Thermoelectric Power and Electrical Conduction Behavior of Bi2Ge2Se2Cu3Ox

M. M. Ibrahim ； H. A. Abd El-Ghanny ； A. M. Ahmed

《Chinese Journal of Physics》 42卷4期 (2004/08) Pp. 371-391

並列摘要

In analogy to the high-Tc superconductor Bi2Sr2Ca2Cu3Ox (2223), we proposed the layered chalcogenide composition Bi2Ge2Se2Cu3Ox and studied the temperature dependence of its thermoelectric power (TEP) and electrical conductivity. Moreover, the field dependence of the electrical conductivity was also studied. The composition was synthesized by the usual meltquenching technique. The suggested physical properties were tested for bulk and powder compact samples. Annealing and sintering processes were both carried out isothermally at 573 K, which is slightly higher than the glass transition temperature. The TEP measurements verified the domination of p-type semiconducting behaviour. Transition to n-type seemed possible especially at a relatively high range of temperature and under particular conditions of thermal treatment. The diffusion component of the TEP is comparatively very high with respect to the phonon drag. Hopping conduction was found to be the most predominant mechanism contributing to the observed electrical conductivity. Nevertheless semimetallic behavior could be observed especially in the case of bulk samples at particular conditions of annealing. The electrical conductivity can be either enhanced or inhibited by the applied electric field. Additional scattering and hopping on the grain boundaries seemed to characterize the behaviour of the powder compact samples.