Wang W.-Q.,Key Laboratory of Magnetism and Magnetic Materials at Universities of Inner Mongolia Autonomous Region |
Xiang J.-Y.,Key Laboratory of Magnetism and Magnetic Materials at Universities of Inner Mongolia Autonomous Region |
Wu K.-H.,Key Laboratory of Magnetism and Magnetic Materials at Universities of Inner Mongolia Autonomous Region |
Wan S.-L.,Key Laboratory of Magnetism and Magnetic Materials at Universities of Inner Mongolia Autonomous Region |
And 2 more authors.
Chinese Rare Earths | Year: 2015
The polycrystalline samples of doped perovskite cobalt oxides La0.5-xNdxSr0.5CoO3(x=0, 0.1, 0.15) have been prepared by solid state reaction method. Magnetic properties of these samples were investigated by measuring the magnetization-temperature (M-T) and magnetization-field (M-H) curves. Experimental results show that paramagnetic (PM), ferromagnetic (FM) and antiferromagnetic (AFM) transitions successively occur with decreasing temperatures in these samples. The Curie temperature gradually increase with doping concentration x(θx=0≈215K; θx=0.1≈226K; θx=0.15≈242K), which suggests that doped Nd3+ ions enhance ferromagnetic couplings in such systems. The temperature dependence curves of the inverse susceptibility (χ-1-T) deviate upward from the Curie-Weiss Law, which implies the susceptibility decreases to be smaller than the pure paramagnetic value and Griffiths-like phase is therefore not observed these systems. We argue that the absence of Griffiths-like phase is probably due to the presence of antiferromagnetic interactions. In addition, from experimental measurements and theoretical calculations in high temperature region, it is revealed that the Co4+ ions transform from a low-spin (LS) to intermediate-spin (IS) state upon increasing doping concentration x. © 2015, Editorial Office of "Chinese Rare Earths". All right reserved.
Jin X.,Key Laboratory of Magnetism and Magnetic Materials at Universities of Inner Mongolia Autonomous Region
Zhongguo Xitu Xuebao/Journal of the Chinese Rare Earth Society | Year: 2016
The polycrystalline samples of double-layered manganite (La0.9Eu0.1)4/3Sr5/3Mn2O7 were prepared by the traditional solid state reaction. The magnetic and magnetocaloric properties of bilayered perovskite manganite (La0.9Eu0.1)4/3Sr5/3Mn2O7 were studied. The function M(H,T) was obtained using orthogonal polynomial least square method fitting. The Arrott curves and magnetic entropy changes were calculated according to the magnetization curves. In the low temperature zone, the sample showed paramagnetic behavior. While in the high temperature zone, it exhibited ferromagnetic properties. Near the TC 3D, while the sample exhibited the characteristic of a first-order transition and gave a maximum magnetic entropy change of 1.53 J·(kg·K)-1 under a 1 T magnetic field. This suggested that such materials might be applied to magnetic refrigeration in the temperature range of liquid hydrogen. The results fitted well with experimental data. This method could be used to calculate magnetic and the magnetic entropy changes of our samples. © 2016, Editorial Office of Journal of the Chinese Society of Rare Earths. All right reserved.