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Guo Y.Y.,Nanjing University of Posts and Telecommunications | Liu J.-M.,Nanjing University | Guo Y.F.,Nanjing University of Posts and Telecommunications | Wei T.,Civil Aviation University of China | And 2 more authors.
AIP Advances | Year: 2015

Our experiments on ferroelectric aging phenomena of a series of acceptor-doped BaTiO3 ceramics demonstrate that after well-aging, all samples show a similar double hysteresis loop under smaller applied electric field, regardless of ionic radius or ionic valence of the acceptor. However, with increasing the applied electric field, the completely constricted loops gradually start to open, indicating the aging effect becomes weak under larger electric field. The unified microscopic mechanism responsible for the similar aging behavior in different acceptor-doped BaTiO3 ceramics may be that the larger field is considered to kinetically facilitate a part of oxygen vacancies short-range hopping. As a result, the defect dipole field provided by oxygen vacancies and the associated defect dipoles frozen in the original states decreases, thus contributing to the weaker aging effect. © 2015 Author(s).

Hu Y.-C.,Henan Normal University | Hu Y.-C.,Henan Province Key Laboratory of Photovoltaic Materials | Wang Y.-W.,Xinxiang Medical University | Zhang K.-L.,Henan Normal University | And 3 more authors.
Wuli Xuebao/Acta Physica Sinica | Year: 2012

Samples of Sr2-xKxFeMoO6 (x = 0, 0.01, 0.02, 0.03, 0.04) are prepared by standard solid-state reaction. The crystal structures and magnetic properties for the ordered double perovskite oxides Sr2-xKxFeMoO6 (0 ≤ x ≤ 0.04) are investigated. X-ray powder diffraction studies reveal that all the samples are of single phase and each of them has a I4/m symmetry. The anti-site defects in double perovskite oxides of Sr2FeMoO6 may be adjusted by alkali metal element of K doping. The unit cell magnetizations at 280 K are 1.12 μB for x = 0.00 and 1.26 μB for x = 0.04. The cation-ordering and the variation of structure parameters play improtant roles in determining the magnetism in the doping system. © 2012 Chinese Physical Society.

Li Y.,Henan Normal University | Liu Z.,Henan Normal University | Liu Z.,Henan Province Key Laboratory of Photovoltaic Materials | Wang T.,Henan Normal University | And 2 more authors.
Materials Letters | Year: 2016

A series of nickel/silicone rubber composites, co-filled with micron nickel and submicron nickel particles, were made in this work. The composites with mass ratio of nickel/silicone rubber under 1.8:1 had a high pressure sensitivity; the conductivity changed 9 orders under a low pressure around 0.096 MPa. To our knowledge, this is the lowest content of fillers reported to date in high sensitive polymer-based composites. Furthermore, the composites show good repeatability of piezoresistivity, indicating attractive application prospect. The gauge factor of the composites was studied and a master curve appeared for the composites with different conductive fillers. It showed that the gauge factor of the composites was strain-controlled. © 2016 Elsevier B.V. All rights reserved.

Shang S.,Henan Normal University | Shang S.,Henan Province Key Laboratory of Photovoltaic Materials | Song G.,Henan Normal University | Song G.,Henan Province Key Laboratory of Photovoltaic Materials | And 4 more authors.
Composites Science and Technology | Year: 2014

The conductive composites of silicone filled with nickel were prepared, with a low percolation threshold of around 35vol%. AC and DC conductivity of nickel/silicone composites with the filler content below or around percolation threshold were studied under uniaxial pressure. A pressure-induced percolation appeared at a very low pressure of finger-sensitive range (0.1-0.7MPa) for each DC conductivity curve. The linear dependence of log σDC on p-1/3 at selected pressures proved the existence of tunneling mechanism and the potential barrier height for electron hopping in metal/polymer composite is strongly pressure dependent. The AC conductivity and the dielectric permittivity of the composite under different uniaxial pressures satisfies the universal dynamic power law, σAC∝ωx, e{open}∝ω-y, respectively. The critical exponents show that the frequency dependence of AC conductivity and dielectric permittivity of metal/polymer composite under various pressures could be well described by polarization effects. © 2014 Elsevier Ltd.

Shang S.,Henan Normal University | Shang S.,Henan Province Key Laboratory of Photovoltaic Materials | Zhou X.,Henan Normal University | Zhou X.,Henan Province Key Laboratory of Photovoltaic Materials | And 3 more authors.
Applied Physics Letters | Year: 2012

In this work, the critical pressure-induced electrical properties of metal/polymer composites were studied systematically. The conductivity and dielectric constant satisfied the scaling electric equations: σ AC ω x and ω - y, respectively. The critical exponents x = 0.72 ± 0.006 and y = 0.32 ± 0.027 agreed with the general relation x + y = 1. The results proved that the transport properties of conductive polymer composites under pressure could be ascribed to polarization effects. A striking loss peak appeared in the curve of double logarithmic plot of tan δ vs. pressure, indicating that the formation of current network required maximum amount of electric energy during the increase of uniaxal pressure. © 2012 American Institute of Physics.

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