_3$ using zirconium oxide (ZrO2)$( {{\mathrm{ZrO}}_2} )$ and lanthanum oxide (La2O3)$({\mathrm{La}}_2{{\mathrm{O}}}_3)$ as sintering aids via the co‐precipitation technique. The sintering aids improve the properties, sintering process, and lower the sintering temperature. Five different compositions of Y2O3(((Y1−xZr0.02Lax)2O3),wherex=0,3,6,and9at.%)${{\mathrm{Y}}}_2{{\mathrm{O}}}_3\ ( {({{( {{{\mathrm{Y}}}_{1 - x}{\mathrm{Zr}}_{0.02}{\mathrm{La}}_x} )}}_2{{\mathrm{O}}}_3} ),{\mathrm{\ where\ }}x = 0,\ 3,\ 6,{\mathrm{\ and\ }}9{\mathrm{\ at}}.{\mathrm{\% }})$ were synthesized and they were then used to analyze for their structural, morphological, physio‐chemical, and electrical characteristics. For the system studied, the addition of ZrO2${\mathrm{ZrO}}_2$ and La2O3${\mathrm{La}}_2{{\mathrm{O}}}_3$ does not change the phase of pure Y2O3${{\mathrm{Y}}}_2{{\mathrm{O}}}_3$, but an increase in the crystal and grain size from 31.2$31.2$ to 42.5nm$42.5{\mathrm{\ nm}}$ and 10.2 µm to 16.4 µm was noticed. The thermal characterization over thermogravimetric analysis/differential thermal calorimetry (TGA/DSC) determines the temperature at which pure Y2O3${{\mathrm{Y}}}_2{{\mathrm{O}}}_3$ undergoes a phase transition, specifically over 700°C. A reduction in the band gap due to strain induced by the dopant resulted in a decrease in energy from 5.54$5.54$ to 4.8eV$4.8{\mathrm{\ eV}}$. The dielectric constant of Y2O3${{\mathrm{Y}}}_2{{\mathrm{O}}}_3$ doped with 9at.%La$9{\mathrm{\ at}}.{\mathrm{\% \ La}}$ exhibits a significant increase of ∼50%${\sim}50\%$. [ABSTRACT FROM AUTHOR]

Transparent yttrium aluminum garnet (YAG) exhibits high hardness and abrasive resistance, making it a promising candidate for applications involving material contact, such as protective optical elements, windows, domes, and armors. When transparent YAG is employed in such applications, it may be susceptible to degradation due to friction, chemical exposure, or thermal stress. Despite its potential, there is limited research on the tribological behavior of transparent YAG. In the present study, transparent YAG ceramics were fabricated by reaction sintering of high‐purity Al2O3 and Y2O3 powders. The transparent YAG specimens had an average grain size of 20 ± 6 µm and hardness of 1068.98 ± 115.15 HV, and fracture toughness of 1.27 ± .06 MPa.m0.5. The effect of load variation from 5 to 15 N on the tribological behavior of transparent YAG was investigated when slid against chrome steel (100Cr6) balls with a hardness of 815 ± 75 HV. The low coefficient of friction (COF) and wear rate were observed due to the wedge formation (fish‐scale‐like pattern) at the surface when the load was increased from 5 to 10 N. Moreover, tribochemical layer formation, fracture, and material transfer were observed when the load was increased from 10 to 15 N, leading to high COF and increased wear rate. [ABSTRACT FROM AUTHOR]

SrAl2O4:Eu2+, Dy3+ (SAED) is one of the most popular materials for information storage and night display applications because it has a wide excitation range and long afterglow duration. However improving the hydrolytic resistance of SAED remains a challenge. In this study, the SAED is presented to be the ceramic type by a solid‐state reaction in a vacuum ambiance. The achieved SAED ceramic has 8200 mcd m−2 initial luminescence intensity. It can also obtain long‐persistent luminescence after UV light irradiation even soaking in water for more than 30 days. This ceramic demonstrates sustained imaging capability irradiated under 365 nm UV light and X‐ray, as well as erasability and reproducibility of storage by lighting and heating. These results indicate the promising applications of SAED ceramics in optical information storage and night display in complex environments. The phase evolution in the SAED ceramic is identified directly in the micromorphology for the first time based on scanning electron microscopy coupled with a cathodoluminescence system. [ABSTRACT FROM AUTHOR]

