Dingquan Xiao

Publications (65)110.46 Total impact

• Article: A method to improve electrical properties of BiFeO3 thin films.

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: A method is used to improve the electrical properties of BiFeO(3) thin films by modifying the Bi content in ceramic targets, where all thin films were prepared on SrRuO(3)/Pt/TiO(2)/SiO(2)/Si(100) substrates by radio frequency sputtering. The Bi content in the ceramic target strongly affects the electrical properties of BiFeO(3) thin films. BiFeO(3) thin films prepared by using the ceramic target of Bi/Fe ≈ 1.15 with a molar ratio demonstrate a low leakage current density and a low dielectric loss. Moreover, a larger remanent polarization of 2P(r) ≈ 167.6 μC/cm(2) is also demonstrated for the BiFeO(3) thin films prepared by using the ceramic target of Bi/Fe ≈ 1.15, together with an improved fatigue behavior. Therefore, it is an effective way to improve the electrical properties of bismuth ferrite thin films by modifying the Bi content in ceramic targets.
  ACS Applied Materials & Interfaces 03/2012; 4(3):1182-5. · 4.53 Impact Factor
• Article: Multiferroic and fatigue behavior of BiFe(0.95)Mn(0.05)O3/Bi(0.90)La(0.10)Fe(0.85)Zn(0.15)O3 bilayered thin films.

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: Bilayered thin films consisting of BiFe(0.95)Mn(0.05)O(3) (BFMO) and Bi(0.90)La(0.10)Fe(0.85)Zn(0.15O3) (BLFZO) layers were prepared on Pt-coated silicon substrates without any buffer layers by RF sputtering. The (110) orientation was induced with a high phase purity for all bilayers as a result of the introduction of the bottom (110)-oriented BLFZO layer. The low leakage current density of BFMO/BLFZO bilayers could be attributed to a combined effect of the BFMO and BLFZO layers. The dielectric constant increases, the remanent polarization decreases, and the coercive field slightly increases with increasing thickness of the BLFZO layer in BFMO/BLFZO bilayers. Magnetic properties in BFMO/BLFZO bilayers are improved by increasing the BFMO layer thicknesses. A large polarization value of 2Pr ~ 189.5 μC/cm2 is obtained for the BFMO/ BLFZO bilayer with a thickness ratio of 3:1, which is much larger than those reported for BFO-based single layers or multilayers, and a good fatigue behavior is demonstrated with an increase in measurement frequencies and driving electric fields.
  IEEE transactions on ultrasonics, ferroelectrics, and frequency control 01/2012; 59(1):14-20. · 1.80 Impact Factor
• Article: Effect of New Phase Boundary on the Dielectric and Piezoelectric Properties of K0.5Na0.5NbO3- xBaZrO3- yBi0.5Na0.5TiO3Lead-free Ceramics

  Wenfeng Liang, Zhuo Wang, Dingquan Xiao, Jiagang Wu, Wenjuan Wu, Tao Huang, Jianguo Zhu
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  ABSTRACT: doi: 10.1080/10584587.2012.737221
  Integrated Ferroelectrics 01/2012; 139(1):63-74. · 0.30 Impact Factor
• Article: DEPOSITION OF PLCT THICK FILMS BY A MODIFIED SOL-GEL PROCESSING

  XIAOWU YUAN, DINGQUAN XIAO, ZHAOHUI PU, HONG LIU, JIAGANG WU, JIANGUO ZHU
  Integrated Ferroelectrics 10/2011; 80(2006):253-264. · 0.30 Impact Factor
• Article: Synthesis and Characterization of ZnSe Nanocrystals by W/O Reverse Microemulsion Method: The Effect of Cosurfactant

  Lin Yang, Ruishi Xie, Lingyun Liu, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: ZnSe nanocrystals with a cubic zinc blende crystal structure were synthesized by reverse microemulsions of water/Triton X-100/2-propanol/cyclohexane. The phase formation, state of particle size distribution, morphological characteristics, composition, and optical properties of the obtained nanocrystals were investigated by means of X-ray diffraction, PSD, transmission electronic microscope, Fourier transform infrared, UV–visible spectroscopy, and photoluminescence. All the measurement results showed that the particle size of ZnSe nanocrystals is governed by the amount of cosurfactant (2-propanol) besides the molar ratio of water to surfactant in the reverse micelles system. The presence of cosurfactant favors the modulation of the strength of surfactant film and the exchange dynamics of micelles. ZnSe nanocrystal synthesized by using an appropriate amount of 2-propanol possesses a narrow particle size distribution and a good crystallinity. A growth mechanism involving the possible formation of nanoparticles based on the effect of cosurfactant in microemulsion has been explored in this paper.
  08/2011;
• Article: Ferroelectric behavior in bismuth ferrite thin films of different thickness.

