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

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 $$ R\overline{3}c $$ R 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.

Sizable magnetic entropy change in bismuth-substituted La0.75Bi0.1Na0.15MnO3 manganite

“…As such, along with the large moment and significant magnetic sensitivity, the effects like spin-lattice coupling, grain growth and cooperative distortions lead to additional magnetic entropy changes. 6,39 In our case, though spin-lattice coupling is not observed, there is an improvement in the Mn–O–Mn bond angle, the grain size and magnetic sensitivity. The transition was found to be sharp.…”

“…For a given sample to function as a magnetic refrigerant for active MR, it should display nearly zero magnetic hysteresis, a large magnetic entropy change (Δ S m ), and Δ S m distribution in the temperature range of 10–80 K or >250 K, and essentially wider. 8 Our samples being soft ferromagnets have shown nearly zero hysteresis; the sample with 10% Bi substitution has displayed a phenomenal entropy change at low fields (100 Oe) 6 and as desired, the T C is at 275 K (near RT). Thus, the important parameter to focus on is the variation of the magnitude of Δ S m in B10 owing to its contrasting attributes.…”

“…The structural features of B0 and B10 were discussed in detail in our previous report. 6 Here, only the factors that are viable for further analysis are considered. The Rietveld refinement was carried out using the FullProf suite software.…”

“…Magnetic refrigeration (MR) has potential for energy saving, up to 30% as compared to the conventional gas refrigerator, and the major advantage is that it is eco-friendly. 6 The discovery of giant MCE in Gd 5 (SiGe) 4 near RT 7 has made this research multidisciplinary owing to instrumentation and the state-of-the-art material search. Generally, any magnetic material that manifests magnetic transitions between two ground states projects MCE.…”

Tuneable magnetic nanocomposites for remote self-healing

“…The amount of heat generated is correlated to the change in the magnetic entropy in the system 34 . To estimate the heat generation, the change in entropy ΔSm was approximated using the isotherm M-H curves 35 at 100 K and 400 K. Using the limited data, the calculated values of ΔSm were found to be highest for SHMNP and SHMNP composite with magnitude in region of 20.5 J K −1 kg −1 and 0.1 J K −1 kg −1 , respectively. The values for change in entropy demonstrates that SHMNP and SHMNP composite, both will generate highest heat in response to alternating magnetic field.…”