DEVIATIONS FROM LANDAU-LIKE BEHAVIOR IN THERMAL-EXPANSION COEFFICIENT AND DIELECTRIC-CONSTANT OF TGS

Systematic deviations from Landau-like behavior have been observed in the thermal expansion coefficient and the dielectric constant of TGS in the paraelectric phase along the ferroelectric b-axis. A linear relationship between the deviation of the thermal expansion coefficient Δβ2 and (εx-ε∞)·t, the product of the dipolar part of the dielectric constant at constant strain and the reduced temperature, is obtained in the temperature range 0.4 K≤T-Tc≤3 K, which is consistent with the Larkin-Khmel'nitskii theory. © 1978, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.