Above-room-temperature ferroelectricity and piezoelectric activity of dimethylglycinium-dimethylglycine chloride

• Main Authors: Czarnecki, P. (Author), Ghazaryan, V.V (Author), Petrosyan, A.M (Author), Szafrański, M. (Author), Tylczyński, Z. (Author), Wiesner, M. (Author)
• Format: Article
• Language: English
• Published: Elsevier Ltd 2022
• Subjects: Amino acids; Calorimetry; Chlorine compounds; Crystallography; Curie point; Curie points; Curie temperature; Dielectric relaxation; Dimethylglycine; Environmentally compatible; Ferroelectric materials; Ferroelectric property; Ferroelectricity; Ferroelectrics; Glycine; Heavy metals; Hybrid organic-inorganic materials; Inorganic oxides; Metal free; Phase transition; Piezoelectric activity; Piezoelectric effect; Piezoelectricity; Polar space group; Polarization; Single crystals; Spontaneous polarization; Spontaneous polarizations
• Online Access: View Fulltext in Publisher

 Heavy-metal-free ferroelectrics are sought as environmentally compatible alternatives to commonly used inorganic oxides. Here, we demonstrate direct evidence of the ferroelectric properties of a hybrid organic–inorganic material, dimethylglycinium-dimethylglycine chloride. At room temperature, the compound crystallizes in the polar space group P21 and exhibits a switchable spontaneous polarization of 1.9 μC cm−2. Ferroelectric properties are preserved in a wide temperature range up to about 401 K, where the crystal undergoes the transition to the paraelectric phase of the space group P21/c. The temperature-dependent single-crystal X-ray diffraction study and the calorimetric data indicate an order–disorder contribution to the transition mechanism, which is consistent with the critical slowing down of the dielectric relaxation observed near the Curie point. The spontaneous polarization results from ionic displacements that are induced by changes in the disordering of the dimeric cations. In the ferroelectric phase, the crystal exhibits remarkable piezoelectric activity. The electromechanical and elastic properties of the material were thoroughly characterized. © 2022 The Authors