Chao Chen

Chinese Academy of Sciences, Peping, Beijing, China

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Publications (31)44.56 Total impact

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    ABSTRACT: Single crystals of x at.% Fe+0.95(Na1/2Bi1/2)TiO3-0.05BaTiO3 (x%-Fe:NBBT5, x=0.1, 0.2 and 0.5) with ultrahigh ferroelectric response were developed by introducing defect associations. The giant field-induced bipolar and unipolar strains, i.e. Smax~1.1%, εmax/Emax ~1300 pm/V, d33~600 pC/N and permittivity tunability ~120% demonstrate that they are promising candidates as lead-free ferroelectrics. The presence of ferromagnetic properties further provides new application potential as multiferroic materials. The defect chemistry and domain structure were studied systematically. The effects of microscopic defect functional centers on macroscopic properties were discussed in detail.
    J. Mater. Chem. C. 10/2014;
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    ABSTRACT: Dielectric, ferroelectric and piezoelectric properties of lead-free Na1/2Bi1/2TiO3–xK1/2Bi1/2TiO3 (NBT–xKBT) ferroelectric single crystals were characterized systematically. With increasing KBT concentration, the remanent polarization and coercive electric field decrease, while the piezoelectric constant and the electromechanical coupling coefficient increase. The evolution of average and local structures as a function of temperature and composition was investigated using in-situ X-ray diffraction and Raman spectroscopy. The structure/property relationship of NBT–xKBT single crystals was discussed in detail.
    Solid State Communications 08/2014; · 1.53 Impact Factor
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    ABSTRACT: Giant bipolar and unipolar strains i.e. Smax > 0.5%, εmax/Emax > 1000 pm V–1 have been observed in Mn-doped Na0.5Bi0.5TiO3–6BaTiO3 single crystals after being annealed. Temperature-dependent impedance spectra were studied and activation energies of oxygen vacancies were calculated accordingly. The two different binding energies present in X-ray photoelectron spectra for Na and Bi were assigned to different coordinate environments. However, titanium exhibits only one oxidation state (e.g. Ti4+). The site occupation and valence fluctuation of Mn were characterized by electric paramagnetic resonance spectra.
    Scripta Materialia 03/2014; 75:50–53. · 2.82 Impact Factor
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    ABSTRACT: Eu3+-doped Na0.5Bi0.5TiO3 (Eu:NBT) single crystals were grown by a top-seeded solution growth method. Photoluminescence emission and excitation spectra of Eu:NBT were investigated. The two transitions in 7F0 → 5D0 excitation spectra reveal that Eu3+ ions were incorporated into two adjacent crystallographic sites in NBT, i.e., Bi3+ and Na+ sites. The former has a symmetrical surrounding, while the later has a disordered environment, which was confirmed by decay curve measurements. The dielectric dispersion behavior was depressed and the piezoelectric and ferroelectric properties were improved after Eu doping.
    Applied Physics A 01/2014; · 1.69 Impact Factor
  • Journal of Inorganic Materials 01/2014; 29(1):33-37. · 0.53 Impact Factor
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    ABSTRACT: Lead-free (K0.25Na0.75)NbO3 (KNN25/75) single crystals with dimensions of empty set30 x 10 mm were successfully grown by a top seeded solution growth technique (TSSG). The X-ray diffraction pattern shows that the as-grown crystals possess an orthorhombic perovskite structure. The concentrations of K, Na, and Nb elements in the as-grown crystal were measured by X-ray fluorescence analysis. The dielectric, ferroelectric and piezoelectric properties of KNN25/75 crystals with different orientations, i.e., pseudocubic (100) and (110) ((100)(pc) and (110)(pc)), were investigated. A higher piezoelectric constant d(33) similar to 145 pC N-1 and electromechanical coupling coefficient k(t) similar to 69% were observed along the (100)(pc) orientation compared with d(33) similar to 70 pC N-1 and k(t) similar to 51% along (110)(pc). However, when a bipolar electric field was applied, a two times higher strain value can be achieved in crystals oriented along (110)(pc) than along (100)(pc). These orientation dependent physical properties can be explained in the framework of domain engineering and the switching effect.
