Electron paramagnetic resonance study of ZnO varistor material

Baraki, Raschid; Zierep, Paul; Erdem, Emre; Weber, Stefan; Granzow, Torsten

doi:10.1088/0953-8984/26/11/115801

Cited by 37 publications

(21 citation statements)

References 70 publications

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“…We observed EMR lines from helium to room temperature without visible hyperfine structures. This proves the correctness of the assumptions and is consistent with the description of EMR spectra of cobalt ions reported in the literature [26].…”

Section: Discussionsupporting

confidence: 90%

Magnetic properties of ZnO:Co layers obtained by pulsed laser deposition method

Stefaniuk

Cieniek

Rogalska

et al. 2018

Materials Science-Poland

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We have studied magnetic properties of zinc oxide (ZnO) composite doped with Co ions. The samples were obtained by pulsed laser deposition (PLD) method. Electron magnetic resonance (EMR) measurements were carried out and temperature dependence of EMR spectra was obtained. Analysis of temperature dependence of the integral intensity of EMR spectra was carried out using Curie-Weiss law. Reciprocal of susceptibility of an antiferromagnetic (AFM) material shows a discontinuity at the Néel temperature and extrapolation of the linear portion to negative Curie temperature. The results of temperature dependence of EMR spectra for the ZnO:Co sample and linear extrapolation to the Curie-Weiss law indicated the AFM interaction between Co ions characterized by the Néel temperatures TN = 50 K and TN = 160 K for various samples. The obtained g-factor is similar to g-factors of nanocrystals presented in literature, and the results confirm that in the core of these nanocrystals Co was incorporated as Co2+, occupying Zn2+ sites in wurtzite structure of ZnO.

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Section: Discussionsupporting

confidence: 90%

Magnetic properties of ZnO:Co layers obtained by pulsed laser deposition method

Stefaniuk

Cieniek

Rogalska

et al. 2018

Materials Science-Poland

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“…Except the blue shift of the UV emission, the Zn interstitial emission at 424 nm is enhanced and an additional emission at 526 nm is observed in the doped films. Emission at 526 nm is attributed to the emission of O vacancies [ 28 ]. The relative intensity of emission at 424 and at 526 nm enhances with an increase in Al concentration.…”

Section: Resultsmentioning

confidence: 99%

Effects of doping and annealing on properties of ZnO films grown by atomic layer deposition

Wang

Chen

et al. 2015

Nanoscale Res Lett

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Undoped and Al-doped ZnO films were synthesized by atomic layer deposition at 150°C and then annealed at 350°C in different atmospheres. Effects of doping and annealing on the film growth mode and properties were investigated. The undoped film has strong UV emission and weak Zn interstitial emission. Annealing introduces O vacancies, decreases Zn interstitials, and results in weakening and blue-shifting of the UV emission which is sensitive to annealing atmosphere. Al doping induces the film growing with its c-axis parallel to the substrate surface. It also introduces non-radiative centers and weakens the UV emission. Al doping widens the film bandgap, which has a quadratic dependence on Al content. Al doping decreases the film resistivity to 5.3 × 10−3 Ω · cm. Annealing has little effect on photoluminescence of the doped films, but it degrades undoped and doped ZnO film conductivity dramatically; and the degradation depends on the annealing ambient.

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“…4(c) for the bulk MgB 2 . This is characteristic for conductive species 30,31 and strong indication of enhancing the metallic character and influencing the ionic conductivity property due to structural defects, namely, V O , in bulk MgB 2 . The same effect has been reported by the aid of X-ray photoelectron spectroscopy (XPS) and SQUID measurements.…”

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confidence: 96%

Defect structure of ultrafine MgB2 nanoparticles

Bateni

Repp

Thomann

et al. 2014

Applied Physics Letters

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Defect structure of MgB2 bulk and ultrafine particles, synthesized by solid state reaction route, have been investigated mainly by the aid of X-band electron paramagnetic resonance spectrometer. Two different amorphous Boron (B) precursors were used for the synthesis of MgB2, namely, boron 95 (purity 95%–97%, <1.5 μm) and nanoboron (purity >98.5%, <250 nm), which revealed bulk and nanosized MgB2, respectively. Scanning and transmission electron microscopy analysis demonstrate uniform and ultrafine morphology for nanosized MgB2 in comparison with bulk MgB2. Powder X-ray diffraction data show that the concentration of the by-product MgO is significantly reduced when nanoboron is employed as precursor. It is observed that a significant average particle size reduction for MgB2 can be achieved only by using B particles of micron or nano size. The origin and the role of defect centers were also investigated and the results proved that at nanoscale MgB2 material contains Mg vacancies. Such vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications.

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Electron paramagnetic resonance study of ZnO varistor material

Cited by 37 publications

References 70 publications

Magnetic properties of ZnO:Co layers obtained by pulsed laser deposition method

Magnetic properties of ZnO:Co layers obtained by pulsed laser deposition method

Effects of doping and annealing on properties of ZnO films grown by atomic layer deposition

Defect structure of ultrafine MgB2 nanoparticles

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