Sintering and grain growth kinetics in undoped and silica doped zinc oxide ceramics

Dilatometric sintering and grain growth kinetics of undoped and silica doped (2, 4, 6 wt% respectively) zinc oxide samples were systematically investigated. Silica (SiO2) as a dopant retards the densification and changes the sintering behavior of zinc oxide (ZnO) ceramics by increasing the apparent activation energy of sintering and changing densification mechanism at the initial stage. At the same time, SiO2 addition restricts the grain growth of ZnO compacts by influencing the mechanism and activation energy of the process. It is observed that the increase in temperature of sintering was more crucial for grain growth than the isothermal holding time. These effects were pronounced up to 4 wt% SiO2 doping, and beyond this level, there was a tendency of saturation (marginal change) regarding the shrinkage behavior as well as grain growth of the compacts.