On the Low Temperature Conduction Mechanism of Ba1-xKxBiO3

Charge localization in Ba1-xKxBiO3 (BKBO) is an interesting subject to understand the normal state as well as the origin of the superconductivity. Even though BiO6 is known to be responsible for the origin, it is not very clear the role of the doping element in the vertex position. We have synthesized several BKBO samples with x = 0.40 and 0.45 by using a modified conventional route of synthesis. By using X-ray diffraction method we have extracted structural parameters including the changes in BiO6 unit. Resistivity as a function of temperature exhibits upturn in both samples. High resistive states have been explained with the help of the variable range hopping conduction mechanism. Within the range of x = 0.40 to 0.45, both samples exhibit three dimensional variable range hopping conduction within 10K to 300K. Disorder introduced by doping in the vertex position may not be very effective in changing the nature of the conduction.