Ion-beam-induced spinel-to-rocksalt structural phase transformation in MgAl2O4

Abstract

An ion-beam-induced metastable phase in magnesium aluminate spinel (MgAl2O4) has been examined in detail using transmission electron microscopy. Single crystals of MgAl2O4 with (111) orientation were irradiated with 180-keV Ne+ ions at 120 K to fluences of 1016 and 1017/cm2. Selected-area electron diffraction patterns obtained from the irradiation-induced damaged layer revealed that all even hkl reflections (e.g., 222) possess strong intensity, while all odd hkl reflections (e.g., 111) are weak. The features of these diffraction patterns corresponded to those of the rocksalt (NaCl) structure, suggesting that an ordered spinel to disordered rocksalt structural phase transformation in MgAl2O4 was induced by ion beam irradiation.