The Family of MII₃(TeIVO₃)₂(OH)₂ (M = Mg, Mn, Co, Ni) Compounds—Prone to Inclusion of Foreign Components into Large Hexagonal Channels

Abstract

MII₃(TeIVO₃)₂(OH)₂ (M = Mg, Mn, Co, Ni) compounds crystallize isotypically in the hexagonal space group P6₃mc (No. 186) with unit-cell parameters of a ≈ 13 Å, c ≈ 5 Å. In the crystal structure, a framework with composition M₃(TeO₃)₂(OH)1.50.5+ defines large hexagonal channels extending along [001] where the remaining OH− anions are located. Crystal-growth studies under mild hydrothermal conditions with subsequent structure analyses on basis of X-ray diffraction methods revealed that parts of other anions present in solution such as CO₃2−, SO₄2−, SeO₄2−, NO₃−, Cl− or Br− could partly replace the OH− anions in the channels. The incorporation of such anions into the M₃(TeO₃)₂(OH)₂ structure was confirmed by energy-dispersive X-ray spectrometry (EDS) measurements and Raman spectroscopy of selected single-crystals.