Abstract
This study elucidates both structural and physical behaviors of Thallium-Zinc Orthophosphate (TlZnPO4) compound via solid-state reaction. Advanced analytical techniques were performed to study the microstructure and investigate the existence of phase transitions in this material. Raman and impedance spectroscopy were studied to understand the behavior of the studied material and to determine its vibrational and electrical properties. At room temperature, the XRPD analysis confirmed that the synthesized material could be satisfactorily indexed using a P2(1) space group of the monoclinic unit cell. DSC analysis reveals the existence of two reversible phase transitions at T-1 = 546/498 K and T-2 = 646/600 K (Heating/Cooling). The first combine both order-disorder and displacive mechanism, while the second is displacive. SEM analysis reveals that the grains size is in the micrometric scale. Raman, as well as impedance spectroscopy analysis, proved the existence of two phase transitions. These transitions arise from the rotation of both ZnOn ((n= 4, 5)) and PO4 in the opposite direction. This rotation provokes a change in coordination of Zn atoms from ZnO5 to ZnO4, achieving higher symmetry. The electrical study confirmed the existence of a non-Debye type relaxation attributed to the grain contribution. The dielectric study proved that the observed phase transitions are ferroelectric.