By pre-milling in glucose aqueous solution, γ-Al 2 O 3 particles were uniformly mixed with carbon via hydrothermal treatment technique. Then, directly heating the γ-Al 2 O 3 /C precursor at 50 °C/min to 1775 °C for 15–30 min in N 2 , single phase AlON powder was fast obtained through one-step carbothermal reduction and nitridation (CRN). By approaching the evolution of phase assemblages and morphology during heating and dwelling, the one-step fast CRN mechanism for preparing fine AlON powder was revealed. The carbon around γ-Al 2 O 3 particles delayed the phase transformation of Al 2 O 3 from γ phase to α one. The undesired particle aggregation and growth before formation of AlON was also auxiliarily inhibited by swiftly achieving AlON formation temperature via high heating speed. Further elevating synthesis temperature enabled high reaction kinetics to boost the speed of AlON formation. By these ways, CRN reactions were quickly completed to fast obtain pure AlON powder with small primary particles due to limited particle aggregation and growth. The as-prepared fine AlON powder was easy to be ball-milled to prepare highly transparent AlON ceramics by pressureless sintering. [ABSTRACT FROM AUTHOR]

Ho3+-Yb3+ co-doped glass ceramics containing LiGd(WO 4) 2 were prepared by melt crystallization method. By using the methods of differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmittance, and scanning electron microscopy (SEM), the optimal heat treatment condition for the samples was identified to be 580 °C/140 min. In these conditions, the transmittance of glass ceramic is about 75 % in the 380–780 nm range. In the upconversion emission spectra, strong green emission (543 nm) and red emission (650 nm) due to 5F 4 /5S 2 , 5F 5 →5I 8 transitions are observed at 980 nm excitation. Additionally, the optimum doping concentrations of Ho3+ and Yb3+ were 0.12 % and 0.4 %. The crystal field changes around dopant ions were analyzed using J-O theory and Eu3+ probe to explain the up-conversion luminescence enhancement of glass ceramics containing LiGd(WO 4) 2. The chrominance coordinates of 0.12 % Ho3+-0.4 % Yb3+ co-doped glass ceramics are located in the green light region, and the color purity is 95.6 %. In summary, Ho3+-Yb3+ co-doped transparent glass ceramics containing LiGd(WO 4) 2 have potential applications in infrared detection and green solid-state lasers. [ABSTRACT FROM AUTHOR]

Next‐generation high‐brightness lighting faces a big challenge in developing laser‐drivable color‐converting materials with effective thermal management. Herein, a new material architecture of Al2O3‐Y3Al5O12: Ce3+ (YAG: Ce) transparent composite ceramics coated with Al film (TCC@Al) is proposed. The as‐prepared material shows the highest thermal conductivity (29.3 W m−1 K−1) among YAG: Ce‐related transparent ceramics (TC) ever reported owing to the combination role of short‐range thermal conduction of Al2O3 microcrystals and long‐range thermal conduction of Al film. Temperature‐dependent photoluminescence (PL) spectra and femtosecond transient absorption (fs‐TA) spectra evidence the importance of thermal management, whereby the luminescent loss of TCC@Al is only 8.92% at 450 K and is far smaller than TC counterpart (15.86%). Importantly, no obvious luminescence saturation is detected upon 20 W mm−2 blue laser irradiation and the inhomogeneous angular color distribution is suppressed by the scatter of Al2O3 microcrystals, yielding uniform white light with ultra‐high luminous flux (LF) of 4294 lm@20 W mm−2 and luminous efficacy (LE) of 215 lm W−1. As a consequence, the present TCC@Al‐converted laser‐driven lighting prototype exhibits much better optical performance than the commercial TC‐based one. [ABSTRACT FROM AUTHOR]

