M. V. Gorev, V. S. Bondarev, S. I. Raevskaya, M. P. Ivliev, I. P. Raevskii, I. N. Flerov, “Studies of the heat capacity and thermal expansion of the Na$_{0.95}$K$_{0.05}$NbO$_3$ solid solution”, Fizika Tverdogo Tela, 2014, Volume 56, Issue 2,Pages 362

This article is cited in 2 papers

Lattice dynamics

Studies of the heat capacity and thermal expansion of the Na$_{0.95}$K$_{0.05}$NbO$_3$ solid solution

M. V. Gorev^ab, V. S. Bondarev^ab, S. I. Raevskaya^c, M. P. Ivliev^c, I. P. Raevskii^c, I. N. Flerov^ab

^a L. V. Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk
^b Institute of Engineering Physics and Radioelectronics, Siberian Federal University, Krasnoyarsk
^c Research Institute of Physics, Southern Federal University, Rostov-on-Don

Abstract: The heat capacity and thermal expansion of ceramic samples of the Na$_{0.95}$K$_{0.05}$NbO$_3$ solid solution have been investigated over a wide temperature range of 100–750 K. The observed anomalies in the heat capacity and thermal expansion at $T_4$ = 297 K, $T_3$ = 535 K, $T_2$ = 665 K, and $T_1\approx$ 710 K correspond to the sequences of phase transitions $N\to Q\to G\to S\to T1$. It has been shown that, as a result of the phase transitions, the unit cell volume at $T_4$ and $T_2$ decreases, and at $T_3$ and $T_1$, increases with increasing temperature. The directions of the shift of the phase transition temperatures induced by hydrostatic pressure have been determined. It has been established that all structural transformations are accompanied by relatively small variations in the entropy. Different mechanisms of the structural distortions have been discussed.

Received: 21.06.2013