Study On Properties Of Doping At Nd And O Sites In Perovskite NdMnO₃

In recent years, with the CMR effect of perovskite manganese oxides Ln1-xAxMnO3(Lnis La, Pr, Nd and other trivalent rare-earth ions, A is Ca, Sr, Ba and other divalent alkali metalions), due to the its rich physical and chemical properties of complex structural phase diagramand potential applications, such as: superconductivity, ferromagnetism, ferroelectricity,thermoelectric, piezoelectric, thermal conductivity, fluorescence properties, catalytic activity,giant magnetoresistance effect, these properties caused widespread concern.In this paper, we use solid-phase sintering method, use rare earth oxides Nd2O3,manganese oxide MnO2as raw materials, prepared perovskite manganese oxides. Alkalimetal ions Sr2+to A-doping, doping was ten percent, twenty percent, thrity percent. ReuseNaOH solution and (NH4)2SO4solid reaction to produce ammonia for O-doping. Sample sizeand morphology and crystal structure, magnetic properties, electrical properties were studiedto characterize the analysis.The results showed that: by doping the sample A site, the performance of the samplechanged. Since the incorporation of Sr2+, B bits of Mn3+valence was changed, exchangeinteraction of the sample increased. According to the performance analysis of XRD patternsshowed that the series are not completely orthorhombic, and impurity phase is existed.According to the nature of the M-H measurement showed that the magnetic moment of thesamples decreases with increasing magnetic field, and the more content of Sr2+, the moreeasily magnetized. According to the nature of the M-T measurement showed that the samplein the temperature range80K-300K, the spontaneous magnetization decreases withtemperature, and it is not appearing the transition from ferromagnetic to paramagnetic withinthe measured temperature range. These properties indicated that the Curie temperature ishigher than300K. According to the nature of the R-T measurement shows that the amount often percent Sr2+-doped sample resistance is very large, fully exhibits semiconducting behavior,and the behavior of metallic conductivity does not appeared. But the electrical properties ofthe amount of twenty percent and thirty percent Sr2+-doped samples showed a transition fromthe behavior of metallic conductivity to the behavior of semiconducting, and they haveexcellent electromagnetic resistance effect.We used ammonia to dope samples at O site. According to the performance analysis of XRD patterns show that the series are not completely orthorhombic, and impurity phase isexisted. According to the nature of the M-H measurement showed that the magnetic momentof the samples decreases with increasing magnetic field, and N-doped samples compared tosamples without N-doped, behaving more easily magnetized; According to the nature of theM-T measurement showed that the magnetic moment of the N-doped sample is not more thanthe none N-doped samples with greater temperature decreases in the temperature range80K-300K, and it is not appearing the transition from ferromagnetic to paramagnetic withinthe measured temperature range. These properties indicated that the Curie temperature ishigher than300K. According to the nature of the R-T measurement shows that the resistanceof N-doped sample is smaller than the resistance of none N-doped samples, so it behavdexcellent electromagnetic resistance effect.