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arXiv · 1106.1029

Entanglement of charge transfer, hole doping, exchange interaction and octahedron tilting angle and their influence on the conductivity of La1-xSrxFe0.75Ni0.25O3-δ: A combination of x-ray spectroscopy and diffraction

Selma Erat·Artur Braun·Cinthia Piamonteze·Zhi Liu·Alejandro Ovalle·Hansjürgen Schindler·Thomas Graule·Ludwig J. Gauckler
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Abstract

Substitution of La by Sr in the 25% Ni doped charge transfer insulator LaFeO3 creates structural changes that inflect the electrical conductivity caused by small polaron hopping via exchange interactions and charge transfer. The substitution forms electron holes and a structural crossover from orthorhombic to rhombohedral symmetry, and then to cubic symmetry. The structural crossover is accompanied by a crossover from Fe3+-O2--Fe3+ superexchange interaction to Fe3+-O2--Fe4+ double exchange interaction, as evidenced by a considerable increase of conductivity. These interactions and charge transfer mechanism depend on superexchange angle, which approaches 180° upon increasing Sr concentration, leading an increased overlap between the O (2p) and Fe/Ni (3d) orbitals.

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Selma Erat, Artur Braun, Cinthia Piamonteze, Zhi Liu, Alejandro Ovalle, Hansjürgen Schindler, Thomas Graule, Ludwig J. Gauckler. 2011-06-06. Entanglement of charge transfer, hole doping, exchange interaction and octahedron tilting angle and their influence on the conductivity of La1-xSrxFe0.75Ni0.25O3-δ: A combination of x-ray spectroscopy and diffraction. https://doi.org/10.1063/1.3517822

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