BaClBF4: a new noncentrosymmetric pseudo-Aurivillius type material with transparency range from deep UV to middle IR and a high laser damage threshold

Abstract

A new noncentrosymmetric alkaline earth metal halide borate, BaClBF₄, has been synthesized with crystal size up to 6 mm × 6 mm × 3 mm via the hydrothermal method at 200 °C. The crystal structure can be described as an alternate stacking of cationic [Ba₂Cl₂]²⁺ layers with anionic [BF₄]⁻ layers along the b direction, and the [Ba₂Cl₂]²⁺ layer is a pseudo-Aurivillius type layer similar to the [Bi₂O₂]²⁺ layer. The transmittance range of BaClBF₄ is from 0.18 to 8.5 μm, and the laser damage threshold of the crystal is about 6.8 GW cm⁻². EDS, TG-DSC and second harmonic generation investigations are reported. The electronic structure is discussed to explain the structure–property relationships.