STUDY ON THE PREPARATION AND PHYSICAL PROPERTY DETERMINATION OF NaVO2.

Article abstract of DOI:10.1016/0022-4596(88)90124-7

Stoichiometric and near-stoichiometric NaVO//2 phases have been prepared by the hydrogen reduction of NaVO//3 or mixtures of Na//2CO//3 and V//2O//5 at 650 degree C. The black reduction products react instantly with air to generate nonstoichiometric Na//xVO//2 phases with the formation of NaOH. Stoichiometry of the compound could be maintained by working in a dry box under a gettered argon atmosphere. Pure NaVO//2 was characterized by X-ray diffraction studies, thermoanalytical methods, and magnetic measurements. The semireversible crystallographic transition was noted at 115 degree C by means of a differential scanning calorimetry experiment. This transition, however, is very weak and quite broad. At room temperature, NaVO//2 appears to be orthorhombic, but above the transition temperature, it adopts the alpha -NaFeO//2 structure. The magnetic properties indicate a moderate interaction between vanadium centers.