17735-75-0Relevant academic research and scientific papers
Ferroelastic phase transition in T1H2PO4
Yoshida, Hideyo,Endo, Manabu,Kaneko, Tsutomu,Osaka, Toshio,Makita, Yasuharu
, p. 910 - 912 (1984)
The dielectric constant along the b axis, εb, of T1H 2PO4 was measured and its domain structures were observed. It is found that T1H2PO4 is ferroelastic with the spontaneous shear strain x5S=2.3 × 102 at room temperature and undergoes a ferroelastic phase transition at 84 °C (T 1), above which x5S vanishes. εb shows a small anomaly at T1. There are two kinds of domain structures at room temperature; one is the domain structure with the (100) and/or (001) domain walls which disappears above T1 and the other is the structure with the (201) wall which has no relation with the 84 °C transition.
Study of the Ferroelastic Phase Transition of TIH2PO4 Acoustic Phonon Softening
Hanazawa, Kazuhiro,Komukae, Masaru,Osaka, Toshio,Makita, Yasuharu,Arai, Masazumi,Yagi, Toshirou,Sakai, Akira
, p. 188 - 195 (1991)
Elastic, thermal and dielectric measurements of TIH2PO 4 were carried out in a temperature range covering the upper phase transition point at 357 K. The specific heat shows a λ-type anomaly associated with the upper phase transition of second order and yields the transition entropy ΔS= 1.46 J/mol-K. The elastic stiffness c55 among cu(i= 1, 2, ..., 6) determined from the ultrasonic velocity data at a frequency of 10 MHz shows a large anomaly with a tendency to approach zero in value at the upper phase transition point. It was shown that the upper, ferroelastic phase transition is caused by an instability of the B2g transverse acoustic mode, and the elastic, thermal and dielectric behaviours near the ferroelastic phase transition point can be reasonably explained by a phenomenological theory.