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: The ferroelectric behavior of BiFeO(3) thin films is modified by changing the film thicknesses, where the BiFeO(3) thin films with different thicknesses were grown on SrRuO(3)/Pt/TiO(2)/SiO(2)/Si(100) substrates by radio frequency sputtering. The mixture of (110) and (111) orientations is induced for all BiFeO(3) thin films regardless of their thicknesses, together with the columnar structure and the dense microstructure. Their dielectric behavior is almost independent of the film thickness where all thin films have a low dielectric loss. A giant remanent polarization of 2P(r) ≈ 156.6-188.8 μC/cm(2) is induced for the BiFeO(3) thin films in the thickness range of 190-600 nm. As a result, it is an effective way to improve the ferroelectric behavior of the BiFeO(3) thin film by tailoring the film thickness.
  ACS Applied Materials & Interfaces 08/2011; 3(9):3261-3. · 4.53 Impact Factor
• Article: Valence-driven electrical behavior of manganese-modified bismuth ferrite thin films

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: BiFe0.95R0.05O3 (Mn2+, Mn3+, and Mn4+) thin films with (110) orientation were fabricated on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates via rf sputtering. With the increasing valence of Mn in BiFe0.95R0.05O3, the concentration of Fe2+ increases, whereas the concentration of oxygen vacancies decreases. The electrical properties of BiFe0.95R0.05O3 are correlated with the valence of Mn. Their leakage current density is dependent on the concentration of oxygen vacancies caused by different valences of Mn. Their P-E loops become better with the increasing valence of Mn owing to a lower leakage current density in high electric field regions, and a large remanent polarization of 2Pr ∼ 145.2 μC/cm2 is obtained for the Mn4+-doped film. For the Mn2+-doped bismuth ferrite film, the space-charge-limited conduction and Schottky barrier dominate its leakage behavior under a negative electric field, the Ohmic conduction and Schottky barrier are involved in the leakage behavior under a positive electric field, and the interface-limited Fowler–Nordheim tunneling is their dominant mechanism in a high electric field region. In contrast, an Ohmic conduction dominates the leakage behavior of Mn3+- and Mn4+-doped films regardless of negative and positive directions or measurement temperatures.
  Journal of Applied Physics 06/2011; 109(12):124118-124118-8. · 2.17 Impact Factor
• Article: Migration kinetics of oxygen vacancies in Mn-modified BiFeO₃ thin films.

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: Migration kinetics of oxygen vacancies in BiFe(0.95)Mn(0.05)O(3) thin film were investigated by the temperature -dependent leakage current as well as the electric field and temperature-dependent impedance spectroscopy. The BiFe(0.95)Mn(0.05)O(3) is of an abnormal leakage behavior, and an Ohmic conduction is observed regardless of varied temperatures and electric fields. The temperature-dependent impedance spectroscopy under different resistance states is used to illuminate different leakage behavior between BiFe(0.95)Mn(0.05)O(3) and pure BiFeO(3). The impedance spectroscopy under a high resistance state shows that the first ionization of oxygen vacancies is responsible for the dielectric relaxation and electrical conduction of BiFe(0.95)Mn(0.05)O(3) in the whole temperature range of 294 to 474 K; the BiFeO(3) exhibits similar dielectric relaxation and electrical conduction behavior in the low-temperature range of 294-374 K, whereas the short-range motion of oxygen vacancies was involved in the high-temperature range of 374-474 K. The impedance spectroscopy under a low resistance state demonstrates that the dielectric relaxation and conduction mechanisms almost keep unchanged for BiFe(0.95)Mn(0.05)O(3), whereas the hopping electrons of Fe(2+)-V(O)(•)-Fe(3+) and Fe(2+)-Fe(3+) are responsible for its dielectric relaxation and conduction mechanism of BiFeO(3). Different impedance spectroscopy under low and high resistance states confirms that an abnormal leakage behavior of BiFe(0.95)Mn(0.05)O(3) is related to different migration kinetics of oxygen vacancies, obviously differing from that of BiFeO(3).
  ACS Applied Materials & Interfaces 06/2011; 3(7):2504-11. · 4.53 Impact Factor
• Article: Effect of sintering temperature on phase transitions, properties and temperature stability of (K0.465Na0.465Li0.07)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

