Search

Macadamia oil cake (MOC) is a type of macadamia nut by‐product, that is extremely rich in amino acids and has beneficial health effects. It lowers blood lipid levels and regulates the intestinal microbiota. MOC effectively attenuated total cholesterol (TC), triglyceride (TG), low‐density lipoprotein cholesterol (LDL‐C), and high‐density lipoprotein cholesterol (HDL‐C) levels in model rats. Depending on the morphology of the colon, MOC can effectively attenuate damage to the tissue structure. The 16S rDNA gene of the rat intestinal microbiota was sequenced using Illumina PE250 high‐throughput sequencing technology, and the changes in the intestinal microbiota in each group are discussed. Supplementing MOC at different doses significantly increased the microbiota of Dorea, Erysipelotrichaceae, Stercoris, etc. in the intestinal tracts of rats fed a high‐fat diet. Therefore, MOC can be included in lipid healthy dietary patterns to lower lipid characteristics and restructure the intestinal microbiota. Future clinical trials are required to determine the therapeutic effects and mechanisms of hypolipidemia. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is a marine and estuarine bacterium that poses a major threat to human health worldwide. In this study, from 2017 to 2019, we evaluated 900 food samples collected from China in 2017, with the aim of determining the incidence and features of V. parahaemolyticus in ready-to-eat (RTE) foods, shrimp and fish in China. The contamination rates in these were 3.67, 19.33 and 10.67%, respectively, and the prevalence of V. parahaemolyticus was higher in summer than in winter. In addition, 101  V. parahaemolyticus strains were isolated. Our results suggested that most of the isolates were resistant to aminoglycosides based on the antimicrobial resistance patterns of these aquatic product isolates against 14 antimicrobial agents. Furthermore, most of the isolates were multidrug-resistant. Serotyping showed that the isolates of the O2 serotype comprised the maximum proportion. Enterobacterial repetitive intergenic consensus sequence (ERIC)-PCR results indicated that the isolates (n  = 101) could be classified into 12 clusters. There were 82 STs suggesting genetic variation and relatedness among these isolates. Our findings demonstrated the presence of V. parahaemolyticus in foods from Chinese retail markets and show that this methodology can be used for microbiological risk assessment in China. [ABSTRACT FROM AUTHOR]

Salmonella enterica is a common foodborne pathogen responsible for major global health problems such as paratyphoid fever and gastroenteritis. Here, we report the prevalence, antibiotic resistance phenotypes, serotypes, and molecular subtyping of Salmonella isolated from eggs in Guangdong, China. Out of 1,000 egg samples, 54 (5.40%) were positive. S. Enteritidis made up the largest proportion of samples with 11 serotypes. Antimicrobial susceptibility test indicated that most strains were resistant to β‐lactam, aminoglycoside, and tetracycline antibiotics (27.00%–40.00%). There were 37 STs based on MLST typing. MLST and ERIC‐PCR classified 54 isolates into three and five clusters, respectively, which revealed the genetic relatedness and diversity. In conclusion, frequent monitoring of eggs for Salmonella, antibiotic resistance profiles and genetic diversity is essential for improving food safety. [ABSTRACT FROM AUTHOR]

Hot-pressing of infrared transparent ZnS ceramics from nanopowders calls for proper particle size of the raw nanopowders to avoid the size-induced low-temperature sphalerite-to-wurtzite phase transition during calcination and sintering. In this paper, ZnS precipitate was solvothermally treated at 180 °C for 10–50 h. After solvothermal treatment, the particle size increased from 4 nm of the as-prepared precipitate to more than 10 nm, which results in better sphalerite phase stability. Even after calcination at 800 °C for 2 h, the major phase of the solvethermally synthesized powders kept as sphalerite phase. Due to the optically isotropic sphalerite phase, as well as the less organic impurities, the hot-pressed ceramic showed much better optical quality than that from the precipitated powders. [ABSTRACT FROM AUTHOR]

Ho:Lu3Al5O12(Lu AG) transparent ceramics are potential 2 μm eye-safe laser materials. Polycrystalline 0.8 at.% Ho:Lu AG ceramics with high optical quality were successfully fabricated by solid-state reactive sintering of high-purity oxide powders. The microstructure, the optical transmission, the spectrum characteristic, and the laser performance were investigated in this paper. The average grain size of Ho:Lu AG ceramics vacuum sintered at 1830°C for 30 hour is about 14 μm. The in-line transmittance of the sample is measured to be 81.7% and 82.0% at 1000 and 2250 nm, respectively. The absorption and the emission cross sections are calculated to be 0.88 × 10−20 cm2 at 1906 nm and 1.26 × 10−20 cm2 at 2094 nm. Using a thulium-doped yttrium-lithium-fluoride (Tm: YLF) laser with the central wavelength of 1907.5 nm as the pump source, 2.67 W continuous wave ( CW) laser operation at 2100.74 nm was obtained with a slope efficiency of 26.5%. The beam quality factor M2 was calculated to be 1.1, which indicated nearly diffraction-limited beam propagation and the laser was the fundamental TEM00 Gaussian mode. [ABSTRACT FROM AUTHOR]

