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Phase Transition in b-Alanine Amino Acid Crystals

Author(s): Girnyk I., | Mys O. | Gridyakina G. | Dovbeshko G. | Vlokh R.

Journal: Ukrainian Journal of Physical Optics
ISSN 1609-1833

Volume: 4;
Issue: 3;
Start page: 144;
Date: 2003;
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Keywords: birefringence | thermal expansion | biological crystals

Single b-alanine crystals are grown by a triple cross-crystallization from the saturated aqueous solution of chemically pure b-Ala powder and then dried in the vacuum thermostat at 340K. b-Ala single crystals belong to the point group of symmetry mmm at the room temperature. It is found that the temperature dependences of thermal expansion and the optical manifest anomalous behaviour at T=204K, thus testifying the existence of phase transition at this temperature. The temperature hysteresis of the Curie temperature Tc means that the phase transition in b-Ala crystals is of the first order. The spontaneous deformations and birefringence increments calculated by us depend linearly on temperature. It is shown that the phase transition in b-Ala crystals could be ferroelectric or higher-order ferroic.
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