Structural and magnetic properties with reversible magnetocaloric effect in PrSr_1–xPb_xMn₂O₆ (0.1 ≤ x ≤ 0.3) double perovskite manganite structures

ABSTRACT

In this study, the effect of Pb substitution with Sr on structural, magnetic and magnetocaloric properties in Pr(Sr_1–xPb_x)Mn₂O₆ (0.1 ≤ x ≤ 0.3) double perovskite manganite compounds prepared by the sol–gel method has been reported. Crystallinity has been worked by X-ray diffraction measurement and the Rietveld refinement method, which shows all samples are in monoclinic structure with P21/n space group without impurity phase. Scanning electron microscope analysis shows that all samples constituted from square-shaped grains with distinct grain boundaries, and energy-dispersive X-ray spectroscopy analysis shows that all expected elements are detected and there is no impurity element in the sample. All samples exhibit a magnetic phase transition from ferromagnetic to paramagnetic phase at T_C determined as 274, 282 and 286 K for x = 0.1 (PSPM-1), 0.2 (PSPM-2) and 0.3 (PSPM-3) in the PrSr_1–xPb_xMn₂O₆ structure, respectively. Isothermal magnetisation curves near T_C are used to determine the nature of the magnetic phase transition and the magnetic entropy change values (−ΔS_M), which are found as 2.78, 3.11 and 3.52 J kg⁻¹ K⁻¹ for PSPM-1, PSPM-2 and PSPM-3 samples, respectively. Relative cooling power (RCP) values of the samples are also determined as 241, 311 and 246 J kg⁻¹ for PSPM-1, PSPM-2 and PSPM-3 samples, respectively. ΔS_M and RCP values are also calculated by using the Landau theory and the results are in accordance with the experimental results, which indicate the role of electron condensation energy and magneto-elastic coupling in magnetic entropy change value of the samples.

KEYWORDS:

• Perovskites
• manganites
• magnetic phase transition
• magnetocaloric effect
• magnetic cooling
• Landau theory

Acknowledgements

The author thanks Dr Ahmet Ekicibil and Dr Mustafa Akyol for their valuable discussion.

Disclosure statement

No potential conflict of interest was reported by the author.

ORCID

Ali Osman Ayaş http://orcid.org/0000-0002-6186-8191

Additional information

Funding

This work was supported by the Research Fund of Adıyaman University [grant contracts no. TFMAP/2017-0001].