Morphology and microstructure evolution of solid-state phase transition of LaPO4: Experimental and theoretical investigations

Abstract

LaPO4 was synthesized by hydrothermal process, and the morphology and microstructure evolutions in the crystal growth process were investigated by the combination of experimental results and theoretical calculations. The experimental results illustrated the solid-state phase transition and the consequent morphology changes, and the calculations accounted for the phenomena. The morphology evolution was attributed to the variations of surface energies of the two phases of LaPO4. We speculated that the process of the microstructure evolution was associated with the bond structures, and assessed that the monoclinic LaPO4 had higher stability by using the calculated band structures and the formation enthalpy, which led to the phase transition. This work identified the morphology and microstructure evolutions of LaPO4 in the crystal growth process, and provided a theoretical method to calculate the inherent properties of lanthanide orthophosphates, which was significant to gain better understanding of nanocrystal growth.