Electrical conductivity measurements were carried out, under uniaxial stress, in this H-bonded super-protonic conductor. It was found that an increase in the superprotonic phase transition temperature was observed under uniaxial stress along the b-axis at room temperature. On the other hand, no change in phase transition temperature was observed under uniaxial stress along the c-axis. It was also found, from the point of view of free energy, that the value of spontaneous strain a0 in the a–b plane was closely related to an increase in the phase transition temperature under uniaxial stress. From the results, it was deduced that the increase in the superprotonic phase transition temperature under uniaxial stress was caused by suppression of the release of spontaneous strain in the a–b plane.

Effect of Uniaxial Stress in Superprotonic Phase Transition in Cs3H(SeO4)2. Y.Matsuo, Y.Tanaka, J.Hatori, S.Ikehata: Solid State Ionics, 2008, 179[21-26], 1125-7