Synthesis, structural evolution and optical properties of a new family of oxychalcogenides [Sr3VO4][MQ3] (M = Ga, In, Q = S, Se)

Abstract

A new family of oxychalcogenides, [Sr₃VO₄][MQ₃] (M = Ga, In, Q = S, Se), was successfully synthesized via the high-temperature flux method. The Ga analogues feature a centrosymmetric (P2₁/c) 0-D structure containing isolated [Ga₂Q₆]⁶⁻ dimers, [VO₄]⁵⁺ tetrahedra and Sr²⁺ ions, while the In analogues crystallize in a noncentrosymmetric (Pmc2₁) 1-D structure which comprises _∞[InQ₃]³⁻ chains, [VO₄]⁵⁺ tetrahedra and Sr²⁺ ions. The structural evolution from In to Ga analogues occurs once the Ga/In ratio increases higher than 62%/38%. [Sr₃VO₄][GaSe₃] and [Sr₃VO₄][InSe₃] possess optical band gaps of 2.51 and 2.62 eV, respectively. DFT calculations revealed their similar band edge compositions of the Se 4p–V 3d states. [Sr₃VO₄][InSe₃] exhibited a single PL emission band at 455 nm, while [Sr₃VO₄][GaSe₃] showed two emission bands at 455 and 640 nm. The calculated SHG coefficients of [Sr₃VO₄][InS₃] and [Sr₃VO₄][InSe₃] are 10.8 and 6.9 times that of KDP. We suppose that this work would inspire the exploration of oxychalcogenide-based functional materials.