Superconducting phase diagram of InxWO3 synthesized by indium deintercalation

We report the superconducting phase diagram of the hexagonal tungsten bronze (HTB) InxWO3. The InxWO3 samples were prepared by indium deintercalation of the thermodynamically stable parent phase In0.33WO3. By employing this technique, a lowest indium content in the HTB phase of x similar to 0.07 was achieved, which cannot be obtained by conventional solid-state reaction. In addition, accurately and reproducibly controlled indium content and homogeneous samples enable us to perform a systematic study of the physical properties of InxWO3. Most of the InxWO3 samples exhibit a superconducting transition and the highest transition temperature T-c = 4.2 K in InxWO3 was observed at x = 0.11. The indium content dependence of T-c(x) shows remarkable similarities to other MxWO3 (M = K and Rb) HTBs. Our results reveal the universality of physical properties in the HTB family and give a strategy to achieve higher T-c in HTBs. Copyright (c) EPLA, 2013