A. Memon et al., THE EFFECT OF OXYGEN AND LEAD DOPING ON ELECTRICAL AND OPTICAL-PROPERTIES OF HIGH T-C GDBA2(CU1-XPBX)(3)O-DELTA COMPOUND SUPERCONDUCTORS, Journal of Materials Science, 30(23), 1995, pp. 5991-5994
A systematic study of the electrical and infrared properties of the hi
gh critical temperature, T-c, compound superconductor GdBa2(Cu1-xPbx)(
3)O-delta has been performed. Resistivity and a.c. susceptibility meas
urements show a significant drop in T-c when copper is replaced by lea
d in the range 0.005 less than or equal to x less than or equal to 0.0
25 Infrared measurements show that the conductivity of the compound in
creases with the increase in lead concentration. For undoped samples,
all the Restrahlen vibrations, common to these materials, are present
in the infrared reflectance spectra. As the concentration of lead is i
ncreased, a shift of the phonon modes, as well as broadening of the 15
0 cm(-1) phonon mode, is observed. Also the Restrahlen vibration aroun
d 410 cm(-1) present in the normal material starts to disappear. This
150 mode is attributed to a change in the oxygen concentration, and is
shown to be correlated with the critical temperature.