Transparent Fe 2+ :ZnS polycrystals are 3–5 μm mid-IR laser gain materials with great importance. In this paper, a novel route combining wet-chemical co-precipitation, hot-pressed sintering and post hot isostatic pressing (HIP) treatment was proposed for Fe 2+ :ZnS transparent ceramics. Fe 2+ :ZnS powders were synthesized successfully by the wet-chemical co-precipitation method, which was suitable for particle size and morphology controlling and then ceramics consolidation. Transparent Fe 2+ :ZnS ceramics with comparatively high optical quality were successfully fabricated by two step sintering method combining hot pressing and post-HIP treatment. This approach is a promising candidate for fabricating Fe 2+ :ZnS ceramics with large size, low cost, short cycle, and flexible concentration distribution design. [ABSTRACT FROM AUTHOR]

Transparent 1.0 at% Nd:Lu 2.7 Gd 0.3 Al 5 O 12 (Nd:LuGdAG) ceramics were fabricated by the solid-state reactive sintering method using commercial powders as starting materials. The powders were mixed in ethanol with tetraethoxysilane (TEOS) and MgO, dried and pressed. The compacts were vacuum-sintered from 1725 °C to 1800 °C for observing the microstructure and the optical transmittance of Nd:Lu 2.7 Gd 0.3 Al 5 O 12 ceramics. The sample sintered at 1800 °C for 10 h has an almost dense and homogenous structure with the average grain size of 12.8 μm, whose in-line transmittance is about 70% at 1064 nm. The absorption and emission cross sections were calculated to be 1.0 × 10 −20 cm 2 and 1.23 × 10 −18 cm 2 , respectively. It is proved that Nd:LuGdAG ceramics have the potential to be a new solid-state laser material. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is a common foodborne pathogen found in aquatic products and represents a major threat to human health worldwide. Though not all this bacteria were harmful to human beings, the pathogenic V . parahaemolyticus always harbors either tdh (the thermostable direct hemolysin) or trh (TDH-related hemolysin) gene, or both. Additionally, the extensive use of antibiotics has been shown to be a contributing factor to the increasing incidence of antimicrobial-resistant strains. In this study, thirty-one clinical isolates were examined and compared with 95 (38.0%) aquatic product isolates (fishes, n = 28; shrimps, n = 67) collected from 250 samples in Guangdong, China. All isolates were studied by antibiotic susceptibility analysis, tdh and trh genes detection, serotyping and molecular typing (ERIC-PCR). The antimicrobial resistance patterns of these aquatic product isolates to 12 antimicrobial agents revealed that most of the isolates were resistant to streptomycin (90.53%). The isolates were also resistant to follow by ampicillin (33.68%) and cephalothin (30.53%). For clinical isolates, they were resistant to streptomycin (93.55%), ampicillin (87.10%), and cefazolin (64.52%). All isolates showed no resistance to azitromycin, chloramphenicol, ciprofloxacin, or nalidixic acid. The clinical isolates were positive for tdh (100%) and trh gene (77.42%), with ratios of only 2.11% and 28.42%, respectively in the aquatic product isolates. Serotyping detected shown that the isolates contained O1, O2, O3, O4, and O11, with the O3 serotype being the most common among the clinical isolates (48.39%), while the O2 (41.05%) makes the maximum proportion on aquatic product isolates. ERIC-PCR results demonstrated the isolates (n = 126) were classified into eight clusters, revealing genetic variation and relatedness between clinical and aquatic product isolates. This study provided a foundation for understanding the distinction between aquatic product and clinical isolates and yielded basic information for achieving food safety through control of V . parahaemolyticus contamination. [ABSTRACT FROM AUTHOR]

In this paper, we reported mixed garnet laser ceramic gain media with composition of 15 at.% Yb:Lu x Y 3-x Al 5 O 12 (x = 0, 0.75, 1.5, 3.0, Yb:LuYAG) fabricated by the solid state reactive sintering in vacuum. After being sintered at 1850 °C for 30 h, all the Yb:LuYAG ceramics have dense microstructure and high optical quality. The in-line transmittances of the 1.6 mm thick ceramics with x = 0, 0.75, 1.5 and 3.0 are 84.8%, 84.1%, 82.4% and 83.4% at 1100 nm wavelength, respectively. The influences of the Lu3+ content on the absorption and emission spectra were discussed. With the increase of Lu3+ content, the crystal field increases, causing a blue shift of position and bigger absorption coefficient of the about 938 nm absorption peaks. The main emission peaks for all Yb:LuYAG ceramics retain at 1030 nm. The samples have shown a high laser emission slope efficiency, near to exceeding 60% in optimized output coupling conditions. The comparable optical properties and excellent thermo-mechanical qualities mean that the Yb:LuYAG ceramics are promising gain media used for high power laser application. • Yb:LuYAG ceramics with the in-line transmittance over 82% at 1100 nm were fabricated by reactive sintering. • The introduction of Lu3+ caused the blue shift and bigger absorption for Yb:Lu x Y 3-x Al 5 O 12 ceramics at ~938 nm. • For Yb:Lu x Y 3-x Al 5 O 12 ceramics with x = 0.75, the laser outpower of 8.7 W and the slope efficacy of 65.6% were obtained. [ABSTRACT FROM AUTHOR]

