Thermomagnetic Correlation in La0.85-xBixNa0.15MnO3 Soft Ferromagnet due to Nonmagnetic Bi3+ Substitution

Lozil Denzil Mendonca,M S Murari,Mamatha D Daivajna

doi:10.1007/s10948-021-05887-x

Abstract

We report the structural, magnetic, and magnetocaloric properties of Bismuth (Bi)-substituted manganite La0.85-xBixNa0.15MnO3 (x=0, 0.1, 0.2, 0.25, and 0.3). X-ray diffraction data implicates the rhombohedral structure with Roverline{3}c space group. Bi2O3 has helped in ensuring phase pure, densified compounds even at low sintering temperature and hence avoiding the evaporation of volatile sodium. The increase in grain size and decrease in magnetic transition temperature (TC) are due to the Bi chemical activity and electronic structure. The samples have shown indirect magnetic transformation from soft ferromagnet to canted ferromagnet/antiferromagnet with Bi. Griffiths phase-like behavior in the inverse magnetic susceptibility was observed for x=0.1; with further increase in Bi, the samples are found to develop the antiferromagnetic competing phase. The phenomenological model was used to model the thermomagnetic behavior of all the samples. The sample with x=0.1 shows an increase in magnetic entropy change upon Bi substitution and the maximum of magnetic entropy change is seen at 275K emphasizing its potential in room temperature magnetic refrigeration.

Highlights

Today most of the scientific advancements with a motive of industrial application have sought the help of century old physical phenomena to reduce the green footprints
Manganites are the class of material whose physical and chemical properties do not depend only on the valence state of the substituent and on the size of it
The specimens hold homogenous crystalline form evidenced by the sharp diffraction peaks in the XRD patterns (Fig. 1) taken at room temperature

Summary

Introduction

Today most of the scientific advancements with a motive of industrial application have sought the help of century old physical phenomena to reduce the green footprints. The physical phenomena discovered century back were revisited and exploited to have working materials which would cater the needs of present households and industries, upholding the green globe policy. A magnetic material contains two energy reservoirs: the lattice degrees of freedom leading to usual phonon excitations and spin degrees of freedom enabling magnetic excitations. These two reservoirs are coupled by the spin–lattice coupling which ensures lossfree energy transfer within a small interval of time [8]. Amidst the emphasis of material with respect to (w.r.t) magnetocaloric properties, rare-earth-based oxides, in particular lanthanumbased manganites, have not been versatile compared to the alloys and crystalline compounds containing rare earths

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