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Physics and Chemistry of Minerals

, Volume 5, Issue 1, pp 83–93 | Cite as

A room-temperature phase transition in maximum microcline

Heat capacity measurements
  • R. E. Openshaw
  • B. S. Hemingway
  • R. A. Robie
  • K. M. Krupka
Article

Abstract

The thermal hysteresis in heat capacity measurements recently reported (Openshaw et al., 1976) for a maximum microcline prepared from Amelia albite by fused-salt ion-exchange is described in detail. The hysteresis is characterized by two limiting and reproducible curves which differ by 1% of the measured heat capacities. The lower curve, denoted curve B, represents the values obtained before the sample had been cooled below 300 K. Measurements made immediately after cooling the sample below 250 K followed a second parallel curve, curve A, to at least 370 K. Values intermediate to the two limiting curves were also obtained. The transitions from the B to the A curve were rapid and observed to occur three times. The time required to complete the transition from the A to the B curve increased from 39 h to 102 h in the two times it was observed to occur. The hysteresis is interpreted as evidence of a phase change in microcline at 300±10 K The heat effect associated with the phase change has not been evaluated.

Keywords

Phase Transition Heat Capacity Mineral Resource Phase Change Material Processing 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

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Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • R. E. Openshaw
    • 1
  • B. S. Hemingway
    • 2
  • R. A. Robie
    • 2
  • K. M. Krupka
    • 2
  1. 1.Centre de Recherches Pétrographiques et Géochimiques, C.O. No. 1Vandoeuvre-les-NancyFrance
  2. 2.U.S. Geological SurveyRestonU.S.A.

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