    CrystEngComm 01/2014; 16(13):2760-2765. · 3.88 Impact Factor
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    ABSTRACT: A micro-Raman scattering technique was used to investigate the electric-field and temperature dependent phase stability of Mn-doped Na1/2Bi1/2TiO3-5.0at. %BaTiO3 single crystal. The Ti–O mode was found to exhibit a slight shift at a low electric field (E = 10 kV/cm) and splitting at higher electric field (E ≥ 30 kV/cm), ascribed to field-induced local distortion and phase transition, respectively. The temperature-dependent Raman scattering was also measured over a wide range of 150–800 K to study the phase stability of poled samples. A new Raman mode at about 200 cm−1 and an anomaly in intensity of the Ti-O modes were detected at 390 K, indicating a ferroelectric to antiferroelectric phase transition. The frequency shift of TiO6 octahedral modes implied a transition to a paraelectric state at 550 K. Furthermore, the Ti-O and TiO6 octahedral modes were found to be sustained in the high-temperature paraelectric state.
    Applied Physics Letters 01/2014; 104(14):142902-142902-5. · 3.52 Impact Factor
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    ABSTRACT: Lead‐free single crystal (Na1/2Bi1/2)TiO3–1.5 at.%Bi(Zn1/2Ti1/2)O3 (NBT–1.5BZT) with dimension of Φ35 mm × 12 mm was successfully grown by a top‐seeded solution growth technique. The average and local structure were studied by a combination of X‐ray diffraction and Raman spectroscopy. The electric and optical properties of ‐oriented single crystals were investigated systematically. Compared with pure NBT, the piezoelectric constant and transmission coefficient were both enhanced, that is, from 62 pC/N and ~60% to 121 pC/N and ~70%, respectively. Furthermore, domain structure observation suggested that the ‐oriented tetragonal ferroelastic domains in NBT were suppressed at room temperature with addition of BZT, which was responsible for the improved piezoelectric and optical properties of NBT–1.5BZT single crystal.
    Journal of the American Ceramic Society 01/2014; 97(6). · 2.43 Impact Factor
  • Bing Jia, Chao Chen, Chunsheng Zhao
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    ABSTRACT: This work deals with the dynamics of a levitated rotor, which is also rotated by a fluid squeeze film created by a vibrating cylinder type stator. The model, which describes the transient behavior of the rotation of a rotor, by means of the squeeze film generated by a traveling flexural wave of the stator surface, is presented. In such problems, the control equations of fluid in the squeeze film are firstly simplified on the basis of several reasonable assumptions. These equations, together with control equation of the rotor, are solved by using explicit finite difference methods. Then, the vibration mode of pressure at the stable time and the transient rotating speed of the rotor with time are evaluated. Finally, the rotating speeds, with different parameters of vibration of the stator, the squeeze film and inertial moment of the rotor, are compared in order to study how to effectively increase and control the rotating speed. This paper will provide the foundations to study the driving technology of squeeze film and will be helpful in the design and application of non-contact ultrasonic actuators.
    Journal of Vibration and Control 09/2013; 19(12):1872-1880. · 4.36 Impact Factor
  • Journal of Inorganic Materials 03/2013; 28(3):326-330. · 0.53 Impact Factor
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    ABSTRACT: Bi deficient, Mn doped 0.92(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3 single crystals were grown by carefully controlled top-seeded solution growth method. Local structures were investigated by transmission electron microscopy. The site occupation and valence state of manganese were characterized by electron paramagnetic resonance spectrum. The leakage current density in the as-grown single crystals is effectively depressed. The introduced defect complexes suppress the temperature induced phase transformation, increasing the depolarization temperature (165 °C) and thermal stability of ferroelectric properties.
