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HL: Fachverband Halbleiterphysik

HL 79: Poster: New Materials

HL 79.9: Poster

Donnerstag, 23. März 2017, 15:00–19:00, P2-OG3

Theoretical and experimental investigation of Iron doped hexagonal BaTiO₃ — •Waheed A. Adeagbo¹, Sanjeev K. Nayak², Hichem B. Hamed¹, Hans T. Langhammer³, Wolfram Hergert¹, and Thomas Müller⁴ — ¹Institute of Physics, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany — ²Department of Materials Science and Engineering, University of Connecticut, USA — ³Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle, Germany — ⁴Faculty of Physics and Earth Sciences, Leipzig University, 04103 Leipzig, Germany

EPR measurements on Fe-doped hexgonal BaTiO₃ (h-BTO), with Fe concentration between 0.5−2.0 mol%, show the detection of isolated Fe³⁺ which occupies only one of the two crystallographic different Ti sites, that could be the exclusively corner-sharing octahedron, in all different annealing prepared samples. Also, there is speculation about EPR non-detectable states of Fe²⁺ and Fe⁴⁺ presence, but Fe⁵⁺ formation is completely ruled out. Recent further defect center detected is identified as Fe³⁺ associated with an oxygen vacancy (V_O) in the first coordination sphere. The exact Fe³⁺ and V_O occupation sites and the V_O roles in the complex are still unknown. Thus, we have used the first principles approach to study the defect properties of substitutionally doped Fe in h-BTO and to examine the role played by the V_O in structure, electronic and magnetic properties due to the introduced defects in the pure crystal. Our theoretical analysis of the defect formation energy derived from the total energies of defective supercells in various charge states will be presented with respect to available EPR-data.