Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 3: Crystal Structure, Defects, Real Structure and Microstructure in Materials
KFM 3.3: Vortrag
Montag, 12. März 2018, 10:10–10:30, E 124
Band gap engineered multicomponent equitatomic rare earth oxides synthesized by nebulized spray pyrolysis — •Leonardo Velasco Estrada1, Abhishek Sarkar1,2, and Horst Hahn1,2,3 — 11Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany — 2Joint Research Laboratory Nanomaterials, Technische Universität Darmstadt and Karlsruhe Institute of Technology, Alarich-Weiss-Str. 2, 64287 Darmstadt, Germany — 3Helmholtz Institute Ulm, Electrochemical Energy Storage, Helmholtzstr. 11, 89081 Ulm, Germany
Several multicomponent equitatomic rare earth oxides (ME-REOs) systems containing up to 7 elements (Ce, Gd, La, Nd, Pr, Sm and Y) were synthesized by nebulized spray pyrolysis. The systems showed narrow direct and indirect band gaps in the range of 1.95 * 2.14 eV, respectively. X-ray diffraction as well as transmission electron microscopy confirmed that all the systems crystallized as phase pure fluorite type (fm3m) structure. X-ray photoelectron spectroscopy revealed that Ce and Pr are in a 4+ and in a mixed oxidation state (3+/4+), respectively, while the other constituent elements are in a 3+ oxidation state. In this study the observed narrow band gap is closely related to the presence of multivalent Pr, since the phase pure fluorite type systems that were synthesized without Pr exhibited a band gap > 3eV. Interestingly, the narrow band gaps were not highly affected by the high chemical complexity of the systems. Therefore, this category of materials offers flexibility for band gap engineering and tunability.