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Terbium aluminum garnet (Tb3Al5O12, TAG) ceramics have become a promising magneto‐optical material owing to the outstanding comprehensive performance, including the magneto‐optical, thermal, and mechanical properties. Fine‐grained TAG ceramics with high optical quality and mechanical properties have attracted much attention. In this study, TAG ceramics with fine grains and high optical quality are fabricated successfully by a two‐step sintering method from co‐precipitated nano‐powders. After pre‐sintered at 1525°C in vacuum and hot isostatic pressed at 1600°C, the in‐line transmittance of TAG ceramics reaches 81.8% at 1064 nm, and the average grain size is 7.1 μm. The Verdet constant of TAG ceramics is −179.6 ± 4.8 rad T−1 m−1 at 633 nm and −52.1 ± 1.9 rad T−1 m−1 at 1064 nm, higher than that of commercial Tb3Ga5O12 crystals. The thermal conductivity of TAG ceramics is determined from 25 to 450°C, and the result is 5.12 W m−1 K−1 at 25°C and 3.61 W m−1 K−1 at 450°C. A comparison of mechanical properties between large‐ and fine‐grained TAG ceramics fabricated under different conditions is conducted. The fine‐grained TAG ceramics possess a bending strength of 226.3 ± 16.4 MPa, which is 9.7% higher than that of the large‐grained ceramics. These results indicate that reducing the grain size on the premise of high optical quality helps improve the comprehensive performance of TAG ceramics. [ABSTRACT FROM AUTHOR]

In order to fully pump and smoothen the temperature gradient of the gain medium, multistage gradient doping Yb:YAG laser ceramics were designed. The composite green bodies were fabricated by tape casting, and multistage gradient doping Yb:YAG ceramics with high optical quality were prepared by vacuum sintering and hot isostatic pressing. For samples pre‐sintered at 1740°C for 30 h and then HIP‐ed at 1700°C for 3 h in argon at 200 MPa, the in‐line transmission values at 1100 nm of YAG, 0.6 at.%Yb:YAG, and 1.5 at.%Yb:YAG ceramics were found to be 83.9%, 84.1%, and 83.3%, respectively. Finally, the 940 nm laser diode was used as the pump source to realize the 1030 nm laser output of multistage gradient doping Yb:YAG ceramic slab with a total energy of 3.43 J. The corresponding optical‐to‐optical conversion and slope efficiencies were 30% and 45%. [ABSTRACT FROM AUTHOR]

In recent years, transparent terbium aluminum garnet (TAG) ceramics have attracted much attention for use in high-power Faraday isolators. Fine-grained ceramics usually possess better mechanical properties and accordingly better service performance. In this work, transparent TAG ceramics with fine grains were prepared using a two-step sintering procedure based on the low-temperature sintering process to suppress grain growth. The composition of TAG precursor and powders calcined at different temperatures was studied in detail. The microstructure and relative density of air pre-sintered TAG ceramics were studied to meet the requirements of hot isostatic pressing (HIP) post-treatment. Driven by the low pre-sintering temperature in air, the average grain sizes of the obtained TAG ceramics after HIP treatment are about 2.9–5.3 μm. The TAG ceramics (1.2 mm thick) pre-sintered at 1450 °C with HIP post-treatment at 1550 °C for 3 h under a 176 MPa Ar atmosphere possess the highest in-line transmittance of 80.3% at 1064 nm. The Verdet constant of the TAG ceramics at 632.8 nm is −180.5 rad·T−1·m−1 at room temperature, which is about 1.3 times larger than that of the commercial Tb3Ga5O12 single crystals. [ABSTRACT FROM AUTHOR]

Transparent terbium aluminum garnet (TAG)‐based ceramics were fabricated by vacuum pre‐sintering and hot isostatic pressing (HIP) posttreatment from the co‐precipitated TAG powders with different stoichiometric ratios. After component optimization, the transparent ceramics with TAG single‐phase and attractive optical quality were obtained. The in‐line transmittance of optimal Tb(1+x)3(Al0.996255Si0.003745)5O12.0093625+3x/2 (x = −.004, −.002) ceramics (1.7‐mm thick) pre‐sintered at 1700°C for 20 h with HIP posttreatment at 1700°C for 3 h under 176‐MPa Ar reaches 82.6% at the wavelength of 1064 nm. With increasing terbium components, the secondary phase TAP appears in ceramics, which significantly degrades the optical quality of TAG‐based ceramics. The Verdet constant of the TAG‐based ceramics at 632.8 nm is about −181 rad T−1 m−1 at room temperature, which is about 33% higher than that of the TGG single crystals (−134 rad T−1 m−1). [ABSTRACT FROM AUTHOR]

