Study of magnetic and electrical properties of Pr₀.₆₅Ca₀.₂₅Ba₀.₁MnO₃ manganite
2018
Mleiki, Ali | Hanen, R. | Rahmouni, H. | Guermazi, N. | Khirouni, K. | Hlil, E. K. | Cheikhrouhou, A.
The magnetic properties and magnetocaloric effect (MCE) in Pr₀.₆₅Ca₀.₂₅Ba₀.₁MnO₃ have been investigated supplemented by electrical data. X-ray diffraction shows that the sample crystallizes in the distorted orthorhombic system with the Pnma space group. Pr₀.₆₅Ca₀.₂₅Ba₀.₁MnO₃ undergoes paramagnetic–ferromagnetic (PM–FM) phase transition at TC ∼ 85 K. For a magnetic field change of 5 T, the maximum value of the magnetic entropy change (−ΔSmaxM) is estimated to be 4.4 J kg⁻¹ K⁻¹ around TC with a large relative cooling power (RCP) value of 263.5 J kg⁻¹. While the modified Arrott plots suggested that the magnetic transition belongs to the second order phase transitions, the universal curves of the rescaled magnetic entropy (ΔSM) proved the opposite. The electrical properties of Pr₀.₆₅Ca₀.₂₅Ba₀.₁MnO₃ have been investigated using impedance spectroscopy techniques. The dc-resistivity (σdc) study shows the presence of semiconductor behavior. Ac-conductivity (σₐc) analysis shows that the conductivity is governed by a hopping process. From the analysis of the alternating regime, the exponent s variation obtained is in good agreement with Mott theory. The impedance spectrum analysis reveals the presence of a relaxation phenomenon. Based on these analyzes, the sample can be modeled by an electrical equivalent circuit.
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