    Applied Physics Letters 01/2013; 103(21):212906-212906-5. · 3.52 Impact Factor
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    ABSTRACT: Bismuth layer-structured ferroelectric ceramics Na0.25K0.25Bi2.5Nb2O9+xmol% MnCO3 (NKBN–Mn) were synthesized by a traditional solid-state reaction. The effects of Mn addition on the microstructure and electrical properties of ceramics have been investigated in details. It was found that the ceramics possess a pure phase of bismuth oxide layer-type structure. The Curie temperature Tc gradually decreases from 653 to 624 °C with increasing the Mn modification. The electrical properties of NKBN-based ceramics are improved significantly by the addition of Mn. The piezoelectric constant d33, dielectric loss tan δ, mechanical quality factor Qm and remanent polarization Pr for the NKBN ceramics with 3.0 mol% MnCO3 modification were found to be 25 pC/N, 0.28%, 2817, 14.50 μC/cm2, respectively, together with the high Tc (∼643 °C) and stable piezoelectric properties, demonstrating that the Mn modified NKBN-based ceramics are the promising candidates for high-temperature applications.
    Journal of Alloys and Compounds 12/2012; 544:125–128. · 2.73 Impact Factor
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    ABSTRACT: K0.5Na0.5NbO3-xCa0.3Ba0.7TiO3 [abbreviated as (1–x)KNN–xCBT] lead-free piezoelectric ceramics were prepared by a solid state reaction method. The effects of the content of CBT(x = 0–0.08) on the phase, microstructure, dielectric, and piezoelectric properties of samples were investigated. The results show that all the samples possess a perovskite structure. The phase structure of the samples at room temperature changed from orthorhombic symmetry to tetragonal symmetry, and the piezoelectric constant d33 and planar coupling factor kp of samples both first increased and then decreased, and the Curie temperature decreased with increasing the amount of CBT. In addition, a polymorphic phase transition from orthorhombic to tetragonal symmetry located in the composition range of 0.03≤x≤0.04. The ceramic sample in the composition when x = 0.03 had optimal piezoelectric properties (d33 = 142 pC/N, kp = 40%), and its dielectric losses were stable (i.e., Articles that cite this article? Keywords: calcium barium titanate; lead-free piezoelectric ceramic; polymorphic phase transition; potassium sodium niobate; relaxation Document Type: Research Article Affiliations: Jiangxi Key Laboratory of Advanced Ceramic Materials, College of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, Jiangxi, China Publication date: April 1, 2012 More about this publication? Journal of the Chinese Ceramic Society (JCCS), published in Chinese and in English, is a comprehensive monthly periodical focused on the fields of inorganic and non-metallic materials. The main purpose of the JCCS is to report the latest creative achievements in research, production and design for ceramics, glass, cementing materials, refractory, artificial crystals and other non-metallic materials. JCCS is regarded as an important journal in inorganic and non-metallic materials sciences in China and has been awarded by China Association for Science and Technology. The full-text of papers in JCCS is also published by CNKI (China National Knowledge Infrastructure). JCCS is indexed in EI Compendex, CA( Chemical Abstracts) ,SA and Ж and more than 20 databases. Editorial Board Information for Authors Submit a Paper Subscribe to this Title ingentaconnect is not responsible for the content or availability of external websites $(document).ready(function() { var shortdescription = $(".originaldescription").text().replace(/\\&/g, '&').replace(/\\, '<').replace(/\\>/g, '>').replace(/\\t/g, ' ').replace(/\\n/g, ''); if (shortdescription.length > 350){ shortdescription = "" + shortdescription.substring(0,250) + "... more"; } $(".descriptionitem").prepend(shortdescription); $(".shortdescription a").click(function() { $(".shortdescription").hide(); $(".originaldescription").slideDown(); return false; }); }); Related content In this: publication By this: publisher By this author: JIANG, Xiangping ; YI, Wenbin ; CHEN, Chao ; TU, Na ; LI, Xiaohong ; ZHAN, Hongquan GA_googleFillSlot("Horizontal_banner_bottom");
    Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 01/2012; 40(4).
