Thermoelastic and Piezoelastic Properties of Hexagonal RbMnCl₃

Abstract

Temperature and pressure derivatives of the elastic constants, indices of refraction, diclectric constants, Faraday erfect and thermal expansion of RbMnCI, near T, = 278 K confirm the existence of a second-order phasc transition. A strongly anomalous bchaviour is obscrved with the elastic shcar stiffncss c4,, which possesses a positive tempcraturc derivative and a ncgative pressurc derivative. Thcse properties and also the pressure derivative of the transition tempcrature, clTJdp = 6.2 K kbar-' closely rcsemble the anomalous behaviour of two other ferroelectric species, betainc borate and betainc hydrogen maleinate.

Study on Ferroelastic Phase Transition of Hexagonal System by Slowness-Curved-Surface and Polarization

“…But all the results in relevant references [7][8][9] coincide with the theory suggested in this paper.…”

“…For hexagonal RbMnCl 3 , there is a second-order phase transition [9]. The elastic shear stiffness c 44 is softening at Curie temperature.…”

Solid-State 87Rb NMR Study in Powdered RbMnCl3

“…RbMnCl 3 crystal supplied from the Dielectric Crystal Bank was synthesized from a mixture of RbCl and MnCl 2 powder according to the method described by Jeong and Haussuhl [8]. Samples were ground to powders just before experimental measurements because of their hygroscopic property.…”