Magnetic susceptibility, XPS and NEXAFS spectroscopy of Ni-doped CaCu3Ti4O12 ceramics

N. A. Zhuk, S. V. Nekipelov, V. N. Sivkov, B. A. Makeev, R. I. Korolev, V. A. Belyy, M. G. Krzhizhanovskaya, M. M. Ignatova

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7 Scopus citations

Abstract

Two series of Ni-doped CaCu3Ti4O12 ceramics with CaCu3Ti4-4хNiO12-δ and CaCu3-3хNiTi4O12 compositions were obtained by the solid-phase synthesis method. The magnetic behavior of the samples in the range of 77–400 K was studied by magnetic dilution. For the first time the samples of both series were characterized by the spectroscopic methods: XPS and NEXAFS. As a result of XPS spectroscopy, it was found that calcium, copper and nickel atoms mainly have the oxidation state (II), and titanium atoms can exhibit oxidation states of (III) and (IV). NEXAFS-study of Ni-doped CCTO showed that titanium atoms mainly have the oxidation state (IV). In the NEXAFS spectra of nickel of the both series of the samples, a feature associated with the presence of Ni(II) in the square-planar environment was manifested. It was concluded that nickel atoms were distributed in the positions of copper and titanium in the samples of both series. The magnetic behavior of the nickel-doped solid solutions of both types of substitution was different only at x ≥ 0.03, which indicated the advantage of placing nickel (II) atoms in the Cu(II) position. According to the magnetic dilution data, the antiferromagnetic exchange was realized between the nearest paramagnetic nickel atoms in CaCu3Ti4-4хNiO12-δ and the ferromagnetic one between the paramagnetic clusters.

Original languageEnglish
Article number123310
Number of pages9
JournalMaterials Chemistry and Physics
Volume252
DOIs
StatePublished - 15 Sep 2020

Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

Keywords

  • Calcium-copper titanate
  • Magnetic properties
  • XPS and NEXAFS spectroscopy

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