Densification and grain growth during solid state sintering of LaPO4
Résumé
This work is devoted to the kinetic study of densification and grain growth of LaPO4 ceramics. By sintering at a temperature close to 1500 degrees C, densification rate can reach up to 98% of the theoretical density and grain growth can be controlled in the range 0.6-4 mu m. 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.