A new congruent-melting oxyborate, Pb4O(BO3)2 with optimally aligned BO3 triangles adopting layered-type arrangement

Abstract

Introduction of the stereo-effect of the lone pair of the Pb²⁺ cation in borate with layered-type arrangement of BO₃ triangles generates a new phase-matching nonlinear optical material, Pb₄O(BO₃)₂. In the structure, the interesting Pb₄O₁₀ tetramers are connected to each other by sharing O atoms to form a 3D framework. In the space of the framework, the isolated BO₃ and B₂O₅ groups are arranged parallel to the (100) to balance charge. The title compound melts congruently and exhibits a SHG response of ∼3 times that of KDP and ∼160 times that of a-SiO₂. And it has a wide transparent region from the UV to near IR region with a UV cut-off edge of 280 nm, which means that Pb₄O(BO₃)₂ is a very promising NLO material for potential application.