X-Ray Peak Broadening Analysis in LaMnO3+δ Nano-Particles with RhombohedralCrystal Structure

In this work, structural and magnetic properties of the LaMnO3+δ compound prepared by citrate precursor method and annealed in the presence of oxygen are investigated. The structural characterization of LaMnO3+δ by X-ray powder diffraction and X‟pert package and Fullprof program provides evidence for a rhombohedral structure (R-3c space group) confirmed by FTIR measurement as well. The magnetic measurements show a super-paramagnetic behavior of LaMnO3+δ due to low values of the coercive field and remanance magnetization and also high value of saturation magnetization. In addition, a comparative study of the crystallite size of the compounds obtained from powder XRD is reported. The Williamson-Hall analysis, size-strain plot and Halder-Wagner methods were used to study the individual contributions of the crystallite sizes and lattice micro-strain to isotropic line broadening of all the reflection peaks of the LaMnO3+δ compound. The results show that the Halder-Wagner method is more accurate, with all data points touching the fitting line better than in the other methods. The crystallite sizes estimated from XRD (30.86 nm) and particle size estimated from TEM method (36 nm) and also the magnetic core size (33.6 nm) estimated from magnetic measurement are in good agreement, while a little difference reflects a spherical shape of the nanoparticles.