Atomic structure of manganese-doped yttrium orthoaluminate

Abstract

Abstract Using hybrid exchange-correlation functional within density functional theory we have performed first-principle total energy calculations of Mn-doped yttrium orthoaluminate (YAlO3). Its equilibrium atomic structure has been predicted through optimization of coordinates of all atoms using a supercell approach. In our research both Mn3+ and Mn2+ ions have been substituted for the host alumina atom at orthorhombic Pbnm unit cell of YAlO3. F-center has been implemented as charge-compensating defect in case, when Mn2+ dopant is under study. In this study we thoroughly analyze the atomic displacements in seven nearest to Mn ion coordination spheres. Insertion of isoelectronic substitutional point defect Mn3+ leads to modest expansion of distorted oxygen octahedra, while the cage of Y atoms closest to the dopant remains mostly unchanged. Insertion of compensating F-center in the 1st oxygen coordination sphere breaks the symmetry of YAlO3 and heavily distorts the surrounding oxygen octahedron. That is why the Mn2+-F-center bonds is contracted about 32% with respect to reference Mn-O bond of Mn3+-doped orthorhombic YAlO3. Distortion is also well pronounced at Y coordination spheres of Mn2+/YAlO3. The influence of atomic relaxation near the Mn-dopants to the electronic structure of YAlO3 is also discussed.