Fe掺杂多晶样品DyMn1-xFexO3的磁热效应和电性

采用传统的固相反应法制备DyMn1-xFexO3多晶样品,通过测量了样品的磁化强度与温度的变化关系曲线(M-T)、磁化强度与温度的变化关系曲线(M-H)和电阻率与温度的变化曲线(ρ-T),对各组分下样品的磁性和电性进行了研究。研究结果表明,在低温区x=0和x=0.025样品表现为反铁磁态,而x=0.075样品在低温区ZFC曲线与FC曲线出现分叉,表现为铁磁反铁磁共存。分别在57,137和157 K以下观察到类Griffiths相,TG温度以上样品都表现为顺磁特性。在外加磁场为7 T时磁熵变达到最大值,最大值分别为10,12,9 J/(kg·K)。最大制冷能力为320 J/kg(x=0.025)。综合磁熵变最大值及制冷能力数值来看,该材料可以作为磁制冷候选材料。通过对ρ-T曲线及ρ-T曲线的拟合曲线研究发现,系列样品均为半导体且加磁场后的电阻率高于零场下的电阻率,说明在低温处磁场有不利于电传导。系列样品在高温部分的导电方式均遵循小极化子的导电方式。

Magnetocaloric effect and electrical properties of Fe-doped polycrystalline samples DyMn1-xFexO3

The DyMn1-xFexO3 polycrystalline samples were prepared by the conventional solid-state reaction method. By measuring the magnetic and electrical properties of the samples under each component, the relationships between magnetization and temperature(M-T), magnetization and magnetic field(M-H), and resistivity versus temperature(ρ-T) were studied. The change curve(M-T) studies the magnetic entropy change of the x=0, 0.025 and x=0.075 samples. The results show that in the low temperature region, the x=0 and x=0.025 samples exhibited an antiferromagnetic state, while the x=0.075 sample showed a bifurcation between the ZFC curve and the FC curve in the low temperature region, showing the presence of ferromagnetic antiferromagnetic coexistence. Below 57, 137 and 157 K, Griffiths-like phases were observed, respectively, and the samples above the Tg temperature exhibited paramagnetic properties. The maximum magnetic entropy change values were 10, 12 and 9 J/kg·K at 7 T. The maximum cooling capacity was 320 J/kg(x=0.025). Based on the maximum value of the magnetic entropy change and the cooling capacity value, the material could be used as a magnetic refrigeration candidate material. Through the fitting curves of the ρ-T curve, it was found that the polycrystalline samples were all semiconductors and the resistivity after the magnetic field was applied was higher than that under the zero field, indicating that the magnetic field was not conducive to electrical conduction at a low temperature. The conductance of the sample at the high temperature portion followed the conductivity of the small polaron.