In this article, 5 at.% Yb:Lu2O3 transparent ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) posttreatment using co‐precipitated nano‐powders. The influence of precipitant molar ratio, ammonium hydrogen carbonate, to metal ions (AHC/M3+, R value) on the properties of Yb:Lu2O3 precursors and calcined powders was investigated systematically. It was found that the powders with different R value calcined at 1100°C for 4 hours were pure cubic Lu2O3 but the morphologies of precursors and powders behaved differently. The opaque samples pre‐sintered at 1500°C for 2 hours grew into transparent ceramics after HIP posttreatment at 1750°C for 1 hour. The final ceramic with R = 4.8 showed the best optical quality with the in‐line transmittance of 79.7% at 1100 nm. The quasi‐CW laser operation was performed at 1034 nm and 1080 nm with a maximum output power up to 8.15 W as well as a corresponding slope efficiency of 58.4%. [ABSTRACT FROM AUTHOR]

The 0.05 at.% Co:MgAl2O4 precursor was synthesized by the coprecipitation method from a mixed solution of magnesium, aluminum, and cobalt nitrates using ammonium carbonate as the precipitant. 0.05 at.% Co:MgAl2O4 transparent ceramics were successfully obtained via vacuum sintering and hot isostatic pressing (HIP) of 0.05 at.% Co:MgAl2O4 nanopowder calcined at 1100°C for 4 hours. The properties of powder and ceramics were comprehensively investigated. X‐ray diffraction (XRD) results showed that Co:MgAl2O4 nanopowder had a pure spinel phase. Also, the in‐line transmittances of the HIP posttreated Co:MgAl2O4 ceramics with the thickness of 1.2 mm were 82% at 400 nm and 84.7% at 900 nm. The average grain sizes of 0.05 at.% Co:MgAl2O4 ceramics before and after the HIP posttreatment were 11 and 28 μm, respectively. The calculated ground state absorption cross section of 0.05 at.% Co:MgAl2O4 ceramics was 2.9 × 10−19 cm2, indicating that this ceramics is a promising material applied as a saturable absorber for passive laser Q‐switches in the 1.3‐1.7 μm domain. [ABSTRACT FROM AUTHOR]

Using the tape casting method combined with vacuum sintering and hot isostatic pressing, high‐quality planar waveguide YAG/10 at.%Yb:YAG/YAG ceramics were successfully prepared. For the sample presintered at 1750°C for 30 hours and then HIPed at 1700°C for 3 hours in 200 MPa argon, the in‐line transmittance reached 82.5% at 400 nm and the average grain size was ~17.1 μm. The diffusion behaviors of Yb ions across the contact boundary between the cladding YAG layer and the core Yb:YAG layer were determined by Fick's second law. Then, a 1030 nm continuous‐wave (CW) Yb:YAG planar waveguide ceramic laser based on the structure of master oscillator power amplification (MOPA) was realized. After a single‐pass amplification, the maximum output of the ceramic slab (60 × 10 × 1 mm3) reached 1251 W and the corresponding optical‐to‐optical efficiency was 30.0%, which is the highest output power of a Yb:YAG planar waveguide ceramic laser to the best of our knowledge. [ABSTRACT FROM AUTHOR]

Highly transparent aluminum oxynitride (AlON) ceramics were fabricated by pressureless sintering with hot isostatic pressing (HIP) post-treatment. The experimental results showed that the optical transparency of AlON ceramics was improved markedly over the visible and near-infrared range by HIP at 1825 °C for 3 h in 200 MPa argon gas, which derived from the elimination of residual pores in the prepared ceramics. For AlON ceramics pre-sintered at 1800 °C, the transmittances of the sample increased from 63.6% to 84.8% at 600 nm and from 75.4% to 86.1% at 2000 nm, respectively. The average grain size of the HIPed sample was about 47.9 μm. [ABSTRACT FROM AUTHOR]

