ATHERMAL TRANSFORMATION BEHAVIOR AND THERMAL HYSTERESIS AT THE SIO2-ALPHA BETA-CRISTOBALITE PHASE-TRANSITION/

The alpha/beta-phase-transition of cristobalite (SiO2) shows a stable and reproducible hysteresis loop with phase coexistence on both slopes . The transition proceeds as a function of temperature rather than iso thermally. The non-thermally-activated (athermal) behaviour is analogo us to martensitic transformations in metals and alloys, and similar to the hysteresis of ferroics in an applied field. The observations sugg est that self-pinning by coherency-strain is the cause of the 'thermal ' hysteresis of non-quenchable structural phase transitions.