LOW-TEMPERATURE SINTERING OF 0.99 SNO2 0.01 CUO - INFLUENCE OF COPPERSURFACE-DIFFUSION

The influence of CuO on the surface reactivity and on the shrinkage be haviour of a SnO2 powder has been studied at low temperature (T less t han or equal to 900 degrees C). Surface diffusion of copper ions, effe ctive at a temperature as low as 400 degrees C, results in an homogene ous distribution of copper cations on the grain surfaces. The powder's ability to fix water and oxygen-derived species is then modified. Sim ultaneously to the formation of oxygen vacancies in the outer part of the grains, a densification phenomenon is observed at 850 degrees C. T he corresponding shrinkage kinetics can be fitted using the model prop osed by Scherer to describe viscous flow sintering of a low-density ar ray of particles. A relation between the atomic defects present near t he surface of the grains and the viscous flow-like behaviour is suspec ted. Copyright (C) 1996 Elsevier Science Ltd