Effect of surface chemistry on morphology evolution of LaPO4: Experiment and density functional theory calculations

Abstract

The morphology of the nanocrystals has a considerable effect on their performances in particular applications, and the study of morphology has become a challenging topic in nanometer materials. In our experimental work, LaPO4 with diverse morphologies were synthesized by hydrothermal method to investigate the morphology evolution. The results revealed the corresponding relationship between the pH value of growth solution and the specific exposed surfaces and morphologies of monoclinic LaPO4. Combining the experimental findings, density functional theory calculations were used to calculate the surface energies and to simulate the morphologies. With the increase of pH value, the surface energies increased with different rates, which can be responsible for the evolution of the morphologies. The equilibrium shapes of monoclinic LaPO4 nanorods for each type of surface chemistry were predicted according to the calculated surface energies, whose tendency was consistent with our experimental findings. This work identified the mechanism for the morphology evolution of LaPO4 and provided a theoretical method to calculate the morphologies of lanthanide orthophosphates, which was crucial to gain better control of materials growth.