Study On The Phase Transition Properties Of Metal Sb(?),Bi(?) And Organic Amine Hybrid Compounds

Organic-inorganic hybridization,which benefits from the structural flexibility and adjustability of components composed of organic and inorganic,is an important method to construct multifunctional materials.Among them,organic cations undergo order and disorder changes under the excitation of external(light,electricity,etc.),leading to phase transition and stable switching characteristics;the inorganic frameworks provide opportunities for semiconducting behaviour and a wide range of band gaps.In a wide range of mixtures,hybrids of lead-based or tin-based represent an important class of semiconductor materials that exhibit superior electrical and optical properties.For instance,CH₃NH₃PbI₃^[1-7],CH₃NH₃SnI₃^[8]perfectly show the electrical properties and semiconductor properties of hybrid materials,although their electrical and semiconductor performance have been well applied,environmental friendliness and stability have yet to be improved.Therefore,the researchers eliminated toxic lead(Pb)and unstable tin(Sn),such as antimony(Sb)and bismuth(Bi),by introducing isoelectronic ions;In particular,Bi seems to be a better choice because some coordination complexes of bismuth have been used in antibacterial and anticancer drugs and are very friendly to human beings^[9].Therefore,we selected ethylamine and cyclohexylamine were used as non-halogenated amines,2-chloroethylamine hydrochloride and 2-bromoethylamine hydrochloride as halogenated amines,and they were used as organic cations,and the halogenation of Bi and Sb metals as inorganic anions,organic-inorganic hybrids based on Bi and Sb were synthesized,and their single crystal structure,dielectric and semiconductor band gap properties were characterized.The research divided into two research parts:The first part:six compounds were synthesized by using non halogenated amines as organic cations and halides of Bi and Sb metals as inorganic anion framework,which are[CH₃CH₂NH₃]₃[Bi Cl₆](1),[CH₃CH₂NH₃][Bi Br₆](2),[CH₃CH₂NH₃]₃[BiI₆](3),[CH₃CH₂NH₃]₂[Bi Br₅](4),[C₆H₁₁NH₃]₂[Sb Br₅](5)and[CH₃CH₂NH₃]₂[Sb Br₅](6).Among them,compound 1,2,4,6 show dielectric anomalies and structural phase transitions.The comparison of compounds 1 and 2 shows that the phase transition temperature and band gap can be adjusted simultaneously by halogen substitution.The second part:using halogenated amines as organic cations,and Bi and Sb metal halides as inorganic anions,five compounds were synthesized,which are[CH₂Cl CH₂NH₃]₃[Bi Cl₆](7),[CH₂Cl CH₂NH₃]₃[Bi Br₆](8),[CH₂Cl CH₂NH₃]₃[BiI₆](9),[CH₂Cl CH₂NH₃]₃[Sb Cl₆](10)and[CH₂Br CH₂NH₃]₃[Sb Br₆](11).Among them,compound 7,8,9,and 11 exhibit structural phase transitions,and comparing the phase transition temperatures and band gaps of compound 7,8,and 9 also shows that the phase transition temperature and band gap adjustment are achieved by halogen substitution.