Borate Hydrides as a New Material Class: Structure, Computational Studies, and Spectroscopic Investigations on Sr5(BO3)3H and Sr5(11BO3)3D

Abstract

The unprecedented borate hydride Sr5(BO3)3H and deuteride Sr5(11BO3)3D crystallizing in an apatite-related structure are reported. Despite the presence of hydride anions, the compound decomposes only slowly in air. Doped with Eu2+, it shows broad-band orange-red emission under violet excitation owing to the 4f65d–4f7 transition of Eu2+. The observed 1H NMR chemical shift is in good agreement with previously reported 1H chemical shifts of ionic metal hydrides as well as with quantum chemical calculations and very different from 1H chemical shifts usually found for hydroxide ions in similar materials. FTIR and Raman spectroscopy of different samples containing 1H, 2H, natB, and 11B combined with calculations unambiguously prove the absence of hydroxide ions and the sole incorporation of hydride ions into the borate. The orange-red emission obtained by doping with Eu2+ shows that the new compound class might be a promising host material for optical applications.