Regensburg 2025 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 14: Poster

KFM 14.18: Poster

Wednesday, March 19, 2025, 17:00–18:30, P1

Isovalent exchange of Al, Mg and Zr in strontium hexagallate (SrGa12O19) — •Finn. H. Bietz¹, Ch. Rhode², and S. Sanna^{1, 3} — ¹Institut für Theoretische Physik, Justus-Liebig-Universität Gießen, Gießen 35392, Germany — ²Leibniz Institut für Kristallzüchtung, Max Born Straße 2, 12489 Berlin — ³Center for Materials Research (ZfM), Justus Liebig University Gießen, Gießen 35392, Germany

SrGa₁₂O₁₉ can be used as a substrate for the growth of barium hexaferrite, a ferrimagnetic and quantum paraelectric material. The lattice parameters of SrGa₁₂O₁₉ can be adjusted by substitution of Ga by Al or Mg and Zr respectively for lattice-matched growth and strain engineering of barium hexaferrite. A microscopic picture of the doping mechanisms and their effect on the lattice parameters is missing.
In this contribution, we report on first-principles calculations performed to determine the lattice site of Al, Mg and Zr atoms in the SrGa₁₂O₁₉ structure, and support corresponding experiments performed at the IKZ in Berlin. Thereby the defect formation energies of Al, Mg and Zr atoms incorporated in the dilute limit at different lattice sites were calculated within density functional theory.
The atomistic models reveal that Mg populates the so called Ga⁽³⁾ position, Al prefers the Ga⁽¹⁾ site, but also populates the Ga⁽⁴⁾ and Ga⁽⁵⁾ sites, and that the Zr is incorporated the Ga⁽⁴⁾ site. While the results are in very good agreement with the experimental results in the case of Mg and Al doping, the experimentally determined lattice site of Zr differs from the theoretical predictions, suggesting the formation of defect complexes or co-doping related effects.

Keywords: SGAMZ