Magnetic Propeties Of Eu Doping In Double Perovsktie Sr₂FeMoO₆

Since the 20th century,with the development of social science and technology rapidly,perovskite type oxides gradually become a hot focus of people.It is because the perovskite materials special physical and chemical properties,which can produce huge magnetoresistance effect,moreover,with the development of the electronics industry,information storage industry is gradually widely used.Now,most of the electronic products have very small volume,therefore,it can accommodate a lot of data in the hard drives and other devices,and special properties of the double perovskite materials,it can read the great and accurate data in computer hard disk.In the perovskite structure,Sr₂FeMoO₆ is a typical double perovskite oxide,and the Curie temperature is up to 420K,showing a giant magnetoresistance effect（CMR）at room temperature.To further understand the properties of Sr₂FeMoO₆ and further expand its application prospects,scientists have used a variety of means to improve it.Rare metal doping is a common technique,because europium is rare earth element,the valence electron is 4f⁷6s²,its common valence is Eu³⁺,Eu is the most active metal in lanthanide ion,Eu doping is electronic doping,and it also belongs to magnetic ion doping.Therefore,in this paper,Eu ion doping is mainly carried out on Sr₂FeMoO₆,and the structure and physical properties of the samples were measured.The main contents and results of this paper are as follows:1)A series of double perovskite oxides Sr_2-xEu _XFeMoO₆（X=0.00,0.05,0.10,0.15,0.20）were prepared by standard solid-state reaction,The X ray powder diffraction measurement results show that the series of samples are in the whole doping range,the single phase were phase,the crystal system were tetragonal system,the space group were I4/m,all the samples have no second phase formation.When2theta=32.15°,the Prague diffraction peak of the sample reaches the maximum value.Due to the orderly arrangement of Fe and Mo,the diffraction peak（011）of the superlattice exists at about 2theta=19.5°.According to obtained results,the strength of the sample peak gradually decreases with the increase of the amount of Eu doping in the sample.The refinement of X-ray diffraction spectrum by GSAS software showed that the structural parameters of the cell changed obviously with the increase of doping X.The microstructure of this series of samples was analyzed by scanning electron microscope.The results showed that with the increase of Eu doping amount,the grain size became smaller and the grain boundary became less and more obvious.The results of X ray photoelectron spectroscopy show that Mo⁶⁺/Mo⁵⁺and Fe³⁺/Fe²⁺exist in all Sr_2-x-x Eu_XFeMoO₆ samples,with the increased of Eu,the proportion of Fe³⁺/Fe²⁺and Mo⁵⁺/Mo⁶⁺increased gradually,which directly affected the conductivity of Sr_2-xEu_XFeMoO₆.The magnetic transport properties of the samples were measured by a vibrating sample magnetometer.The samples after the doping had a better saturation magnetization curve.Near the Curie temperature,the sample changed from paramagnetic to ferromagnetic.The M²-H/M curve analyses indicate a second-order magnetic phase transition.2)A series of double perovskite oxide Sr_2-x□xFeMo O₆（X=0.00,0.01,0.02,0.03,0.04）were prepared by sol-gel method.X-ray powder diffraction was detected by step size scanning,X-ray powder diffraction measurements are Bruker D8 discover on the instrument,step length is 2theta=0.02°,integration time for t=0.5 s,working voltage and current are set to 45 kv,35ma,scan angle is set to 10°to 90°,the measured X-ray spectrum through the Rietveld refinement GSAS program structure refinement,The structure parameters of the refined structure were compared and studied,the XRD diagram shows that the structure of the sample is single phase.