Comparative study of Fe₂B₃O₇ and Mn₄(B₆O₁₃(OH)): a new structure linking melilite and johachidolite

Abstract

The two compounds Fe₂B₃O₇ (a = 663.61(4), c = 438.39(3) pm, space group: P

2₁ m) and Mn₄(B₆O₁₃(OH)) (a = 445.14(1), b = 683.56(2), c = 1330.34(3) pm, β = 90.42(1)°, space group: P2₁/c) were synthesized under high-pressure/high-temperature conditions of 9 GPa and 800 °C. Their crystal structures have been determined via single-crystal X-ray diffraction and the occurring side-phases have been identified. Fe₂B₃O₇ crystallizes in the melilite structure type, whereas the novel structure of Mn₄(B₆O₁₃(OH)) can be derived from the structures of the minerals melilite or johachidolite.