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Phase Transition in b-Alanine Amino Acid Crystals
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Girnyk I., Mys O., Gridyakina G., Dovbeshko G., Vlokh R.
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.
PACS 42.25.Lc, 65.70.+y, 77.80.Bh
Key words: birefringence, thermal expansion, biological crystals
doi 10.3116/16091833/4/3/147/2003 |
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