Structural modifications of dodecatungstophosphoric acid hexahydrate induced by temperature in the 10–358 K range. In situ high-resolution neutron powder diffraction investigation

Dodecatungstophosphoric acid hexahydrate H3PW12O40·6H2O crystal structure has been investigated by neutron powder diffraction (NPD) at different temperatures in the 10–358 K range. A nonconvergent reversible phase transition has been noticed at about 320 K. This transition is associated with a change in dynamic equilibrium of hydrate species and partial reduction/oxidation (redox) W6+↔W5+. Expressive structure changes lie in the PO bonding inside Kegginʹs anion and the H5O2+ conformational angle.