Co-reporter:Xiaodong Tian, Hongli Zhu, Chan Jiang, Mingbao Huang, Yuanfu Deng, and Songping Wu
ACS Applied Materials & Interfaces October 4, 2017 Volume 9(Issue 39) pp:33896-33896
Publication Date(Web):September 12, 2017
DOI:10.1021/acsami.7b09853
An novel exfoliation strategy to few-layered graphene (FLG) combined with in situ synthesized amorphous MnOx has been established via a facile and robust ball milling route in the presence of KMnO4. The facile synthesis approach has the features of low cost, environmentally friendly nature and scalable capability. As an anode for lithium-ion batteries, amorphous MnOx@FLG delivered a wonderful electrochemical performance under extremely operational conditions, that is, an excellent reversible capacity of 856 mAh g–1 at a high current density of 1 A g–1 after 75 cycles under a high temperature of 85 °C. Those excellent electrochemical performances could be ascribed to elaborately designed three-dimensional nanostructure, the well-chosen electrolyte, significant incorporation of in situ Mn(IV) nanocrystal and few-layered graphene, and the contribution of pseudocapacitance. Remarkable electrochemical performance under a widely operational temperature window makes the amorphous MnOx@FLG composites promising anode of Li-ion batteries for heavy-duty application.Keywords: amorphous; few-layered graphene; harsh environment; in-situ exfoliation; lithium-ion battery;
Co-reporter:Songping Wu, Yao Du, Shuijing Sun
Chemical Engineering Journal 2017 Volume 307(Volume 307) pp:
Publication Date(Web):1 January 2017
DOI:10.1016/j.cej.2016.08.044
•This is an important and timely review to advanced energy materials.•A brief commentary on state-of-the-art progress of TMDs has been presented.•Potential research directions and important scientific problems are also proposed.Transition metal dichalcogenide based (TMD-based) nanomaterials have emerged as important candidates of electrode materials for rechargeable batteries due to their unique physical properties. TMDs are abundant in environmentally friendly natural ore and have excellent large-current charge/discharge capability, ultra-long life and wide operation temperature region. In this review, a brief introduction of recent developments about TMD-based nanocomposite electrodes was provided. Subsequently, synthetic routes to TMD-based nanocomposites and their electrochemical performances in rechargeable batteries were stated in detail. The state-of-the-art advances in the relation between rationally designed structures and electrochemical performances of TMD-based nanocomposite electrode materials were summarized. Potential research directions and important scientific problems of TMD-based materials were also proposed in the hope of solving the emerging problems of TMD-based batteries. It is predicted that TMD materials, particularly MoS2 and FeS2, will slowly re-establish themselves as promising candidates for crucial components of heavy-duty energy-storage devices such as electric cars, energy-storage stations, smart grids and so on.
Co-reporter:Yao Du, Songping Wu, Mingbao Huang, Xiaodong Tian
Chemical Engineering Journal 2017 Volume 326(Volume 326) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.cej.2017.05.111
•A facile route to rGO wrapped cauliflower-like FeS2 microspheres has been provided.•FeS2@rGO electrodes possessed outstanding performance under harsh environments.•These attributes make FeS2@rGO particles promising candidate as anode materials.Cauliflower-like FeS2 microspheres tightly wrapped by reduced graphene oxide (rGO-wrapped FeS2) have been synthesized by a facile and eco-friendly solution route. Self-assembled mesostructured FeS2 microspheres wrapped by rGO delivered excellent cycle performances, i.e. a remarkable reversible capacity of 1720 mAh g−1 at a current density of 0.2 A g−1 after 700 cycles at ambient temperature and an outstanding reversible capacity of 340 mAh g−1 at a current density of 5.0 A g−1 after 800 cycles as operated at an extreme temperature of 85 °C. All of these characteristics of rGO-wrapped FeS2 could be ascribed to artificially designed microstructure and gradual change of electrochemical reaction upon Li-cycling, making them promising anode materials for power batteries with ultra-long lifetimes and large energy density under harsh operational windows.Cauliflower-like FeS2 microspheres tightly wrapped by reduced graphene oxide (FeS2@rGO) have been synthesized by a facile and eco-friendly solution reaction route. Self-assembled mesostructured FeS2 microspheres @rGO delivered excellent cycle stability, i.e. a remarkable reversible capacity of 1720 mAh g−1 at a current density of 0.2 A g−1 after 700 cycles at ambient temperature and an outstanding reversible capacity of 340 mAh g−1 at a current density of 5.0 A g−1 after 800 cycles as operated at an extreme temperature of 85 °C. All of these characteristics make FeS2 microspheres@rGO promising anode materials for LIBs with ultra-long lifetimes and large energy density.Download high-res image (88KB)Download full-size image
Co-reporter:Mingjia Lu, Chan Liao, Chan Jiang, Yao Du, Zhen Zhang, Songping Wu
Electrochimica Acta 2017 Volume 250(Volume 250) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.electacta.2017.08.019
A solution-based “hot-injection” approach was developed to synthesize amorphous carbon-decorated and graphene-anchored hollow Co9S8 nanoparticles as anode material for Li ion battery application. Such a rationally designed dually-protected structure could effectively accommodate the volume expansion of Co9S8 nanoparticles during Li-cycling. As a result, as-synthesized nanocomposites could be successfully operated under ultrawide temperature window of −20 °C–70 °C, rendering excellent electrochemical performances, i.e., remarkable reversible capacities of 910 mA h g−1 after 100 cycles (at 500 mA g−1) and 622 mA h g−1 after 200 cycles (at 1000 mA g−1) at 70 °C. These attributes enable three-dimensional structured Co9S8 nanoparticles to be promising anode materials of advanced Li-ion batteries for large-power applications such as electric vehicles under extreme temperature environments.