Transparent glass‐ceramics, merging the attributes of both glass and ceramics, have diverse applications in ballistic protection, armor materials, dentistry, light‐emitting diode, and optical domains. A limitation of conventional methods for glass‐ceramic fabrication is their inadequacy in precisely controlling the morphology of crystallization, consequently constraining their prospective advancements in diverse areas. Here, a method that facilitates precise control over the formation and growth of polarization‐dependent nonperiodic anisotropic nanocrystals, with a short axis ranging from 15 to 280 nm, in Li2O‐Al2O3‐SiO2 (LAS) glass is proposed. The method utilizes the principles of near‐field anisotropy between light and matter, building upon the classical nucleation‐growth model of glass crystallization. Notably, the glass‐ceramics possessing laser‐induced nanocrystals within the Rayleigh size regime showcase an impressive 99.7% transmittance in the visible and near‐infrared wavelengths. Additionally, the glass‐ceramics with non‐periodic anisotropic nanocrystals macroscopically exhibit form‐birefringence properties, thus enabling transparent optical applications, such as polarization elements, geometric phase elements, and multi‐dimensional optical data storage. This work opens up new avenues for morphological manipulation of nanocrystallization, with potential applications in optics, nanophotonics, functional glass‐ceramics, and high mechanical performance devices. [ABSTRACT FROM AUTHOR]

The optical properties and microstructure of composites based on yttrium aluminum garnet were studied. The composites were produced by vacuum sintering of pre-formed compacts of nanocrystalline powder (Y3Al4.995Cr0.005O12) with a YAG single crystal. The transmittance spectra of the composite samples exhibited the presence of Cr3+ absorption bands following vacuum sintering, as well as Cr4+ bands following annealing in air. The impact of varying heating rates during vacuum sintering on the transmittance of composite samples was examined. It was determined that the optimal heating rate during the vacuum sintering of composites should be less or equal to 120 K/h. In addition, the impact of the vacuum sintering temperature on the optical properties and microstructure of YAG:Cr (ceramics)/YAG:Nd (single crystal) composite samples was investigated. The samples exhibiting the highest transparency were obtained at a temperature of 1850°C. Microstructure studies of the composites revealed the presence of regular residual porosity in the vicinity of the interface, predominantly located in the YAG single crystal. It is postulated that the formation of these pores occurs during the fusion of ceramic grains with a single crystal during sintering. [ABSTRACT FROM AUTHOR]

The paper deals with transparent MgAl2O4 ceramics reinforced with 0.1 vol.% Al2O3 nanofibers and manufactured by spark plasma sintering at 1400°C and 100 MPa. The microstructure of MgAl2O4 ceramic samples is studied by the X-ray phase analysis and scanning electron microscopy. The optical properties are investigated in 190 to 8000 nm wavelength range. The influence of Al2O3 nanofibers on optical and mechanical properties of ceramics is discussed herein. [ABSTRACT FROM AUTHOR]

A vanadium ion valence state constant high-entropy perovskite system was synthesized using the hydrothermal method with a trivalent vanadium ion as the vanadium source. The B-site of the perovskite crystal lattice was loaded with five atoms in equal proportions. We tried to synthesize the Sr(TiZrHfVNb)O3 high-entropy system using different methods. However, the valence state of the vanadium ion could only be kept constant using the hydrothermal process in the valence balanced high-entropy composition system. There was significant vanadium element segregation and second phase in the Sr(TiZrHfVNb)O3 system prepared using the solid-state reaction process. Also, obvious vanadium ion valence state ascending from V3+ to V5+ appeared in this high-entropy system with an increase in calcination temperature. Inconspicuous vanadium element segregation appeared at 900 °C, the significant segregation phenomenon and second phase appeared at 1200 °C, and the particle size increased with the temperature. This meant that the high-entropy value could not only stabilize the crystal phase, but also stabilize the ionic valence state. Moreover, the constant trivalent vanadium ion valence state could provide coordinated performance with a wide optical response range and a low band gap for the high-entropy system. This suggests that the system might grow a potential ceramic material for optical applications. [ABSTRACT FROM AUTHOR]

