Selenite bromide nonlinear optical materials Pb2GaF2(SeO3)2Br and Pb2NbO2(SeO3)2Br: synthesis and characterization

Abstract

Two new isomorphic selenite bromides, namely Pb₂GaF₂(SeO₃)₂Br (1) and Pb₂NbO₂(SeO₃)₂Br (2), were synthesized by mild hydrothermal reactions. These two compounds crystallize in the noncentrosymmertric space group P2₁ and feature 3D structures consisting of 1D (Pb₂Br)³⁺ cationic chains and 2D [Ga₂F₄(SeO₃)₄]⁶⁻/[Nb₂O₄(SeO₃)₄]⁶⁻ anonic chains. As measured, 1 and 2 are phase-matchable and exhibit excellent second harmonic generation (SHG) responses of 4.5 and 1.4 times that of KDP, respectively. Moreover, these two compounds possess wide bandgaps (>3.17 eV) and high thermal stabilities (>425 °C), indicating their suitable performances as potential nonlinear optical materials. First-principle density functional theory (DFT) calculations were also performed to explicate the structure–property relationship.