Dingquan Xiao

Sichuan University, Hua-yang, Sichuan, China

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Publications (262)482.59 Total impact

  • Ting Zheng, Jiagang Wu, Dingquan Xiao, Jianguo Zhu
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    ABSTRACT: A giant d33 was attained in the 0.96(K0.46Na0.54+x)Nb0.95Sb0.05O3–0.04Bi0.5(Na0.82K0.18)0.5ZrO3 ceramic by doping nonstoichiometric sodium. A rhombohedral–tetragonal phase boundary is constructed in the ceramic with a wide Na+ nonstoichiometry. Enhanced piezoelectric activity (e.g. d33 ≈ 496 pC N−1 and kp ≈ 47%) was observed in the ceramics with a 0.5% excess of Na+. In addition, enhanced stability of ferroelectricity and piezoelectricity is also shown in this ceramic. We suggest that such a giant piezoelectricity might spark enthusiasm for research into potassium–sodium niobate ceramics.
    Scripta Materialia 01/2015; 94. · 2.97 Impact Factor
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    ABSTRACT: The obvious conflicts between large piezoelectricity and high strain could be solved by developing new phase boundaries in potassium–sodium niobate materials. Here, we have solved this problem by extensive experimental researches and induced a larger strain as well as a higher piezoelectricity in (K, Na)NbO3. Large converse piezoelectric coefficient (d*33 = 599–1553 pm V−1) and high strain (0.18–0.46%) were achieved, which are the highest values reported to date in potassium–sodium niobate, suggesting that such a system is a promising lead-free candidate for electromechanical actuator applications. In addition, high d33 values of 400–490 pC N−1 have also been attained in the ceramic due to its rhombohedral–tetragonal phase boundary, as well as its composition.
    J. Mater. Chem. A. 12/2014;
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    ABSTRACT: Mn-doped BiFeO3 (BFO) thin films with nominal composition of BiFe1−x Mnx O3 (x = 0.00, 0.01, 0.03, 0.05, 0.07) were deposited on (111)Pt/Ti/SiO2/Si substrates via a simple sol–gel spin-coating method with rapid thermal annealing process. The BFO films with different Mn dopant contents were well crystallized in the perovskite structure and their overlapped (110) diffraction peaks shifted toward higher angles with the increase in Mn content, indicating a slight distortion in the lattice structure. Improved microstructure with smaller grain size and diminished structural defects can be observed in the films of x around 0.03. X-ray photoelectron spectroscopy analysis confirmed the coexistence of 2+ and 3+ electronic states for Fe element and proper substitution of Mn for Fe can decrease the amount of Fe2+ while excess doping results in increasing Fe2+ content. The intrinsic ferroelectric polarization was hard to be measured in the pure BFO film due to high leakage contribution, whereas the x = 0.03, 0.05 and 0.07 films exhibited well-saturated rectangular shape-like ferroelectric hysteresis loops, and more importantly, perfectly closed hysteresis loops were obtained for the x = 0.03 film with a 2Pr value of 85.2 µC/cm2. The leakage current density in high electric field region was dramatically decreased by Mn doping, e.g. decreased to 3.3 × 10−4 A/cm2 at electric filed intensity of 170 kV/cm for the x = 0.03 film. Detailed leakage current characteristic analysis suggested that the dominant conduction mechanism in the pure BFO film was the space charge limited conduction at medium/high electric fields, which was associated with the space charges originated by oxygen vacancies; however, the leakage current of the x = 0.03 film was dominated by the Schottky mechanism in medium/high electric field region.
    Journal of Materials Science Materials in Electronics 12/2014; · 1.97 Impact Factor
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    ABSTRACT: A high strain is important for practical applications of piezoelectric actuators. Here we reported a high strain in the (K,Na)NbO3 -based ceramics by doping alkaline earths or transition metals. The ceramics possess a high strain (∼0.29%) as well as a large converse piezoelectric coefficient (d33*) up to 688 pm/V, which almost matches that of PZT4 ceramics. The obtained d33* is high for nontextured (K,Na)NbO3-based ceramics. In addition, a higher d33 value (340-407 pC/N) was also attained in the ceramics. Enhanced d33 and d33* values of this work should be attributed to the multiphase coexistence's effect induced by alkaline earths or transition metals. We believe that our research can benefit the developments of (K,Na)NbO3 ceramics and widen their applications range.
