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Yin W.,Key Laboratory of Polar Materials and Devices | Huang R.,Japan Fine Ceramics Center | Qi R.,Key Laboratory of Polar Materials and Devices | Duan C.,Ministry of EducationEast China Normal UniversityShanghai200062 China
Microscopy Research and Technique | Year: 2016

With the development of spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM), high angle annular dark filed (HAADF) imaging technique has been widely applied in the microstructure characterization of various advanced materials with atomic resolution. However, current qualitative interpretation of the HAADF image is not enough to extract all the useful information. Here a modified peaks finding method was proposed to quantify the HAADF-STEM image to extract structural and chemical information. Firstly, an automatic segmentation technique including numerical filters and watershed algorithm was used to define the sub-areas for each atomic column. Then a 2D Gaussian fitting was carried out to determine the atomic column positions precisely, which provides the geometric information at the unit-cell scale. Furthermore, a self-adaptive integration based on the column position and the covariance of statistical Gaussian distribution were performed. The integrated intensities show very high sensitivity on the mean atomic number with improved signal-to-noise (S/N) ratio. Consequently, the polarization map and strain distributions were rebuilt from a HAADF-STEM image of the rhombohedral and tetragonal BiFeO3 interface and a MnO2 monolayer in LaAlO3/SrMnO3/SrTiO3 heterostructure was discerned from its neighbor TiO2 layers. © 2016 Wiley Periodicals, Inc.

Han H.L.,Shanghai Normal University | Liu A.Y.,Shanghai Normal University | Wei L.L.,Shanghai Normal University | Wang P.,Shanghai Normal University | And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Highly (222)-oriented 90%Pb(Zn1/3Nb2/3)O 3-10%PbTiO3(abbreviated PZN-PT) thin films, about 550nm in thickness, have been successfully grown on (111)Pt/Ti/SiO2/Si substrate by pulsed laser deposition method. Pure pyrochlore phase with highly (222)-preferred orientation, determined by X-ray diffraction, was formed in the PZN-PT thin films when the temperature of substrates is 550 °C. FE-SEM investigation shows that the surface appearance and the cross section of the films are smooth and crack-free with some dispersive spherical protrusions. The dielectric constant and loss of the thin films were measured using an impedance analyzer (HP4194A). The dielectric constant (εr) and the dissipation factor (tanδ) at 1 kHz are 205 and 0.03, respectively. © 2013 SPIE.

Miao F.,Key Laboratory of Polar Materials and Devices | Miao F.,Qiqihar University | Tao B.,Key Laboratory of Polar Materials and Devices | Tao B.,Qiqihar University | And 5 more authors.
Journal of Power Sources | Year: 2010

A novel anode structure based on the three-dimensional silicon microchannel plates (Si-MCP) is proposed for direct methanol fuel cells (DMFCs). Ni-Pd nanoparticles produced by electroless plating onto the Si-MCP inner sidewalls and followed by annealing at 300 °C under argon serve as the catalyst. In order to evaluate the electroactivity of the nanocomposites, Ni-Pd/silicon composites synthesized by the same method are compared. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical methods are employed to investigate the Ni-Pd/Si-MCP anode materials. As a result of the synergetic effects rendered by the MCP and Ni-Pd nanoparticles, the Ni-Pd/Si-MCP nanocomposites exhibit superior electrocatalytic properties towards methanol electro-oxidation in alkaline solutions, as manifested by the negative onset potential and strong current response to methanol even during long-term cyclical oxidation of methanol. This new structure possesses unique and significant advantages such as low cost and integratability with silicon-based devices. © 2009 Elsevier B.V. All rights reserved.

Jing C.,Key Laboratory of Polar Materials and Devices | Bai W.,Key Laboratory of Polar Materials and Devices | Hu Z.,Key Laboratory of Polar Materials and Devices | Yang P.,Key Laboratory of Polar Materials and Devices | And 4 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2014

Attenuated total reflectance (ATR) infrared hollow waveguide attracts particular interest since it has both advantages of a hollow fiber and a light guiding mechanism similar to that of solid-core fibers. Presently, ATR hollow waveguides are mainly structured with single-crystal sapphire or glassy materials. These waveguides are somewhat brittle. More robust ATR hollow fibers are required in many military and domestic applications. In this work, ATR GeO2 hollow waveguides were prepared based on a copper capillary tube for transmitting CO2 laser light. The inner wall of the copper structural tube was polished using a high-pressure pulsed nanofluid technique. A hexagonal crystalline GeO2 reflective layer with sufficient thickness (>4 μm) was grown on the inner tube wall via a simple liquid phase deposition process at room temperature. The GeO2 coated copper hollow fiber exhibits a low-loss band within 10-11.5 μm. It can still be bent since the hollow-core size (1.4 mm) and the wall thickness (50 μm) are not too large. The transmissions of CO2 laser light are 91% and 43% under a straight condition and a 90° bend with a 30-cm radius condition, respectively. The waveguide displays high heat-resisting properties due to high thermal conductivity of the copper substrate tube and a high melting point (1115°C) of the GeO2 reflective layer. This work opens a door for low-temperature, low-cost growth of long ATR GeO2 infrared hollow fibers based on various substrate tubes, even including plastic capillary tubes. © 2014 SPIE.

Jing C.,Key Laboratory of Polar Materials and Devices | Guo H.,Key Laboratory of Polar Materials and Devices | Bai W.,Key Laboratory of Polar Materials and Devices | Hu Z.,Key Laboratory of Polar Materials and Devices | And 5 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

Ge99.04Mn0.96 thin film was fabricated by thermal evaporation of Mn doped GeO2 ceramic film under hydrogen atmosphere. Secondary phases were not detected by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analyses. The film is p type. Room-temperature ferromagnetism was detected in the film. The ferromagnetic behavior may arise from alignment of the bound magnetic polarons (BMP) mediated by the localized holes in the system as well as ultra small secondary phases unable to be detected by XRD and HRTEM analyses. © 2013 SPIE.

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