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X‐ray photoelectron spectroscopy study of neodymium niobate and tantalate precursors and thin films
Author(s) -
Brunckova Helena,
Kolev Hristo,
Kanuchova Maria
Publication year - 2019
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6583
Subject(s) - x ray photoelectron spectroscopy , tantalate , thin film , orthorhombic crystal system , valence (chemistry) , analytical chemistry (journal) , materials science , monoclinic crystal system , tetragonal crystal system , neodymium , crystallography , chemistry , crystal structure , nanotechnology , nuclear magnetic resonance , ferroelectricity , optics , dielectric , physics , optoelectronics , organic chemistry , chromatography , laser
Neodymium niobate NdNbO 4 (NNO) and tantalate NdTaO 4 (NTO) thin films (~100 nm) were prepared by sol‐gel/spin‐coating process on Al 2 O 3 substrate with LaNbO 4 /PbZrO 3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X‐ray photoelectron spectroscopy (XPS). The core‐level XPS studies of sol‐gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd 3+ ) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X‐ray diffraction analyses verified formation of the monoclinic (M‐NdNbO 4 or M′‐NdTaO 4 ), orthorhombic (O‐NdNbO 4 ) and tetragonal (T‐NdTaO 4 ) phases in precursors and films. Single valence state of Nd 3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices.