Crystal Structures And Properties Of Double Perovskites Sr-Fe-Mo-O-N System

In this paper, double perovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） series had beensuccessfully synthesized at1100and1000by solid-state reaction processing. Thecrystal structures, magnetic and electric properties of these samples were researched by x-raypowder diffraction （XRD）, vibrating sample magnetometer and four-point probe method. Wedetermined N content by GB11894-89potassium persulfate in alkaline ultravioletspectrophotometry. The main results of this dissertation as follows:The crystal structures of double perovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） seriessamples had been successfully synthesized at1100all belong to tetragonal system. Thespace groups of these samples are all I4/mmm. The lattice volumes increase with theincreasing content of N. After refinement respectively by Fulprof software, we know that theseries of the experimental value of samples and the theoretical accord with relatively good.The magnetic moment of double perovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） series hadbeen successfully synthesized in1100increases gradually with the increase of magneticfield. This is same to N proportion which is measured by the ultraviolet spectrophotometryand to measured M-H curve. To the same magnetic field, the magnetic moment increase withthe increasing content of N. It doesn’t appear phase transition temperature between80K to300K, therefore, we can infer the Curie temperatures of the series are higher300K. Theelectrical transmission properties of double perovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h）series samples had been successfully synthesized at1100show the property fromconductor to semiconductor. The transition is Sr₂FeMoO_6-xN_x（t=5h）. All the samples showthe negative magnetoresistance effect obviously.The crystal structures of double perovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） serieshad been successfully synthesized at1000which belongs to tetragonal system. The spacegroups of these samples are all I4/mmm. The lattice volumes increase with the increasingcontent of N. After refinement respectively by Fulprof software, we can see the value of theexperimental of samples is simple with the theoretical. The magnetic moment of doubleperovskite Sr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） series had been successfully synthesized at1000increases gradually with the increase of magnetic field. To the same magnetic field,the magnetic moment increase with the decreasing content of N. It doesn’t appear phase transition temperature between80K to300K, so we can infer the Curie temperatures of theseries are higher300K.The electrical transport properties of double perovskiteSr₂FeMoO_6-xN_x（t=0,3h,5h,8h,10h） series had been successfully synthesized at1000show the property from conductor to semiconductor. The transition is when t=5h. All thesamples show the negative magnetoresistance effect obviously.