Electron spin resonance of defects in single crystal and thin films of tungsten trioxide

Abstract

The ESR spectra of single crystals and amorphous thin films of W${\mathrm{O}}_{3}$ have been measured in the temperature range 77-300\ifmmode^\circ\else\textdegree\fi{}K. In the case of single crystal the observed resonance lines were identified as due to ${\mathrm{Mo}}^{5+}$ ions. The observed values are: ${g}_{\mathrm{I}}=1.776$, ${g}_{\mathrm{II}}=1.796$, and ${g}_{\mathrm{III}}=1.833$ and the hyperfine splitting constants are ${A}_{\mathrm{I}}=0.0029$, ${A}_{\mathrm{II}}=0.0026$, and ${A}_{\mathrm{III}}=0.0074$. In the case of thin-film broad resonance absorption at $g=2.012$ and $g=1.918$ was observed for colorless film which on electrocoloration showed an additional resonance at $g=1.75$. The temperature dependence of the electrical conductivity and spin density gave activation energies of 0.21 and 0.04 eV, respectively.