High-pressure synthesis and crystal structure of the samarium meta-oxoborate γ-Sm(BO2)3

gamma-Sm(BO2)(3) was obtained via a high-pressure/high-temperature approach in a multi-anvil apparatus at 10 GPa and 1673 K. It crystallizes in the orthorhombic space group Pca2(1) (no. 29) with the lattice parameters a = 18.3088(8), b = 4.4181(2), and c = 4.2551(2) angstrom. The compound was analysed by means of X-ray diffraction and vibrational spectroscopy. The structure is isotypic to that of the already known meta-oxoborates gamma-Sm(BO2)(3) (RE = La-Nd) and built up of a highly condensed borate framework containing three-, four-, six-, and ten-membered rings. Next to neodymium, samarium represents the second rare earth element that forms the alpha-, beta-, and gamma-modification of the four known rare earth meta-oxoborate structure types.