A local Hamiltonian is introduced to study BaPb_(1-x)Bi_(X)O_(3).The usual CPA method is used to deal with the substitutional disorder effect-The superconducting Tc^x relation is calculated and the result is in agreem...A local Hamiltonian is introduced to study BaPb_(1-x)Bi_(X)O_(3).The usual CPA method is used to deal with the substitutional disorder effect-The superconducting Tc^x relation is calculated and the result is in agreement with experiments.Some remarks on the characteristics of oxide superconductivity are presented.展开更多
A series of Hg-doped BaPb0.75Bi0.25O3 with a nominal composition of BaPb0.75-xHgxBi0.25O3 （x=0 to 0.40 with 0.05 intervals） have been synthesized by solid-state reaction. These compounds exhibit a cubic perovskite-r...A series of Hg-doped BaPb0.75Bi0.25O3 with a nominal composition of BaPb0.75-xHgxBi0.25O3 （x=0 to 0.40 with 0.05 intervals） have been synthesized by solid-state reaction. These compounds exhibit a cubic perovskite-related structure with the lattice parameter being expanded by Hg doping. Superconducting transition temperature Tc and superconducting volume fraction are suppressed by Hg doping in the low doping level region （0≤ x ≤0.25）. However, further increasing Hg content makes the superconductivity recovered at x〉0.3. The superconductivity suppression in Hg-doped BaPb0.75Bi0.25O3 can be explained by the decrease of electron carrier concentration as well as the bandnarrowing-induced electron localization.展开更多
Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semicon...Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi（Pb）O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi（Pb）O6 rigid rotation, but also on the energy shift of the mode.展开更多
文摘A local Hamiltonian is introduced to study BaPb_(1-x)Bi_(X)O_(3).The usual CPA method is used to deal with the substitutional disorder effect-The superconducting Tc^x relation is calculated and the result is in agreement with experiments.Some remarks on the characteristics of oxide superconductivity are presented.
基金This work was supported by the National Science Foundation of China under Grant No. 50372052, 50588201the National Basic Research Program of China (973 program) under Grant No. 2007CB616906+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University,Australian Research Council under Grant No. DP0559872, DP0881739.
文摘A series of Hg-doped BaPb0.75Bi0.25O3 with a nominal composition of BaPb0.75-xHgxBi0.25O3 （x=0 to 0.40 with 0.05 intervals） have been synthesized by solid-state reaction. These compounds exhibit a cubic perovskite-related structure with the lattice parameter being expanded by Hg doping. Superconducting transition temperature Tc and superconducting volume fraction are suppressed by Hg doping in the low doping level region （0≤ x ≤0.25）. However, further increasing Hg content makes the superconductivity recovered at x〉0.3. The superconductivity suppression in Hg-doped BaPb0.75Bi0.25O3 can be explained by the decrease of electron carrier concentration as well as the bandnarrowing-induced electron localization.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10104013 and 50421201, and the National Basic Research Programme of China under Grant No 2006CB601003.
文摘Crystal structure, electrical properties and Raman spectra of BaBi1-xPbxO3 are reported. The result of x-ray diffraction shows that the specimen is pure, and the lattice parameters decrease continuously in the semiconducting range, whereas it vibrates similarly to a sine wave in the superconducting range, which is ascribed to the existence of oxygen vacancies and the function of breathing modes of Bi（Pb）O6. The temperature dependence of resistivity indicates that the electrical property of the samples is connected sensitively with the crystal structures. Raman spectra show that the specimen becomes disorder when x increases, and the critical temperature To depends not only on the deformation potential of the soft A19 mode derived from the Bi（Pb）O6 rigid rotation, but also on the energy shift of the mode.
