Critical behaviour and magnetocaloric effect of nano crystalline La0.67Ca0.33Mn1 xFexO3 (x ¼ 0.05, 0.2) synthesized by nebulized spray pyrolysis

Abstract

The structure, critical exponents and magnetocaloric effect (MCE) of Nebulized Spray Pyrolysis (NSP)synthesized nano crystalline La0.67Ca0.33Mn1 xFexO3 (x ¼ 0.05, 0.2) were investigated. The Reitveld refinement of XRD patterns show that the samples adopt an orthorhombic structure with Pnma space group. TEM inspection reveals that the average particle size is about 15 nm and 42 nm for NSP synthesized LCMFe0.05 and LCMFe0.2 samples respectively. The temperature and field dependent magnetization studies reveal the superparamagnetic state of La0.67Ca0.33Mn0.95Fe0.05O3 and spin-glasslike state of La0.67Ca0.33Mn0.8Fe0.2O3. The critical behaviour at the transition region studied using modified Arrott plot provides a second order nature of phase transition for both samples. The magnetocaloric studies show the maximum value of magnetic entropy change (DSmax) is in the range 2.3 J kg 1 K 1 at 158 K for LCMFe0.05 and 0.3 J kg 1 K at 92 K for LCMFe0.2 respectively at 5 T field. The field dependence of the magnetic entropy changes are also analysed, which show a power law dependence(DSM N Hn, n ¼ 0.72 (2)) at transition temperature, TC ¼ 162 K for LCMFe0.05 and n ¼ 1.11(3) at 92 K for LCMFe0.2