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

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.