Grain growth of ZnO in binary ZnO-V2O5 ceramics

Grain growth of ZnO during liquid-phase sintering of binary ZnO-V2O5 ceramics has been studied for V2O5 contents from 0.5 to 4 mol% and sintering from 900degreesC to 1200degreesC. The results are discussed and compared with previous studies in terms of the phenomenological kinetic grain growth expression: G(n) - G(o)(n) = K(o)t exp(- Q/RT). Addition of V2O5 is found to decrease the ZnO grain growth exponent, n, as well as the apparent activation energy, Q. The activation analysis also reveals a change in the rate-controlling mechanism for ZnO grain growth. Following a low-V2O5-content (less than or equal to2 mol%) of nearly constant Q values of about 88 kJ/mol, further V2O5 additions cause an increase of the Q value to about 115 kJ/mol. Consistent with accepted models of liquid-phase sintering, it is concluded that the rate-controlling mechanism of ZnO grain growth during liquid-phase sintering in the presence of V2O5 changes from one of a phase-boundary reaction at low V2O5 levels to one of diffusion through the liquid phase at more than 2 mol% V2O5 levels. (C) 2003 Kluwer Academic Publishers.