• Tb 2 Ti 2 O 7 transparent ceramics were fabricated from co-precipitated nano-powders by two-step sintering. • The in-line transmittance of Tb 2 Ti 2 O 7 ceramics reaches 65.5 % at 1064 nm. • The Verdet constant of Tb 2 Ti 2 O 7 ceramics (−229.0 ± 0.6 rad·T−1 m−1@633 nm) is 71 % higher than TGG crystals. • Tb 2 Ti 2 O 7 ceramics are very promising magneto-optical materials for Faraday isolators. Transparent Tb 2 Ti 2 O 7 magneto-optical ceramics were fabricated from co-precipitated nano-powders by vacuum pre-sintering with hot isostatic pressing (HIP) post-treatment. The formation of pyrochlore phase, decomposition of the precursor, and the morphology of powders calcined at different temperatures were investigated. The in-line transmittance of Tb 2 Ti 2 O 7 ceramics, which were pre-sintered at 1350 ℃ for 2 h with HIP post-treatment at 1450 ℃ for 3 h and subsequently annealed at 800 ℃ for 20 h in NH 3 atmosphere, reaches 65.5 % at 1064 nm. The Verdet constant of Tb 2 Ti 2 O 7 ceramics is −229.0 ± 0.6 rad·T−1 m−1 at the wavelength of 633 nm, which is 71 % higher than that of the commercial Tb 3 Ga 5 O 12 crystals. Tb 2 Ti 2 O 7 magneto-optical ceramics show a promising application for Faraday rotators. [ABSTRACT FROM AUTHOR]

Ho 2 O 3 transparent ceramics were fabricated by vacuum pre-sintering combined with hot isostatic pressing (HIP) post-treatment at relatively low temperature from high-purity Ho 2 O 3 powder calcined at 1000 °C for 4 h. The optimal Ho 2 O 3 ceramic sample prepared by vacuum pre-sintering at 1250 °C and HIP post-treating at 1450 °C has a dense microstructure with average grain size of 0.77 μm, and the in-line transmittances reach 80.7 % at 1550 nm and 76.7 % at 1064 nm. The effect of air annealing on the optical quality of Ho 2 O 3 ceramics was studied, and the existence of compressed pores in the HIP-ed Ho 2 O 3 ceramics was confirmed. The Verdet constants of Ho 2 O 3 ceramics were measured to be -47.4 rad/(T m at 1064 nm and -15.4 rad/(T m at 1561 nm. High transmittance and large Verdet constant in the wavelength regions 1–1.07 μm, 1.3–1.5 μm make Ho 2 O 3 transparent ceramics promising for magneto-optical devices for lasers based on Yb-, Nd-doped materials and telecom lasers. [ABSTRACT FROM AUTHOR]

(Tb 0.99 Ce 0.01) 3 Ga 5 O 12 powders were synthesized by calcining the co-precipitated precursor at 1150°C. The powders showed low-agglomeration and high sinterability, so that the powders compact could be sintered to be transparent by a two-step sintering method. By using the best synthesis condition of air pre-sintered at 1525°C for 3 h and hot isostatic pressed at 1500°C for 3 h under 150 MPa, (Tb 0.99 Ce 0.01) 3 Ga 5 O 12 transparent ceramics with the in-line transmittance of 81.7% at 1064 nm were successfully prepared. The Verdet constant of the (Tb 0.99 Ce 0.01) 3 Ga 5 O 12 ceramics at 633 nm was about −143.4 ± 3.2 rad T−1 m−1, which was about 7% higher than that of the Tb 3 Ga 5 O 12 crystals (−134 rad T−1 m−1). Image, graphical abstract [ABSTRACT FROM AUTHOR]