High‐quality magnesium aluminate spinel (MAS) transparent ceramics were successfully fabricated using Y3Al5O12 (YAG) as the sintering additive. The influence of the YAG content on the sintering behavior, microstructure, and optical properties of the MAS transparent ceramics was systematically investigated. A 4 mm‐thick sample with 0.01 wt.% YAG hot isostatic pressed at 1600°C achieved the highest in‐line transmittance of 84.0% at 400 nm and the flexural strength of the sample was as high as 347.3 MPa, which represents the highest‐performing reported MAS transparent ceramics that were sintered with oxide additives. [ABSTRACT FROM AUTHOR]

Pore-closed ZnAl 2 O 4 ceramic can hardly be pressureless sintered from conventional (>100 nm) powder, which restricts the fabrication of the transparent ceramic by capsule-free hot isostatic pressing technique. This work focused on the effect of yttrium-doping on the microstructural evolution in the sintering of a ∼180-nm ZnAl 2 O 4 powder. At a concentration of 300 or 600 ppm, the yttrium ions segregated along the grain boundaries and contributed to ordered nanostructures, which could suppress abnormal grain growth in both air sintering and hot isostatic pressing. The optimized Y-doped ZnAl 2 O 4 transparent ceramic owned good visible light transmittance (>65 %) and a wide transmission range (6.0 μm at the 60 % transmittance) at a thickness of 1.5 mm, as well as high thermal conductivity (24.9 W·m−1·K−1) and reasonable mechanical properties (Vickers hardness of 12.9 GPa and Young's modulus of 281.3 GPa), meeting the application requirements for infrared windows. [ABSTRACT FROM AUTHOR]

Thermal plasma melting was applied to mixtures of MgO, Al 2 O 3 and Tb 4 O 7 to synthesize the MgAl 2 O 4 :Tb3+ (0.1–10 % wt. Tb 4 O 7) luminescent ceramics series. Coarse-grained spinel materials (0.1–1 mm) with preferred crystal orientation were obtained. Structural, morphological (XRD and SEM) and spectroscopic (cathodoluminescence and Raman spectroscopy) analysis were used to investigate the influence of Tb 4 O 7 content on ceramics phase composition, cell parameter of MgAl 2 O 4 :Tb3+, the inversion degree, and luminescent properties. It was found that the thermal plasma synthesized spinel ceramics exhibit a non-controlled inversion degree. The formation of TbAlO 3 as a by-product was observed in materials containing more than 1 wt% of Tb 4 O 7. It was demonstrated that the thermal plasma melting method could be potentially applied for fast preparation of MgAl 2 O 4 :Tb3+ luminescent ceramics. [ABSTRACT FROM AUTHOR]

Transparent glass-ceramics containing nanorods are attractive for many applications. In this work, transparent aluminoborosilicate glass-ceramics containing aluminum borate nanorods are reported. Effects of Al 2 O 3 and SiO 2 concentrations on the thermal properties and crystallization of aluminoborosilicate glasses are studied. It is found that lithium aluminosilicate nanocrystals and Al 4 B 2 O 9 nanorods are co-precipitated in glasses with Al 2 O 3 /SiO 2 molar ratios of 0.29 and 0.33, and only Al 4 B 2 O 9 nanorods are precipitated in glasses with Al 2 O 3 /SiO 2 molar ratios of 0.375 and 0.42. Precipitation of these nanocrystalline phases leads to the enhancement in Vickers hardness. Glass-ceramics with Al 2 O 3 /SiO 2 molar ratios of 0.375 and 0.42 are highly transparent in the visible region due to the small size of the Al 4 B 2 O 9 nanorods precipitated inside. [ABSTRACT FROM AUTHOR]