    ACS Applied Materials & Interfaces 11/2014; · 5.90 Impact Factor
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    ABSTRACT: The tightly coupled heterostructure g-C3N4/Au/poly(3-hexylthiophene) (P3HT)/Pt was successfully prepared by self-assembling method. The heterojunction photocatalyst displayed high activity for hydrogen production from water which contains triethanolamine as an electron donor under visible light irradiation. The samples were characterized by X-ray diffraction (XRD), UV-vis spectroscopy, photoluminescence (PL) spectra analysis and transmission electron microscopy (TEM), respectively. The experimental results demonstrated that the g-C3N4/Au/P3HT/Pt structure was conducive to the efficiently separation of photo-generated electron-hole pairs, which can be explained by the strong junction of chemical bond between Au and P3HT. The effect of P3HT content on the activity of the photocatalysts was investigated with a series of g-C3N4/Au/P3HT heterostructure samples loaded Pt as a cocatalyst in triethanolamine aqueous solutions. The optimal P3HT content was determined to be 0.5 wt%, and the corresponding hydrogen evolution rate was 320 mol h-1.
    J. Mater. Chem. A. 11/2014;
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    ABSTRACT: 0.95(K0.5Na0.5)NbO3–0.05(Bi0.5Na0.5)ZrO3–xZnO (KNN–BNZ–xZnO) lead-free piezoceramics were prepared by the conventional solid-state method, and effects of ZnO content on their phase structure, microstructure, and electrical properties were studied. The ceramics with x=0.01 possess the mixture of both rhombohedral–orthorhombic and orthorhombic–tetragonal phase boundaries. Their grain size becomes more homogenous and much smaller with the addition of ZnO. Enhanced dielectric and piezoelectric properties (e.g., d33=320 pC/N, kp=0.484, TC=320 °C) were observed in the ceramic with x=0.01. These results show that such a material system belongs to be a promising lead-free piezoelectric material.
    Ceramics International 11/2014; 40(9):14601–14605. · 2.09 Impact Factor
  • Materials Research Bulletin 11/2014; 59:125–130. · 1.97 Impact Factor
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    ABSTRACT: In this work, the rhombohedral–tetragonal (R–T) phase coexistence has been designed using the ternary system consisting of (0.99−x)K0.48Na0.52NbO3–0.01B0.5Na0.5TiO3xBi0.5(Na0.7K0.2Li0.1)0.5ZrO3. The R–T phase coexistence zone was identified in the ceramics with 0.03 ⩽ x < 0.05, as confirmed by the phase diagram derived from both temperature-dependent dielectric constant and the X-ray diffraction patterns. The relationship between R and T phase boundary and their electrical properties is investigated. For the compositions near the R–T phase boundary, the ceramics show the enhanced dielectric, ferroelectric, and piezoelectric properties. The ceramic with x = 0.035 has an optimum electrical behavior (e.g., d33 ∼ 310 pC/N, kp ∼ 0.45, Pr ∼ 23.4 μC/cm2, EC ∼ 17.4 kV/cm, εr ∼ 1249, tan δ ∼ 0.025, and TC ∼ 338 °C). In addition, the good temperature and thermal stability of ferroelectric and piezoelectric properties were shown in the ceramic with x = 0.035. Underlying physical mechanisms for enhanced electrical properties were addressed. As a result, the design of ternary system can effectively promote the piezoelectricity of potassium–sodium niobate materials.
