Research On Structural Tunning And Electromagnetic Properties Of Several 112-type Selenides

Dimensions are one of the most important parameters in materials.The novel physical properties exhibited by low-dimensional structural materials make people full of expectations for materials with special structures.112-type iron selenium compounds and chromium selenium compounds with low dimensional structures,similarly exhibiting novel physical phenomena such as fast ion conduction,interaction between magnetic and electric/dielectric and elastic properties.These low dimensional structure interchain or interlayer weak interaction forces provide rich possibilities for interlayer intercalation or doping for structural regulation and physical evolution.In this work,KFeSe2?RbFeSe2 with the one-dimensional chain structure and NaCrSe2?LiCrSe2 with two-dimensional layered structure was prepared,and the effects of doping to influence its structure and regulation of physcial properties were investigated.The main research contents are as follows:Firstly,AFeSe2(A=K,Rb)with one-dimensional chain structure was successfully prepared by solid-phase synthesis and studied the effect of Co?Mn doping on their crystal structure and physical properties.And Co or Mn doping makes the lattice constant of KFeSe2 behave differently was studied briefly.The electrical transport properties of KFe1-xMxSe2(M=Co,Mn)series materials and RbFeSe2 show semiconductor behavior.In the magnetic test,KFe1-xMnxSe2 series materials exhibit paramagnetism,while RbFeSe2 exhibits antiferromagnetism;Then,ACrSe2(A=Na,Li)with two-dimensional layered structure was prepared by solid-phase synthesis method,and the effect of Mn doping on its crystal structure,electrical conductivity and magnetic properties was systematically studied.The study found that Mn doping has a certain influence on the cell parameters a and c,and the lattice constants of the two series of samples have different changing laws.NaCr1-xMnx Se2 exhibits semiconductor behavior,and the phase transition from antiferromagnetic to ferromagnetic occurs at low temperature,causing the magnetization to become saturated with the increase of the applied magnetic field.The LiCr1-xMnxSe2 series samples exhibit antiferromagnetism.In this paper,the study of the effect of doping with two classes of low dimensional ternary transition metal chalcogenides on their structures and electromagnetic properties will be of great significance for further experimental discovery of low dimensional structural materials,as well as modulating their physical properties,to promote their future applications.