Magnetic, electric and structural properties of β-AxV2O5 (A - Na, Ag)

Article abstract of DOI:10.1143/JPSJ.68.2735

Physical properties of β-A_xV₂O₅ (A = Na, Ag) have been systematically reconsidered from structural, electric, and magnetic points of view. We prepared samples, both powder and single crystal, with precise composition for this purpose. The single crystals have been successfully grown by a self flux method using NaV₃O₈ as a flux. The precise adjustment of x was performed by embedding the as-grown crystals in a large amount of powder and heating them. β-Na_0.33V₂O₅ was not a conventional semiconductor but a possible anisctropic metal at higher temperatures. It exhibited a metal-insulator transition at 136 K, suggesting a charge ordering. The ordered structure underwent a magnetic ordering with T_c = 24 K. We also observed a development of 1 x 2 x 1 superstructure below 230K. suggesting an ordering of the intercalated ion. Those transitions similarly occurred in β-Ag_0.33V₂O₅. The deviation from x = 0.33 drastically decreased the transition temperatures or magnitudes of anomalies at the transitions, and both metallic behavior in the high temperature phase and magnetic ordering were lost.