On the nature of change in Ni oxidation state in BaTiO<sub>3</sub>–SrTiO<sub>3</sub>system

Лебедев, А. И.; Sluchinskaya, I. A.

doi:10.1080/00150193.2016.1198196

Cited by 15 publications

(11 citation statements)

References 28 publications

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“…More recent work on Ni-doped hexagonal BaTiO 3 ceramics confirmed the majority of defects to be Ni 2? as determined by x-ray photoelectron spectroscopy (XPS) [10,26] or to be a mixture between Ni 2? and small amounts of Ni 3? as derived from extended x-ray absorption fine structure (EXAFS) measurements [27]. In the latter paper, the presence of the charge-compensating oxygen vacancy in the first coordination sphere of the Ni defect was excluded.…”

Section: Introductionmentioning

confidence: 99%

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

et al. 2020

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Systematic measurements of the magnetic moment of hexagonal 6H-BaTiO3 + 0.04 BaO + x NiO (0.005 ≤ x ≤ 0.02) ceramics were performed to study the influence of Ni ions on the magnetic properties. By temperature-dependent measurements of the paramagnetic susceptibility at 90 kOe, the Ni2+ ion was identified as the majority defect in air-sintered Ni-doped hexagonal barium titanate. Q-band EPR investigations of a 2.0 mol% Ni-doped single crystal revealed three different Ni centers located at Ti sites: first, Ni3+ ions at Ti sites in intact oxygen octahedra, second, Ni3+ associated with an oxygen vacancy and third, the presence of Ni2+ centers leading to a forbidden transition. The Ni3+—VO associate characterized by a vacancy in the face-sharing oxygen plane of the oxygen octahedra can be ruled out. The crystal field parameters of the Ni2+ defect were estimated by a combined fitting of the paramagnetic susceptibility and the EPR fine structure parameter D to $$B_{0}^{4}$$ B 0 4 ≈ −17,300 cm−1, $$\left| {B_{0}^{2} } \right|$$ B 0 2 ≈ 2500 cm−1 and $$B_{3}^{4}$$ B 3 4 ≈ 19,000 cm−1.

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Section: Introductionmentioning

confidence: 99%

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

et al. 2020

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“…Therefore, the grain boundary segregation and dissolution of cations determine the grain boundary resistance. Ni is known as an acceptor-type dopant for BT and it readily dissolves into Ti sites by introducing oxygen vacancies in BT [23]. Oxygen vacancies are one of the major causes for IR degradation during constant poling with a DC bias [8].…”

Section: Resultsmentioning

confidence: 99%

Characterizing electrical breakdowns upon reoxidation atmosphere for reliable multilayer ceramic capacitors

Lee

Song

Jung

et al. 2021

J. Korean Ceram. Soc.

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Electrical breakdowns of multilayer ceramic capacitors (MLCCs) manifest an increase in leakage current and are characterized as a function of atmospheric reoxidation. The atmospheric reoxidation is controlled with respect to the theoretical oxygen partial pressure for the oxidation of Ni internal electrodes. The breakdowns are characterized by a Maxwell-Wagner polarization technique, which dominantly exhibits space-charge-limited and Poole-Frenkel currents for all measured samples. The threshold voltage for the transition between these two conduction modes is suggested as an index for the robustness of the grain boundary resistance of BaTiO 3 ; therefore, the breakdown voltage. The reoxidation atmosphere, which prevents the Ni oxidation, increases the threshold voltage, dramatically enhancing the breakdown voltage and insulation resistance. Impedance spectroscopy and scanning transmission electron microscopy-energy-dispersive X-ray spectroscopy reveal that the cation distribution throughout BaTiO 3 grains and grain boundaries changes during the reoxidation, including Ni cations from the internal electrodes, which affects the grain boundary resistance and determines the breakdown voltage of MLCCs with Ni internal electrodes. These observations emphasize that the reoxidation should be concurrently optimized in terms of the cation redistribution and elimination of oxygen vacancies.

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“…Параметры, описывающие кулоновское и обменное взаимодействие для примесного атома, полагались равными U = 5 eV и J = 0.9 eV. Как было показано в наших более ранних исследованиях [35], чтобы получить относительно узкие примесные полосы в энергетическом спектре, необходимо использовать сверхъячейки, содержащие более 40 атомов. Поэтому для моделирования изолированных примесных центров нами использовались 80-атомные ГЦК-сверхъячейки, в которых один из ионов Ti 4+ в узле B или ионов Sr 2+ в узле A замещался атомом примеси.…”

Section: эксперимент и техника расчетовunclassified

О возможности введения примеси железа в узлы A в SrTiO-=SUB=-3-=/SUB=-

Случинская¹,

Лебедев²

2022

Физика Твердого Тела

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The local environment and oxidation state of the Fe impurity in strontium titanate are studied using XAFS spectroscopy. The influence of annealing temperature and deviation from stoichiometry on the possibility of incorporation of the impurity into the A and B sites of the perovskite structure is studied. The results obtained from the X-ray diffraction, XANES spectra, and EXAFS spectra suggest that at high annealing temperature the iron atoms, at least partially (up to 30%), enter the A sites in SrTiO3. The obtained results agree with results of first-principles calculations, according to which the iron at the A site exhibits strong off-centering (the displacement of ~1 Angstrom), similar to that previously established in SrTiO3 samples doped with Mn and Co.

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On the nature of change in Ni oxidation state in BaTiO₃–SrTiO₃system

Cited by 15 publications

References 28 publications

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

Characterizing electrical breakdowns upon reoxidation atmosphere for reliable multilayer ceramic capacitors

О возможности введения примеси железа в узлы A в SrTiO-=SUB=-3-=/SUB=-

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On the nature of change in Ni oxidation state in BaTiO3–SrTiO3system

Cited by 15 publications

References 28 publications

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

On the incorporation of nickel into hexagonal barium titanate: magnetic properties and electron paramagnetic resonance (EPR)

Characterizing electrical breakdowns upon reoxidation atmosphere for reliable multilayer ceramic capacitors

О возможности введения примеси железа в узлы A в SrTiO-=SUB=-3-=/SUB=-

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On the nature of change in Ni oxidation state in BaTiO₃–SrTiO₃system