Compressibility and vibration modes of the supramolecular compound assembly from arsenic vanadates and [Co(H₂O)₆]²⁺ cations

Abstract

The high‐pressure behavior of new supramolecular compound based on arsenic vanadates formulated as [H2As6V15O42(H2O)][Co(H2O)6]2.2H2O is investigated by Raman spectroscopy using a diamond anvil cell up to 21GPa. A reversible pressure‐induced phase transition was observed at a pressure above 8.3 GPa. Upon compression, the intensity of modes at lower‐frequency from 100‐600 cm‐1V1, V2, V3, V4, softens and vanishes at about 8.3 GPa. Also, the high‐frequency v7(937cm‐1) disappears at about 8.3 GPa. The reversible transition may be due to both the extinct of vanadyl(V=O) double bonds in VO5 pyramids and the changes in the AsO3 network under pressure. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)