STRUCTURE AND MICROSTRUCTURE STUDY ON LaMnO3 AND La0.67Ba0.33MnO3: COMPARISON BETWEEN BULK AND THIN FILMS

Abstract

Bulk LaMnO₃ and La_0.67Ba_0.33MnO₃ polycrystalline manganite were prepared via solid state reaction and converted into thin films via pulsed laser deposition technique. Comparison between bulk and thin films on structure and microstructure were studied. Crystal structure transformation was observed when bulk LaMnO₃ converted into thin film. Clear grains was observed in bulk LaMnO₃ while LaMnO₃ thin film shows melted-like grains accompanied by island growth mode. Positive misfit was observed in La_0.67Ba_0.33MnO₃ thin films due to strains induced by the lattice misfit between the deposited film and substrate. Nano-sized cracks were observed due to dissimilarity in coefficient of thermal expansion between thin film and substrate. In both LaMnO₃ and La_0.67Ba_0.33MnO₃ systems, larger lattice strain was observed in thin film sample compared to bulk. Thus, enhanced the density of system by invoke MnO₆ octahedral to stretch its Mn-O-Mn bond angle and Mn-O bond length. Denser crystal system was observed in thin film sample compared to bulk.