Spring water is an important direct drinking water resource. Enterococcus faecalis is a significant opportunistic pathogen from environment that causes human neonatal sepsis and urinary tract infections. Our study investigated the prevalence, virulence genes, antimicrobial resistance, and molecular characterization of E. faecalis from spring water in Guangdong, China. A total of 285 spring water samples were collected from January 2017 to January 2018, in which 47 (16.49%) samples were contaminated by E. faecalis. Antimicrobial susceptibility result showed that many isolates were resistant to tetracycline (93.6%), gentamicin (29.8%), and ciprofloxacin (25.5%). The virulence gene test revealed the positive rate of gelE, asa1, ace, and cylA were 100, 82.3, 76.6, and 70.2%, respectively. Enterobacterial repetitive intergenic consensus‐polymerase chain reaction and multilocus sequence typing classified 47 isolates into 12 and 5 clusters, respectively, which revealed the genetic relatedness and diversity. This finding illustrated the presence of virulence genes and provided understanding on the spread of antibiotic‐resistant and genetic diversity isolates. It can help us gradually increase our knowledge of microbiological risk management in E. faecalis from spring water. Practical applications: Investigating the prevalence of Enterococcus faecalis isolates from spring water could increase this microbial safety ondrinking water. In our research, antibiotic susceptibility, virulence genes, serotypingand molecular characteristic were selected to thorough comparison among Enterococcus faecalis isolates. Spring water is common in China as drinking water, then understanding the dissemination and monitoring the prevalence of this microorganism is necessary to improve the drinking water safety. [ABSTRACT FROM AUTHOR]

With the increase in mining depth, the problem of the floor heave of a roadway is becoming increasingly prominent. Solving this problem for a deep high-stress roadway is the key to ensure safe supply and utilization of coal resources in China. This study investigates the floor heave of a horizontal transportation rock roadway at the depth of 960 m at the Xieyi Mine. A four-way loading simulation test frame similar to the Xieyi Mine was used to reproduce the high-stress environment of a deep roadway by loading different pressures on the roof, floor, and two sides of the roadway. The experimental results show that after the tunnel had been excavated, the surrounding rock failure could be divided into three stages: the initial deformation stage, fissure development stage, and mild deformation stage. The destruction time periods of these stages were 0–0.5 h, 0.5–2 h, and 2–6 h, and the destruction ranges were 0.4 m, 1 m, and 1.5 m, respectively. The amount of roof subsidence, the displacement of the two sides, and the floor heave influence each other, and the range of the bearing ring (5.6 m) of the floor is larger than that of the roof (3.4 m) after the surrounding rock has been damaged. The findings suggest that the floor should be supported first, before the two sides and the roof; then, the support of the key parts (roof and floor corners) should be strengthened. The roof, floor, and two sides are considered for controlling the deformation of the surrounding rock in a coupled trinity support mode. Because of the unfavorable conditions in the area, overexcavation backfill technology was used. The new support was successfully applied during the subsequent construction of the rock tunnel. Based on the long-term monitoring results of the surrounding rock deformation, the floor heave control yielded satisfactory results and maintained the long-term stability of the roadway. Therefore, this study can serve as a reference for preventing floor heave in similar high-stress roadways in the future. [ABSTRACT FROM AUTHOR]

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]

Ready‐to‐eat (RTE) foods are widely marketed in China and are important components of everyday diet. In this study, a total of 2000 RTE food samples were analyzed, 252 (12.60%) of which were positive for Enterobacteriaceae, and 48 were identified as containing extended‐spectrum β‐lactamase (ESBL)‐producing Escherichia coli isolates. Furthermore, the antimicrobial resistance patterns of these isolates to 14 antimicrobial agents revealed that most isolates were resistant to aminoglycosides and β‐lactam antibiotics. The TEM‐type gene was prevalent in our isolates (79.17%). The isolates (n = 48) were classified into three clusters based on the ERIC‐PCR results. Forty‐eight sequence types were found without duplicates, revealing genetic variation and relatedness among isolates. Thus, the results demonstrated the presence of ESBL‐producing Enterobacteriaceae in Chinese RTE foods. The results of this study provide insights into the spread of antibiotic‐resistant strains and improve understanding of microbial risks. [ABSTRACT FROM AUTHOR]

A novel magneto-optical material, (Tb 0.995 Ho 0.005 ) 3 Al 5 O 12 transparent ceramic, was successfully fabricated using co-precipitated powders. The prepared (Tb 0.995 Ho 0.005 ) 3 Al 5 O 12 ceramic exhibits outstanding optical quality and magneto-optical property. For the (Tb 0.995 Ho 0.005 ) 3 Al 5 O 12 ceramic pre-sintered at 1650 °C for 20 h with HIP post-treatment at 1700 °C for 3 h, the optical transmittance exceeds 80% in the 500–1500 nm region (except for the absorption bands). The Verdet constant of the sample at 633 nm is about 1.4 times higher than that of the commercial Tb 3 Ga 5 O 12 single crystal. High transparency and Verdet constant make it an attractive magneto-optical material for the high-power Faraday isolators. [ABSTRACT FROM AUTHOR]