  Wenfeng Liang, Dingquan Xiao, Wenjuan Wu, Xuhai Li, Yong Sun, Jianguo Zhu
  Current Applied Physics 05/2011; 11(3, Supplement):S138-S142. · 1.90 Impact Factor
• Article: Combined effects of bilayer structure and ion substitutions on bismuth ferrite thin films

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: To understanding the combined effects of bilayer structure and ion substitutions on electrical behavior of BiFeO3 thin films, the Bi0.90La0.10Fe0.90Zn0.10O3/Bi0.90La0.10Fe0.90Sn0.10O3 bilayers with different thickness ratios were fabricated on SrRuO3/Pt/TiO2/SiO2/Si(100) substrates by radio frequency sputtering. Their dielectric constant increases and the fatigue endurance becomes better with increasing Bi0.90La0.10Fe0.90Zn0.10O3 thickness ratios. The bilayer with the thickness ratio of 210: 90 exhibits a high remanent polarization, and a better fatigue behavior is induced by higher driving electric fields and frequencies.
  Journal of Applied Physics 04/2011; 109(7):074101-074101-4. · 2.17 Impact Factor
• Article: Synthesis, structural, and optical properties of core/shell ZnS:Fe/ZnS nanocrystals

  Lingyun Liu, Ruishi Xie, Lin Yang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: ZnS:Fe/ZnS core/shell nanocrystals (NCs) were synthesized by a simple liquid-solid-solution (LSS) method and the influence of ZnS shell thickness on the optical properties of ZnS:Fe/ZnS NCs was investigated. The crystalline and optical properties of ZnS:Fe/ZnS core/shell NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, UV–Visible spectrometer and FT-IR spectrometer, respectively. It was found that the ZnS:Fe/ZnS core/shell NCs are highly crystalline and show zincblende structure with an average particle size of about 7 nm. The lattice constants of the ZnS:Fe/ZnS NCs decrease slightly by the introduction of Fe, and the Fe dopants were well doped into the ZnS:Fe/ZnS NCs, as confirmed by XPS. Compared to the pure ZnS:Fe NCs, the ZnS:Fe/ZnS core/shell NCs exhibited significantly enhanced luminescence properties. A red-shift can be observed in the absorption and PL spectra as the ZnS shells thickened.
  Physica Status Solidi (A) Applications and Materials 02/2011; 208(4):863 - 867. · 1.46 Impact Factor
• Article: Giant magnetoelectric effects in multilayered composites of cobalt ferrite and lead magnesium niobate titanate

  Xiaohong Zhu, Hui Yang, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: The magnetoelectric (ME) coupling responses of [CoFe2O4/(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3]n, represented as (CFO/PMNT)n, multilayered composites were theoretically investigated by using an average method. It is found that a stronger interface coupling could be obtained in multilayers than in bilayers if the number of layers (n) is reasonably increased. Using an empirical dependence of the interface coupling parameter on the number of layers n, it is theoretically estimated that the ME coupling effect is first enhanced and then deteriorated with the gradual increase in n. The best ME response is estimated to occur at n=15, where the transverse ME voltage coefficient αE,31 reaches as high as 658 mVcm−1Oe−1. Moreover, it is theoretically found that the ME coupling effect in (CFO/PMNT)n multilayered composites is strongly dependent on the volume fraction of the piezoelectric (or magnetostrictive) phase, and the ME voltage coefficient for transverse field orientation (αE,31) is estimated to be roughly 90% higher than that for the longitudinal case (αE,33), revealing a large anisotropy in the ME coupling effect of (CFO/PMNT)n multilayered composites. These findings pave the way for experimental achievement of strong ME coupling responses, and provide important implications for the design and performance optimization of related devices comprising this kind of multiferroic magnetoelectric materials.
  Journal of Physics Conference Series 01/2011; 263(1):012015.
• Article: Thin film bilayers of multiferroic bismuth ferrite on Pt–Si substrate

