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

Abstract

Using density functional theory with local spin density approximation and taking SrRuO3 as an example, the crystal structure of ABO3 perovskite oxide and the rectangular deformation of the BO6 octahedron were studied. It was found that the degree of octahedral rectangular deformation of orthorhombic SrRuO3 is much larger than Jahn–Teller distortion, therefore, cannot be ignored. The lattice constant a is greater than b in SrRuO3 (as well as LaCrO3, LaGaO3, and PbRuO3) because the side length of rectangle along x direction, aoct, is larger than that along y direction, boct; and the tilting angle of the octahedron, φT, is smaller than arccos (boct/aoct). We found that in ABO3 oxide, BO6 octahedral rectangular deformation has a universality and, consequently, aoct ≠ boct. We discussed in detail the changes of lattice constants caused by rectangular deformation of the octahedron and divided orthorhombic ABO3 oxides into the following three categories: aoct ​> ​boct with a >b; aoct ​> ​boct with a <b; and aoct ​≤ ​boct 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 SrRuO3 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 SrRuO3 was also calculated using first principles.