Study On Electromagnetic Properties Of A And B Site Doped Perovskite Manganese Oxide

The poly crystalline samples of the perovskite manganese oxide series studied in this paper are all prepared by the high-temperature solid-phase reaction method.The lattice structure and electromagnetic properties of all the samples are tested by X-ray diffractometer and multifunctional physical property measurement.The analysis of the data obtained by the system such as M-T curve,M-H curve,p-T curve is as follows:(1)The structure,magnetic and electrical properties of the La0.87R0.13MnO3(R=La,Dy,Gd,Eu)series poly crystalline samples doped with different elements at the A site were studied.The study found that the magnetization,Curie temperature of the sample decrease with the decrease of the radius of the doped ions at the A site;magnetocrystalline anisotropy exists in the sample;the magnetic transformation method is a second-order phase transition;Except for the parent phase,the sample La0.87Dy0.13MnO3 has a better magnetic refrigeration effect.(2)The electromagnetic properties of polycrystalline samples of perovskite manganese oxide La0.87-xNdxDy0.13MnO3(x=0,0.07,0.27)with different A-site doping concentrations were studied.The study found that:the series of samples belong to the orthogonal structure,the magnetic transition mode is a secondary phase transition,the parent phase La0.87Dy0.13MnO3 and La0.6Nd0.27Dy0.13MnO3 samples have the highest similarity with the average field model,The La0.8Nd0.07Dy0.13MnO3 sample has the best fit with the 3D-Heisenberg model;this series of samples follows the variable-range jump conduction mode in the high temperature zone.(3)The magnetic and magnetocaloric effects of the B-site doped perovskite manganese oxide La0.87Dy0.13Mn1-xFexO3(x=0,0.1,0.2,0.4)series of poly crystalline samples were studied.The study found that the samples in this group are all orthogonal polycrystalline samples with the space group of Pbnm;the doping of Fe ions causes the double exchange effect in the sample to weaken,and the super exchange effect increases.and the magnetization is reduced;the undoped samples are at temperature When the temperature is higher than the Curie temperature,it exhibits the behavior of pre-formed clusters.There is a Griffiths-like phase in the sample doped with Fe ions at the B site;the doping of Fe ions changes the magnetic transition of the sample.