  Jiagang Wu, John Wang, Dingquan Xiao, Jianguo Zhu
  physica status solidi (RRL) - Rapid Research Letters 01/2011; 5(2):83 - 85. · 2.22 Impact Factor
• Article: Effect of the Addition of CaZrO3 and LiNbO3 on the Phase Transitions and Piezoelectric Properties of K0.5Na0.5NbO3 Lead-Free Ceramics

  Wenfeng Liang, Wenjuan Wu, Dingquan Xiao, Jianguo Zhu
  Journal of the American Ceramic Society 01/2011; 94(12):4317-4322. · 2.27 Impact Factor
• Article: Effect of CoFe2O4 Content on the Dielectric and Magnetoelectric Properties in CoFe2O4/ Pb(Mg1/3Nb2/3)0.35Ti0.65O3 Composites

  Ying Pei, Qishou Li, Wei Shi, Bin Zhang, Qiang Chen, Xi Yue, Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: Ferrimagnetic CoFe2O4 (CFO) and ferroelectric Pb(Mg1/3Nb2/3)0.35Ti0.65O3 (PMNT) composite ceramics, [xCFO-(1−x) PMNT for x = 20, 30, 40 and 50 wt.%], were prepared using conventional ceramic processing. The phase structures, surface morphology, dielectric, piezoelectric, and magnetoelectric properties of CFO/PMNT composite ceramics were analyzed. It was found that the phase structures of the CFO/PMNT were mix phase structure of spinel phase and perovskite phase. The maximum value of the piezoelectric constant d 33, 212 pC/N, was obtained for the composite with x = 0.2. However, the maximum value of the ME voltage coefficient, 14.4 mV/cm.Oe, was observed for the composite with x = 0.5.
  Ferroelectrics. 01/2011; 410(1):82-87.
• Article: New crystallographic dielectric phase boundary in K Na NbO -based lead-free ceramics

  Wenfeng Liang, Wenjuan Wu, Dingquan Xiao, Jvmu Zhu, Jianguo Zhu, Jiagang Wu
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  ABSTRACT: 0.979K0.5Na0.5Nb1-xSbxO3-0.021Bi0.5Na0.5TiO3 (KNNSx-BNT) lead-free piezoelectric ceramics were fabricated by conventional solid state reaction technique, and their phase transition and electrical properties were studied. With the increase of x, the rhombohedral–orthorhombic phase transition temperature of the ceramics increases. Finally, both the rhombohedral–orthorhombic and orthorhombic–tetragonal phase transitions of the ceramics were modified to be around room temperature when about 6% Sb were substituted for the Nb site, resulting in the formation of a new phase boundary separating rhombohedral and tetragonal phases. The formation of the new phase boundary results in excellent properties for the ceramics, that is, the KNNS0.05-BNT ceramic shows an enhancement in piezoelectric properties: d33 = 380 pC/N and kP = 0.438.
  physica status solidi (RRL) - Rapid Research Letters 01/2011; 5:220-222. · 2.22 Impact Factor
• Article: Construction of new morphotropic phase boundary in 0.94(K0.42xNa0.6BaxNb12xZrx)O3–0.06LiSbO3 lead-free piezoelectric ceramics

