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We perform density functional theory method to study the electronic structure of relaxor ferroelectrics Pb(Mg 1/3 Nb 2/3 )O 3 . An ordered perovskite structure based supercell was examined with the B sites Nb-Mg-Nb stacking along the [001] direction. Band structure, density of states and electron density have been obtained. The calculated band gap is a direct one with the value of 1.05 eV. It is found that the Mg-O bond presents no covalency, whereas there is a considerable Nb-O covalent bonding. The different B-O bonding characters might be responsible for the relaxor properties of Pb(Mg 1/3 Nb 2/3 )O 3 crystal. [ABSTRACT FROM AUTHOR]

A first‐principles investigation on the electronic structure, mechanical, and thermal properties of Zr–Si compounds has been investigated to prompt the development of new materials. The influence of Si content on mechanical and thermal properties is clarified. All the Zr–Si compounds are strikingly incompressible under uniaxial stress along x, y, and z axes. β‐ZrSi possesses the strongest resistance to shape change and uniaxial tensions. α‐ZrSi presents better performance of the resistance to volume change. The bulk modulus first increases and then decreases with the increase of the Si concentration. All the compounds exhibit brittle behavior. These zirconium silicides have relatively low bulk and shear modulus, but the shear anisotropy is strongly dependent on diverse directions. Debye temperature increases linearly with the increase of Si content. ZrSi2 shows the best capacity of thermal conductivity. The minimum thermal conductivity in all the crystallographic directions is progressively increased with the increase of Si content except for β‐ZrSi in the [010] direction. [ABSTRACT FROM AUTHOR]