Low-temperature sintering of 0.99 SnO2 0.01 CuO: Influence of copper surface diffusion

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