Pressure induced structural transition and optoelectronic modification in inorganic metavanadate phosphor

Abstract

AVO3 metavanadates (A: alkali metal) have been reported as promising inorganic white-light-emitting phosphors due to their self-activated broadband luminescence caused by the charge transfer transition in the VO4 tetrahedra. In particular, CsVO3 attracts much attention due to its highest quantum efficiency. Here, the optical and structural properties of CsVO3 are investigated under high pressure by a combination of theoretical and experimental studies. A pressure-induced structural transition from the orthorhombic to monoclinic phase is found by crystal structure prediction and further verified by x-ray diffraction and Raman spectroscopy measurements. The structural transition is accompanied by the distortion and reorientation of VO4 tetrahedra, resulting in an ultrabroad emission tunability both in peak position (from 542 to 672 nm) and full-width at half-maximum (from 158 to 194 nm) and, therefore, making CsVO3 present a white-light emission tendency after pressurization. Moreover, absorption spectra and first-principles calculations reveal a direct-indirect bandgap transition at ∼12 GPa, corresponding to the structural phase transition. These results provide new insights into the structural and optical modulation of metavanadate phosphor and promote the development of inorganic solid luminescent materials under pressure.