The European Physical Journal Plus ( IF 3.4 ) Pub Date : 2020-10-12 , DOI: 10.1140/epjp/s13360-020-00838-2 Y. Moualhi , R. M’nassri , Muaffaq M. Nofal , H. Rahmouni , A. Selmi , M. Gassoumi , N. Chniba-Boudjada , K. Khirouni , A. Cheikrouhou
We investigated the effect of iron substitutions upon the structural, magnetic, electric, and dielectric properties in Pr0.7Ca0.3Mn1–xFexO3 mixed-valence manganite. The samples were synthesized using the solid-state reaction method and were analyzed by X-ray diffraction, magnetic and impedance spectroscopy measurements. X-ray diffraction analysis shows that all samples were found to be single phase and crystallize in the orthorhombic structure with Pnma space group. While the parent compound Pr0.7Ca0.3MnO3 exhibits a charge order sate, the substituted samples with low amount of iron exhibit a paramagnetic to ferromagnetic transition. However, the Curie temperature TC decreases with Fe content when we move from x = 0.02 to x = 0.1. From DC-conductance measurements, a typical semi-conducting behavior without any transition is observed for all investigated samples. Beyond a certain critical temperature noticed Tsat, the DC-conductance begins to saturate and reaches a maximum value. Then, the saturation temperature increases with increasing Fe content to attain Tsat = 260 K for x = 0.10. The correlated barrier hopping model was used to explain the frequency dependence of AC conductance. Impedance measurements confirm the contribution of the resistive grain boundary on the conduction mechanism. Then, it proves the existence of multiple electrical relaxation phenomena in the studied samples. The dielectric constant is found to be temperature dependent indicating that the compounds are polar dielectrics where the dipole orientation is governed by increasing temperature.
中文翻译:
铁掺杂对电荷有序-钙-锰矿材料物理性能的影响
我们研究了铁替代对Pr 0.7 Ca 0.3 Mn 1– x Fe x O 3混合价锰矿中结构,磁,电和介电性能的影响。使用固态反应方法合成样品,并通过X射线衍射,磁和阻抗谱测量进行分析。X射线衍射分析表明,所有样品均为单相,并在具有Pnma空间群的正交结构中结晶。而母体化合物Pr 0.7 Ca 0.3 MnO 3表现出电荷顺序状态,铁含量低的取代样品表现出顺磁性到铁磁性的转变。但是,当我们从x = 0.02移至x = 0.1时,居里温度T C随Fe含量降低。从直流电导率测量中,对于所有调查样品,观察到典型的半导体行为而没有任何过渡。超过某个特定的临界温度T sat,直流电导开始饱和并达到最大值。然后,随着x的增加,饱和温度随Fe含量的增加而达到T sat = 260 K = 0.10。相关的势垒跳跃模型用于解释交流电导的频率依赖性。阻抗测量证实了电阻性晶界对传导机制的贡献。然后,证明了所研究样品中存在多种电弛豫现象。发现介电常数是温度依赖性的,这表明化合物是极性电介质,其中偶极子取向受温度升高的支配。