Effects of electrochemical hydrogen charging on electrical properties of WO₃ ceramics

Excerpt

Tungsten trioxide (WO₃) films are used extensively in eletrochromic devices [1], surface acoustic wave gas sensors [2] and photo-catalytic degradation [3]. In recent years, there has also been a growing interest in WO₃-based ceramics. Due to their high dielectric constant, WO₃ ceramics have been proposed for applications in ceramic capacitors [4]. WO₃-based semiconducting ceramics have been successfully used for detection and control of toxic gases. In 1994, Makarov et al. reported nonlinear current–voltage characteristics of Na₂CO₃ and MnO₂-doped WO₃ ceramics [5]. Now much progress has been achieved in preparing WO₃-based ceramic varistors with low breakdown voltage [6]. Their high dielectric constant enables them to act as a varistor in parallel with a capacitor, which is attractive for applications in elimination of electrical noise of micro-motors, protecting contact of delays and absorbing discharges of some circuits. …