Study On Dielectric Iron Elastic Properties Based On Succinimide And Ethylenediamine Complexes

The invertible phase transition materials has great potential applications in the field of the multi-function materials for its versatility can meet different needs in the application of materials.Therefore,the research on finding new reversible phase transition materials and synthesizing functional complexes with excellent dielectric and ferroelastic properties is very popular.In this paper,two new types of complexes with reversible phase transition were found:[M?en?₃]SO₄?en=ethylenediamine;M=Cd,Zn,Ni and Cu??1-4?and[Li?PDD?₂X]_n,?PDD=succinamide,X=ClO₄^-,BF₄^-,PF₆^-??5-7?.X-ray single crystal diffraction,dielectric measurement,differential scanning calorimetry?DSC?,thermogravimetric measurement were performed to research their structures,thermodynamic property and reversible phase transition.The main contents are divided into three parts,as follows:In first section,A brief introduction of phase transition materials are presented.Illustrate the research status of reversible phase transition materials,ethylenediamine complexes and succinimide complexes.The research significance and main results of this thesis are also summarized.In second section,four ethylenediamine complexes[M?en?₃SO₄]?M=Zn?Cu?Cd?Ni?1-4were obtained by ethylenediamine and corresponding transition metal salts.The complexes 1displays unusual multi-sequential reversible phase transitions.However,the complexes of 2-4 only possess a reversible phase transitions in low temperature period.The synergistic effect of the symmetry breaking of M?en?₃²⁺cation and SO₄^2-anion in the complexes leads to the reversible phase transitions.What's more,the complexes 1 is crystallized in ferroelastic point group and have ferroelastic effect at near the phase transition temperature.In last section,with succinimide as organic ligands,by solution method successfully synthesized three succinimide complexes of[?succinimide?₂LiX]_n?X=ClO₄^-,BF₄^-,PF₆^-?5-7,Complexes 5-7 with the same coordination environment,so only the complexes 5 was studied.The complexes 5 have a secondary reversible phase transition occurred near room temperature of 228K.Interestingly,this reversible phase transition is accompanied by a ultralarge dielectric relaxation behavior.The investigation suggests that the twist motion of pyrrolidine heterocycles and the order-disorder motion of ClO₄^-anions caused the reversible phase transition of complexes 5.This research opens a new avenue for exploring switchable dielectric materials and phase transition materials.