Zhiwei Zhou,Bingchu Mei,Jinghong Song,Weiwei Li,Yu Yang,Guoqiang Yi
CaF 2 -SrF 2 hosts with substitution disorder of Ca 2+ /Sr 2+ sites in the lattice provide lower local symmetry for RE 3+ ions compared with pure CaF 2 or SrF 2 hosts, thereby facilitating more efficient 4f → 4f transitions. Here we report a study of effects of Sr 2+ content on microstructure and spectroscopic properties of Nd 3+ doped Ca 1-x Sr x F 2 transparent ceramic. Phase and microstructure analyses show that when x is in the range of 0–0.25, Nd: Ca 1-x Sr x F 2 nanoparticles keep pure CaF 2 phase with their size, morphology and agglomeration degree mildly changed. Increasing x from 0 to 0.2 significantly improves the luminescence intensity, emission lifetime and emission cross-section of Nd: Ca 1-x Sr x F 2 , however, hardly affects the concentration quenching. The luminescence intensities and emission lifetimes of x = 0.2 and 0.25 samples are very close, probably indicating SrF 2 phase has already formed in x = 0.25 sample. Based on the spectroscopic properties, the optimal Sr 2+ content is found to be x = 0.2.
Dan Liu,Peng Shi,Wei Ren,Yantao Liu,Ming Liu,Yijun Zhang,Qijing Lin,Bian Tian,Zhuangde Jiang,Zuo-Guang Ye
La 1-x Sr x CrO 3 -In 2 O 3 thick film thermocouples were fabricated by screen-printing method for high temperature sensing and the effects of Sr 2+ content were investigated systematically. All La 1-x Sr x CrO 3 thick films showed well crystallization with orthorhombic unit cell. Their average particle sizes showed the tendency of first increase then decrease gradually with the increase of Sr 2+ content, and the maximum of average particle size was 1.76 μm. At the same time, the conductivities were improved with the increase of Sr 2+ content. The thermoelectric properties of La 1-x Sr x CrO 3 depended on the Sr 2+ content and the average Seebeck coefficients had an exponential decay tendency with the increase of Sr 2+ content. For La 1-x Sr x CrO 3 (x = 0.1–0.4)-In 2 O 3 thermocouples, excellent repeatability and stability were observed through multi-cycles and long-time usage testing at high temperature. The La 0.7 Sr 0.3 CrO 3 -In 2 O 3 thick film thermocouple with excellent thermal stability (drift rate: 0.81 °C/h) and reliability makes it become a promising candidate high sensitivity thermal sensor .
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