    Journal of Alloys and Compounds 10/2014; 610:86–91. · 2.73 Impact Factor
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    ABSTRACT: (1−x)(K0.42Na0.58)(Nb0.96Sb0.04)O3–x(Bi0.5Na0.5)0.90Mg0.10ZrO3 [(1−x)KNNS–xBNMZ] lead-free ceramics have been prepared by the normal sintering, and effects of BNMZ content on their phase structure, microstructure, and electrical properties have been systematically investigated. These ceramics with 0.045 ≤ x ≤ 0.05 possess a rhombohedral–tetragonal (R–T) phase boundary, as confirmed by the temperature dependence of dielectric properties and X-ray diffraction patterns. The grain size of the ceramics first increases and then decreases as the BNMZ content increases, and the ceramic with x = 0.06 possesses much smaller grains (2+ was homogenously distributed in the ceramic matrixes. These ceramics with R–T phase boundary show enhanced dielectric, ferroelectric, and piezoelectric properties as compared with a pure KNN, and optimum electrical properties (e.g., P r ~ 16.23 μC/cm2, E C ~ 7.58 kV/cm, ε r ~ 2,663, tan δ ~ 0.034, d 33 ~ 434 pC/N, k p ~ 0.47, and T C ~ 244 °C) were found in the ceramic with x = 0.0475. We believe that the (1−x)KNNS–xBNMZ ceramic is a promising candidate for lead-free piezoelectric devices.
    Journal of Materials Science Materials in Electronics 10/2014; 25(10). · 1.97 Impact Factor
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    ABSTRACT: (1−x)K0.42Na0.58Nb0.95Sb0.05O3–x[Bi0.5(Na0.82K0.18)0.5]0.95Pb0.05ZrO3 ceramics with rhombohedral–tetragonal phase boundary were designed to attain a giant piezoelectricity. Adding a low Pb content results in the dense microstructure, and the Pb element has been homogeneously distributed. The R–T phase boundary was formed in the ceramics with 0.035 < x ⩽ 0.045. In addition, an improved d33 of the ceramics with x = 0.04 was observed after second poling. Enhanced dielectric and piezoelectric properties of εr ∼ 2900, tan δ ∼ 0.022, d33 ∼ 460 pC/N, and kp ∼ 0.46 were observed in the ceramic with x = 0.04.
    Scripta Materialia 10/2014; 88:41–44. · 2.97 Impact Factor
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    ABSTRACT: We have attained both large piezoelectricity and high strain in (1 − x)(K0.40Na0.60)(Nb0.955Sb0.045)O3–xBi0.50Na0.50ZrO3 [(1 − x)KNNS–xBNZ] lead-free ceramics by forming a rhombohedral (R) and tetragonal (T) phase boundary. The ceramics with 0.035 < x < 0.05 possess R and T phases' coexistence. A large d33 value of 450 pC N−1 has been attained when the x value reached 0.04 owing to the involved R–T phase boundary, which is higher with respect to d33 416 pC N−1 of textured (K,Na,Li)(Nb,Ta,Sb)O3 ceramics reported by Saito et al. [Nature, 2004, 432, 84]. In addition, it is worth noting that such a ceramic simultaneously possesses a high electric field-induced strain (0.2%) under a low driving electric field of 2 kV mm−1, and its Smax/Emax value is equal to be 1071 pm V−1. As a result, we can believe that the (1 − x)KNNS–xBNZ ceramics will become one of the promising material systems in the practical applications of electrical devices.
    J. Mater. Chem. C. 09/2014;
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    ABSTRACT: The 0.9Pb(Sc0.5Ta0.5)O3-0.1%PbTiO3/0.55Pb(Sc0.5Ta0.5)O3-0.45%PbTiO3 (PSTT10/PSTT45) multilayer thin films were deposited on SiO2/Si(1 0 0) substrates by radio frequency magnetron sputtering technique with a LaNiO3 buffer layer, and the films were subsequently annealed by a two-steps rapid thermal approach. With this method, the films possess a highly (1 0 0) orientation, which is attributed to the introduction of LaNiO3 buffer layer. Enhanced dielectric and ferroelectric properties were observed in the multilayer thin films with low anneal temperatures of 700–750 °C. Typically, the films annealed at 700 °C have a high dielectric constant of ∼698.5 and a low dielectric loss of 0.054. In addition, such a thin film also exhibits a large remnant polarization of 5.45 μC/cm2. The crystallization, the percentage pyrochlore and the loss of Pb are considered to play an important role on electric properties of the films.
