Abstract
We have investigated the structural and magnetization properties of the nanocrystalline Pr0.7Ba0.2Ca0.1MnO3 sample, synthesized using the sol–gel method. The Rietveld refinement of the X-ray diffraction pattern of the nanocrystalline sample (recorded at room temperature) confirmed the formation of the orthorhombic crystal structure with Pnma space group. The temperature dependent magnetization M(T) measurements suggested that the present sample undergoes a paramagnetic to ferromagnetic phase transition and the Curie temperature was found to be ∼ 126 K. The positive slopes observed from the Arrott plots for the present sample indicate the second order of magnetic phase transition, as per the Banerjee’s criterion. The maximum value of magnetic entropy change |ΔSMmax| and relative cooling power (RCP) were found to be ∼ 2.2 J kg-1K-1 and 261 Jkg-1 for a magnetic field change of 5 T. The phenomenological universal curve was constructed for the present sample and ΔSM curves were found to collapse into one, and the universal curve confirmed the second order of magnetic phase transition. The relatively large values of |ΔSM| and RCP make the present nanocrystalline compound promising for the magnetic refrigeration technology.
Highlights
In the application of electric or magnetic fields on these kinds of materials, the physical properties can be altered which further open the field to significant technological applications such as in spintronics devices, magnetic sensors, and magnetic refrigeration
The magnetic refrigeration technology is based on the magnetocaloric effect (MCE)
The MCE is a fundamental quantity that can be defined as the temperature change of any magnetic substance when varying the intensity of the applied magnetic field
Summary
The magnetic refrigeration is an alternative technology which shows numerous positive characteristics, for example, responsive, effective, smaller and successful.. The Curie temperature, electrical and magnetic transport properties of these materials can be modified by doping at A-site or Mn-site.. The correlation between magnetism and transport properties in the manganites was well explained by numerous theories, for example, double exchange (DE) and superexchange (SE) interactions, phase separation effects and polaronic effects.. The 3d4 levels of Mn3+ in PrMnO3 compound get split by the octahedral crystal field of oxygen into a lower energy (t2g, triplet) level and a higher energy (eg, doublet) level. These two levels are filled in accordance to the Hund’s rule. The phenomenological universal curve was constructed to confirm the order of magnetic phase transition
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