Electrical Characterization of Pressure-Induced Phase Transitions
A procedure has been developed for the direct Observation of the pressure-induced polymorphic phase transitions. The resistance Variation, which is due to the different electronic structures of the two phases of the mercury chalcogenides [1,2], is measured directly on the sample. Small sample volume increases the sensitivity of the technique; therefore, the interaction of its volume Variation with the generated pressure is negligible. Thus, the pressure remains an independent variable during the transition. The kinetics and the mechanism of the reaction can be followed directly and independently of the pressure-transmitting medium. Although the measurement of volume Variation as a function of pressure seems to closely follow the advancement of the transition reactions, as is detected through the pressure-transmitting medium, the technique is an indirect one. Furthermore, to achieve sufficient accuracy, large sample volumes are required. Consequently, the volume change of the sample generates an auxiliary uncontrollable pressure Variation which counteracts the experimentally adjusted pressure. This phenomenon is called retropressure [3,4].
KeywordsResistance Variation Hysteresis Curve Transition Pressure Nucleation Center Transition State Theory
Unable to display preview. Download preview PDF.
- 6.F. Birch, in Solids Under Pressure, W. Paul and D. M. Warschauer, eds., McGraw-Hill Book Company, New York (1963), p. 131.Google Scholar
- 8.F. Birch, in Geol. Soc. Am. Mem., S. P. Clark, Jr., ed. (1966), p. 97.Google Scholar
- P. W. Bridgman, Proc. Am. Acad. Arts Sei. 76, 55 (1948).Google Scholar
- 15.B. Gutenberg and C. F. Richter, Seismicity of the Earth and Associated Phenomena, Hafner Publishing Company (1965), p. 10.Google Scholar