Highly transparent terbium aluminum garnet (Tb 3 Al 5 O 12 , TAG) magneto-optical ceramics were fabricated from co-precipitated nanopowders with tetraethoxysilane (TEOS) as sintering aid by vacuum sintering combined with hot isostatic pressing (HIP) post-treatment. The ball milled TAG powder shows better dispersity than the as-synthesized powder, and its average particle size is about 80 nm. For the ceramic sample pre-sintered at 1720 °C for 20 h with HIP post-treated at 1700 °C for 3 h, the in-line transmittance exceeds 76% in the region of 400–1580nm (except the absorption band), reaching a maximum value of 81.8% at the wavelength of 1390 nm. The microstructure of the TAG ceramic is homogeneous and its average grain size is approximately 19.7 μm. The Verdet constant of the sample is calculated to be −182.7 rad·T −1 ·m −1 at room temperature. [ABSTRACT FROM AUTHOR]

To suppress heat effects in a high‐power laser system, it has been proposed to use a few composite laser gain media to improve the heat management ability. The surface‐gain structure has the advantages of both slab and thin‐disk configurations, which has huge potential in high‐power laser. For the first time, novel composite laser ceramics with surface‐gain structure have been fabricated by tape casting and sintering technology. The in‐line transmittances of surface‐gain ceramics in 1100 and 400 nm are 83.5% and 79.1%, respectively. According to the laser ablation–coupled plasma mass spectrometry, the diffusion distance of Yb3+ is about 150 µm. The laser experiment yields a low repetition rate pulse of 1.9 J with a pump absorption energy of 11 J and an optical‐to‐optical conversion efficiency of 17.2%. [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]

Cobalt-doped magnesium aluminate spinel (Co:MgAl 2 O 4 ) is one of the most important saturable absorbers for the passive Q-switching of solid-state lasers operating at eye-safe wavelength of 1.5 μm. In this work, highly transparent Co:MgAl 2 O 4 ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) post-treatment, using the mixture of the commercial spinel and the lab-made Co:MgAl 2 O 4 powder as the raw materials. The densification mechanism of Co:MgAl 2 O 4 transparent ceramics was discussed. The microstructure and optical properties of the samples were investigated. The ground state absorption cross section (σ GSA ) was calculated from the fitted curve of the absorption coefficient spectrum. The results show that Co:MgAl 2 O 4 ceramics fabricated by vacuum sintering at 1500 °C for 5 h and then HIP post-treatment at 1650 °C for 3 h perform good transparency, whose in-line transmittance exceeds 80% at 2500 nm. Moreover, the ground state absorption cross section of 0.02 at.% Co:MgAl 2 O 4 ceramics is calculated to be 3.35 × 10 −19 cm 2 at the wavelength of 1540 nm, which is promising for the application to the passive Q-switching of solid-state laser operating in the near infrared region (NIR). [ABSTRACT FROM AUTHOR]

Carbon aerogel (CA) cathode was adopted to an undivided-chamber photoelectrocatalytic system with TiO 2 nanotube arrays (TNA) photoanode to enhance the oxidation of hypophosphite (H 2 PO 2 −) and simultaneous recovery of metallic nickel (Ni). Both the efficiencies of H 2 PO 2 − oxidation and Ni recovery were significantly enhanced after replacing Ti or carbon fiber paper cathode with CA cathode. With 1.0 mM H 2 PO 2 − and 1.0 mM Ni2+, the ratio of PO 4 3− production increased from ∼41% or ∼54% to ∼100%, and the ratio of Ni recovery increased from ∼20% or ∼ 37% to ∼93% within 180 min at 3.0 V. H 2 PO 2 − was finally oxidized to PO 4 3− by •OH radicals, which was speculated to be generated from UV/H 2 O 2 and bound on TNA photoanode. Meanwhile, Ni2+ was eventually electro-reduced to metallic Ni by a two-electron reduction reaction. The efficiencies of H 2 PO 2 − oxidation and Ni recovery were favored at higher cell voltage, faintly acid conditions and larger H 2 PO 2 − concentration. The stability of this system exhibited that the ratio of PO 4 3− production increased significantly in each cycle, which was attributed to the increase of H 2 O 2 in-situ-generation via CA cathode caused by deposition of metallic Ni. Finally, the treatment of actual electroless nickel plating effluents was demonstrated. [Display omitted] • H 2 PO 2 − oxidation and Ni recovery were largely enhanced via carbon aerogel cathode. • The pathways of H 2 PO 2 − oxidation by •OH radicals and Ni2+ deposition were proposed. • Oxidation of H 2 PO 2 − and cathodic deposition of metallic Ni were mutually promoted. • The treatment of actual electroless nickel plating effluents was demonstrated. [ABSTRACT FROM AUTHOR]

