The Study Of Organic-inorganic Hybrid Dielectric,Ferroelectric Materials

Organic-inorganic hybrid compounds are an important class of functional materials.Since the organic amine cations components can usually respond to external stimuli triggering the structural phase transitions,accompanied by the response of the physical,electrical,magnetic,thermal,and other physical properties,thus this kind of material can be used as multifunctional materials in various fields,such as storage,switching,sensing,energy conversion and so on.Based on the organic-inorganic hybrid stragegy,eleven hybrid halogenmetallic compounds were synthesized,in which seven of them have the perovskite structures.In the second chapter of this dissertation,we synthesized a series of organic-inorganic hybrid compounds:((N-(2-ammoniumethyl)piperazinium)CuCl5·2H2O)(1),the total deuterated compounds((N-(2-ammoniumethyl)piperazinium)CuCl5·2D2O)(2),C11H21Cl3MnN2(3),C11H22Cl4MnN2(4),(IBA)CdBr3(5)and(IBA)2CdBr4(6)(IBA= iso-butylamine cation).Compounds 1 and 2 exhibit sequential dielectric transition properties because of the vibration of water molecules subjected to external temperature change,and compound 3 shows bright red luminescence with a quantum yield of 35%.Compound 4 displays low temperature dielectric transition behavior accompanied by an ultra-high green luminescence quantum yield of 92.3%.Compounds 5 and 6 with completely different structures are obtained through changing the reaction ratio of the starting reagents.Compound 5 has a one-dimensional hexagonal perovskite organic-inorganic hybrid structure with dual structural phase transitions at low temperatures accompanied by dielectric transition behaviors.Compound 6 with a two-dimensional layered perovskite organic-inorganic hybrid structure exhibits a triplet phase transitions accompanied by significant dielectric anisotropies.In the third chapter,we synthesized three layered organicinorganic hybrid perovskite compounds using chain organic amines:(IBA)2PbBr4(7)and(IAA)2CdX4(IAA = iso-amylamine cation,X = Cl,8 and Br,9).Compound 7 presents a sequential structural phase transitions accompanied with remarkable dielectric properties and dielectric anisotropies.By changing the halogen atoms,we synthesized compounds 8 and 9.The phase transition behaviors of them are obviously different because that the different halogen atoms make the size of the inorganic anion frameworks different.Thus,the organic cation exhibits different states of motion in the space formed by the inorganic metal anions.In the fourth and fifth chapters,we synthesized two layered organic-inorganic hybrid perovskite compounds using chain organic amines:(IBA)2CdCl4(10)and(IBA)2MnCl4(11).Compound 10 shows sequential structural phase transitions and the second phase transition is a ferroelectric phase transition,accompanied by a rare dynamic dielectric behavior.In addition,compound 10 has prominent mechanical flexibility,and its thin film exhibits very good flexibility and can be bent in a larger curvature.Compound 11 displays similar properties as that of 10 except that the metal ion Mn endows the compound with ferromagnetic and luminescent properties,making compound 11 a rare two-dimensional layered luminescent and multi-ferroic hybrid material.Therefore,organic-inorganic hybrid strategy provides an effective way to synthesize and design molecular dielectric,ferroelectric materials.