First-order phase diagram of thiourea and raman spectroscopy

In this paper, the first-order phase diagram of thiourea has been determined by means of low-frequency Raman spectroscopy. This high-pressure phase (phase HP) previously discovere by Bridgman has been shown to be different from any of the five low-pressure modifications. But thermodynamical data der...

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Bibliographic Details
Published in:Chemical physics letters 1975-05, Vol.33 (1), p.99-103
Main Authors: Figuiere, Pierre, Ghelfenstein, Michel, Szwarc, Henri
Format: Article
Language:English
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Summary:In this paper, the first-order phase diagram of thiourea has been determined by means of low-frequency Raman spectroscopy. This high-pressure phase (phase HP) previously discovere by Bridgman has been shown to be different from any of the five low-pressure modifications. But thermodynamical data derived from the phase diagram show that phase HP should be orthorhombic too. They also prove that a negative volume change accompanies the transition from the low-temperature ferroelectric phase to phase II. No conclusion concerning an eventual ferroelectric behaviour of phase HP could be drawn.
ISSN:0009-2614
1873-4448
DOI:10.1016/0009-2614(75)85462-5