In order to enhance Ni-EDTA decomplexation and Ni recovery via photoelectrocatalytic (PEC) process, TiO 2 /Ni-Sb-SnO 2 bifunctional electrode was fabricated as the photoanode and activated carbon fiber (ACF) was introduced as the cathode. At a cell voltage of 3.5 V and initial solution pH of 6.3, the TiO 2 /Ni-Sb-SnO 2 bifunctional photoanode exhibited a synergetic effect on the decomplexation of Ni-EDTA with the pseudo-first-order rate constant of 0.01068 min−1 with 180 min by using stainless steel (SS) cathode, which was 1.5 and 2.4 times higher than that of TiO 2 photoanode and Ni-Sb-SnO 2 anode, respectively. Moreover, both the efficiencies of Ni-EDTA decomplexation and Ni recovery were improved to 98% from 86% and 73% from 41% after replacing SS cathode with ACF cathode, respectively. Influencing factors on Ni-EDTA decomplexation and Ni recovery were investigated and the efficiencies were favored at acidic condition, higher cell voltage and lower initial Ni-EDTA concentration. Ni-EDTA was mainly decomposed via ·OH radicals which generated via the interaction of O 3 , H 2 O 2 , and UV irradiation in the contrasted PEC system. Then, the liberated Ni2+ ions which liberated from Ni-EDTA decomplexation were eventually reduced to metallic Ni on the ACF cathode surface. Finally, the stability of the constructed PEC system on Ni-EDTA decomplexation and Ni recovery was exhibited. [Display omitted] [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]

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]

Ce,Ca:LuAG scintillation ceramics with different Ca2+ co-doping concentrations were prepared by the solid-state reaction method. The concentration of Ce3+ was fixed at 0.3 at% and the concentration of Ca2+ ranged from 0 to 1.2 at%. We systematically studied how the Ca2+ concentration affects the optical quality of Ce,Ca:LuAG ceramics by influencing the microstructure in the vacuum sintering and HIP post-treatment. Good optical transmittance could be obtained with Ca2+ concentrations between 0.05 and 0.8 at%, which reached 76.0–81.9 % at 520 nm. The PL and scintillation decay times decrease with increasing Ca2+ concentration up to 0.6 at% with no clear trend above this value. The light yield (LY) values at different shaping times decrease with increasing Ca2+ concentration but the fast scintillation component (LY 0.5 μs / LY 3.0 μs) increases significantly from 79 % to 97 %. The co-doping of Ca2+ also reduces the afterglow level by more than one order of magnitude. • Ce,Ca:LuAG scintillation ceramics were fabricated by the two-step sintering method. • A wide range of Ca2+ co-doping concentration was systemically investigated. • Scintillation decay accelerate with increasing Ca2+ concentration up to 0.6 at%. • Ca2+ co-doping optimizes the fast scintillation component from 79 % to 97 %. [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]

0.5 at.% Cr:ZnGa2O4 precursor was synthesized by the co‐precipitation method with nitrates as raw materials, using ammonium carbonate as the precipitant. Low‐agglomerated Cr:ZnGa2O4 powders with an average particle size of 43 nm were obtained by calcining the precursor at 900℃ for 4 h. Using the powders as starting materials, 0.5 at.% Cr:ZnGa2O4 ceramics with an average grain size of about 515 nm were prepared by presintering at 1150℃ for 5 h in air and HIP post‐treatment at 1100℃ for 3 h under 200 MPa Ar. The in‐line transmittance of 0.5 at.% Cr:ZnGa2O4 ceramics with a thickness of 1.3 mm reaches 59.5% at the wavelength of 700 nm. The Cr:ZnGa2O4 ceramics can be effectively excited by visible light and produce persistent luminescence at 700 nm. For Cr:ZnGa2O4 transparent ceramics, the brightness of afterglow was larger than 0.32 mcd/m2 after 30 min, which is far superior to that of Cr:ZnGa2O4 persistent luminescence powders. [ABSTRACT FROM AUTHOR]

Transparent terbium aluminum garnet (TAG) ceramics were achieved by the vacuum sintering plus HIP post‐treating from the coprecipitated TAG nanoparticles. The influences of vacuum sintering temperature and sintering aid TEOS on the optical quality of the TAG ceramics were studied. The results show that with the increase of sintering temperature, the optical quality of TAG ceramics is improved gradually, and the in‐line transmittance of the TAG ceramics treated at 1720°C for 20 hours under vacuum and then HIP post‐treated at 1700°C for 3 hours under 200 MPa argon gas is 81.6% at 1064 nm. The sintering additive TEOS can improve the optical quality of TAG ceramics and inhibit the valence state change of Tb3+ ions to Tb4+ during the annealing process. The Verdet constant of the TAG ceramics at 632.8 nm is about −178 rad·T−1·m−1 at room temperature, which is 1.3 times that of the commercial TGG crystals (−134 rad·T−1·m−1). [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]

