EFFECT OF COPPER ON THE ELECTRICAL-PROPERTIES OF K-1.6(MG1-YCUY)(0.8)TI7.2O16 CERAMICS

The electrical conductivity of the K-1.6(Mg1-yCu)(0.8)Ti7.2O16 ceramic s has been investigated as a function of copper fraction (0 less than or equal to y less than or equal to 1). At the calcination temperature of 1000 degrees C, a tetragonal-single phase was obtained for the all compositions. In the specimens sintered at 1100 degrees C for 4 h, th e electrical conductivity of the specimens increased with the increasi ng copper fraction, y. This result can be explained by the weakness of the K-O bonding and the increase of the bulk density and grain size. For the specimens with copper fraction (0 less than or equal to y < 0. 8), the electrical conduction was developed mainly by ionic conduction while electronic conduction abruptly occurred at copper fraction y gr eater than or equal to 0.8. This resulted from the valence transition of copper ions associated with the formation of oxygen vacancies.