Abstract Planar waveguide LuAG/10 at.%Yb:LuAG/LuAG laser ceramics were fabricated by the tape casting method combined with the vacuum pre-sintering and hot isostatic pressing (HIP) post-treatment. The morphologies of the raw materials, tapes and green bodies were observed. The microstructure, optical transmittance and the Yb3+ ions distribution of the LuAG/10 at.%Yb:LuAG/LuAG ceramics with different pre-sintering temperatures after HIP post-treatment were mainly studied. The experimental results showed that the average grain size and in-line transmittance of the HIPed ceramics increased with the increase of pre-sintering temperature. For the LuAG/10 at.%Yb:LuAG/LuAG ceramics pre-sintered at 1825 °C for 20 h and then HIPed at 1700 °C for 3 h under 200 MPa Ar atmosphere, the in-line transmittance of the sample with the thickness of 2 mm was about 74% at 1100 nm and the maximum diffusion distance of Yb3+ was about 166 μm. The bulk and grain boundary diffusion coefficients of Yb3+ ions for the samples pre-sintered at 1775 °C–1825 °C after HIP post-treatment were calculated by Fick's second law by using the LA-ICP-MS. What's more, CW laser at 1030 nm was demonstrated and the maximum output power of 0.4 W with a slop efficiency of 9.4% was achieved. Highlights • Planar waveguide LuAG/10 at.%Yb:LuAG/LuAG laser ceramics were fabricated by the tape casting and two-step sintering method. • Laser oscillation of planar waveguide LuAG/Yb:LuAG/LuAG ceramics was demonstrated for the first. • The diffusivity of Yb3+ increased with increasing the pre-sintering temperature, especially for the grain boundary diffusion. [ABSTRACT FROM AUTHOR]

Using the 1 at.% Er:SrF 2 nano-powders synthesized by the co-precipitation method as starting powders, 1 at.% Er:SrF 2 transparent ceramics were successfully prepared by air pre-sintering at different temperatures for 2 h combined with hot isostatic pressing (HIP) post-treatment at 600 °C for 2 h under 100 MPa Ar. The influences of the pre-sintering temperature on optical quality, microstructure, phase composition and EPR spectrum of ceramics were investigated. Among all the HIP post-treated 1 at.% Er:SrF 2 ceramics in the thickness of 2.5 mm, the sample pre-sintered at 650 °C shows the best optical quality, whose transmittance at 2500 nm and 1500 nm reaches 83.4% and 73.6%, respectively. Furthermore, the spectral characteristics of this ceramic sample were systematically analyzed. The fluorescence lifetime for the 1 at.% Er:SrF 2 ceramics at 1530 nm is 49.62 ms. The strongest absorption and emission cross section for the peaks at around 1530 nm are 6.20 × 10−21 and 3.47 × 10−21 cm2, respectively. In brief, the above findings indicate that the Er:SrF 2 ceramics is a promising candidate as middle infra-red laser gain media. • Pure-phase Er:SrF 2 nano-powders were synthesized by the co-precipitation method. • 1 at.% Er:SrF 2 ceramics with fine grains were fabricate by two-step sintering. • Spectral properties for 1. at.% Er:SrF 2 ceramics were systemically explored. [ABSTRACT FROM AUTHOR]

Abstract Praseodymium doped terbium aluminum garnet (Pr:TAG) magneto-optical ceramics with different doping concentrations were fabricated by vacuum pre-sintering and hot isostatic pressing (HIP) post-treatment from the co-precipitated Pr:TAG nanopowders. It is found that all the as-synthesized powders exhibit a pure TAG phase and show good dispersity. The in-line transmittance of Pr:TAG ceramics fabricated by pre-sintering at 1700 °C for 20 h and HIP post-treating at 1700 °C for 3 h decreases from 80.6% to 76.3% at 1064 nm with the Pr3+ doping concentration increasing from 0 at% to 2.0 at%. The Verdet constant of the 2.0 at% Pr:TAG ceramics at 633 nm is −189.8 rad T-1 m-1, which is 42% larger than that of the commercial TGG single crystals (−134 rad T-1 m-1). The superior characteristics of the Pr:TAG ceramics indicate that they have great potential to meet the increasing requirements for magneto-optical devices used in the visible and near-infrared wavelength. Highlights • Pr:TAG transparent ceramics with good magneto-optical properties were fabricated from co-precipitated powders. • The influence of doping concentration on the microstructure and properties of Pr:TAG ceramics were investigated. • The Vertdet constant at 633 nm of the 2 at% Pr:TAG ceramics is 42% larger than that of TGG crystals. [ABSTRACT FROM AUTHOR]

Neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated from Nd:YAG nanopowders synthesized via a reverse precipitation method by vacuum sintering and successive hot isostatic pressing (HIP) post-treatment. The powders obtained by calcining the precursor at 1100 °C for 4 h and then ball milling for 2 h with 0.5 wt% TEOS as sintering aid were used to fabricate Nd:YAG ceramics. The green bodies were vacuum sintered at 1500–1800 °C for 10 h, followed by the HIP at 1600 °C for 3 h in 200 MPa Ar atmosphere. Influence of the calcination temperature on the phase, morphology and particle size evolution of the nanopowders, as well as the optical transparency and microstructure of the obtained Nd:YAG ceramics before and after the HIP post-treatment was investigated in detail. It was found that for the post-treated 1800 °C-vacuum-sintered Nd:YAG ceramic sample, the in-line transmittance increased from 48.0% up to 81.2% at the lasing wavelength of 1064 nm. [ABSTRACT FROM AUTHOR]

The sintering behavior of neodymium doped yttrium aluminum garnet (Nd:YAG) ceramics was investigated on the basis of densification trajectory, microstructure evolution and transmittance. Nd:YAG ceramics with in-line transmittance of 83.9% at 1064 nm and 82.5% at 400 nm were obtained by direct cold isostatic pressing (CIP) at 250 MPa and solid-state reactive sintering at 1790 °C for 30 h under vacuum. Compared with the porosity and the average pore diameter of the sample from uniaxial dry-pressing followed by CIP, those from direct CIP are much smaller. The samples pressed at 250 MPa were sintered from 1500 °C to 1750 °C for 0.5–20 h to study their sintering behavior. At the temperature higher than 1500 °C, pure YAG phase is formed, followed by the densification and grain growth process. The relative density and the grain size increase with the increase of sintering time and temperature, and the sintering behavior is more sensitive to temperature than holding time. The mechanism controlling densification and grain growth at sintering temperature of 1550 °C is grain boundary diffusion. [ABSTRACT FROM AUTHOR]

Diffusion-controlled solid-state reactive sintering is one of the most important steps in fabrication of highly transparent Nd:YAG ceramics using commercial oxide powders as starting materials. The difference in raw powders, especially for the characteristic of Y 2 O 3 powder, will seriously influence the sintering behavior and finally lead to the large difference in microstructure and optical property. Thus, interactions between commercially available α-Al 2 O 3 submicron particles and severely agglomerated Y 2 O 3 nanoparticles during vacuum sintering were investigated in details in the present paper. Upon examining the influence of solid-state reactive diffusion in Nd:YAG ceramics, by optimizing the sintering parameters, highly transparent Nd:YAG ceramics were fabricated by solid-state reactive sintering of Y 2 O 3 , α-Al 2 O 3 and Nd 2 O 3 powders. The in-line transmittances of the ceramics achieved 83.8% and 81% at 1064 nm and 400 nm, respectively. [ABSTRACT FROM AUTHOR]

Transparent ytterbium doped calcium-fluoride (Yb:CaF 2) ceramics were successfully fabricated by air pre-sintering and hot isostatic pressing (HIP) post-treatment from the powders synthesized by the co-precipitation method. The influence of pre-sintering temperature on the densification, microstructures and optical quality of 5 at.% Yb:CaF 2 ceramics was systematically investigated. The ceramic sample pre-sintered at 650 °C for 2 h and HIP post-treated at 650 °C for 1 h shows the best transparency with the in-line transmittance of 90% at 1200 nm. The upper level lifetime of the Yb3+ in Yb:CaF 2 ceramics was evaluated to be 1.95 ms by the pinhole method. In addition, the laser emission from an optimized 5 at.% Yb:CaF 2 ceramic sample yields in the maximum output power of 0.81 W with a maximum slope efficiency of 22.6% at 1028.5 nm under quasi-CW pumping. • Yb:CaF 2 nano-powders were synthesized by the co-precipitation method. • Yb:CaF 2 ceramics with the in-line transmittance of 90% were obtained by air pre-sintering and HIP post-treatment. • Yb:CaF 2 ceramic laser with the slope efficiency of 22.6% and the output power of 0.81 W was obtained at 1028.5 nm. [ABSTRACT FROM AUTHOR]