    Applied Surface Science 09/2014; 314:124–128. · 2.54 Impact Factor
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    ABSTRACT: In this work, we elucidate the influence of Bi0.5Li0.5ZrO3 (BLZ) content on the phase structure, microstructure, and electrical properties of (1 - x)K0.40Na0.60Nb0.965Sb0.035O3-xBi0.5Li0.5ZrO3 lead-free ceramics. We simultaneously achieved a giant d33 and a high TC in this material system. The coexistence of rhombohedral and tetragonal phases is responsible for such a large d33 in the ceramics with BLZ contents (x) ranging from 0.025 to 0.035. Doping with BLZ not only induces the formation of the phase boundary, but also maintains a high TC. The ceramic with x = 0.03 shows an enhanced piezoelectric behaviour (d33 ∼ 400 pC N(-1) and kp ∼ 0.47) together with a high TC of 292 °C. A good temperature stability for ferroelectricity and piezoelectricity is also observed in these ceramics. This study is the first time that such a good comprehensive performance has been obtained in potassium-sodium niobate materials. We believe that this type of material system possessing giant-d33 and high-TC is a promising candidate for use in high-temperature piezoelectric devices.
    Dalton Transactions 06/2014; · 4.10 Impact Factor
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    ABSTRACT: In this work, the rhombohedral (R) and tetragonal (T) phase boundary of the 0.97(K0.4Na0.6)(Nb1-xSbx)O3-0.03Bi0.5Li0.5ZrO3 piezoceramics has been attained in a wide composition range of 0.035 ≤ x ≤ 0.08, and the Sb(5+) could simultaneously shrink its TR-O and TO-T. A giant d33 of 380-405 pC N(-1) and a TC of 200-292 °C have been observed in the ceramics with the coexistence of both R and T phases. In addition, the ceramics with 0.035 ≤ x ≤ 0.08 also show a good thermal stability of the d33, and an enhanced temperature stability of ferroelectricity could be observed in the ceramic with x = 0.035. As a result, adding the optimum antimony content is an efficient way to promote the electrical properties of potassium-sodium niobate ceramics with the R-T phase boundary.
    Dalton transactions (Cambridge, England : 2003). 05/2014;
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    ABSTRACT: In this work, 0.96(K0.48Na0.52)1-xLixNbO3-0.04Bi0.5Na0.5ZrO3 lead-free piezoceramics were prepared using the conventional solid state reaction method in order to attain both a high TC and an enhanced d33. The effect of Li content on their phase structure, electrical properties, and stability was systematically investigated. These results indicate that adding Li could result in the increase of TC and the decrease of TO-T. Here we obtain the ceramics with an orthogonal-tetragonal phase boundary in the composition of x=0.02, and then enhanced piezoelectric properties and a high Curie temperature (i.e., d33∼255 pC/N, kp∼41%, and TC∼360 oC) were observed, showing the realization of our objective. In addition, a good stability of piezoelectric and ferroelectric properties has been shown in such a material system.
    Current Applied Physics 05/2014; · 2.03 Impact Factor
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    ABSTRACT: For potassium-sodium niobate, poor piezoelectric properties always perplex most researchers, and then it becomes important to attain a giant piezoelectricity. Here we reported a giant piezoelectric constant in (1 - x)(K0.48Na0.52)(Nb0.95Sb0.05)O3-xBi0.5Ag0.5ZrO3 lead-free ceramics. The rhombohedral-tetragonal phase boundary was shown in the ceramics with 0.04 < x ≤ 0.05, and then the ceramic with x = 0.0425 possesses a giant d33 of ∼490 pC/N. We also discussed the physical mechanisms of enhanced piezoelectricity. As a result, such a research can benefit the sustainable development of (K,Na)NbO3 materials.
