Study On Physical Properties Of Antiperovskite Magnetic Functional Materials Based On Mn₃SnC

The lattice structure of Mn-based antipervoskite compounds is similar to perovskite.Mn-based antipervoskite compounds as magnetic multifunctional materials have attracted more and more attention because of their potential application value.At present,the magnetocaloric effect has been found in a variety of Mn-based antipervoskite compounds.And they are expected to be used as magnetic refrigerants for solid-state refrigeration.Based on the magnetocaloric effect of Mn₃Sn C,this paper studied how to broaden the temperature range of magnetocaloric effect.At the same time,the effects of Dy doping or C vacancy on the lattice,magnetic and thermal properties of the system materials were studied.The conductivity of Mn-based anti-perovskite compound materials can be compared with that of metal materials,but its valence bond structure has been unclear.Whether this type of material is a semiconductor material or a metal material has not been finalized.This paper used optical characterization methods to explore the bond information of the system materials,which plays an important role in determining the properties of the materials and the scope of application.The temperature range of the magnetocaloric effect was widened by physical mixing.(Mn₃Sn C)_x/(Mn₃Cu N)_y(x:y=10:1,9:1,8:1,7:1)with continuous change of phase transition temperature were obtained by sintering the same lattice structure of Mn₃Sn C and Mn₃Cu N at high temperature.They were mixed and ground evenly to form composite materials.Compared with Mn₃Sn C,the temperature range of magnetocaloric effect of the composite material changed from 275 K-285 K to 220 K-300 K,but the change of magnetic entropy decreased.Further research had discovered the competitive relationship between expanding the refrigeration temperature zone and increasing the value of magnetic entropy in composite materials.This research has important reference value not only for the anti-perovskite material system,but also for the study of other composite magnetic refrigeration material systems.Mn₃Sn C shows a first-order phase transition,accompanied by latent heat of phase transition,but the phase transition temperature range is too narrow.In order to adjust the performance of Mn₃Sn C,Dy doping and C vacancy of Mn₃Sn C were studied.Mn₃Sn_1-xDy_xC(x=0,0.05,0.10)show cubic antiperovskite structure,and the lattice constant decreases with the increase of x.With the increase of x,the phase transition temperature region of Mn₃Sn_1-xDy_xC move to low temperature,and the entropy change decrease.Mn₃Sn C_x(x=0.8,0.9,1.0,1.1)showe cubic antiperovskite structure.With the increase of C vacancy,the lattice constant of Mn₃Sn C_x decrease,the phase transition temperature zone moves to lower temperature,and the entropy change value first increase slightly and then decrease.The study found that both Dy doping and C vacancy reduce the lattice constant of Mn₃Sn C,its phase transition type gradually change from the first-order phase transition to the second-order phase transition,and the widening of the phase transition temperature zone and the increase of its entropy change value show a competitive relationship.Therefore,the selection of magnetic refrigeration materials suitable for practical applications should comprehensively consider the broadening of the phase change temperature zone and the increase of its entropy change value.To determine the material type,the photoluminescence spectrum,Fourier infrared spectroscopy and UV-visible spectroscopy of Mn₃Sn_1-xDy_xC were measured.Through optical testing,it is found that the material does not show a significant optical band gap and photoluminescence in the visible light range.Dy and Mn ions have photoluminescence,optical testing shows that Dy and Mn do not exist in the form of ions,ionic bond is not the main bond in the material.Optical testing shows that the materials do not have electronic,rotational and vibrational energy transitions.they have the same absorption for all visible light bands,which shows metal characteristics,and the bonding bond is mainly metal bond.The materials are a kind of intermetallic compounds with metal property.