MgAlON ceramics with excellent optical properties were synthesized using high-purity AlON and commercially available MgO powder. The effect of MgO amount on ceramic sintering was examined in terms of microstructural evolution and grain growth. Furthermore, the process of MgAlON phase formation through the reaction between AlON and MgO was studied. The results revealed that the addition of MgO significantly hindered the formation of α-Al 2 O 3 and AlN phases at temperatures ranging from 1350 °C to 1600 °C, thereby facilitating the stabilization of the spinel-type phase. The optical transmittance and Vickers hardness of MgAlON were investigated through pressureless sintering followed by hot isostatic pressing (HIP). The resulting ceramics, with a MgO mass ratio of 10.0 wt%, exhibited an excellent in-line transmittance of ∼82.9 % at 0.6 μm and 87.7 % at 3.7 μm, and a remarkable Vickers hardness of approximately 13.65 ± 0.21 GPa. [ABSTRACT FROM AUTHOR]

In this study, instrumented indentation experiments were performed under different loads on the polished surface of aluminum oxynitride (AlON) ceramics to investigate their surface fracture behavior and indentation response under quasi-static conditions. The results showed that the AlON transparent ceramics exhibited a typical indentation size effect (ISE) at the microloading scale, unlike the nano-indentation experiments, owing to a change in the material's destruction mechanism. The loading response process of the ceramics under the indenter shape was analyzed using different material parameters. The strain gradient effects were considered, and the ISE on the materials was characterized and analyzed. Based on the experimentally derived indentation stress-strain curve, an improved analytical model is proposed to estimate the stress field around an elastoplastic indentation/contact. The proposed model demonstrates excellent agreement with finite element analysis. The results suggest that a significant geometrical similarity exists in the conical indenter loading, and the state of the stress field is strongly dependent on the indentation index ε i. [ABSTRACT FROM AUTHOR]

Yb:CaF2 transparent ceramics represent a promising laser gain medium for ultra-short lasers due to their characteristics: low phonon energy, relatively high thermal conductivity, negative thermo-optical coefficient, and low refractive index. Compared to single crystals, Yb:CaF2 ceramics offer superior mechanical properties, lower cost, and it is easier to obtain large-sized samples with proper shape and uniform Yb3+ doping at high concentrations. The combination of air pre-sintering and Hot Isostatic Pressing (HIP) emerges as a viable strategy for achieving high optical quality and fine-grained structure of ceramics at lower sintering temperatures. The properties of the powders used in ceramic fabrication critically influence both optical quality and laser performance of Yb:CaF2 ceramics. In this study, the 5 atomic percentage (at.%) Yb:CaF2 transparent ceramics were fabricated by air pre-sintering and hot isostatic pressing (HIP) using nano-powders synthesized through the co-precipitation method. The co-precipitated powders were optimized by studying air calcination temperature (from 350 to 550 °C). The influence of calcination temperature on the microstructure and laser performance of Yb:CaF2 ceramics was studied in detail. The 5 at.% Yb:CaF2 transparent ceramics air pre-sintered at 625 °C from powders air calcined at 400 °C and HIP post-treated at 600 °C exhibited the highest in-line transmittance of 91.5% at 1200 nm (3.0 mm thickness) and the best laser performance. Specifically, a maximum output power of 0.47 W with a maximum slope efficiency of 9.2% at 1029 nm under quasi-CW (QCW) pumping was measured. [ABSTRACT FROM AUTHOR]

