U.P.B. Sci. Bull., Series B, Vol. 81, Iss. 1, 2019 ISSN 1454-2331 INVESTIGATION OF Ag2HgI4 NANOPARTICLES: THERMAL PHASE TRANSITION AND NON-ISOTHERMAL KINETIC STUDY A.M. MANSOUR A* , I.M. EL RADAF B , TALAAT A. HAMEED A , G. B. SAKR C Ag2HgI4 nano-powder was successively prepared by the solvothermal method. The structure and morphology of the resulted powder were characterized by X-ray diffraction technique, electron dispersive x-ray spectroscopy (EDX), and scanning electron microscope (SEM). Phase transformation was studied by differential thermal analysis (DTA) at 5, 10, 15, 20, 25, and 30 degrees/minute heating rates. The non-isothermal apparent activation energy of the attained thermal transitions was calculated by Kissinger, Flynn-Wall-Ozawa, and Augis- Bennett approaches respectively. Keywords: Ag2HgI4; DTA; Kissinger; Flynn-Wall-Ozawa; Augis-Bennett 1. Introduction A variety of solids exhibits transformations from one structure to one other by changing temperature [1]. The subject of phase transitions was increased extensively in last few years, with new types of transitions including new approaches to discuss the event. The high ionic conductivity achieved by many superionic conductors is through clear phase transitions, at particular temperatures [2–4]. 1 During the phase transition, the free energy of the solid is kept constant but thermodynamic quantities including heat capacity, volume and entropy display discontinuous changes [5,6]. Phase transitions in solid are frequently associated with significant variations in its benefits. Several techniques are employed to inspect phase transition, based upon the feature of the solid and properties of interest. Those studies were carried out not only for academic understanding structural and mechanisms attributes of phase transitions but can also be of manufacturing great importance. Study of phase transitions in solid employs a broad selection of techniques including XRD, thermal and electrical conductivity methods. 1a Solid-State Physics Department, Physics Division, National Research Centre, Dokki, Giza, Egypt b Electron Microscope and Thin Films Department, Physics Division, National Research Centre, Dokki, Giza, Egypt c Nanoscience laboratory for environmental and biomedical applications (NLEBA), Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt, *Corresponding author e-mail: amamansour@gmail.com