F. Y. Xie

Sun Yat-Sen University, Shengcheng, Guangdong, China

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Publications (9)15.64 Total impact

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    ABSTRACT: A CoCO3-added Pb((Zn1/3Nb2/3)0.20(Zr0.50Ti0.50)0.80)O3 (0.2PZN–0.8PZT) system was prepared and investigated. The results reveal that Co ions are present in the mixed valence form of +2 and +3, and their relative mole ratio depends on doping content. Co doping induces a phase transformation from the MPB to the tetragonal phase side, and the corresponding domain size increases accordingly. The solubility limit of Co ions in the perovskite matrix is near 0.2 wt.% in CoCO3 form. Below the solubility limit, Co ions enter the B sites of the oxygenic octahedral center, and the charge-compensating oxygen vacancies accelerate mass transport, which assists in the densification of the specimens. Above the solubility limit, excess Co ions gather in the grain boundaries and triple junctions, which facilitate the formation of a liquid phase with excess PbO and lead to remarkable grain growth. The resulting size effect plays a dominant role in improving the piezoelectric properties, which compensates for the hardening effect of acceptor doping. The optimum piezoelectric parameters are obtained at 0.8 wt.% CoCO3-doped 0.2PZN–0.8PZT system: d33 = 310 pC N−1, kp = 0.66, and εmax = 14,600.
    Acta Materialia 03/2013; 61(5):1489–1498. · 3.94 Impact Factor
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    ABSTRACT: WO3 nanowire film was bombarded by Ar ion beam in the analysis chamber of an X-ray photoelectron spectroscopy (XPS) system to produce uniform tungsten cone arrays. The WO3 nanowire film itself served as an etching mask during the Ar+ bombardment. The changes of surface chemical states and electronic structures during bombardment were monitored by in situ XPS. The morphological evolution with different Ar+ bombardment time was observed by ex situ scanning electron microscopy (SEM). At the start of Ar+ bombardment partial W6+ in WO3 was reduced to W5+ immediately, subsequently to W4+ and then to Wx+ (intermediate chemical state between W4+ and W0), finally to W0. Multiple oxidation states of tungsten coexisted until finally only W0 left. SEM images showed that the nanowires were broken and then fused together to be divided into clusters with a certain orientation after long-time high-energy ion beam bombardment. The mechanism of the ion-induced reduction during bombardment and the reason of the orientated cone arrays formation were discussed respectively.
    Journal of Electron Spectroscopy and Related Phenomena 04/2012; 185(s 3–4):112–118. · 1.55 Impact Factor
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    ABSTRACT: Room temperature ferromagnetism in pure ZnO thin films prepared by spin-coating method was observed. X-ray photoelectron spectroscopy and inductively coupled plasma-mass spectrometry showed no or extremely little presence of impurities, which were unlikely to be responsible for the large magnetization moment observed. In order to study the origin of ferromagnetism, ZnO thin films were rapidly annealed in N2 and O2 ambient in a repetitive way. Electrical and magnetic performance after each annealing was measured. It is found that ferromagnetism is diminished and re-appeared, in accordance with the decrease and increase of conductivity. Cathodoluminescence spectra show evidence of reversible variation of oxygen vacancy defect in the annealing process. These results provide strong evidence that oxygen vacancies play a significant role in inducing ferromagnetism in ZnO thin films.
    Journal of Nanoscience and Nanotechnology 12/2011; 11(12):10557-61. · 1.34 Impact Factor
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    ABSTRACT: A nanodiamond thin film is deposited on a single crystal silicon substrate by dip-coating technique. Surface characterization of the unannealed nanodiamond sample, and the samples annealed at various temperatures in nitrogen ambient, is conducted by XPS and Raman spectroscopy. The fitting data of the C1s core level XPS peak reveal that the sp2/sp3 ratio in the unannealed sample and the sample annealed at 900 °C and 1500 °C are 0.44, 0.55 and 6.08 respectively. All spectra including the C1s core level XPS spectrum, the plasmon energy-loss spectrum associated with C1s peak, C KVV Auger spectrum of the sample annealed at 900 °C are similar to those of the unannealed sample. However, the spectra of the sample annealed at 1500 °C are very different. Annealing at 900 °C fails to produce appreciable graphitization, and an onion-like carbon structure with a small diamond core is formed when the nanodiamond is heated to 1500 °C. Copyright © 2010 John Wiley & Sons, Ltd.
