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The positron annihilation lifetime spectra and their temperature dependence for the YBa2Cu3Oy superconducting ceramics doped with Sn have been studied. The results of analyses indicate that the element Sn is substituted for Cu(1) sites, and this leads to the ordering of the oxygen atoms as well as the increase of local electronic density in the Cu(1)-O layer where Cu(1) is substituted by Sn.

A cadmium-antimony-oxide semiconductor ceramic synthesized by heating CdO and Sb/sub 2/O/sub 5/ is discussed. Its composition, structure, phase transition, and electrical properties have been systematically studied. The study indicates that the material is an n-type semiconductor, Cd/sub 6/Sb/sub 2/O/sub 10/. A reversible structural phase transformation occurs at about 240 degrees C. The transition temperature of the heating and cooling processes are 246 degrees C and 228 degrees C, respectively. The R-T curves can be divided into three temperature regions. The conduction mechanism in the three regions and the associated defect structure and phase transformation properties are discussed. The activation energy and carrier mobilities are calculated. >

The synthesizing process and mass transport mechanism of CdO-Sb2O5 ceramics are discussed. Two compounds with stable structure have been obtained and the crystal structures and microstructures are examined by XRD and SEM. A differential scanning calorimeter is used to determine the phase transformation and latent heat. The defect structure of these semiconducting ceramics are investigated by varying the atmosphere, trivalent ion doping, and Seebeck effect experiments.