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

In this paper, double perovskite Sr2FeMoO6-xNxand Sr2-xNdxFeMoO6-xNxseries had beensuccessfully synthesized at1100℃by solid-state reaction processing. The crystal structuresand magnetic properties of these samples were researched by X ray powder diffraction (XRD)and vibrating sample magnetometer. N content is determined by the formaldehyde method.The crystal structures of double perovskite Sr2FeMoO6-xNx(t=0h,1h,4h,6h,9h and12h)series samples had been successfully synthesized at1100℃all belong to tetragonal system.The space groups of these samples are all I4/mmm. The lattice volumes decrease with theincreasing content of N. The average bond lengths of Fe (O, N) and Mo (O, N) decreasewith Fe and Mo content increasing, respectively, expect that of ammonolysis6h. The bondangles of Fe (O, N) Mo are all near180.0°. The bond-valence for Sr is close to+2. Thebond-valence for Mo demonstrates an increase with ammonolysis time. The bond-valence forFe demonstrates a decrease with ammonolysis time, expect that of ammonolysis4h. Thedegree of order demonstrates an increase with ammonolysis time. The fitted M-T curvesindicate that in low temperature range the spontaneous magnetization follows spin-wavetheory and in high temperature region almost obeys spin wave model. B obtained from lowtemperature increase at first and then decrease with ammonolysis time, expects that ofammonolysis9h. B obtained from high temperature decrease with ammonolysis time. Thespontaneous magnetization decrease firstly and then increase with ammonolysis time. Themagnetic moment is not saturated in a1.0T magnetic field in the M H curve. The saturationmagnetization increase at first and then decrease with the increasing content of N at300K and78K, respectively.The crystal structures of double perovskite Sr2-xNdxFeMoO6-xNx(t=1h,4h,6h,9h and12h)series samples had been successfully synthesized at1100℃all belong to tetragonal system.The space groups of these samples are all I4/mmm. The lattice volumes increase withammonolysis time (the increasing content of Nd). The average bond lengths of Fe (O, N) andMo (O, N) increase with Fe and Mo content increasing, respectively, expect that of ammonolysis12h. The bond angles of Fe (O,N) Mo are all180.0°. The averagebond-valence for Sr and Nd is close to+1.9. The bond-valence for Fe is close to+4. Thebond-valence for Mo is less than+5. The degree of order demonstrates a decrease withammonolysis time (the increasing content of Nd). The fitted M T curves indicate that bothin low temperature region and in high temperature region the spontaneous magnetizationfollows spin-wave theory. B obtained from low temperature increase with ammonolysis time(the increasing content of Nd). B obtained from high temperature decrease with ammonolysistime (the increasing content of Nd), expect that of ammonolysis12h. The spontaneousmagnetization decreases with ammonolysis time (the increasing content of Nd). The magneticmoment is not saturated in a1.0T magnetic field in the M H curve. The saturationmagnetization decrease with the increasing content of N (the increasing content of Nd) at300K and78K, respectively.