V_2O_4·0.25H_2O nanowires are synthesized via hydrothermal route. The nanowires are of metastable phase, and transverse grain boundaries are observed in their microstructures. Transport through individual V_2O_4·0.25H_2O nanowires shows nonlinear current-voltage (Ⅰ-Ⅴ) characteristics in the bias range of -3 to 3 V. The resistance rapidly decreases from 2.54 to 0.5 MΩ as the bias is raised from 0 to 1 V. Such behaviors can be attributed to the presence of the barrier at the transverse grain boundary. By analyzing the Ⅰ-Ⅴ curves at various temperatures, the effective barrier height is estimated to be about 0.13 eV. Our results provide important information about how the microstructure mismatch affects the electrical properties.
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