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    ABSTRACT: Na0.5Bi0.5TiO3–K0.5Bi0.5TiO3–BaTiO3–SrTiO3 (NBT–KBT–BT–ST) lead-free piezoelectric ceramics with the compositions of (1–2x)(0.8NBT–0.2KBT)–x(0.94NBT–0.06BT)–x(0.74NBT–0.26ST)(x = 0.10, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45) were fabricated by a solid state reaction method. The structure and electrical properties for NBT–KBT–BT–ST samples were investigated. The morphotropic phase boundary (MPB) between the rhombohedral and tetragonal phases was identified in all the samples. The results demonstrate that such ceramic systems near the MPB exhibit superior electrical properties. The piezoelectric constant d33, electromechanical planar coupling factor kp and remanent polarization Pr firstly increased and then decreased with the increase of x. The optimum electric properties (d33 = 210 pC/N, kp = 0.319, Pr= 39.3 μC/cm2, Ec = 20.2 kV/cm) could be obtained for a composition with x = 0.35. It is suggested that NBT–KBT–BT–ST with the composition (x = 0.35) could be a candidate material for lead-free applications. Therefore, the MPB linear combination rule could be used to search for the composition near MPB with the excellent properties of NBT–KBT– BT–ST ceramics.
    Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 01/2012; 40(11).
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    ABSTRACT: (1–x)(K0.48Na0.48Li0.04)NbO3-x (Na0. 8K0.2)0.5Bi0.5TiO3 lead-free piezoelectric ceramics were synthesized by solid-state reaction method. The phase structure, microstructure, dielectric and piezoelectric properties of ceramic samples were investigated. The influences of different x(x = 0, 0.5%, 1.0%, 1.5%, 2.0%, 3.0%) content on the phase structure, piezoelectric and dielectric properties of samples were investigated. The results show that Orthorhombic-Tetragonal phase transition temperature and Curie temperature decrease gradually with the increase of x content while both the piezoelectric constant d33 and planar coupling factor kp of samples increase firstly then decrease. The typical PPT (polymorphic phase transition) locates in the composition of 0.5% 33 = 226 pC/N, kp = 0.41) and high Curie temperature(437 ). However, the piezoelectric properties of the ceramic near the PPT is sensitive to temperature.
    Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 01/2012; 40(10).
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    ABSTRACT: Lead-free piezoelectric ceramics (1–x)(K0.52Na0.44Li0.04)(Nb0.86Ta0.10Sb0.04)O3–xBiFeO3 [(1–x)LF4–xBF] were prepared by solid state reaction method. The effect of BF content (0≤x≤0.010 00) on the microstructure and electrical properties of the ceramics were investigated. It is found that all the samples has a pure perovskite phase structure with the tetragonal symmetry. The relative density ρ and mechanical quality factor Qm of LF4-based ceramics increase significantly after BF is added. Moreover, the piezoelectric and ferroelectric properties of LF4-based ceramics increase first and then decrease with the increase of BF content. The ceramic with x = 0.002 50 exhibits the optimal properties: the relative density ρ = 98.6%, piezoelectric constant d33 = 276 pC/N, mechanical quality factor Qm = 454, coercive field Ec = 1.56 kV/mm, and remanent polarization Pr = 21.5 μC/cm2. Thermal annealing and aging studies indicate that the LF4-BF sample (x = 0.002 50) possesses stable electrical properties, showing that the ceramic is a potential material for high temperature application.
    Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 01/2011; 39(5).
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    ABSTRACT: Respectively using pressed method and diffuse reflectance method, the infrared absorption spectrua of sorts of kaolin in various areas were obtained. The relationship between the structure characteristics of kaolin and its absorption peaks was analyzed. The results showed that compared with pressed method, the use of diffuse reflectance Fourier transform infrared spectroscopy, combined with the K-M function, results in corrected infrared spectra with high sensitivity and is more accurate and easier to analyze. Furthermore, based on a high frequency wave of 3 700-3 600 cm(-1) sections of kaolinite-OH characteristic absorption peaks, the crystallinity of all kinds of kaolnite can be known quickly. The result is consistent with the Hinckley index surveyed by X-ray diffraction technique.
