The Family of IM/I[sup.II][sub.3] Compounds—Prone to Inclusion of Foreign Components into Large Hexagonal Channels

M[sup.II] [sub.3](Te[sup.IV]O[sub.3])[sub.2](OH)[sub.2] (M = Mg, Mn, Co, Ni) compounds crystallize isotypically in the hexagonal space group P6[sub.3]mc (No. 186) with unit-cell parameters of a ≈ 13 Å, c ≈ 5 Å. In the crystal structure, a framework with composition M[sub.3](TeO[sub.3])[sub.2](OH)[sub.1.5] [sup.0.5+] defines large hexagonal channels extending along [001] where the remaining OH[sup.−] 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 CO[sub.3] [sup.2−], SO[sub.4] [sup.2−], SeO[sub.4] [sup.2−], NO[sub.3] [sup.−], Cl[sup.−] or Br[sup.−] could partly replace the OH[sup.−] anions in the channels. The incorporation of such anions into the M[sub.3](TeO[sub.3])[sub.2](OH)[sub.2] structure was confirmed by energy-dispersive X-ray spectrometry (EDS) measurements and Raman spectroscopy of selected single-crystals.