We report on the spectroscopic and laser emission properties of 10 at% Yb:Y 3 Sc x Al 5-x O 12 (Yb:YSAG) ceramic varying the amount of Sc (x) ranging from x = 0.25 to x = 1.5. The samples were fabricated by a solid state reaction method followed by vacuum sintering and annealing in air. The spectroscopic investigation has evidenced an increased broadening in both the absorption and the emission spectra for increasing Sc content, as well as an extension of lifetime at increased Sc content. Concerning the laser performance, the maximum slope efficiency, i.e. 76.6%, was obtained with the sample with x = 0.25 while the largest tuning range, i.e. 81 nm, with the sample having the highest concentration of Sc ions (x = 1.5); a steady broadening in the tuning bandwidth for increasing Scandium content was measured. [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]

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]

8.7 mol% Y 2 O 3 -ZrO 2 (Y 0.16 Zr 0.84 O 1.92) precursor was synthesized by the co-precipitation method using ammonia as the precipitant. The Y 0.16 Zr 0.84 O 1.92 powders calcined at 800 °C show a pure c-ZrO 2 phase. The average crystallite size of the powders is 12.4 nm and weakly agglomerated to an average particle size of 15.5 nm. Y 0.16 Zr 0.84 O 1.92 transparent ceramics were then successfully fabricated by pre-sintering at 1350 °C for 2 h and HIP post-treatment at 1750 °C for 1 h under 200 MPa without sintering additives. The in-line transmittance of Y 0.16 Zr 0.84 O 1.92 ceramics (1 mm thick) exceeds 50.3% in the region of 400–850 nm, reaching about 65.3% at 800 nm. Unlabelled Image [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]

Abstract Pr:Lu 3 Al 5 O 12 transparent ceramics with different doping concentrations (0% − 1 at%) were fabricated using the solid-state reaction and vacuum sintering method. The influence of doping concentration on the luminescent properties was investigated in detail. The 5d-4f emission slightly redshifts with the increase of doping concentration under UV light and X-ray excitation. The slow emission below 290 nm related to antisite defects can be suppressed by the increase of doping concentration at room temperature. The suppression of exciton related emission around 250 nm at 77 K is remarkable. The 0.3 at% Pr doped ceramics show the highest light yield that is 6900 ph/MeV with 1 μs shaping time under the excitation of γ-rays (137Cs). There exists slow components of scintillation process in all the Pr-doped transparent ceramics. Higher doping concentration was found to be beneficial for the suppression of the slow components in the scintillation response and therefore acceleration of the scintillation decay and light yield increase up to certain level. These effects are mainly due to competition of Pr3+ ions with the antisite defects for charge carrier capture in the scintillation process which is also supported by the trends observed in the TSL measurements. [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]

Terbium gallium garnet (TGG) ceramics were fabricated by air sintering and successive HIP post-treating from the TGG nanoparticles synthesized via the co-precipitation technique. The influences of the calcination temperature on the phase and morphology evolution of the nano-powders, as well as the optical transparency and microstructure of the obtained TGG ceramics were investigated in detail. The powders calcined at 1100–1250 °C retained the TGG phase purity and displayed significantly less agglomeration. Using the above powders as raw materials, the TGG ceramics pre-sintered at 1500 °C for 3 h in air and then HIP post-treated at 1550 °C for 3 h under 150 MPa argon gas showed the similar optical qualities and the in-line transmittances were about 70% at 1064 nm. The Verdet constants of all the ceramics were calculated to be about 137 rad T−1 m−1 at room temperature, which were nearly independent of the optical quality of the ceramics. • TGG ceramics were prepared by two-step sintering from the co-precipitated powders. • The optimum calcination temperature for the transparent ceramics was demonstrated. • The in-line transmittance of the fabricated TGG ceramics is 70% at 1064 nm. • The TGG ceramics show the similar Verdet constant with the commercial TGG crystals. [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]

Abstract Terbium gallium garnet (TGG) precursor was synthesized by the co-precipitation method from the mixed solution of terbium and gallium nitrates using ammonium hydrogen carbonate (AHC) as the precipitant. Fine and low-agglomerated TGG powders with the average particle size of 158 nm were obtained by calcining the precursor at 1100 °C for 4 h. Then, TGG transparent ceramics were successfully fabricated by a new two-step sintering method. The TGG ceramics pre-sintered at 1500 °C for 3 h in air and then HIP post-treated at 1550 °C for 3 h under 150 MPa argon gas showed the best optical quality and the in-line transmittance was 80.3% at 1064 nm. The Verdet constant of the TGG ceramic at 633 nm was about 136.8 rad T−1 m−1, which was rather close to that of the commercial TGG single crystal. High transparency and high Verdet constant make it an attractive alternative for the high-power Faraday isolators. Highlights • TGG powders with an average particle size of 158 nm were synthesized by a co-precipitation method. • TGG ceramics with the in-line transmittance of 80.3% at 1064 nm were prepared by two-step sintering. • The fabricated TGG magneto-optical ceramics show the similar Verdet constant with the commercial TGG crystals. [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]