    Guang pu xue yu guang pu fen xi = Guang pu 01/2011; 31(1):114-8. · 0.29 Impact Factor
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    ABSTRACT: In present work, lead-free single crystal 0.94 Na <sub>1/2</sub> Bi <sub>1/2</sub> TiO <sub>3</sub>–0.06 BaTiO <sub>3</sub> (NBBT94/6) with dimension of Φ40 mm ×10 mm was grown by a precisely controlled top seeded solution growth method. The crystal structure measurement result indicates that the NBBT94/6 single crystal exhibits the feature of rhombohedral-tetragonal phase coexistence at room temperature. The crystallographic orientation dependence of electrical properties for NBBT94/6 single crystal was investigated in detail. The remnant polarizations (P<sub> r </sub>) of <001> , <001> , and <111> oriented crystals are 16.02 μ C / cm <sup>2</sup> , 22.16 μ C / cm <sup>2</sup> , and 27.23 μ C / cm <sup>2</sup> , respectively. The corresponding coercive fields (E<sub> c </sub>) are 24.89, 20.72, and 15.36 kV/cm. Moreover, a double hysteresis loop appears at the depolarization temperature. High piezoelectric properties d<sub>33</sub> of 360 pC/N and k<sub> t </sub> of 62% were obtained in the <001> oriented crystals due to the engineered domain configuration which make them promising candidates for environmental friendly solid-state actuator applications.
    Journal of Applied Physics 01/2011; · 2.21 Impact Factor
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    ABSTRACT: A novel nanoparticle aggregation structure of barium titanate was obtained by the hydrothermal method. Powder X-ray diffraction (XRD) revealed that the aggregates crystallized in the cubic phase. The crystallization of the products became more significant with reaction progress. The growth characteristics of the aggregates was further confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), and electron diffraction (ED) spectroscopy. The aggregation was composed of many 5-8 nm nanoparticles by orientation attachment and we found that the ED patterns indicated a single-crystal property for the aggregates. The size of the aggregates was about 60 nm and they grew as the reaction continued. From the results of energy dispersive X-ray (EDX) spectroscopy analysis and kinetics modeling using the Johnson-Mehl-Avrami (JMA) equation, the diffusion nucleation of Ba2+ ion was found to be dominant during the early stages of aggregation formation. The growth process of “diffusion nucleation-orientation attachment”revealed the formation mechanism of barium titanate nanoparticle aggregations.
    ACTA PHYSICO-CHIMICA SINICA 01/2011; 27(12). · 0.87 Impact Factor
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    ABSTRACT: (1–x)K0.5Na0.5NbO3–xBaCu0.5 W1 0.5O3 [(1–x)KNN–xBCW] lead-free piezoelectric ceramics were fabricated by the traditional solid state reaction method. Crystal structure and electrical properties of K0.5Na0.5NbO3 (KNN) ceramics were investigated with different BCW contents (x = 0, 0.1%, 0.25%, 0.5%, and 1%, in mole, the same below). Results show that KNN ceramics have an orthorhombic perovskite structure after doping with a small amount (x33, electromechanical planar coupling factor kp, and mechanical quality factor Qm increase first and then decrease promptly with the increase of BCW contents. The relative density of the sample with x = 0.25% is 98.2% and it exhibits optimal properties: dielectric loss tan δ = 0.031, relative permittivity εr = 450, d33 = 128 pC/N, kp = 0.40, and Qm = 201.
    Kuei Suan Jen Hsueh Pao/ Journal of the Chinese Ceramic Society 01/2011; 39(7).

Publication Stats

15 Citations
44.56 Total Impact Points

Institutions

  • 2009–2014
    • Chinese Academy of Sciences
      • • State Key Laboratory of Functional Materials for Informatics
      • • State Key Laboratory of High Performance Ceramics and Superfine Microstructures
      Peping, Beijing, China
    • Northeast Institute of Geography and Agroecology
      • State Key Laboratory of High Performance Ceramics and Superfine Microstructures
      Peping, Beijing, China
  • 2007–2013
    • Nanjing University of Aeronautics & Astronautics
      • State Key Laboratory of Mechanics and Control of Mechanical Structures
      Nan-ching, Jiangsu Sheng, China
  • 2010–2012
    • Jingdezhen Ceramic Institute
      Ching-te-chen, Jiangxi Sheng, China