Community Research and Development Information Service - CORDIS

Phase transitions in minerals: elastic instabilities and domain structures

Measurement of the thickness of twin boundaries in alkali feldspar: the results have been obatained. The data have been used to determine the Ginzburg energy. The temperature evolution of the wall thickness is in rough agreement with the predictions of the Landau Ginzburg theory.

Computer simulations: the simulation of pericline walls in alkali feldspars was achieved showing that these walls show worm-like wiggles at the early stages of their formation.

SiO2 - polymorphis: a general theory for the reconstructive phase transitions in SiO2 has been attempted. The results look promising but need further discussions.

Ultrasonic measurements: An extremely valuable sample was sent to Rotov. Unfortunately it appears that the experiments did not yet succeed in the measurement of the relevant elastic constants. It was found that the relevant elastic constant C46 is very small. It is not clear what further experiments can realistically be undertaken. Recent checks on measurements of elastic constants of quatrz were rather promising.

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E.K.H SALJE
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Record Number: 24239 / Last updated on: 2000-03-28
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Stage of development: Other,