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《Materials Review》 2018-S1
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First Principle Study of Electronic Structures,Mechanical Properties and Debye Temperature of α-Al_2O_3

YAN Yuncheng;School of Materials Science and Engineering,Baise University;  
Electronic structures,mechanical properties and Debye temperature ofα-Al_2O_3 were investigated by means of first principle calculations from CASTEP program based on density functional theory(DFT).The optimized lattice parameters are in substantial agreement with the experimental data.The energy band structure diagram shows thatα-Al_2O_3 has typical ionic compound characteristics,and the band gap is 5.964 eV.The calculated density of states results indicate that the lower valence band ofα-Al_2O_3 ranges from-19.426 eV to-15.370 eV,and the corresponding density of states is mainly contributed by 2 selectrons of oxygen atom.The upper valence band ofα-Al_2O_3 changes from-7.178 eV to 0.711 eV,and the corresponding density of states is mainly from 2 p electrons of oxygen atom.The conduction band is between 5.698 eV and 14.977 eV,and the corresponding density of states is mainly given by 3 sand 3 p of aluminum atom.The charge density difference shows that ionic bond and covalent bond exist inα-Al_2O_3.The mechanical properties were calculated,and the results indicate that the bulk modulus ofα-Al_2O_3 is 224.885 GPa,the shear modulus is 144.687 GPa,the elastic modulus is 357.411 GPa,Poisson's ratio is 0.235,and the anisotropy index is 0.220.The ratio of shear modulus to bulk modulus is equal to 0.643,which suggests thatα-Al_2O_3 exhibits brittleness.Debye temperature ofα-Al_2O_3 was calculated and the value is 974.834 K.
【CateGory Index】: O482
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