Synthesis and Characterization of Manganite Nanocomposites for Magnetic Refrigeration Applications

Abstract

In this thesis, we have studied the effect of substitution of Ag1+ on the physical, magnetic and the magnetocaloric properties for the manganites nano compounds of the system La0.8Sr0.2 xAgxMnO3 (LSAMO) with (x = 0.0, 0.05, 0.1, 0.15 and 0.2). We have synthesized these samples using Sol-Gel method. The samples have been annealed at 600 °C for 4 hrs, then to 800 °C for 2 hrs. We confirmed this annealing procedure using thermogravimetric and differential thermal analysis (TGA/DTA). The microstructure of the samples has been studied by using X Ray Diffraction and High Resolution Transmission Electron Microscope (HR-TEM). The measurements of the magnetic field dependence of the magnetization (M-H curves) have been done at different temperatures (ranging from 245 K to 400 K in steps of 4 degrees) using Vibrating Sample Magnetometer (VSM). We have studied the magnetocaloric effect for the prepa