, Volume 25, Issue 6, pp 1937-1945,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 28 Mar 2012

Magnetic and Magnetocaloric Properties of La0.67Pb0.33−x Ag x MnO3 Compounds

Abstract

In this paper, we have studied the magnetic and magnetocaloric properties of the perovskite manganites La0.67Pb0.33−x Ag x MnO3 (0≤x≤0.15), which show a sharp paramagnetic-ferromagnetic phase transition over a wide temperature range (T=250–401 K). The Curie temperature has been analyzed by two methods: using the numerical derivative dM/dT and the thermodynamic model. The experimental results indicate that T C decreases from 368 to 288 K with increasing Ag substitution independently of the method used to obtain T C. Upon 10 KOe applied magnetic field, the large magnetic-entropy change (|ΔS M|) reaches values of 2.75, 3, 3.25 and 3.5 J/kg K for x=0, 0.05, 0.10 and 0.15 compositions, respectively, which are comparable to that of Gd. The relative cooling power (RCP) increases with increasing Ag content from 68.75 (x=0) to 156.27 J/kg (x=0.15) for ΔH=10 KOe. Through these results, La0.67Pb0.33−x Ag x MnO3 materials are strongly suggested for the use of active refrigerants for magnetic refrigeration technology near room temperature.