LaNiO ₃ Polycrystalline Nature Of Membrane Preparation And Multi-layered

LaNiO3has been studied intensively as a new type of pseudocubic perovskite oxides. It is mainly used in the fields such as transition layer for ferroelectric films and bifunctional catalyst materials, and so on. Through the theoretical calculation, heterojunction film with perovskite type, for instance LaNiO3/LaAlO3superlattice, usually has some special properties such as superconductivity. In this thesis, preparation and characterization of LaNiO3powder, polycrystal target, single film and LaNiO3/LaAlO3superlattice have been investigated.Firstly, in this thesis, LaNiO3nano-powder was synthetized by sol-gel method using deionized water and alcohol as solvent. Experiment show that the sintered powders which synthetized in deionized water has homogeneous and smaller particle size, while the powders synthetized in alcohol displays heterogeneity and bigger particle size, pH values are in therange between0.9and1.9When deionized water is selected as solvent. The higher the pH values the less foam will be produced in the drying process and the more obvious self-propagating will occur in the presintering process. When pH=1.3and1.5the crystallization temperature of LaNiO3isthe lowest. When pH=1.7and1.9the crystallization temperature is higher (pH=1.7, crystallization temperatures are between500℃and600℃). When pH=1.1the crystallization temperature of LaNiO3is higher than pH=1.7and1.9. When pH=0.9the crystallization temperature of LaNiO3is the hightest. Whichever solvent were used, ethanediol which was added as dispersant in the sol will inhibit foaming.Secondly, LaNiO3targets were pressed and sintered using the nano-powder prepared by sol-gel method. According to the experiments results, pH value of the precursor has some influence on the room temperature resistivity of LaNiO3target. When pH=1.3and pH=1.5LaNiO3target have the lowest room temperature resistivity. a phase transition will happen at950℃and complete at1100℃for LaNiO3. When sintered by spark plasma sintering (SPS) in vacuum, we found LaNiO3targets will decomposed to oxygen, La2NiO4and NiO at950℃.Finally, we prepared LaNiO3thin films by pulsed laser deposition (PLD) technique. the best preparation conditions for preparing LaNiO3single film are that deposition temperature and oxygen pressure is750℃and20Pa respectively. XRD patterns show thatthe LaNiO3single film growed along c-orientation. The best deposition oxygen pressure of LaAlO3single film is50Pa and only when the deposition temperature above900℃the crystal quality of LaAlO3single film meets requirements. In addition, LaNiO3/LaAlO3superlattice thin films are successfully prepared in this thesis. When the period of superlattice thin film is16, the satellite peaks of the film appear in the XRD pattern. Thought calculation we found that the deposition rate of LaNiO3layer and LaAlO3layer are0.72A/pulse, and1.58A/pulse, respectively.