Preparation And Property Investigations Of Novel Molecular-based Phase Change Crystal Materials

Phase change materials have attracted great interest of scientists to research it owing to the break change in electrical,thermal,optical properties during its phase transition.In recent years, the research papers on phase transition crystal materials have been increasing exponentially year by year, especially ferroelectric crystal materials have been found important values in theory and applications of industry fields.In order to explore new phase change materials,we have synthesized several phase transition compounds and investigated their micro crystal structural and physical properties of thermal and dilelectric.1. we have synthesized a phase transition compound [C4H10N]2[ZnCl4]?1? by the reaction of pyrrolidine,hydrochloride and bischlorozincate.DSC measurements reveals that 1 undergoes a revesible phase transiton at 339.5 K. Its structure of room temperature and high temperature have been acquired and analysised to further investigate the phase transition mechanism. By comparing the high temperature with room temperature structures, we find the displacement of zinc ions mainly response for the phase transition. Dielectric measurements indicate that 1 undergoes a transformation in dielectric constant from a high state to a low state.2. Dbco molecular has a order-disorder structure switching depending on variable temperature. We successfully construct a phase change compound[HN?CH₂CH₂?₃NH][OOC?CH₂?COOH]₂? 2? through combining the dbco molecular and malonic acid. DSC testing confirms its pahsetransition at 228 K.We also got the single crystal data of the compound at different temperture and compared the data for searching the micro-mechanism of its phase transition. The variable temperature dielectric measurement reveals a step-like anomaly at 228 K,which is consistent with the DSC measurement.3. Glycine is used to build compounds with potential phase transition due to its twist molecular motion, thus we use glycine as the functional moiety, fluosilicic acid as the anion and synthesized the phase change compound triglycine fluosilicate.DSC measurements reveals that the compound?3? undergoes a reversible phase transition at 258 K. The structure of high temperature and low temperature during the phase transition have been measured and analysized to further study the origin of the phase transition. We find that the phase transition can be ascribed to the displacement of silicon atoms together with the fluorion order-disorder motions and N-H���F bonds.