Study of Electric Resistance and Magnetoresistance for Agx(Tl0.8Pb0.1Bi0.1)Ba2Ca2Cu3O9-δ Superconductors

Superconducting samples of the type Agx(Tl0.8Pb0.1Bi0.1) Ba2Ca2O9-δ
with (0< x < 0.4) are prepared from the high purity oxides Tl2O3, PbO, Bi2O3,
BaO2, CaO, CuO, and Ag metal at 870oC for 4h. The characterization, electric
resistance and magnetoresistance for the prepared samples are performed. Ag
addition to (Tl0.8Pb0.1Bi0.1)Ba2Ca2Cu3O9-δ shows a reduction in both lattice
parameters "a" and "c" while the grain size is improved till about x=0.2.
Resistance data show that the superconducting critical temperature "Tc" has
little variation with increasing silver addition. Oxygen annealing of these
samples causes an improvement in zero resistance temperature "T0". The excess
conductivity studies show that there are three-dimension fluctuations (3D) in
the mean field region for either pure sample or samples containing Ag. As the
silver addition increases the transverse magentoresistance decreases till x=0.2
and then increases. Transverse magnetoresistance vs. applied magnetic field at
different temperatures shows a decrease as the temperature reaches the
superconducting critical temperature. The driving current has an effect in the
value of magnetoresistance near the zero resistance temperature but it does not
affect the value of the magnetoresistance near the superconducting critical
temperature.