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Temperature induced reduction of the trivalent Ni ions in LiMO2 (M=Ni, Co) thin films

Cherkashinin, Gennady and Ensling, David and Komissinskiy, Philipp and Hausbrand, René and Jaegermann, Wolfram (2013):
Temperature induced reduction of the trivalent Ni ions in LiMO2 (M=Ni, Co) thin films.
In: Surface Science, Elsevier Science Publishing, pp. L1-L4, 608, ISSN 00396028, [Online-Edition: http://dx.doi.org/10.1016/j.susc.2012.09.023],
[Article]

Abstract

We report on an in-situ photoelectron spectroscopy study of the LiMO2 (M = Ni,Co) thin film layered materials. In the stoichiometric Lix(NiCo)O2 films grown by RF-magnetron sputtering at 20–600 °C, Ni3+ ions exist in the low-spin state. The growth temperatures T > 650 °C lead to better crystallinity of the films, Li-deficiency, and reduction of Ni3+ to Ni2+ in the high-spin state. The Co3+ ions in the low spin state are stable at 400–670 °C. The missing electron at the Ni-site is compensated by a less negative charge at the oxygen site or by the oxygen deficiency in Lix(NiCo)O2.

Item Type: Article
Erschienen: 2013
Creators: Cherkashinin, Gennady and Ensling, David and Komissinskiy, Philipp and Hausbrand, René and Jaegermann, Wolfram
Title: Temperature induced reduction of the trivalent Ni ions in LiMO2 (M=Ni, Co) thin films
Language: English
Abstract:

We report on an in-situ photoelectron spectroscopy study of the LiMO2 (M = Ni,Co) thin film layered materials. In the stoichiometric Lix(NiCo)O2 films grown by RF-magnetron sputtering at 20–600 °C, Ni3+ ions exist in the low-spin state. The growth temperatures T > 650 °C lead to better crystallinity of the films, Li-deficiency, and reduction of Ni3+ to Ni2+ in the high-spin state. The Co3+ ions in the low spin state are stable at 400–670 °C. The missing electron at the Ni-site is compensated by a less negative charge at the oxygen site or by the oxygen deficiency in Lix(NiCo)O2.

Journal or Publication Title: Surface Science
Volume: 608
Publisher: Elsevier Science Publishing
Uncontrolled Keywords: X-ray photoelectron spectroscopy, Li- ion transition metal oxides, Thin films, Valence and spin states of Ni and Co ions
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Thin Film Technology
11 Department of Materials and Earth Sciences > Material Science > Surface Science
Zentrale Einrichtungen
Exzellenzinitiative > Clusters of Excellence > Center of Smart Interfaces (CSI)
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis > Subproject A3: Boundary layers and thin films of ionic conductors: Electronic structure, electrochemical potentials, defect formation and degradation mechanisms
Exzellenzinitiative
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Exzellenzinitiative > Clusters of Excellence
Date Deposited: 09 Jan 2014 08:35
Official URL: http://dx.doi.org/10.1016/j.susc.2012.09.023
Additional Information:

SFB 595 A3

Identification Number: doi:10.1016/j.susc.2012.09.023
Funders: The work is supported by Deutsche Forschungsgemeinschaft (German Research Foundation) in the frame of the Research Collaborative Centre SFB 595 “Electrical Fatigue in Functional Materials”.
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