Thermal conductivity of (VO2)1-xCux composites across the phase transition temperature.

The thermal conductivity across the metal-insulator transition (MIT) of hot-pressed polycrystalline vanadium dioxide (VO2) samples is studied. The change in the total thermal conductivity (k) of hot-pressed VO2 is insignificant across the MIT temperature. By adding copper (Cu) to make (VO2)1-xCux composites with x from 0 to 0.5, we find an increase in the electrical conductivity from 4×104S m-1 to 1×106S m-1 at 120 °C, resulting in an electronic thermal conductivity increase from 0.38W m-1 K-1 for x=0 to 3.8W m-1 K-1 for x=0.3, which is a significant increase. However, the total thermal conductivity did not increase due to the decrease in the value of the Lorenz number by an order of magnitude than its standard value using the Wiedemann-Franz relationship. On the basis of our experimental result, an empirical model is proposed to explain the thermal conductivity behavior of all (VO2)1-xCux samples with different Cu concentrations. [ABSTRACT FROM AUTHOR]