Effect of Fe substitution on magnetocaloric effect in La0.7Sr0.3Mn1-xFexO3 (0.05≤x≤0.20)

We have studied the effect of Fe substitution on magnetic and magnetocaloric properties in La0.7Sr0.3Mn1-xFexO3 (x=0.05, 0.07, 0.10, 0.15, and 0.20) over a wide temperature range (T=10-400K). It is shown that substitution by Fe gradually decreases the ferromagnetic Curie temperature (T-C) and saturation magnetization up to x=0.15 but a dramatic change occurs for x=0.2. The x=0.2 sample can be considered as a phase separated compound in which both short-range ordered ferromagnetic and antiferromagnetic phases coexist. The magnetic entropy change (-Delta S-m) was estimated from isothermal magnetization curves and it decreases with increase of Fe content from 4.4 J kg(-1) K-1 at 343 K (x=0.05) to 1.3 J kg(-1) K-1 at 105 K (x=0.2), under Delta H=5 T. The La0.7Sr0.3Mn0.93Fe0.07O3 sample shows negligible hysteresis loss, operating temperature range over 60 K around room temperature with refrigerant capacity of 225 J kg(-1), and magnetic entropy of 4 J kg(-1) K-1 which will be an interesting compound for application in room temperature refrigeration. (C) 2010 Elsevier B.V. All rights reserved.