Study On Ferroelectric Properties Of Compounds Containing Transition Metal Thiocyanate Coordination Ion And Monopine Molecule

A ferroelectric material is a kind of spontaneous polarization that occurs with the change of temperature,and its polarization intensity can be reversed with the application of an electric field,thereby causing a hysteresis loop.Because of its wide application in communication,information storage,infrared sensing,piezoelectric sensing and military industry,it is currently one of the most popular research topics in the academic field.In recent years,with the rapid development of molecular-based ferroelectricity at home and abroad,great progress has been made,but it has a variety of superior physical properties such as high Curie temperature,large SHG effect,luminescence and semiconductor properties.Multifunctional rare earth molecular ferroelectric materials are few.There are reports in the literature.At the same time,a variety of bivalent metal multifunctional materials with novel structure and superior performance were synthesized.?1?This article introduces rare earth elements such as rare earths Nd,Pr,Ce,Dy,Eu,Er,Tm,Yb,Lu into simple molecular systems?CH₃CH₂CH₂CH₂?₄N)₃[M?NO₃?_x?SCN?_y]?CH₃CH₂CH₂CH₂?₄=tetrabutylammonium,M=Rare earth element),we obtained nine new multifunctional molecular ferroelectrics?CH₃CH₂CH₂CH₂?₄N)₃[Ln?NO₃?₄?SCN?₂],compound 1-2.Through hysteresis loops,second-order harmonic generation?SHG?effects,piezoelectric microscopy?PFM?and other tests,this kind of material is found to have a high Curie temperature and stable large SHG response.Luminescent material for switches.?2?We designed and synthesized two novel complexes[?BPP?₂Mn?NCS?₄]and[?BPP?₂Cd?NCS?₄])by solution method.The properties of compounds 3 and 4 were characterized by means of infrared spectroscopy?IR?,X-ray single crystal structure analysis,thermogravimetric analysis?TGA?,and powder X-ray diffraction analysis?PXRD?.X-ray single crystal diffraction analysis shows that compound 3 belongs to the monoclinic system,Cc space group,the complex forms a2D layered structure through the action of hydrogen bonding,has a symmetry plane parallel to the ab axis,and Mn²⁺ions adopt four coordination Coordination with four SCN^-forms a twisted tetrahedral configuration.Solid fluorescence studies show that the emission peak of the complex is396 nm,which is of great significance for the development and development of new metal organic complex fluorescent materials.?3?We designed and synthesized the compound 6 which reacted with 5 pinoic acid and nooline acid and diethylamine by solution method.The properties of compound 5 and compound 6were characterized by infrared spectroscopy?IR?,X-ray single crystal structure analysis,thermogravimetric analysis?TGA?,powder X-ray diffraction analysis?PXRD?and other technical means.X-ray single crystal diffraction analysis shows that compound 5 belongs to the ferroelectric phase transition from low temperature space group P1 to room temperature space group C2,and compound 6 belongs to the reversible phase transition from room temperature P2₁2₁2₁ to high temperature.