Effect of sintering temperature and P2O5 concentration on the grain shape and grain growth behavior in the ZnO–P2O5 system

In this study, ZnO was sintered with the addition of P2O5–a liquid forming oxide, and the effects of the sintering temperature and P2O5 content on microstructure evolution were investigated. When sintering was conducted below 1100 °C the grain size was almost constant in the studied range, regardless of the P2O5 content, and elongated/faceted grains with straight solid–liquid interfaces were observed. However, the grain size decreased as the amount of P2O5 increased, and rounded/spherical grains were observed when sintering was conducted at temperatures above 1100 °C. The observed changes in grain size and microstructural evolution are explained by the reaction and the diffusion controlled grain growth at low and high temperatures, respectively.