Abstract
La0.4Pr0.3Ca0.1Sr0.2MnO3 has been investigated as a potential candidate for room temperature magnetic refrigeration. Results from X-ray powder diffraction reveal an orthorhombic structure with Pnma space group. The electronic and chemical properties have been confirmed by X-ray photoelectron spectroscopy and ion-beam analysis. A second-order paramagnetic to ferromagnetic transition was observed near room temperature (289 K), with a mean-field like critical behaviour at low field and a tricritical mean-field like behaviour at high field. The field induced crossover in critical behaviour is a consequence of the system being close to a first-order magnetic transition in combination with a magnetic field induced suppression of local lattice distortions. The lattice distortions consist of interconnected and weakly distorted pairs of Mn-ions, where each pair shares an electron and a hole, dispersed by large Jahn–Teller distortions at Mn3+ lattice sites. A comparatively high value of the isothermal entropy-change (3.08 J/kg-K at 2 T) is observed and the direct measurements of the adiabatic temperature change reveal a temperature change of 1.5 K for a magnetic field change of 1.9 T.
Highlights
La0.4Pr0.3Ca0.1Sr0.2MnO3 has been investigated as a potential candidate for room temperature magnetic refrigeration
We argue that the mean-field critical behaviour is a consequence of local lattice distortions consisting of weakly distorted pairs of Mn-ions, where each pair shares one electron and one hole, dispersed by Jahn–Teller (JT) distorted Mn3+-ion lattice sites[24]
The Rietveld refinement of the X-ray powder diffraction (XRPD) pattern confirmed the orthorhombic structure with Pnma space group for the sample, similar as previously reported for L a0.5Pr0.2Ca0.1Sr0.2MnO312
Summary
La0.4Pr0.3Ca0.1Sr0.2MnO3 has been investigated as a potential candidate for room temperature magnetic refrigeration. This is the advantage of oxide materials, their second-order magnetic phase transition results in a broad temperature span in which magnetic cooling is effective.
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