The metal-insulator transition in trivalent-ion-doped tungsten bronzes.
Electrical transport measurements have been made on a series of trivalent-ion-doped tungsten bronzes MxWO3, with M = Y (0.05 ≤ x ≤ 0.12) or La (0.05 ≤ x ≤ 0.19), over the temperature range 2-300 K. The results are consistent with a metal-insulator transition (MIT) at a critical concentration xC ≃ 0.06, which corresponds to an electron concentration nC ≃ 3.3 × 10(21) cm(-3). The appearance of small concentrations of non-cubic phases for x ∼ xC does not have a significant impact on the evolution of the electronic properties of the trivalent bronzes in the low x range. Analysis of the transport results, and a comparison of the findings with those obtained by other workers for the sodium tungsten bronzes, suggest that electron-electron interaction effects play a significant role in inducing the MIT in this type of disordered system.
School of Physics, University of the Witwatersrand, Johannesburg, PO Wits 2050, South Africa.
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D017097:Electric Impedance; D004583:Electrons; D010087:Oxides / Q000737:chemistry; D012964:Sodium / Q000737:chemistry; D013696:Temperature; D014414:Tungsten / Q000737:chemistry*
D010087:Oxides; D012964:Sodium; D014414:Tungsten