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831.
832.
Li‐Ping Li Guang‐She Li Wen‐Hui Su Xu‐Dong Zhao Xiaoyang Liu 《Hyperfine Interactions》2000,128(4):409-415
A series of hexaborides La1?xEuxB6 (x=0.0–1.0) were synthesized under a pressure of 3.5 GPa and at a temperature of 1600○C using La2O3, Eu2O3 and amorphous boron as the starting materials. The products were characterized by X‐ray Diffraction (XRD) and Mössbauer spectroscopy. XRD data analysis shows that all samples crystallize in a cubic CsCl‐type structure, and the cell volume increases with x. Room temperature 151Eu Mössbauer measurements reveal that Eu ions in all samples are in the divalent state, except for the x=1.0 sample where a small amount of Eu3+ ions was detected. The quadrupole splitting of the Eu2+ ions is positive. Eu ions were reduced from trivalent to divalent during the high‐pressure and ‐temperature processes. The isomer shifts of the Eu2+ ions are all smaller than ?12.5 mm/s, suggesting that there is no valence fluctuation in the samples. The hexaborides doped by divalent Eu are not metallic. 相似文献
833.
From Maxwell’ s equations for electromagnetic fields, time-averaged energy flow density vector of stable monochromatic linearly
polarized light in an isotropic insulative nonmagnetic medium is deduced. By the introduction of time-averaged energy flow
density rays and the definition of new generalized refractive indexn
G1, Fermat’s principle of geometric optics is further generalized and its application conditions are discussed. The generalized
Fermat' s principle can be used to describe stable transmission of light in a medium with variable refractive index. The necessary
and sufficient conditions of a nondivergent and nonfocusing light beam are derived from this Fermat’s principle.
Project supported by the National Natural Science Foundation of China (Grant No. 69789801) and Guangdong Provincial Natural
Science Foundation of China. 相似文献
834.
835.
离子色谱法(安培检测器)测定血清、尿及头发中微量碘 总被引:7,自引:0,他引:7
This paper intreduces a reasonable pretreatment method for IC-amperometric method employed to measuretrace amount of iodine in serum, urine and hair. The resultant graph is simple and clear,and withoutinterference in a general way. The limits of detection for iodine in serum,urine and hair are 0.007,0.003μg/mL and 0. 046μg/g, respectively.The recovery of iodine added into the sample is 82~93%. The coefficient ofvariation is less than 9%. Trace amount of bromine in the sample can also be measured simultan 相似文献
836.
Ying Tian Yang She Jiafeng Wu Mu Chai Liansheng Huang 《Journal of Solid State Electrochemistry》2023,27(8):2185-2197
Journal of Solid State Electrochemistry - Alleviating and restraining thermal runaway (TR) of lithium-ion batteries is a critical issue in developing new energy vehicles. The battery state of... 相似文献
837.