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Theoretical Study On Structures And Properties Of Complex Oxides LaBO3Crystals

Posted on:2013-09-15Degree:MasterType:Thesis
Country:ChinaCandidate:L L SongFull Text:PDF
GTID:2250330392965509Subject:Theoretical Physics
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In recent years, First principles calculation method based on density functional theory (DFT) has become one of the most important research tools in quantum chemistry and materials science. And it has obtained a great success in the geometric structure, electronic structure and magnetic properties. This article used this calculation method and studied electronic structure and optical properties of LaCrO3with the orthorhombic structure (O-LaCrO3) and the rhombohedral structure(R-LaCrO3), as well as LaLuO3, and LaInO3crystals with orthorhombic perovskite type structure. Refering to the experimental lattice parameters reported in the literature, the unit cells of LaCrO3, LaLuO3and LaInO3crystals are constructed with Visualizer module of Materials Studio software package. Then, the geometry optimizations about these unit cells are carried out by using CASTEP module of the code with calculation schemes. The calculation schemes are selected for properties calculations of these crystals through comparing the obtained lattice parameters with the experimental ones reported. Based on the optimized unit cells, the electronic structure and optical properties of crystals are calculated and analyzed.Analysis for the energy bands, density of states, the population number, charge density and electronic structure and optical properties are described. That O-LaCrO3is direct band gap semiconductor is obtained, in which the energy gap about2.445eV, while the R-LaCrO3is indirect band gap semiconductor, in which energy gap is about2.503eV; LaLuO3is wide band gap (4.577eV) indirect semiconductor; LaInO3is direct band gap semiconductor, the energy gap (Eg) is2.764eV. The calculated results of the complex dielectric function, absorption coefficient and the photoconductivity indicated that O-LaCrO3, R-LaCrO3, LaLuO3, and LaInO3crystals have good absorption intensity and photocatalytic activities in the range of visible light. And we forecast O-LaCrO3crystal materials possess better optical performance.
Keywords/Search Tags:LaCrO3, LaLuO3, LaInO3, first-principles, electronic structure, optical property
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