Thesis (M.Sc.) - Cairo University -The National Institute of Laser Enhanced Sciences - Department of Laser Sciences Interaction

LLa(1-x)SrxMnO3 (LSM, x 0.3) is an interesting material for many applications, such as spintronic, catalysis and in manufacturing cathodes of solid oxide fuel cell (SOFC); due to its intrinsic magnetoresistance properties, electric field tunable metal insulator transitions and half metallic band structure. LSM is very sensitive to the preparation methodologies and to many parameters controlling the shape, size and surface morphology. In this work, LSM cathode in powder form was prepared by two different chemical methods; hydrothermal and sol gel by altering different parameters such temperature, time and pH to obtain LSM powder with optimum pure phase. Using hydrothermal method, LSM cathode in the form of powder was successfully synthesized at acidic environment (pH=5) and at annealing temperature of 900 {u00B0}C (below which powdered LSM could not be obtained in pure phase by hydrothermal method) for 3 hours. In case of sol gel method LSM was obtained at 600 {u00BA}C for 5h and pH = 1. The phase purity was examined by X- ray diffraction (XRD) and showed that LSM synthesized by either of the two methods had a polycrystalline phase with rhombohedral crystal system and no other phases were observed. High resolution transmission electron microscope (HR-TEM) and particle size distribution (PSD) showed that hydrothermal-synthesized LSM particles were spherical, agglomerate easily and particle size ranges between 400- 1000 nm with average particle size at ~657 nm while sol gel-synthesized LSM particle size ranges between 100- 200 nm with average particle size 107.9 nm. The selected area electron diffraction pattern (SAED) also revealed the polycrystalline nature of the synthesized LSMs. Energy dispersive X-ray (EDX) confirmed the presence of all LSM elements with proper stoichiometric ratios, and no other undesirable phases were observed

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