Crystal structure and octahedral deformation of orthorhombic perovskite ABO3: Case study of SrRuO3.

Using density functional theory with local spin density approximation and taking SrRuO 3 as an example, the crystal structure of ABO 3 perovskite oxide and the rectangular deformation of the BO 6 octahedron were studied. It was found that the degree of octahedral rectangular deformation of orthorhombic SrRuO 3 is much larger than Jahn–Teller distortion, therefore, cannot be ignored. The lattice constant a is greater than b in SrRuO 3 (as well as LaCrO 3 , LaGaO 3 , and PbRuO 3) because the side length of rectangle along x direction, a oct , is larger than that along y direction, b oct ; and the tilting angle of the octahedron, φ T , is smaller than arccos (b oct / a oct). We found that in ABO 3 oxide, BO 6 octahedral rectangular deformation has a universality and, consequently, a oct ≠ b oct. We discussed in detail the changes of lattice constants caused by rectangular deformation of the octahedron and divided orthorhombic ABO 3 oxides into the following three categories: a oct ​> ​ b oct with a > b ; a oct ​> ​ b oct with a < b ; and a oct ​≤ ​ b oct with a < b. The relationship between the rectangular deformation and the rotation (tilting) angle or tolerance factor is analyzed. As the symmetry and lattice constants of SrRuO 3 are rather inconsistent, we have analyzed and clarified them. The influence of rectangular deformation of the octahedron on the electronic structure and magnetic properties of SrRuO 3 was also calculated using first principles. [Display omitted] • With the rotation and tilting of octahedron Pbnm SrRuO 3 will experience rectangular deformation. • SrRuO 3 (as well as LaCrO 3 , LaGaO 3 and PbRuO 3) all have a > b, the reasons are analyzed. • Dozens of literatures give lattice constants a < b for Pbnm SrRuO 3 , to which we have paid attention in this paper. • The relationship between the rectangular deformation and the rotation (tilting) angle or tolerance factor is analyzed. [ABSTRACT FROM AUTHOR]