  Wenfeng Liang, Wenjuan Wu, Dingquan Xiao, Jianguo Zhu, Jiagang Wu
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  ABSTRACT: 0.94(K0.4-xNa0.6BaxNb1-xZrx)O3–0.06LiSbO3 ceramics were prepared by conventional technique, and the effect of BaZrO3 on the phase transitions, dielectric, ferroelectric, and piezoelectric properties of the ceramics were investigated. The phase transitions for the ceramics were determined by the temperature dependence of dielectric properties and X-ray diffraction patterns. BaZrO3 changes the symmetry of the ceramics from tetragonal dominant phase with x = 0–0.06 to rhombohedral phase with x = 0.07–0.09. The phase transition near room temperature for the composition with x * 0.06 is different from previously reported phase transition between orthorhombic and tetragonal phases. It is suggested that a new morphotropic phase boundary (MPB) is constructed with both rhombohedral–orthorhombic and orthorhombic–tetragonal phase transitions near room temperature, and the enhanced piezoelectric properties (d33 = 344 pC/N and kP = 32.4% with x = 0.06) are obtained. The results indicate that the construction of new MPB is of significance for further development of KNN-based ceramics.
  Journal of Materials Science 01/2011; 46:6871–6876. · 2.02 Impact Factor
• Article: Effects of CuO on the Electrical Properties of CaTiO3‐Modified [(Na0.52K0.48)0.955Li0.045](Nb0.955Sb0.045)O3 Lead‐Free Piezoceramics

  Xiaolei Huang, Dingquan Xiao, Xuhai Li, Wenjuan Wu, Wenfeng Liang, Ruishi Xie, Jianguo Zhu
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  ABSTRACT: CuO-doped and undoped 0.99[(Na0.52K0.48)0.955Li0.045](Nb0.955Sb0.045)O3–0.01CaTiO3 (KNNLSCT) lead-free piezoelectric ceramics have been synthesized by the conventional ceramic processing, where the effects of CuO on the phase structure and electrical properties were studied. All ceramics possess a perovskite structure with tetragonal symmetry. Because of the dipolar complex migration, the P–E loops of undoped ceramics become slanted and constricted at a high temperature, while this phenomenon disappears after the addition of CuO. The d33 value decreases with the increasing poling temperature for the undoped ceramics, while the d33 value increases with the increasing poling temperature after the addition of CuO. These phenomena have been explained by a model based on the formation of the defect polarization induced by spontaneous polarization, indicating that the spontaneous defect polarization has an important influence on the ferroelectric behavior of the KNNLSCT ceramics.
  Journal of the American Ceramic Society 04/2010; 93(9):2563 - 2566. · 2.27 Impact Factor
• Article: The Crystalline Structure and Phase‐Transitional Behavior of (Li0.12Na0.88)(Nb1−x%Sbx%)O3 Lead‐Free Piezoelectric Ceramics with High Qm

  Qiang Chen, Zhihang Peng, Hong Liu, Dingquan Xiao, Jiliang Zhu, Jianguo Zhu
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  ABSTRACT: Lead-free piezoelectric ceramics with formula (Li0.12Na0.88) (Nb1−x%Sbx%)O3 were prepared by the conventional solid-state reaction method. The effects of Sb5+ doped into (Li0.12Na0.88) NbO3 B site were studied. Within the selected compositional range, all the samples have a single perovskite structure. The crystal structure changed from rhombohedral to orthorhombic at x=1, and from orthorhombic to tetragonal symmetry at x=6. The presence of orthorhombic to tetragonal morphotropic phase boundary was proposed when 3<x<6. By substituting Sb5+ for Nb5+, dielectric property and impedance characteristic were enhanced, but the Curie temperature and the ferroelectricity were decreased. The optimum composition was x=3, for which the maximum value of the mechanical quality factor Qm was as high as 1780, piezoelectric constant d33 and Curie temperature Tc were 45 pC/N and 300°C, respectively.
  Journal of the American Ceramic Society 04/2010; 93(9):2788 - 2794. · 2.27 Impact Factor
• Article: Effect of Doping Ions on the Properties of KNN-Based Lead-Free Piezoelectric Ceramics

  Dingquan Xiao, Jianguo Zhu
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  ABSTRACT: Different ions modified (K0.5Na0.5)NbO3(KNN)-based lead free piezoelectric ceramics were prepared by conventional mixed oxide ceramic processing. The roles of different doping ions, at the A or B sites of perovskite structure of KNN, on the properties of KNN-based ceramics were analyzed. The XRD analysis and dielectric spectra measurement show that the dopant at B site of perovskite structure has more significant influence on the stability of the crystal structures of KNN-based ceramics. Some prospects to be resolved in coming years from the viewpoint of the actual applications are pointed out.
  Ferroelectrics. 01/2010; 404(1):10-18.