Electrical Resistivity and Diffusionless Phase Transformations of Zirconia at High Temperatures and Ultrahigh Pressures

Abstract

The resistivity of chemically pure monoclinic zirconia has been investigated at pressures to 45,000 bars and temperatures to 1200°C. Measurements were made on thin, prepressed wafers of situated between the opposed, cemented carbide Bridgman anvils of a uniaxial Griggs and Kennedy simple squeezer. Observation of discontinuous changes in electrical resistance at various temperatures under isobaric conditions have been used to define the phase diagram. The pressure dependence of the temperature of the reversible monoclinic ⇌ tetragonal phase transition in zirconium dioxide agreed with the slope of the P‐T equilibrium curve up to 15 kilobars as calculated from thermodynamics, i.e., . Activation energy for electrical conduction followed the Arrhenius equation and was found to be pressure dependent, decreasing from 3.56 ev at atmospheric pressure to an apparently constant value of 0.86 ev from 30 to 45 kilobars.