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In recent years, transparent terbium gallium garnet (TGG) ceramics have garnered significant interest for their application in high‐power Faraday isolators. However, challenges in achieving high transparency have led researchers to explore the addition of various sintering aids as a key strategy to enhance the optical quality of TGG ceramics. Through this work, the effect of germanium (Ge) addition on the microstructure and optical transparency of TGG magneto‐optical ceramics was investigated. TGG powders were synthesized by the co‐precipitation method, and the source Ge was Ge ethoxide added through a ball‐milling step. Transparent TGG ceramics were prepared by air pre‐sintering combined with hot isostatic pressing post‐treatment and subsequent annealing. The ceramics containing 200 ppm Ge exhibit optimal transmittance of 81.3% at 1064 nm (a value of theoretical transmittance), the Verdet constant was −133.0 rad·T−1·m−1 at 633 nm. When the addition of Ge reaches 600 ppm, a secondary phase can be observed on the surface of ceramic. Subsequently, TGG ceramics prepared from 1425°C to 1500°C with 200 ppm of Ge were analyzed, which revealed that the optimal pre‐sintering temperature is 1450°C. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3) has attracted much attention due to its promising applications in optical and electronic devices, while it is difficult to fabricate high‐quality Ga2O3 transparent ceramics because of the non‐cubic crystal structure. In this work, fully densified undoped and rare earth (RE = Tb, Dy. Er)‐doped Ga2O3 transparent ceramics were successfully fabricated by using spark plasma sintering (SPS) and co‐precipitated ceramic powders. Both the powders and ceramics showed pure monoclinic β‐ Ga2O3 crystal structure and unique orientation. After sintering by SPS for 30 min, all the ceramics reached a relative density higher than 99.21%. The total transmittance of RE‐doped Ga2O3 transparent ceramics ranges from 60% to 69% originating from the oriented and dense microstructures. The photoluminescence spectra and fluorescence lifetime of RE‐doped Ga2O3 transparent ceramics confirm characteristics of energy transfers corresponding to Tb3+, Dy3+, or Er3+ ions in the visible and NIR spectral region. This study demonstrates that oriented RE‐doped Ga2O3 transparent ceramics have great potential to be used in various optical applications. [ABSTRACT FROM AUTHOR]

The 8.3 at.% Yb-doped yttrium-scandium-aluminum garnet (YSAG) ceramics were fabricated by a modified reverse co-precipitation method followed by uniaxial and cold isostatic pressing, annealing in air and high-temperature sintering in vacuum. Spectroscopic and lasing properties were investigated in dependence on Y/Sc/Al ratio in ceramic composition. Optical transmission of Yb:YSAG ceramics in visible and near-infrared spectral range exceeds 80 % that indicates a high quality of the Yb:YSAG samples. Among all the ceramics, the Y 2.35 Yb 0.25 Sc 1.00 Al 4.40 O 12 composition demonstrates the best lasing performance and the highest slope efficiency up to 75 %. [ABSTRACT FROM AUTHOR]

In the case of low-temperature fabrication aiming at transparent polycrystalline YAG ceramics with fine grain size, it is easy to retain trace amounts of the intermediate YAP phase, thereby reducing the optical transmittance. To address this issue, adding a small amount of Al 2 O 3 to the starting YAG powder was found to promote the transformation of the residual YAP phase to the YAG phase at low temperatures. The study investigated the effect of sintering temperature and excess Al 2 O 3 amount on preparing transparent YAG ceramics by hot pressing. The transmittance of the Al 2 O 3 -aided single-phase YAG ceramic (2 mm thick) prepared using the two-step sintering reached 43.4 % at 400 nm and 71.8 % at 1064 nm, with a grain size of about 2 μm, while the transmittance of the multiphase YAG ceramic without Al 2 O 3 addition was less than 1 % at both wavelengths. [ABSTRACT FROM AUTHOR]

Highly sinterable nanopowder of 8 mol% yttria-stabilized cubic zirconia (8YSZ) was synthesized via a hydrothermal homogeneous precipitation (HHP) method. The nanopowder with an average particle size of 26 nm, exhibits good dispersibility, narrow particle size distribution and high purity, making it ideal raw material for preparing transparent ceramics. Utilizing spark plasma sintering (SPS) under mild conditions (1200–1350 °C, 80 MPa, 10 min) in contrast to hot isostatic pressing (HIP), cubic zirconia ceramics with favorable optical and mechanical properties were produced. The sample sintered at 1250 °C achieved the highest transmittance of 74 %@850 nm, significantly surpassing the performance of samples prepared from two other commercial 8YSZ powders. Furthermore, the specimen sintered at 1200 °C with a dense fine microstructure (relative density: 99.51 %, grain size: 460 nm), demonstrated the highest hardness and fracture toughness, reaching 15.72 GPa and 1.28 MPa m1/2, respectively. [ABSTRACT FROM AUTHOR]

