Direct Control of Defects on Positron Lifetimes and Dielectric Constant of Microwave Ceramics

Tang, Yu; Zhang, Yi; Du, Piyi; Deng, Wen

doi:10.1111/jace.12354

Cited by 17 publications

(4 citation statements)

References 44 publications

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“…Recently, Deng et al 8 suggested that the Nb addition was effective in enhancing the d-d interactions by Positron Annihilation Techniques (PAT). The defects of the ZnNb 2−x Ti x O 6−x ceramics could be also investigated by PAT 9 . The PALS of TiAl alloys had been analyzed 10 .…”

Section: Introductionmentioning

confidence: 99%

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

et al. 2019

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The influence of the Nb 5+-doped content and the doping CaCO 3 on the electrical properties and the microdefects of BSTN ceramics by Positron Annihilation Techniques were studied, which were fired at 1350 °C for 2 hours in air. The PTCR characteristics in the BSTN samples were also investigated. Moreover, the information on microdefects in BSTN ceramics was demonstrated by coincidence Doppler broadening spectrum measurements and positron annihilation lifetime spectra. Meanwhile, the influence of the defects on the electrical properties of the ceramics was also revealed. Furthermore, the critical donor-dopant content was 0.4 mol%, which corresponding room-temperature resistivity and the resistivity jumping ratio was 714.3 Ω•cm and 2.77 × 10 2 , respectively. In addition, the average positrons annihilate lifetime τ of the BSTN ceramics was investigated as well.

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Section: Introductionmentioning

confidence: 99%

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

et al. 2019

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“…Hence, the dielectric loss of the composite would increase quickly with an increasing conductive phase near the percolation threshold due to the formation of a conducting path and current leakage. 12,17,18 It is well known that the current leakage is not only related to the charge concentration but is also related to the charge mobility. Hence, restraining the migration of charge carriers by some methods, such as increasing the barrier layer (phase interface 19 ) inside and separating the conductive particles by a non-magnetic low-conductive layer, may be important and impressive ways to decrease the current leakage and dielectric loss.…”

Section: Introductionmentioning

confidence: 99%

Control of the nanostructure in percolative multiferroic composites on the dielectric loss and magnetism threshold

Tang

Zhang

et al. 2015

J. Mater. Chem. C

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Revealing clearly the control of microstructure on dielectric and magnetic properties of multiferroic composite is of great importance in designing the composite with high performance. In this paper, the BTO/NZFO composite thin films with solid solution constituent phases around 20 nm were prepared by RF magnetron sputtering. The lattice constant, grain size, intrinsic and extrinsic oxygen vacancies and non-stoichiometric defect in the nanocomposite thin film are measured by XRD, TEM and XPS. The conductivity, dielectric properties and magnetic performances of the nanocomposite are measured by impedance analyzer and MPMS respectively.In this multisusceptible nanocomposite thin film, the permittivity is compatible with Kirkpatrick model, and the dielectric loss is controlled importantly by the high fraction of grain boundary which restrains the charge migration and makes thus the loss low significantly. The saturation magnetization of the nanocomposite thin film is influenced mainly by the lattice deformation of nanosized constituent phases. The magnetic threshold of the nanocomposite shifts low from the real topological one, which is profitable for the composite to contribute simultaneously the low dielectric loss and high permeability. The coercivity, which is controlled by the grain size of NZFO and magnetic communication among NZFO nanoparticles, displays a novel percolation behavior.increasing ferrite content when x < 0.6 and keeps stable when x > 0.6; and the lattice constant of the NZFO phase decreases slowly with increasing ferrite when x < 0.4 and speedily when x > 0.4 in the (1−x)BTO/xNZFO composite. Fig. 3(c) exhibits the grain sizes of the BTO and NZFO phases in the composite thin film which are calculated from the X-ray diffraction peak by Scherer's equation.The grain size of the NZFO phase increases linearly from 14.3 nm to 20.0 nm while that of the BTO

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“…Therefore, PALS offer the annihilation information in lattice and defective region, which presents the characteristics of lattice and defect, such as the electrons density, defect type and defect concentration in solid qualitatively. According to multichannel positron trapping model, at least three independent components including three diverse lifetimes of positron (two for positron trapping and one for o-Ps decaying) as well as their corresponding intensities, which denote the quantity of defect can be acquired in the resolved PALS [36].…”

Section: Pals Analysismentioning

confidence: 99%

Regulation of Cr³⁺ doping on the defect characteristics and magnetic order in the CuFe_1-xCr_xO₂ ceramics

Sun

et al. 2021

Journal of Asian Ceramic Societies

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The defect characteristic and magnetic properties of CuFe 1-x Cr x O 2 (x = 0.0-0.4) compounds have been investigated in detail. The results demonstrate that Cr 3+ ions enter into the CuFeO 2 lattice sites and induce local lattice contraction but do not change the valance state of Cu + and Fe 3+ ions. We calculate the positron annihilation lifetime in the bulk and vacancy defect trapping states by the atomic superposition method in 3 × 3 × 1 CuFeO 2 super-cell. Combined with theoretical calculation results, the positron annihilation results indicate that the positrons are mainly annihilated in vacancy clusters in CuFe 1-x Cr x O 2 . The substitution of Cr 3 + for Fe 3+ ions decreases the open volume and increases the concentration of vacancy defects but does not change the integral defect surroundings at annihilation sites. Magnetization measurements manifest that doping with Cr 3+ reduces the antiferromagnetic transition temperature and promotes the formation of short-range magnetic correlation. Meanwhile, the enhanced short-range magnetic correlation in Cr 3+ -doped CuFeO 2 is more readily driven by thermal activation energy and a faster dynamic behavior can be seen in time windows.

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Direct Control of Defects on Positron Lifetimes and Dielectric Constant of Microwave Ceramics

Cited by 17 publications

References 44 publications

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

Control of the nanostructure in percolative multiferroic composites on the dielectric loss and magnetism threshold

Regulation of Cr³⁺ doping on the defect characteristics and magnetic order in the CuFe_1-xCr_xO₂ ceramics

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Direct Control of Defects on Positron Lifetimes and Dielectric Constant of Microwave Ceramics

Cited by 17 publications

References 44 publications

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

Investigation on Electrical Properties and Microdefects of Nb5+-Doped BaTiO3 Based Ceramics by Positron Annihilation Techniques

Control of the nanostructure in percolative multiferroic composites on the dielectric loss and magnetism threshold

Regulation of Cr3+ doping on the defect characteristics and magnetic order in the CuFe1-xCrxO2 ceramics

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Regulation of Cr³⁺ doping on the defect characteristics and magnetic order in the CuFe_1-xCr_xO₂ ceramics