Understanding structure and structural formation in Mg & Zr-substituted Sr(Ga 12– x Al x )O ₁₉ -crystals. A study combining X-ray diffraction and DFT-modeling

The crystal structure of Mg and Zr- substituted strontium-hexagallate/-aluminate Sr(Ga 12− x Al x )O 19 single crystals is investigated by combining single crystal diffraction and quantum mechanical modeling based on density functional theory (DFT). The crystal structure is solved within the magnetoplumbite structure type (space group P 6 3 / mmc , Z = 2). Moreover, a refinement is carried out to determine the Wyckoff sites occupied by the substituent atoms Mg and Zr, as well as the shared occupancy of Ga and Al in the Sr(Ga 12− x Al x )O 19 solid solution. Through DFT calculations, the formation energies for the introduction of Mg, Zr and Al into the structure are determined, thus revealing the energetically most preferred sites for these cations. Both methods show results which are in good agreement, thus corroborating each other and providing the basis for a deepened understanding of the material in question.