Red cerium doped 8 mol% yttria stabilized zirconia (Ce-doped 8YSZ) transparent ceramics were prepared by the two-step sintering method using commercial powders as raw materials. The ceramics after pre-sintering at 1300 °C for 2 h and hot isostatic pressing (HIP) post-treatment at 1700 °C for 3 h showed a high in-line transmittance and a large redness due to the 4f-5d transition absorption of Ce3+ at about 390–550 nm , and the values were 70.7% (@ 700 nm) and 57.1, respectively. The influences of air annealing temperature on the color and optical quality of the red Ce-doped 8YSZ transparent ceramics were studied. With the increase of annealing temperature, the color of the ceramics shifted from red to orange-red and then to nearly colorless, while the redness value decreased from 57.1 to 0.8 due to the oxidation of Ce3+ to Ce4+. The in-line transmittance of the ceramics decreased from 70.7% to 46.5% at 700 nm due to the expansion of the compressed residual pores, and the cut-off wavelength blue-shifted from 580 to 380 nm due to the disappearance of absorption peak at about 390–550 nm of Ce3+after annealing at 1200 °C. • Transparent Ce-doped yttria stabilized zirconia ceramics with bright red color were prepared by two-step sintering. • The ceramics showed a high in-line transmittance of 70.7% (@ 700 nm) and a large redness of 57.1. • With the increase of annealing temperature, ceramics color changed from red to orange-red and then to nearly colorless. [ABSTRACT FROM AUTHOR]

ZnGa 2 O 4 (ZGO) persistent luminescence (PersL) ceramics doped with different concentrations of Cr3+ were prepared by the co-precipitation method and hot isostatic pressing (HIP) post-treatment. After HIP post-treatment, the ZGO PersL ceramics was significantly improved from opaque to transparent visual appearance due to the elimination of micro-pores during HIP process. The effects of Cr3+ concentration on the morphology, transmittance and PersL properties of ZGO PersL ceramics were systematically investigated. The ZGO PersL ceramics with higher Cr3+ dopant concentrations show less micro-pores and higher transmittance, which indicates that the Cr3+ can also work as a sintering additive to increase the density and to improve the optical quality of ZGO PersL ceramics. The photoluminescence excitation (PLE) and emission (PL) intensities increase with the increase of Cr3+ concentration up to 0.25 at.%. At yet higher Cr3+ concentrations, the ZGO PersL ceramics exhibits weaker PL and PLE intensities which is probably caused by the concentration quenching effect. However, the PersL decay curves show that the PersL performance of ZGO ceramics increases with increasing Cr3+ concentrations, indicating that the doping by Cr3+ ions may cause another traps formation leading to stronger and longer PersL. The PersL decay curves of all ZGO PersL ceramics were fitted by the second-order exponential function, indicating that at least two kinds of traps with different electron release rates exist in the ZGO ceramics. The influence of Cr3+ concentration on the thermoluminescence (TL) of ZGO PersL ceramics was also studied, and the results showed that the TL curves of the pre-sintered ceramics shifted to lower temperatures, indicating that the depth of trap related to Cr3+ ions is shallower than the depth of trap caused by the intrinsic defects. • Cr3+:ZnGa 2 O 4 ceramics were prepared by co-precipitation and HIP post-treatment. • Cr3+ can work as a sintering aid to improve the optical quality of ZGO ceramics. • Concentration quenching occurs when Cr3+ concentration is more than 0.25 at-%. • Oxygen vacancy can lead to the formation of deeper trap. [ABSTRACT FROM AUTHOR]

Ytterbium-doped yttrium oxide (5 at.%Yb:Y 2 O 3) nanopowders were synthesized by the co-precipitation method in this work. The influence of the molar ratio of ammonium hydrogen carbonate to metal ions (NH 4 HCO 3 /M3+, defined as R) on the properties of the precursors and powders was studied. The powders calcined at 1100 °C from the precursors with different R showed the same phase as the pure cubic Y 2 O 3. However, the agglomerations of the calcined powders were influenced by the R evidently and the 5 at.%Yb:Y 2 O 3 powders with R = 4.0 showed better dispersivity. Using the obtained powders as starting materials, 5 at.%Yb:Y 2 O 3 transparent ceramics were fabricated by vacuum sintering and hot isostatic pressing (HIP) post-treating. The 5 at.%Yb:Y 2 O 3 ceramics with R = 4.0 possessed the best optical quality with the in-line transmittance of 81.2% at 1100 nm with fine grains. In addition, the microstructures of the 5 at.%Yb:Y 2 O 3 transparent ceramics with different R values were also studied and the HIP post-treated ceramics exhibited homogeneous microstructures. Meanwhile, the absorption and emission cross-sections of the 5 at.%Yb:Y 2 O 3 ceramics were calculated to be 0.99 × 10−20 cm2 at 976 nm and 0.97 × 10−20 cm2 at 1031 nm, respectively. The gain spectra also were obtained from the absorption and emission spectra. • Yb:Y 2 O 3 nano-powders with the average particle size of 59 nm were obtained by the co-precipitation method. • Fine-grained 5 at%Yb:Y 2 O 3 transparent ceramics were prepared by vacuum sintering and hot isostatic pressing. • In-line transmittance of 5 at%Yb:Y 2 O 3 ceramics from the optimal nano-powders reaches 81.2% at 1100 nm. [ABSTRACT FROM AUTHOR]

