Preparation Process Of Sr₂TiO₄ Powder, Thin Film And Research Of Formation Mechanism

Sr₂TiO₄ is a two-dimensional layered perovskite oxide with wide band gap. It not only has more extensive space changes and more special structural characteristics than perovskite oxide ?SrTiO₃?, but also show many specific electromagnetic characteristics, such as dielectric, thermoelectricity, superconductivity and ferromagnetic and so on. Thus it has gradually become a new kind of promising inorganic material like perovskite oxide. But the structural stability of Sr₂TiO₄ is poor, which leads to the preparation of single-phase Sr₂TiO₄ is difficult. So the key problem is how to realize the preparation of high purity Sr₂TiO₄ material. In this paper, we researched the technological condition of preparing Sr₂TiO₄ powder by Sol-Gel method, dielectric properties of Sr₂TiO₄ powder and photoluminescence properties of Pr doped Sr₂TiO₄ powder. We also explored the difficulties of the preparation of Sr₂TiO₄ thin films by Sol-Gel method and magnetron sputtering method and the growth mechanism of this kind of film.Firstly, we studied the influence of four different precursor fluid systems of sol-gel method to the structure and morphology of Sr₂TiO₄ powder. The results show that the purity of sample is highest when the precursor fluid system was annealed at 1200? for 12 h, the shape of the samples is irregular, the particle size in microns and additives in the precursor solution have important influence on the morphology of samples. What's more, the complex permittivity of Sr₂TiO₄ powders prepared by Ethylene glycol methyl ether-ice acetic acid system is the largest, Pr doped Sr₂TiO₄ powders have strong photoluminescence peak in red light range.Secondly, we researched the influence of different technological conditions of Sol-Gel method to the structure and morphology of thin film. The results show that the thickness of film is an important factor which affects the crystalline structure of the film. When the film thickness is in deep submicron level, the thin film is SrTiO₃, but when the film thickness is in micron scale, the thin film layer near the substrate is SrTiO₃, the surface layer of the thin film is Sr₂TiO₄. Which may be result from thin film is subjected to the action of the force field from the substrate surface, lead to uneven distribution of elements and different force on atoms.Finally, we studied the influence of different technological conditions of magnetron sputtering method on the structure and morphology of thin films. The results show that the preparation of thin films in different argon oxygen ratio, substrate temperature, gas pressure, sputtering power and different types of substrates which under the bombardment of Sr₂TiO₄ target material are SrTiO₃ thin films. Film thickness has important influence on distribution of elements, with thin film thickness increases from deep submicron to micron level, strontium titanium ratio changes from less than 1 to 2. The lack of Sr in the film and the uneven distribution of Sr lead to the failure of preparing Sr₂TiO₄ thin film.