Cerium doped terbium aluminum garnet (Ce:TAG) magneto-optical ceramics with different doping concentrations were fabricated using the co-precipitated powders. All the as-synthesized powders exhibit a pure TAG phase and show good dispersity. Highly transparent Ce:TAG ceramics were then successfully fabricated by pre-sintering at 1650 °C for 20 h and HIP post-treating at 1700 °C for 3 h. The 0.5at% Ce:TAG ceramic shows the best transparency, and its transmittance is ~80% in the 600–1500 nm range. The Vertdet constant at 633 nm of the 2.0at% Ce:TAG ceramics is −196.2 rad T −1  m −1 , which is 46% larger than that of the commercial TGG single crystals. [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]

Sintering aids may enter the host lattice, create defects, and seriously deteriorate the scintillation properties of ceramic scintillators. In this study, the 0.3at%Pr:LuAG ceramics with different excess of Lu were fabricated by the solid-state reactive sintering without aids. The influences of stoichiometry on the sintering behaviors, optical and scintillation properties of the ceramics are systematically studied. The results show that the stoichiometric ceramics experience an abnormal grain growth during sintering. The Lu excess can restrain the abnormal grain growth of the ceramics because of the impurity drag effect. The excess Al 2 O 3 as optical scattering centers, can also pin in the grain boundary to limit the fast migration of the grain boundaries. The light yield value of the as-sintered ceramics decreases with the increase of Lu content. After air-annealing, the ceramics with appropriate excess of Lu can achieve better optical quality and higher light yield compared to the stoichiometric Pr:LuAG ceramics. [ABSTRACT FROM AUTHOR]

Ce,Mg:LuAG scintillation ceramics with Ce dopant content ranging from 0.025 at.% to 0.3 at.% and constant 0.2 at.% Mg codoping were fabricated by solid-state reaction. The effects of Ce concentration and annealing conditions on the microstructure, optical quality and scintillation properties are studied in great details. Lattice parameters as well as the absorption, photoluminescence, radioluminescence and thermoluminescence characteristics are investigated as a function of Ce content. Both the photoluminescence and scintillation decays are measured as well in order to study re-absorption and concentration quenching processes. In addition, an enhanced positive effect of air annealing on radioluminescence intensity and light yield is put in evidence. Moreover, the role of the charge transfer absorption of Ce 4+ is investigated. Thermoluminescence measurements are performed to investigate the influence of both air annealing and Ce concentration on defects acting as traps. Finally, the correlations among steady state scintillation efficiency, light yield, thermoluminescence and Ce 3+ concentration are found and discussed. [ABSTRACT FROM AUTHOR]

Cr 2+ :ZnS is an important mid-infrared laser material, and Cr 2+ :ZnS nanopowders are very important for the fabrication of transparent ceramics. In this paper, Cr 2+ :ZnS nanopowders were synthesized via a hydrothermal method, in which thioacetamide (TAA) was adopted as sulfur source and reducing agent to avoid the oxidation of Cr 2+ ions. The influences of the hydrothermal time and [Zn 2+ ]/[TAA] ratio on the morphology and particle size of the nanopowders were investigated systematically as well as the reaction mechanism. It is believed that the orientated attachment and Oswald ripening both occurred during the hydrothermal reaction, which resulted in the formation of bimodal particle size distribution. After calcination of the nanopowders under Ar/H 2 atmosphere, the Cr 2+ ions were successfully doped into the Zn 2+ lattice sites, which was supported by the X-ray powder diffraction patterns, the absorption and photoluminescence spectra of the calcination products. The optical properties were similar with those of the samples obtained by thermal diffusion, which means that they have the potential application in the fabrication of Cr 2+ :ZnS transparent ceramics. [ABSTRACT FROM AUTHOR]

Tb 4 O 7 nanopowders were synthesized by the precipitation method using ammonium hydrogen carbonate (AHC) as the precipitant. The influence of calcination temperature on the properties of Tb 4 O 7 powders was investigated by FTIR, XRD and FESEM. It is found that 1000 °C is the optimum calcination temperature for Tb 4 O 7 powders used for fabrication of Tb 3 Al 5 O 12 (TAG) transparent ceramics, and the average particle size of the 1000 °C-calcined powder is about 150 nm. Using the 800 to 1100 °C-calcined Tb 4 O 7 powders as raw materials, TAG transparent ceramics were fabricated by vacuum sintering at 1700 °C for 20 h. The sample sintered from 1000 °C-calcined Tb 4 O 7 powders shows the best transparency, and its in-line transmittance is above 55% in the 500–1480 nm region, reaching 58.3% at the wavelength of 633 nm. The microstructures and the magneto-optical properties of the TAG ceramics sintered from 800 to 1100 °C-calcined Tb 4 O 7 powders were also studied. [ABSTRACT FROM AUTHOR]

