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Phase Transition in b-Alanine
Amino Acid Crystals
1Girnyk I., 1Mys O., 2Gridyakina
G., 2Dovbeshko G., 1Vlokh R.
1Institute of Physical Optics, 23 Dragomanov
Str., 70005 L’viv, Ukraine
2Institute of Physics of National Academy
of Sciences of Ukraine, 46 Prospect Nauki, Kiev, Ukraine
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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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