CsB3O4(OH)2: a new deep-ultraviolet birefringent crystal with [B3O4(OH)2] anionic group

Abstract

A new cesium hydroxyborate CsB₃O₄(OH)₂, was designed and synthesized by a hydrothermal method. Remarkably, CsB₃O₄(OH)₂ presents novel [B₃O₄(OH)₂]_∞ chains formed by [B₃O₄(OH)₂] fundamental building blocks (FBBs). The report of less common [B₃O₄(OH)₂] FBBs and [B₃O₄(OH)₂]_∞ chains in CsB₃O₄(OH)₂ enriches the structural diversity of hydroxyborates. In addition, CsB₃O₄(OH)₂ has a wide transparent window in the DUV spectral range and a large birefringence.