    Surface and Interface Analysis 05/2010; 42(9):1514 - 1518. · 1.39 Impact Factor
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    ABSTRACT: Room temperature ferromagnetism in pure ZnO thin film prepared by sol-gel spin-coating method was observed, together with the obvious anisotropic property. In order to study the origin of ferromagnetism, ZnO thin films were rapidly annealed in N2 and O2 ambient in a repetitive way. Electrical and magnetic performance after each annealing was measured. It was found that ferromagnetism was quenched and re-appeared, in accordance with the decrease and increase of conductivity. These results provide further evidence that oxygen vacancies play a significant role in inducing ferromagnetism in ZnO thin films.
    01/2010;
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    ABSTRACT: The diffusion behaviors of Co clusters on clean ZnO(0001)-Zn single crystal surface and their magnetic properties are studied. Co clusters are deposited on the clean ZnO(0001)-Zn surface at room temperature and then undergone ultrahigh vacuum annealing until fully reconstructed. The replacement of Zn2+ by Co2+ is confirmed by scanning tunneling microscopy and x-ray photoelectron spectroscopy. The Co doped ZnO shows a weak ferromagnetism at room temperature with a saturation magnetic moment of 1.08 μB/Co. Our observations indicate that surface Zn vacancies facilitate Co diffusion, and the interplay of Co ion with internal O vacancies leads to the ferromagnetism.
    Applied Physics Letters 12/2009; 95(26):262506-262506-3. · 3.52 Impact Factor
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    ABSTRACT: Uniform amorphous tungsten cone arrays in high density were fabricated by Ar+ reduction etching of WO3 nanowire film. The etching process was performed in the analysis chamber of an X-ray photoelectron spectroscopy (XPS) system. SEM and TEM results revealed that the tip radius of the etched cones was 10 nm, and the cones were amorphous with a high aspect ratio of over 250. XPS analysis proved the cones to be metallic tungsten. In the aspect of field-emission property, the tungsten cone arrays had a lower turn-on field of 3 MV m−1 compared with 5 MV m−1 of the as-grown original WO3 nanowire film.
    Applied Surface Science 11/2009; 256(3):693-697. · 2.54 Impact Factor
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    ABSTRACT: The nanodiamond thin film is deposited on a single crystal silicon substrate by a dip-coating technique from the pretreated nanodiamond suspension. The surface structures of the as-prepared thin film and the annealed sample have been investigated by x-ray photoelectron spectroscopy and nuclear magnetic resonance. The change of surface elements of O, N, and a different hybridized carbon is derived. Initiation of graphitization is observed at an annealing temperature of 900 °C and the dangling bonds from the internal diamond phase are confirmed. The electron field emission property of this annealed sample is better than the as-prepared thin film. The enhancement of electron emission is discussed with the change of surface structure and the surface states.
    Journal of Vacuum Science & Technology B Microelectronics and Nanometer Structures 01/2008; 26. · 1.36 Impact Factor
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    ABSTRACT: In this work, we investigated the preparation and characterization of nanodiamond thin films on silicon substrate and then studied the electron field emission. We concluded that nanodiamond surface sp<sup>2</sup> or sp<sup>3</sup> hybridization play an important role in field emission, and some intrinsic relationship between top surface chemical state and emission feature will be established in our future research.
    Vacuum Nanoelectronics Conference, 2007. IVNC. IEEE 20th International; 08/2007