    ACS Applied Materials & Interfaces 05/2014; · 5.90 Impact Factor
  • Lin Yang, Jianguo Zhu, Dingquan Xiao
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    ABSTRACT: High-quality ZnSe:Fe/ZnSe core/shell nanocrystals were prepared via a hydrothermal microemulsion technique. Effective surface passivation of monodisperse ZnSe:Fe nanocrystals is achieved by overcoating them with a ZnSe shell. The samples were characterized by means of XRD, EDX, TEM, PSD, XPS, photoluminescence, and Raman spectrum. The results show that the as-synthesized nanocrystals are cubic zinc blende ZnSe structure with high purity and the average particle size of ZnSe:Fe/ZnSe core/shell nanocrystal is larger than that of ZnSe:Fe core. The growth of ZnSe shell causes a small red shift in PL spectra, and then the PL quantum yield (QY) increases from 16% before shell growth to the maximum of 37% after increasing shell thickness up to 1.2 monolayers (ML). Moreover, both transverse optic (TO) and longitudinal optic (LO) phonon modes of ZnSe are shifted toward lower frequency as compared with the reported ones.
    Journal of Luminescence 04/2014; 148:129–133. · 2.37 Impact Factor
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    ABSTRACT: The objective of this work is to achieve a giant piezoelectric constant in (K,Na)NbO3-based lead-free ceramics, and then 0.96K0.46Na0.54Nb0.95Sb0.05O3-0.04Bi0.5(Na0.82K0.18)0.5ZrO3 lead-free piezoceramics were designed and prepared by optimizing the sintering temperature (TS). The rhombohedral-tetragonal phase boundary is found in the ceramics sintered at 1070 ∼ 1105 °C and is suppressed when sintered at low TS of 1060 ∼ 1065 °C. The threshold for TS is 1070 °C in terms of their ferroelectric and piezoelectric properties owing to the difference in the phase boundary and the microstructure, and a large d33 of 388 ∼ 465 pC/N could be attained in a wide TS range of 1070 ∼ 1105 °C, benefiting their practical applications because of broad TS. More interestingly, the ceramic sintered at 1075 °C has a giant d33 of ∼465 pC/N. We think that such a giant d33 of this material system can benefit the development of (K,Na)NbO3-based piezoceramics.
    Journal of Applied Physics 03/2014; 115(11):114104-114104-8. · 2.19 Impact Factor
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    ABSTRACT: CuO-doped Ba(Zr0.05Ti0.95)O3 (BZT) ceramics were prepared using conventional solid state reaction method, and their structure and electrical properties were investigated. It was found that a small amount of CuO could lower the sintering temperature significantly and make their microstructure more densified than pure BZT. The ceramics with 1.2 mol% CuO, sintered at 1250 °C, showed excellent piezoelectric properties with d33~320 pC/N and kp=44%. The sintering temperature was decreased by 150 °C than that for pure BZT ceramics while showing comparable piezoelectric properties. Moreover, the influence of sintering temperature on the optimally 1.2 mol% CuO-doped BZT ceramics was studied. With the temperature change, different patterns of crystal growth were observed in the doped BZT ceramics. When the sintering temperature increased from 1200 °C to 1350 °C, the patterns of normal–abnormal–normal grain growth were changed accordingly.
    Ceramics International 03/2014; 40(2):2585–2592. · 2.09 Impact Factor
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    ABSTRACT: Aurivillius phase Bi4Ti3−xWxO12 + 0.2 wt% NiO (BITNW-100x) ceramics were prepared by a conventional sintering method. BINTW-based ceramics were sintered in a low temperature range of 950–1040 °C. The crystallographic evolution was determined by the X-ray diffraction, by which the lattice parameters, a and b were calculated. It was found that the increase of the W doping level reduced the lattice distortion of BITNW-based ceramics, which alleviated the degree of ‘underbonding’ of Bi ions in (Bi2O2)2+ layers. As a result, the value of Curie temperature decreased from 653 °C to 624 °C, whereas both DC resistivity and piezoelectric properties increased. The highest piezoelectric constant (d33 ~ 18.5pC/N) was achieved for BINTW-12 ceramics. The detailed studies on ferroelectric property of BITNW-12 ceramic were determined at various temperatures and electric fields. Not only external electric fields but also measurement temperature strongly influenced the value of remnant polarization (Pr).
    Journal of Alloys and Compounds 03/2014; 590:210–214. · 2.73 Impact Factor