Spectroscopic characterization of Yb:Sc_2O_3 transparent ceramics

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.

Photoluminescent Property Effect of Sc_(3+) on Er_(3+)/Y_(3+)/Yb_(3+) Doped Al_2O_3 Powders

The photoluminescence （PL） property effect of Sc3＋ on the Er3＋/Y3＋/Yb3＋ doped Al2O3 powders prepared by sol-gel method has been investigated. The X-ray diffraction （XRD） and transmission electron microscopy （TEM） implied that the distribution of dopants （Er3＋ , Y3＋ , Yb3＋ , Sc3＋） was improved effectively with the rise of Sc3＋ concentration. The Fourier transform infrared spectra （FTIR） results demonstrated that the ligand around the quenching center -OH and the population of -OH were altered by introducing different amounts of Sc3＋ . The PL intensity centered at 1530 nm was increasingly improved with the rise of Sc3＋ concentration, as well as the corresponding full widths at the half maximum （FWHM） and lifetime. The optimized PL intensity was 4.7 times higher than that non-Sc3＋ doped sample for the Al2O3 powders codoped with 10mol% Sc3＋ . This material can be promising candidates for optical fiber amplifier.

Synthesis and properties of Yb:Sc_2O_3 transparent ceramics

Yb：Sc2O3 transparent ceramics were fabricated by solid-state reaction and vacuum sintering method. CaO was added as sintering aids by a high energy ball milling. Transparent nearly-fully dense samples were obtained after 1840℃ sintefing. Using transmitted-light microscope we get the grain sizes are more than 100μm. Using spectrophotometer we get the absorption coefficient centered at 975 nm was 2.65 cm-1. The phosphorescence spectra showed that the line-widths （FWHM） at 975 and 1041 nm were about 4 and 10 nm and the lifetime of Yb ions in Sc2O3 transparent ceramics was about 883 μs. According to the absorption and fluorescence band centers of Yb：Sc2O3 transparent ceramics, the level scheme of Yb3＋ ions in Sc2O3 ceramics could be gotten.

Fabrication of Ce-doped（Gd2Y）Al5O12/Y3Al5O12 composite-phase scintillation ceramic

In this paper,a novel Ce(Gd2 Y)Al5O12/Ce:Y3Al5O12(Ce:GYAG/Ce:YAG)composite scintillation ceramic was designed and fabricated by a solid-state reaction method.The phase,luminescence and scintillation properties were investigated.The Ce:GYAG/Ce:YAG composite ceramic consisting of two-phase has a broad emission band ranging from 500 to 750 nm.The total mass attenuation coefficient of Ce:GYAG/Ce:YAG is 0.3864 cm^-1,in between those of Ce:YAG and Ce:GYAG ceramics.In addition,the composite ceramic had a high light yield of 20430 ph/MeV.By controlling the ratio of GYAG and YAG,the composite ceramic can realize a spectrum design and total mass attenuation coefficient control to meet the requirements for wide-X-ray-energy-range detectors.

High entropy(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12:A novel high temperature stable thermal barrier material

Ytterbium aluminum garnet(Yb3Al5O12)is considered as a promising thermal barrier material.However,the main limitations of Yb3Al5O12 for thermal barrier applications are relative low thermal expansion coefficient and high thermal conductivity.In order to overcome these obstacles,herein,a new high entropy(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic was designed,and then powders and bulk were prepared through solid-state reaction method and spark plasma sintering(SPS),respectively.The thermal expansion coefficient of HE(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 is(8.54±0.29)×10^-6 K^-1 at 673 K–1273 K,which is about 9%higher than that of Yb3Al5O12.The thermal conductivity of HE(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 ceramic is 3.81 W·m^-1 K^-1 at 300 K,which is about 18%lower than that of Yb3Al5O12.Moreover,there is no reaction between HE(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 and thermally grown(TG)Al2O3 even at 1600℃.After annealing at 1590℃for 18 h,the average grain size of HE(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 increases only from 1.56μm to 2.27μm.Close thermal expansion coefficient to TG Al2O3,low thermal conductivity,good phase stability,excellent chemical compatibility with TG Al2O3 and slow grain growth rate make HE(Y0.2Yb0.2Lu0.2Eu0.2Er0.2)3Al5O12 promising for thermal barrier applications.

LiF对热压烧结YAG陶瓷的影响及其阻抗谱分析

该文以氟化锂(LiF)为烧结助剂,通过热压烧结(HP)的方式制备出钇铝石榴石(Y3Al5O12,YAG)透明陶瓷。表征了YAG透明陶瓷的光学性能及微观结构,并结合电化学阻抗谱进一步分析了LiF对热压烧结YAG陶瓷性能的影响。结果表明,LiF作为烧结助剂有利于促进YAG陶瓷晶粒的增长,有助于提高YAG陶瓷的致密度;阻抗谱分析显示,添加较多LiF的YAG陶瓷的晶界电阻较大,这表明LiF有助于晶界处“碳污染”等杂质的排除。当w(LiF)=1.0%时,通过真空热压烧结在1450℃、50MPa保温1h可以制备出高性能的YAG透明陶瓷,样品在400nm波长处直线透过率为58%,在1100nm波长处直线透过率为68%,在2500nm波长处直线透过率达到75%。

掺镱钇钪铝石榴石透明陶瓷制备及性能研究

采用共沉淀法,以聚乙二醇为分散剂,制备Yb:Y_3Sc_2Al_3O_(12)陶瓷粉体。通过X射线衍射和SEM测试分析,研究不同pH、沉淀干燥时间对粉体制备的影响,得到粉体的最佳制备工艺为:煅烧温度1000℃,pH值为7,煅烧时间2h,干燥时间21h,陶瓷粉体平均粒径约为100nm。采用冷等静压-真空烧结技术,在1750℃烧结20h和在1450℃退火20h得到Yb:Y3Sc2Al3O12透明陶瓷。制备的陶瓷样品尺寸为?10mm×lmm,晶粒的平均粒径为10μm,平均透过率为43%,入射光波长为1100nm时,陶瓷样品的透过率为50%。