We report the first laser oscillations of 5 at %, 10 at % and 20 at % Yb 3+ doped LuYAG ceramic samples and their spectroscopic characterization. The maximum output power, 8.7 W at 1029 nm, is achieved by 10 at % sample. A slope efficiency as high as 90.1% is obtained from the 10 at % doped sample. To our knowledge, these are the highest laser slope efficiencies obtained so far for Yb 3+ doped LuYAG ceramics. With the 20 at % doped ceramic the maximum output power was 7.2 W at 1047.6 nm with a corresponding slope efficiency of 47.4%, whereas a decrease of the output power is observed for absorbed pump power higher than 15.6 W, probably due to the appearance of a non-linear loss mechanism. Finally, we explored the tunability of the ceramics finding the broadest continuous tuning range (from 992 nm to 1060 nm, i.e. 68 nm), with 5 at % and 10 at %, while it decreases to 54 nm with 20 at %. [ABSTRACT FROM AUTHOR]

Terbium aluminum garnet (TAG) precursor was synthesized by a co-precipitation method from a mixed solution of terbium and aluminum nitrates using ammonium hydrogen carbonate (AHC) as the precipitant. The powders calcined at different temperatures were investigated by XRD, FTIR and FESEM in order to choose the optimal calcination temperature. Fine and low-agglomerated TAG powders with average particle size of 88 nm were obtained by calcining the precursor at 1100 °C for 4 h. Using this powder as starting material, TAG transparent ceramics were fabricated by vacuum sintering combined with hot isostatic pressing (HIP) sintering. For the sample pre-sintered at 1700 °C for 20 h with HIP post-treated at 1700 °C for 3 h, the average grain size is about 3.9 μm and the in-line transmittance is beyond 55% in the region of 500–1600 nm, reaching a maximum transmittance of 64.2% at the wavelength of 1450 nm. The Verdet constant at 633 nm is measured to be −178.9 rad T −1 m −1 , which is 33% larger than that of the commercial TGG single crystal (−134 rad T −1 m −1 ). [ABSTRACT FROM AUTHOR]

Terbium aluminum garnet (Tb 3 Al 5 O 12 , TAG) nanopowders were synthesized by the co-precipitation method using ammonium hydrogen carbonate (NH 4 HCO 3 , AHC) as the precipitant. The influence of ammonium hydrogen carbonate to metal ions molar ratio (AHC/M 3+ , R value) on the properties of TAG precursors and powders was investigated by FTIR, XRD and FESEM. It is found that the compositions of the precursors are nearly the same, and all the 1100°C-calcined powders exhibit a pure TAG phase. However, the R value has a significant influence on the morphology and agglomeration degree of TAG precursors and final powders. The precursor with R=3.6 shows a strong agglomeration, which is retained in the resultant powder. For the TAG precursors and powders with R=4.0, 4.4 and 4.8, they show better dispersity and homogeneity. Using the obtained powders as starting materials, TAG transparent ceramics were successfully fabricated by pre-sintering at 1700 °C for 20 h and then HIP post-treating at 1700 °C for 3 h. The ceramic sample with R=4.0 shows the best transparency, and its in-line transmittance exceeds 55% in the region of 500–1600 nm, reaching about 64% at 1450 nm. The microstructures and the magneto-optical properties of the TAG ceramics with different R values were also studied. [ABSTRACT FROM AUTHOR]

Polycrystalline 0.2at%Pr:Lu 3 Al 5 O 12 (Pr:LuAG) transparent ceramics were fabricated by solid-state reaction using 0.01 wt% MgO as sintering aid. The as-sintered ceramics were annealed in air at different temperatures. Optical absorption, photoluminescence, X-ray excited luminescence and pulse height spectra obtained after different annealing were compared. Modifications of the oxygen vacancy concentrations are found to govern the changes of the optical and scintillation response for annealing temperatures lower than 1000 °C, while the oxidation of Pr 3+ to Pr 4+ plays a more important role for higher temperatures. Air annealing up to 700 °C is an effective tool to improve the 5d-4f emission efficiency of MgO co-doped Pr:LuAG transparent ceramics. The highest radioluminescence intensity is obtained for the 700 °C annealed sample. At variance, higher temperature annealing leads to the deterioration of 5d-4f photoluminescence and scintillation properties because of the self-absorption of Pr 4+ and energy transfer from Pr 3+ to Pr 4+ . In addition, we find that the 4f-4f slow emission of ceramics shows different response characteristics under different irradiation sources. [ABSTRACT FROM AUTHOR]

A diode-double-face-pumped Nd:YAG ceramic slab laser amplifier with uniform gain distribution and low depolarization loss was presented. Energy storage of 2.6 J was achieved at 1064 nm with a repetition rate of 200 Hz and a pulse width of 200 us from a 140 mm × 40 mm × 7 mm ceramic slab at a total pump power of 1215 W, corresponding to an optical-to-optical efficiency of 42.8%. An average small signal gain of 5.45 was achieved with a standard deviation of only 0.09 in the cross section, which shown good concentration uniformity. An average depolarization loss of 2.6% at different positions of the slab was obtained due to small thermal gradient of the zigzag configuration. [ABSTRACT FROM AUTHOR]