Transparent Tb 2.45 Hf 2 O 7.68 ceramics were fabricated successfully by reactive sintering at 1700 °C for 3 h with hot isostatic pressing (HIP) post-treatment at 1700 °C for 3 h. In-line transmittance of the Tb 2.45 Hf 2 O 7.68 ceramic specimen with the thickness of 2.0 mm reached 79.4% at 1064 nm. X-ray diffraction was used to verify the existence of pyrochlore phase and the occupation sites of Tb3+ were discussed. Elemental mapping showed no secondary phase in Tb 2.45 Hf 2 O 7.68 ceramics. Verdet constant of the Tb 2.45 Hf 2 O 7.68 ceramics at 633 nm is -165.6 rad•T−1•m−1, which is 23.6% higher than that of commercial Tb 3 Ga 5 O 12 crystal (-134 rad•T−1•m−1) and 8.4% higher than that of Tb 2 Hf 2 O 7 (-152.8 rad•T−1•m−1). Tb 2.45 Hf 2 O 7.68 ceramics with high Verdet constant are promising to be used in compact Faraday rotators. [Display omitted] [ABSTRACT FROM AUTHOR]

Yb,La:CaF 2 nano-powders doped with different Yb3+ concentrations as 1, 2, 3, 5 at.% were synthesized by the co-precipitation method. The Yb,La:CaF 2 powders which were in pure cubic CaF 2 phase. The Yb,La:CaF 2 transparent ceramics were prepared by the air pre-sintering at different temperatures for 2 h with hot isostatic pressing (HIP) post-treatment at 650 °C for 2 h under 62 MPa Ar. The influences of the Yb3+ doping concentration and pre-sintering temperature on optical quality and microstructures of ceramics were investigated. Among all the fabricated ceramics, the 3 at.%La,5 at.%Yb:CaF 2 transparent ceramics pre-sintered at 650 °C showed the best optical quality. For the 1 mm thickness sample, its in-line transmittance reached 92.6% at 1200 nm. Furthermore, the absorption and the emission cross sections of the ceramics were calculated. The strongest absorption and emission peaks are around 977 nm. The lifetime for the Yb,La:CaF 2 transparent ceramics at 1028 nm increased first and then decreased with further increasing the Yb3+ doping concentrations. • Yb,La:CaF 2 transparent ceramics were prepared by the air pre-sintering and HIP post-treatment. • The role of the pre-sintering temperature and Yb concentration on the Yb,La:CaF 2 ceramics were studied. • In-line transmittance of the fabricated 5 at.%Yb,3 at.%La:CaF2 ceramics is 92.6% at 1200 nm. [ABSTRACT FROM AUTHOR]

Terbium aluminum garnet (TAG) transparent ceramics were fabricated by solid-state reactive sintering in vacuum combined with hot isostatic pressing (HIP) post-treatment using tetraethoxysilane (TEOS) as sintering aid. The influences of TEOS amount on the densification, microstructure and optical properties of TAG ceramics were investigated. The in-line transmittance of the TAG ceramic with 0.2 wt% TEOS additive, which was fabricated by pre-sintering at 1700 °C for 20 h and HIP post-treating at 1700 °C for 3 h, can reach about 66% in the visible and near-infrared regions. With appropriate amount of sintering aid, the transmittance of TAG ceramics in the visible wavelength range can be improved significantly by prolonging the holding time. • TAG transparent ceramics were prepared by solid-state reactive sintering and HIP post-treatment. • Influences of TEOS amount on microstructure and optical quality of TAG ceramics were investigated. • Prolonging the pre-sintering time can improve the in-line transmittance of TAG transparent ceramics. [ABSTRACT FROM AUTHOR]