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, (- Delta { ext{S}}_{{ ext{M}}}^{{{ ext{max}}}}), 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 (- Delta { ext{S}}_{{ ext{M}}}^{{{ ext{max}}}}) 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 (- Delta { ext{S}}_{{ ext{M}}}^{{{ ext{max}}}}) 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.