Parameters in the ferroelectric phase of TGS

Abstract

Polarization P(T) of triglycine sulfate (TGS) crystal shows distinct properties versus temperature, between 28 °C and the Curie point Tc. Carefully measured polarization versus temperature on several ranges is presented. The slopes on the curve P(T) on three temperature ranges between 28 ÷ 46 °C appear quite normal, while near the Curie point (47 °C ÷ Tc) behave abnormally, due to the domain walls. The relaxation time LOW, MIDDLE and HIGH appear very interesting. The MIDDLE relaxation time τ_M, between 40 ÷ 46 °C behave like the HIGH relaxation time τ_H between 47 and 48 °C and between −20 ÷ 10 °C (25 K_BT) similar to LOW relaxation time τ_L (28K_BT). The diagrams Cole-Cole of TGS are analyzed here for the first time. Roughly, several parameters change their slopes at 30, 42, and 47 °C. The values of ε′_H and εʺ_H show about the same slope on the zones 42–47 °C and 30–42 °C. For the same zones, ε′_L shows several increasing activation energies toward Curie point, except εʺ_L and R_L whose activation energy decreases. Finally, we mention the opposite variation of the negative ordinate Y_CH, Y_CL of both arcs Cole-Cole and of the radius R_H and R_L.

Keywords:

• Triglycine sulfate crystal
• polarization
• relaxation time versus temperature and frequency
• activation energy
• Cole-Cole parameters