S.A. Saleh

Influence of sintering temperature on excess conductivity in Bi-2223 superconductors

Structural examinations and resistivity measurements were made on Bi1.75Pb0.35Sr2Ca2Cu3O10 samples sintered at different temperatures. The excess conductivity region was analysed using the Aslamazov?Larkin (AL) expression. In agreement with the theoretical predictions, the ln(??/?300)?ln(?) plots exhibited three different regions, namely, critical, mean field and short wave fluctuation regions. In the mean field region, the interlayer coupling strength ?, the effective layer thickness d, and the zero-temperature coherence length ?(0) were estimated using the Lawrence?Doniach (LD) expression.

Influence of sintering temperature on thermopower and hardness of RuSr2GdCu2O8

The structural, mechanical and transport properties of RuSr2GdCu2O8 sintered between 1000 and 1065 ◦ Ci n O 2 atmosphere have been studied by XRD, microhardness and Seebeck coefficient measurements. The pellets have a tetragonal perovskite-type structure. Microhardness and bulk density of the considered samples increase with increasing sintering temperature. TEP is positive for all samples and decreases with increasing sintering temperature. The normal state TEP data are discussed in view of some theoretical models, namely a two-band model with an additional linear T term and variable range hopping models. (Some figures in this article are in colour only in the electronic version)

Studies on sintering effect on the transport properties of Pb1−xSmxSe

Pb1?xSmxSe (x=0.03, 0.06 and 0.09) compounds are synthesized by solid-state reaction. The x-ray diffraction technique, scanning electron microscope, electrical and thermoelectric power measurements were used to characterize the prepared samples. The samples are sintered at 488?K and the effect of the sintering time on the transport properties was investigated. The metal?insulator transition occurrence depends on both the Sm content and the sintering time. The energy band gap Eg was calculated for the sintered samples of 0.06 Sm composition in the intrinsic region. The Seebeck coefficient measurements show that all the samples under investigation are n-type semiconductor materials with electron carrier predomination at low temperature and hole conduction contribution at high temperature. The power factor S2? was calculated and gave a good indication of the wide application of the investigated compositions as thermoelectric materials.

The thermoelectric properties of Bi-2223 superconductors sintered at different conditions

Structural examinations and thermoelectric power measurements were carried out on Bi1.75Pb0.35Sr2Ca2Cu3O10 samples sintered at different conditions. The thermoelectric power of all samples was found to be positive, and it increases almost linearly with the decrease of temperature up to ~140 K, before falling to zero at Tco. However, the thermoelectric power changes slightly with increasing sintering temperature and time. The normal state results are analyzed in terms of a two-band model with an additional term that is linear in T. The effects of sintering temperature and time on the parameters related to this model have been investigated.