Favourable modification of magnetic and magnetocaloric properties of La0.5Sr0.5CoO3 upon Ba substitution

The influence of Ba substitution (5–15%) on magnetic and magnetocaloric properties of La0.5Sr0.5CoO3 ceramics has been investigated in this study. Hysteresis loops confirm the ferromagnetic nature of the Ba-substituted cobaltites. The magnetic entropy change peaks, -ΔSMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$- \Delta {\text{S}}_{{\text{M}}}^{{{\text{max}}}}$$\end{document}, in La0.5(Sr1–xBax)0.5CoO3 are observed at their respective TC values of 241, 239 and 237 K for x = 0.05, 0.1 and 0.15, respectively. However, the position of -ΔSMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$- \Delta {\text{S}}_{{\text{M}}}^{{{\text{max}}}}$$\end{document} shifts to a slightly higher temperature for an applied field above 1 T, which is accounted for by the short-range ferromagnetic correlations existing above TC. The values of -ΔSMmax\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$- \Delta {\text{S}}_{{\text{M}}}^{{{\text{max}}}}$$\end{document} for x = 0.05, 0.1 and 0.15 corresponding to a field change of 5 T are recorded as 2.46, 2.51 and 2.42 J kg–1 K–1, respectively. A remarkable enhancement in relative cooling power is observed with Ba substitution becoming highest at 141.38 J kg–1 for x = 0.15. All these attributes of the studied materials suggest the feasibility to find applications as magnetic refrigerants.