共查询到19条相似文献,搜索用时 62 毫秒
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据媒体报道,"世界钨都""稀土王国"——江西赣州日前由政府牵头筹资约18亿元,在全市启动钨、稀土产品收储计划,储备钨精矿及钨加工产品1万吨和稀土原矿及各类稀土分离产品1万吨。此次收储旨在稳定市场价格,帮助企业渡过难关。 相似文献
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依据GB 11224—89《水中钍的分析测定》的分析方法,对偶氮胂Ⅲ分光光度法测定环境水样中钍含量的不确定度进行评定,分析不确定度来源,测定其分量,合成标准不确定度。水样中钍含量为0.372μg/L时,当包含因子k=2时,给出扩展不确定度为0.032μg/L。 相似文献
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白光LED用稀土红色荧光粉的研究进展 总被引:3,自引:1,他引:3
白光LED具有低压、低功耗、高可靠性和长寿命等一系列优点,是一种符合环保和节能的绿色照明光源。现阶段制造高显色指数、低色温,大功率白光LED是白光LED发展的总体趋势。而红色荧光粉性能对白光LED的显色指数及色温的影响极其显著。本方法着重介绍和评述了白光LED用红色荧光粉硫化物、氮化物、钼酸盐和钨酸盐等几大主要体系的发光性质及最新研究成果和发展现状,并对白光LED用荧光粉的发展进行了展望。 相似文献
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铕配合物与苯乙烯共聚物的研究 总被引:3,自引:0,他引:3
Copolymers containing rare earth complex were prepared via copolymerizing complex Eu^3 (BA)2 (AA) (phen)) with styrene. A sort of semitransparent luminescent polymer material with high fluorescent intensity was obtained. They were characterized by means of IR and UV spectra, which show that they were copolymers, not blendings. The fluorescence spectra of copolymer indicated that it showed intense UV absorption characteristics of rare earth complex as long as only a little complex join in it. Moreover, thermal analysis showed that they had excellent heat-stability. 相似文献
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Neutron spectroscopy is a powerful tool to determine unambiguously the crystal-field (CF) potential in rare-earth (R) based
high-T
c
superconducting materials. This technique provides detailed information on the electronic ground state of the R ions which
is important to understand the thermodynamic magnetic properties as well as the observed coexistence between superconductivity
and long-range magnetic ordering of the R ion sublattice at low temperatures. Moreover, the decay of the antiferromagnetic
state of the parent compound as well as the evolution of the superconducting state upon doping can be directly and quantitatively
monitored. It is found that the observed CF spectra separate into different local components whose spectral weights distinctly
depend on the doping level, i.e., there is clear experimental evidence for cluster formation. The onset of superconductivity
can be shown to result from percolation which means that the superconductivity is an inhomogeneous materials property. Since
the linewidths of CF transitions directly probe the static electronic susceptibility, we discuss temperature-dependent experiments
of the relaxation rate of CF excitations in both optimally doped and underdoped regimes. It is shown that there is clear evidence
for the opening of an electronic gap in the normal state of underdoped superconductors. Furthermore, the relaxation behavior
appears to be extremely dependent upon the energy at which the static susceptibility is being probed. The main observed features
can be reproduced by considering a strongly anisotropic gap function. 相似文献