Phase transitions in monoclinic RbD₂PO₄

Preparation of Different Solid CsHSO4 Phases by Means of Sample Treatment

“…However the reported data on these transitions disagree: The first paper [3] mentions two transitions, one at 373 K and a second one at 413 K, the first one being characterized by a negligible heat capacity anomaly and more pro nounced dielectric constant anomalies. This first transition was not found in the more recent papers [4][5][6]. We could show that it is due to the relaxation of a low-energy state (called state II below), which is created by grinding.…”

“…On the other hand, a phase transition at about 333 K, not found in the first paper [3], has been reported in [4-6], As we shall see, on applying one-dimensional pressure, state II goes over to a state III with a slightly higher energy, which relaxes by a first order phase transition around 333 K with an endothermic enthalpy change. We also shall demonstrate the importance of water vapour for the phase transitions observed, which was completely disregarded before [3][4][5][6]. This seems important in connection with the hydrogen bonds surely involved.…”

“…During the last years solid-solid transitions of CsHS04 [3][4][5][6][7] have become of great interest because of the unusual electrical properties of this substance. However the reported data on these transitions disagree: The first paper [3] mentions two transitions, one at 373 K and a second one at 413 K, the first one being characterized by a negligible heat capacity anomaly and more pro nounced dielectric constant anomalies.…”

Phonon dynamics of RbD2PO4crystal

“…The next phase transition, occurring at T 2 , from intermediate into polar ferrielectric phase P2 1 (2a, b, 2c) is also connected with the appearance of superstructure along the a axis. Such an interesting sequence of phase transitions has been intensively investigated by means of structural [1][2][3][4][5], dielectric [6][7][8][9][10][11][12][13], spectroscopic [14,15], acoustic [16,17], resonance [18,19] and dilatometric [6,20] studies. DRDP has two kinds of hydrogen bonds.…”

EPR Study of VO2+Center in Fast Proton Conductor K3H(SO4)2

“…Crystals, which belong to family M 3 H(XO 4 ) 2 , where M = NH 4 , Rb, Cs, K; X = S, Se, exhibit a high proton conductivity [1][2][3][4][5][6][7]. The crystal structure of K 3 H(SO 4 ) 2 (KHS) was determined by X-ray diffraction [8,9].…”