Phase Identification and Structure Solution by Three-Dimensional Electron Diffraction Tomography: Gd–Phosphate Nanorods

Abstract

Hydrothermal synthesis of GdPO₄ in the presence of poly­(methacrylic acid) yields nanorods with a diameter of 15 nm and an aspect ratio of 20. Powder X-ray diffraction patterns showed that the GdPO₄ nanorods display peaks characteristics for both monoclinic and hexagonal structures. Three-dimensional electron diffraction tomography (3D EDT) was used to determine the structures <i>ab initio</i> on the basis of reciprocal volume reconstruction of electron diffraction data sets collected from single nanorods. The crystal structure of the monoclinic form was shown to be <i>P</i>2₁/<i>n</i>, corroborating previous work. We were able to solve the 3D structure of the hexagonal <i>P</i>6₂22 form, which has not been reported previously. Our work shows that 3D EDT is a powerful method that can be used for solving structures of single nanocrystals