Structural and magnetocaloric properties (0.75)La0.7Ca0.3MnO3/(0.25) La0.84Sr0.16MnO3 nanocomposite

We report the structural, magnetic, and magneto-caloric properties of as-synthesized (0.75)La0.7Ca0.3MnO3/(0.25)La0.84Sr0.16MnO3 nanocomposite material. The parent nanocrystalline samples synthesizes using pechini sol-gel route as well as sample's crystal structure was analyzed by Rietveld analysis of powder X-ray diffraction pattern. The nanocomposite sample showed two structural phases, which correspond to both the parent samples La0.7Ca0.3MnO3 (Orthorhombic structure, Pbnm space group) and La0.84Sr0.16MnO3 (Rhombohedral structure, R (3) over barc space group) respectively. The Williamson-Hall method was employed to calculate the crystallite size as well as strain in both parent samples. The values of crystallite size (D) and strain (epsilon) for La0.7Ca0.3MnO3 are 65 nm and 0.0009 respectively and for La0.84Sr0.16MnO3 are 37 nm and 0.0021. Homogeneity of the prepared compounds was confirmed with scanning electron microscopy (SEM) images. The temperature-dependent magnetization data displayed two successive transitions in the composite sample at 155 K and 255 K, which correspond to the parent samples. The respective maximum values of magnetic entropy change (-Delta S-M) were observed to be 1.9 Jkg(-1)K(-1) and 3.03 Jkg(-1)K(-1) at 5 T magnetic field for La0.7Ca0.3MnO3 and La0.84Sr0.16MnO3. To assess the ordering of the samples, Landau's analysis was carried out that reveals a good concordance with our experimental results. The broadened temperature range was found in the composite sample, consequently, the isothermal entropy change is reduced. An enhancement of 20%-25% of relative cooling capacity is noticed in the composite sample as compared to the parent samples.

Automated summary

The (0.75)La0.7Ca0.3MnO3/(0.25)La0.84Sr0.16MnO3 nanocomposite material exhibited excellent magnetic and magneto-caloric properties, with a higher relative cooling capacity compared to the parent samples. The experimental results showed two successive transitions in the composite sample corresponding to the parent samples La0.7Ca0.3MnO3 and La0.84Sr0.16MnO3.