Intrinsic [VO4]3− emission of cesium vanadate Cs5V3O10

Abstract

Polycrystalline Cs₅V₃O₁₀ micro-particles were synthesized by a solid-state reaction. The vanadate shows intrinsic self-activated luminescence of a single broad band with a peak at 520 nm, extending from about 400 nm to 720 nm. This asymmetric band is composed of two bands due to the electronic transitions from the ³T₁ and ³T₂ excited states to the ¹A₁ ground state in [VO₄]³⁻ centers. The same emission band was obtained for micro- and nanoparticles. It is suggested that the broadening of the emission band arises from single [VO₄]³⁻ molecules. The emission and decay curve profiles indicate that the emission is not due to different kinds of [VO₄]³⁻ centers but only one kind of [VO₄]³⁻ center. When the temperature is increased from 10 K to 450 K, the emission intensity increases below 150 K and decreases above 150 K, and an unusual blue shift is observed. The observed temperature dependence can be understood by the relaxation processes of the emitting ³T₁ and ³T₂ states including the thermal feeding by the lower-energy ³T₁ state to the higher-energy ³T₂ state.