Studies On The Modulation Structures Of SrCrO₃ Induced By Electron Beam Irradiation

The perovskite-type transition metal oxide SrCrO₃ has attracted much attention due to its subtle transitions of structural,electrical and magnetic properties.However,previous researches primarily focused on polycrystalline and thin-film specimens since the single crystal SrCrO₃ is difficult to synthesize.Here,we present a systematic investigation on cubic perovskite single crystal Sr CrO₃ by using transmission electron microscopy（TEM）,scanning transmission electron microscopy（STEM）,electron energy-loss spectroscopy（EELS）and ab initio calculations based on DFT theory.The main content includes:The patent phase SrCrO₃ could transform three mew modulated structures induced by controllable slight electron beam irradiation（EBI）,The EELS results reveal that EBI generates ordered oxygen vacancies and subsequently give rise to structural transformation to three new structures SrCrO_2.5（I4/mmm）,SrCrO_2.8（C2/m）and SrCrO_2.67（Cm）.We proposed three possible structure models and carried out ab initio calculations to optimize them,and explained the forming procedure of the three modulated structures based on thermodynamics.These results show that EBI can be used to tune the crystal structure and physical properties of materials and enrich the content of SrCrO_3-δsystem.