Densification and grain growth during solid state sintering of LaPO4

This work is devoted to the kinetic study of densification and grain growth of LaPO₄ ceramics. By sintering at a temperature close to 1500 °C, densification rate can reach up to 98% of the theoretical density and grain growth can be controlled in the range 0.6–4 μm. Isothermal shrinkage measurements carried out by dilatometry revealed that densification occurs by lattice diffusion from the grain boundary to the neck. The activation energy for densification (E_D) is evaluated as 480 ± 4 kJ mol⁻¹. Grain growth is governed by lattice diffusion controlled pore drag and the activation energy (E_G) is found to be 603 ± 2 kJ mol⁻¹. The pore mobility is so low that grain growth only occurs for almost fully dense materials.