Ferroelectric properties in metal-coordinated complex tris(2-hydroxyethyl) ammonium trichloro cadmium(ii)

Abstract

The metal-coordinated complex tris(2-hydroxyethyl)ammonium trichloro cadmium(II) (TATC) with a space group of P2₁/c at room temperature was obtained in aqueous solution. A paraelectric–ferroelectric phase transition (from the monoclinic P2₁/c phase to the monoclinic P2₁ phase) occurs at a temperature of 270 K/247 K in the heating/cooling process, which belongs to the order–disorder type transition, and is consistent with the thermodynamic analysis from DSC results. The λ-shape dielectric anomaly follows the Curie–Weiss law with a 105.8-fold change at a frequency of 500 Hz. The maximum value of the pyroelectric coefficient P_e is about 0.11 μC cm⁻² K⁻¹, which is higher than the classical ferroelectric crystal TGS (5.5 × 10⁻² μC cm⁻² K⁻¹). The maximum value of the related figures of merit (FOMs) M₁ and M₂ at a frequency of 1 MHz is 0.0108 cm² μC⁻¹ and 0.0245 cm^3/2 J^−1/2, respectively, which is higher than that of TGS (4 × 10⁻³ cm² μC⁻¹ and 0.01 cm^3/2 J^−1/2). The compensation method (the Sawyer–Tower method) and the double-wave method were used to obtain ferroelectric hysteresis loops and display the ferroelectricity of TATC. The spontaneous polarization and the coercive field of TATC can reach about 1.4 μC cm⁻² and 0.3 kV cm⁻¹, respectively. The intense dielectric anomaly and the near-room-temperature T_c value indicate that TATC can be an applicable dielectric switching material.