Phase transitions in antimony at hydrostatic pressure up to 9 GPa

Melting and solid-solid phase transitions in antimony are studied at hydrostatic pressure up to 9 GPa and at temperatures of 20 to 620 °C by means of thermopower and electrical resistance measurements and differential thermal analysis (DTA). The P-T diagram based on the precise measurement of pressure at high temperature is presented. The polymorphic transition of antimony from the rhombohedral (Sb I) to the simple cubic (Sb II) phase observed earlier under nonhydro-static pressure is not found at hydrostatic pressure. The rhombohedral phase (Sb I) transforms directly to the high pressure phase (Sb III) in the range from the room temperature up to the melting of Sb. The kinetics of the Sb I →III transition is specific to thermally activated nucleation and growth transformation, with a pressure hysteresis of the transition increasing exponentially as the temperature decreases. The triple point Sb I-Sb III-liquid is found at 5.03 GPa and 559 °C.