Phase transitions and electrical properties of Bi2O3 up to 2.5 GPa

The effect of pressure between 0.5 and 2.5 GPa on the phase transitions and electrical conductivity of Bi2O3 has been studied by the use of electrical impedance spectroscopy. By analyzing the Arrhenius plots gained from the electrical conductivity measurements in the temperature range of the α – δ phase transition, the pressure dependence of the critical temperature ( T c ) and activation energy were determined. asurements demonstrated that the pressure effect between 0.5 and 2.5 GPa has a significant effect on the α – δ phase transition temperature in Bi2O3, and the increase of T c for the α – δ phase transformation is more than 60 ∘C compared to previous research with DTA [E.M. Levin, R.S. Roth, Polymorphism of Bismuth Sesquioxide. I. Pure Bi2O3, Journal of Research of the National Bureau of Standards–A. Physics and Chemistry 68A (2) (1964) 189–195]. The activation energies of electric conductivity in α – δ phases seem not to be affected by raising the pressure. cooling, the δ – α transformation occurred approximately at the temperature corresponding to T c monitored during the heating cycle. Neither a δ – β , a δ – γ phase transformation nor a hysteresis effect has been found under pressure, which is in contrast with normal pressure studies that used DTA, electrical conductivity measurements and XRD [E.M. Levin, R.S. Roth, Polymorphism of Bismuth Sesquioxide. I. Pure Bi2O3, Journal of Research of the National Bureau of Standards–A. Physics and Chemistry 68A (2) (1964) 189–195; H.A. Harwig, A.G. Gerards, Electrical Properties of the α -, β -, γ - and δ -Phases of Bismuth Sesquioxide, Journal of Solid State Chemistry 26 (1978) 265–274].