Dielectric anomaly of tungsten trioxide WO₃ with giant dielectric constant

Abstract

Temperature dependences of the dielectric constant and the dielectric dispersion of a WO 3 single crystal have been measured in the temperature range from -180 °C to 100 °C and at frequencies from 20 Hz to 1 MHz. A large dielectric anomaly has been observed at 16.2 °C on heating, and the peak value of the dielectric constant is as large as about 10 5 . The anomaly has large thermal hysteresis, long relaxation time and large dielectric dispersion. A transition from ferrielectric state to ferroelectric state induced by an electric field has been observed by D -E hysteresis measurement below room temperature. In the triclinic phase, the coexistence of the monoclinic(II) and the monoclinic(I) phases was observed by EPR (ESR) measurements of doped Cr 3+ ions. These results suggest that a frustration of the antiferroelectric and ferroelectric states exists at the dielectric anomaly temperature. The dielectric anomaly can be interpreted as a result of the phase transition between the triclinic phase with micro ferroelectric regions and the antiferroelectric monoclinic(I) phase.

Optical properties of tungsten trioxide from first-principles calculations

“…However, the use of ω LO = 70 meV does not appear to have a robust justification. Interestingly, with the vdW-DF2 functional we obtained [10] results in better agreement with experiments for ǫ ∞ (5.63), ω LO (125 meV) [71] and ǫ 0 (31) [75,76].…”

Phosphorus solid solution effects of electric and dielectric properties on sintered WO3 ceramics

“…Hirose et al reported that the dielectric constant of the nondoped WO 3 ceramic was 4000 at 16.2°C, 4) and those of the phosphorus-doped WO 3 ceramic was smaller than the value reported for non-doped WO 3 at 100 kHz. Therefore, it assumed that the doping phosphorus in WO 3 host caused decreasing the dielectric constant of WO 3 .…”

Flexopiezoelectricity at ferroelastic domain walls in WO3 films

“…27,28 ), strain gradient (~10 6 m −1 ), vacuum permittivity (~8.85 × 10 −12 C V −1 m −1 ), and electric susceptibility (~5000, ref. 34 Origin of flexoelectricity in WO 3 . To further ensure the existence of strain gradients at the domain walls, we examined the flexoelectric polarization, because flexoelectricity is a universal phenomenon present in all crystalline solids subjected to strain gradients.…”