Magnetocaloric effect in (La1-xSmx)0.67Pb0.33MnO3 (0 ? x ? 0.3) manganites near room temperature

Abstract We present an investigation on structure, magnetic and magnetocaloric properties of the perovskite manganites (La1-xSmx)0.67Pb0.33MnO3 (x = 0, 0.1, 0.2, 0.3) synthesized by sol-gel technique. The XRD patterns show that all synthesized samples have reflections typical of the perovskite structure with orthorhombic symmetry. Thermomagnetic measurements showed that all the samples display a paramagnetic-ferromagnetic transition with decreasing temperature. The Curie temperature decreases with increasing Sm content from 358 K for x = 0-286 K for x = 0.3. We determined the isothermal magnetic entropy changes of all the samples from the magnetization measurements and furthermore measured the adiabatic temperature change of the sample for x = 0.3 directly. The results showed that the adiabatic temperature change, determined using together the entropy change and the specific heat and the value obtained by direct temperature change measurements both give 1.3 K for a magnetic field change of 3 T at about 280 K. We also measured the cyclic adiabatic temperature-change of the sample and the results indicate that the sample undergoes a reversible temperature-change on field-cycling which is essential for magnetic refrigeration. © 2015 Elsevier B.V.This work was supported by the Research Fund of Çukurova University, Adana, Turkey , under grant contracts no. FEF2010D4, no. FEF2013BAP29 and Deutsche Forschungsgemeinschaft SPP1599 . We also acknowledge Adana Science and Technology University Research Project Unit (Project Number: MÜHDBF.MLZM.2014-9). The authors acknowledge the Turkish Council of Higher Education for supporting Selda Kılıç Çetin's visit to Duisburg-Essen University. We thank C. Gökhan Ünlü for the support for X-ray refinement