Using the method of non‐reactive sintering of nanocrystalline powders, highly transparent samples of optical ceramics based on solid solutions of yttrium‐scandium aluminum garnets containing 50 at.% scandium in the dodecahedral position and doped with erbium (1 at.%) and ytterbium (0–49 at.%) cations (YSAG:Yb:Er) were produced. The influence of Yb3+ concentration on the crystal lattice parameter, density, refractive index, stability of YSAG:Yb:Er solid solutions during high‐temperature sintering, thermal conductivity, optical transmittance and absorption coefficients in the wavelength range from 200 to 1100 nm, as well as Stokes and anti‐Stokes luminescence, was determined. The revealed patterns make it possible to fine‐tune the physical and chemical characteristics of ceramics for the design of composite laser materials. [ABSTRACT FROM AUTHOR]

Rare earth ion-doped Y3Al5O12 (YAG)-based transparent ceramics have been used as important laser gain media for a long time, yet the doping concentration of active ions is limited due to concentration quenching, wherein the inflexion concentration quenching of Nd3+ is recognized as 1.0 at%. In this work, YAG–Al2O3 nanocrystalline transparent ceramics with a concentration of Nd3+ (0–5.0 at%) were fabricated via amorphous crystallization, and the crystal structure evolution, morphology, and optical properties were systematically investigated by differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), magnetic resonation (MAS), nuclear magnetic resonation (NMR), and fluorescence spectroscopy. The doping of Nd3+ can promote the transition of Al[5] and Al[6] to Al[4], indicating improvements in the ability of the amorphous material to form Nd3+:Y2O3–Al2O3 vitrified beads, and 1.5 at% Nd3+:YAG–Al2O3 nanocrystalline transparent ceramics can be obtained by crystallization at 1050 °C with a matrix composed of YAG and concomitant δ-Al2O3 and θ-Al2O3. The nanocrystalline transparent ceramics show an internal transmittance of 89.56% at 1064 nm, and the strongest emission peak corresponds to the energy transfer from 4F3/2 to 4I11/2 of Nd3+ with a fluorescence lifetime of 231 μs when pumped by an 808 nm laser. Specifically, spectral broadening begins to occur, indicating the onset of concentration quenching, when the concentration of Nd3+ exceeds 1.5 at%, substantially higher than the 1.0 at% observed in YAG ceramics. YAG–Al2O3 nanocrystalline transparent ceramics obtained by amorphous crystallization can be utilized as the matrix to increase the inflexion point of doping concentration quenching of Nd3+, and this material may have great potential as a laser gain medium.

Ultraviolet (UV) radiation poses risks to both human health and organics. In response to the urgent demand for UV-shielding across various applications, extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films. However, existing UV shielding materials, though suitable for daily use, cannot meet the demands of extreme conditions. In this work, we incorporated CeO2 as a UV absorber into Y2O3 transparent ceramics for UV-shielding. The effect of CeO2 concentration on the optical, mechanical, and thermal properties of Y2O3 ceramics was systematically investigated. These findings indicate that CeO2 serves not only as a UV absorber but also as an effective sintering aid for Y2O3 transparent ceramics. The 5 at% Ce-doped Y2O3 transparent ceramics exhibit the optimal optical quality, with in-line transmittance of ~77% at 800 nm. The introduction of Ce shifted the UV cutoff edge of Y2O3 transparent ceramics from 250 to 375 nm, which was attributed to the visible band absorption of Ce4+. This shift grants UV shielding capabilities to Y2O3 transparent ceramics, resulting in 100% shielding for ultraviolet C (UVC, 100–280 nm) and ultraviolet B (UVB, 280–320 nm) and ~95% shielding for ultraviolet A (UVA, 320–400 nm). The service stability (optical properties) under various corrosive conditions (acid, alkali, UV irradiation, and high temperature) was investigated, confirming the excellent stability of this transparent ceramic UV-shielding material. A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses, films, and coatings was conducted. Our work provides innovative design concepts and an effective solution for UV-shielding materials for extreme conditions.