Direct and indirect measurement of the magnetocaloric effect inLa0.67Ca0.33−xSrxMnO3 ± δ ()

Abstract

The magnetocaloric properties of a series of manganites with the compositionLa0.67Ca0.33−xSrxMnO3 ± δ, (LCSM), have been investigated by direct and indirect measuring techniques. The compoundsshowed a magnetocaloric effect near the Curie temperature, which increased from 267 K forx = 0 to 369 Kfor x = 0.33. Both the adiabatic temperature change and the isothermal magnetic entropy change werefound to decrease upon increased replacement of Ca with Sr, in good agreement withprevious reports. However, all samples showed almost the same relative cooling power,RCP, because the decrease in maximum magnetocaloric effect was accompanied by awidening of the magnetocaloric peaks. The compounds showed RCP values of about300 mJ cm−3 upon a field change of 1.2 T, which is about three times less than the RCP of gadolinium,the prototype material for magnetic cooling at ambient conditions. However, theLCSM materials show a magnetocaloric effect in temperature ranges where themagnetocaloric effect in pure Gd is vanishing. LCSM might therefore have potential as aworking substance in multi-component refrigerant units, where the possibility oftailoring compounds with a specific magnetic transition temperature is essential.