Factor Group Analysis on the Deformed Pyrochlore-Structure Hydroxyl Transition Metal Halides

Factor group analysis on the deformed pyrochlore-structure hydroxyl transition metal halidesM2(OH)3X(M= Co, Fe and Mn;X= Cl, Br and I) with the crystal symmetry ≡D3d5of space group No. 166 for their infrared (IR) and Raman spectroscopic studies are, for the fist time to the best of our knowledge, reported. Through a standard factor group analysis, we predict that there are 17 IR active normal modes (7A2u+ 10Eu) and 12 Raman active modes (5A1g+ 7Eg), caused by five atomic site groups [HOM3], [OM3], [MO4X2], [ClM3] and [MO6], where the black body letters represent the site atoms. In addition we figure out all the atomic displacement patterns of 12 Raman active normal modes, and point out these results are completely same as those of the famous geometric frustration material Herbertsmithite ZnCu3(OH)6Cl2.

Spectral Properties of Alpha-Cu2(OH/D)3Br at Room Temperature

The newly identified magnetic geometric frustration material-botallackite-structure deuteroxyl copper bromide α-Cu2(OD)3Br sample was successfully synthesized in the same single phase (polycrystalline) as the H-isotope substituted sample of α-Cu2(OH)3Br, and its IR (4000-400 cm–1) absorption and Raman (4000-95 cm–1) spectra at room temperature are first, to the best of our knowledge, measured to study the corresponding relationship between these iso-structural compounds. Through the comparative analysis with those of α-Cu2(OH)3Br reported previously, we definitely assign or tentatively suggest their vibration modes according to the result of the factor group analysis.