The effects of different sintering addictives on the preparation of CaF2 transparent ceramics were studied. Transparent CaF2 ceramics were fabricated by vacuum sintering and hot isostatic pressing （HIP） method, usin...The effects of different sintering addictives on the preparation of CaF2 transparent ceramics were studied. Transparent CaF2 ceramics were fabricated by vacuum sintering and hot isostatic pressing （HIP） method, using CaF2 nanopowders synthesized by chemical precipitation method as raw materials. The nanopowders and transparent ceramics were studied using X-ray diffraction, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and spectrophotometer. The experimental results indicated that the obtained nanopowders presented normal distribution with grain size about 30 nm; transmittance of CaF2 transparent ceramics was 39% and 26% at 1100 nm for LiF and NaF as sintering addictives, respectively, with corresponding mean grain size 188 μm and 44 μm. Loss of transmission could be attributed to the residual closed porosity. Sintering mechanism was liquid-phase sintering at pre-stage, then solid-phase sintering at later stage, as well as solid solution of lithium ions and sodium ions in the CaF2 lattice structure.展开更多
Optically transparent alumina ceramics were fabricated by conventional process and sintered without pressure in H2 atmosphere. The results indicate that relative densities of alumina specimens increase to theoretical ...Optically transparent alumina ceramics were fabricated by conventional process and sintered without pressure in H2 atmosphere. The results indicate that relative densities of alumina specimens increase to theoretical densities （T. D. ） with increasing content of La2O3. With increasing holding time during sintering, much less pores and larger grains were found in the sintered alumina samples. Higher transmittance was achieved in alumina codoped with MgO and La2O3 as compared with that doped with MgO only. The total-transmittance of alumina sample is up to 86% at twavelength range of 300 - 800 nm.展开更多
Yb：Sc2O3 transparent ceramics are fabricated by a conventional ceramic process and sintering in H2 atmosphere. The room-temperature spectroscopic properties are investigated, and the Raman spectrum shows an obvious v...Yb：Sc2O3 transparent ceramics are fabricated by a conventional ceramic process and sintering in H2 atmosphere. The room-temperature spectroscopic properties are investigated, and the Raman spectrum shows an obvious vibration characteristic band centred at 415 cm-1. There are three broad absorption bands around 891, 937, and 971 nm, respectively. The strongest emission peak is centred at 1.04 μm with a broad bandwidth （11 nm） and an emission cross-section of 1.8×10^-20 cm^2. The gain coefficient implies a possible laser ability in a range from 990 nm to 1425 nm. The energy-level structure shows that Yb：Sc2O3 ceramics have large Stark splitting at the ground state level due to their strong crystal field. All the results show that Yb：Sc2O3 transparent ceramics are a promising material for short pulse lasers.展开更多
Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in ...Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.展开更多
Highly transparent Yb,Ho doped（YLa）2O3 ceramic was fabricated by conventional ceramic processing with nanopowders.The absorption and emission spectra of the ceramic was investigated.The energy transfer mechanism bet...Highly transparent Yb,Ho doped（YLa）2O3 ceramic was fabricated by conventional ceramic processing with nanopowders.The absorption and emission spectra of the ceramic was investigated.The energy transfer mechanism between Yb3＋ and Ho3＋ was also discussed.The strong emission band around 2 μm indicated that the Yb-Ho：（Y 0.90 La 0.10）2O3 transparent ceramic is a promising gain medium for the generation of 2 μm laser emissions.The laser operation of Yb-Ho co-doped（YLa）2O3 ceramic at 2.1 μm is first reported.展开更多
基金Funded by the National Natural Science Foundation of China (No. 51072144)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing (Wuhan University of Technology) (No. 2009-ZT-1)
文摘The effects of different sintering addictives on the preparation of CaF2 transparent ceramics were studied. Transparent CaF2 ceramics were fabricated by vacuum sintering and hot isostatic pressing （HIP） method, using CaF2 nanopowders synthesized by chemical precipitation method as raw materials. The nanopowders and transparent ceramics were studied using X-ray diffraction, transmission electron microscopy （TEM）, scanning electron microscopy （SEM） and spectrophotometer. The experimental results indicated that the obtained nanopowders presented normal distribution with grain size about 30 nm; transmittance of CaF2 transparent ceramics was 39% and 26% at 1100 nm for LiF and NaF as sintering addictives, respectively, with corresponding mean grain size 188 μm and 44 μm. Loss of transmission could be attributed to the residual closed porosity. Sintering mechanism was liquid-phase sintering at pre-stage, then solid-phase sintering at later stage, as well as solid solution of lithium ions and sodium ions in the CaF2 lattice structure.
文摘Optically transparent alumina ceramics were fabricated by conventional process and sintered without pressure in H2 atmosphere. The results indicate that relative densities of alumina specimens increase to theoretical densities （T. D. ） with increasing content of La2O3. With increasing holding time during sintering, much less pores and larger grains were found in the sintered alumina samples. Higher transmittance was achieved in alumina codoped with MgO and La2O3 as compared with that doped with MgO only. The total-transmittance of alumina sample is up to 86% at twavelength range of 300 - 800 nm.
基金supported by the Key Basic Research Project of Science and Technology Commission of Shanghai, China (Grant No. 09JC1406500)
文摘Yb：Sc2O3 transparent ceramics are fabricated by a conventional ceramic process and sintering in H2 atmosphere. The room-temperature spectroscopic properties are investigated, and the Raman spectrum shows an obvious vibration characteristic band centred at 415 cm-1. There are three broad absorption bands around 891, 937, and 971 nm, respectively. The strongest emission peak is centred at 1.04 μm with a broad bandwidth （11 nm） and an emission cross-section of 1.8×10^-20 cm^2. The gain coefficient implies a possible laser ability in a range from 990 nm to 1425 nm. The energy-level structure shows that Yb：Sc2O3 ceramics have large Stark splitting at the ground state level due to their strong crystal field. All the results show that Yb：Sc2O3 transparent ceramics are a promising material for short pulse lasers.
基金National Key R&D Program of China(2023YFB3507400)。
文摘Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60578041)the Sciences and Technology Commission Foundation of Shanghai,China (Grant No. 08520707300)+1 种基金the Key Basic Research Project of Science and Technology Commission of Shanghai,China (Grant No. 09JC1406500)the Graduate Student Innovation Fund of Shanghai University,China (Grant No. SHUCX120058)
文摘Highly transparent Yb,Ho doped（YLa）2O3 ceramic was fabricated by conventional ceramic processing with nanopowders.The absorption and emission spectra of the ceramic was investigated.The energy transfer mechanism between Yb3＋ and Ho3＋ was also discussed.The strong emission band around 2 μm indicated that the Yb-Ho：（Y 0.90 La 0.10）2O3 transparent ceramic is a promising gain medium for the generation of 2 μm laser emissions.The laser operation of Yb-Ho co-doped（YLa）2O3 ceramic at 2.1 μm is first reported.
