Phase Transitions and Electrophysical Properties of Tungsten(VI) Oxide in a 83–673 K Temperature Range

Resumo

The paper studies the changes in the crystal structure and dielectric properties of tungsten(VI) oxide (WO₃) in the temperature range from 83 to 673 K. Investigations are performed using X-ray phase analysis and scanning electron microscopy of the material under study. It is found that the phase transition from triclinic to monoclinic structure occurs at 83 K for the tungsten(VI) oxide powder. When the powder is heated up to 673 K, its crystal structure again becomes triclinic. The peak intensity of the initial WO₃ powder heated up to 673 K is observed at a Bragg angle of 24.34 degrees, while that of the cooled WO₃ powder occurs at 23.08 degrees. The powder calcination changes the crystal lattice parameter at a Bragg angle of 24.34 degrees, such that а = 6.333 Å and а = 6.339 Å for the initial and calcined WO₃ powder, respectively. The main electrophysical properties are obtained for the WO₃ powder specimens, namely: surface resistance, specific surface resistance and conductivity, electric conductivity, permittivity, dissipation factor.