Co-reporter:Mingbao Huang;Caihong Chen;Xiaodong Tian
Journal of Materials Chemistry A 2017 vol. 5(Issue 44) pp:23035-23042
Publication Date(Web):2017/11/14
DOI:10.1039/C7TA07364J
Herein, a novel and efficient strategy was established to synthesize few-layer graphene-anchored Fe3O4 nanocomposites (FLG-anchored Fe3O4) through a facile ball-milling route followed by annealing treatment. The as-prepared FLG-anchored Fe3O4 nanocomposites, as an anode material of LIBs, presented remarkable electrochemical performances at a high temperature of 85 °C, i.e., an excellent reversible capacity of 1413 mA h g−1 at a current density of 1.0 A g−1 after 100 cycles and an impressive rate performance of 768 mA h g−1 at a large current density of 5.0 A g−1 even after 100 cycles. These superior performances can be considered as a comprehensive consequence of the following factors: (1) the robust anchor between in situ synthesized Fe3O4 nanoparticles and few-layer graphene via a Fe–O–C linkage maintains structural integrity, enabling excellent cycling stability even at high temperatures; (2) accelerated dynamic diffusion of Li+ ions during lithiation/delithiation at 85 °C leads to a decreased polarization effect, producing enhanced reversibility; (3) enhanced pseudocapacitive behaviour at high temperatures holds partial capacity contribution. Due to these attributes, this material is a reliable and promising candidate for an anode material for heavy-duty Li-ion batteries that operate under harsh environments.
Co-reporter:Songping Wu, Rongyun Ge, Chan Jiang
Journal of Alloys and Compounds 2017 Volume 711(Volume 711) pp:
Publication Date(Web):15 July 2017
DOI:10.1016/j.jallcom.2017.04.028
•A facile, scalable route to MnGeO3 microspheres/rGO hybrids has been established.•Robust methods have been adopted to characterise the MnGeO3 microsopheres.•Hybrids afforded reversible capacity of 624.6 mAh g−1 at 200 mA g−1 after 50 cycles.•These attributes make MnGeO3 potential anode materials for LIBs.Reduced graphene oxide (rGO)-encapsulated MnGeO3 microspheres have been yielded via a facile, scalable and environmentally friendly route. Hydrothermal method was utilized to recrystallize MnGeO3 particles and form rGO encapsulation. Such rationally designed rGO-encapsulated MnGeO3 microspheres afforded excellent electrochemical performances, i.e. high first discharge capacity of 1364 mAh g−1 and charge capacity of 810.8 mAh g−1, and reversible capacity of 624.6 mAh g−1 after 50 cycles at a current density of 200 mA g−1 when they were employed as anode materials for Li ion batteries. These advantageous attributes make rGO-encapsulated MnGeO3 microspheres the potential anode materials for Li-ion batteries.
Co-reporter:Rongyun Ge, Songping Wu, Yao Du, Wenchao Zhou, Zhen Zhang
Carbon 2016 Volume 107() pp:352-360
Publication Date(Web):October 2016
DOI:10.1016/j.carbon.2016.06.011
A facile route to dually-protected CoGeO3 nanoparticle hybrids has been established. Reduced graphene oxide(rGO)-covered and carbon-encapsulated CoGeO3 nanoparticles were utilized as anode materials for Li ion batteries. Such a rationally designed structure could effectively accommodate the volume expansion of CoGeO3 nanoparticles during Li-cycling. As a consequence, remarkable electrochemical performances, i.e. high first discharge capacity (2000 mAh g−1) and charge capacity (1300 mAh g−1), excellent reversible capacity of 782 mAh g−1 after 50 cycles under a current density of 200 mA g−1, and outstanding rate performance, have been garnered for CoGCs/C-4 composite electrodes, in which electrochemically active materials contained 19.5 wt% rGO and 3.7 wt% pyrolytic carbon. These advantageous attributes make dually-protected CoGeO3 particles the potential anode materials for LIBs.
Co-reporter:Mingjia Lu, Xin Ouyan, Songping Wu, Rongyun Ge, Rui Xu
Applied Surface Science 2016 Volume 364() pp:775-782
Publication Date(Web):28 February 2016
DOI:10.1016/j.apsusc.2015.12.206
Highlights
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Self-assembled porous ZnGa2O4 particles were synthesized through a facile hydrothermal route.
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ɛr = 9.93, Q × f = 73, 000 GHz (at 14.5 GHz) and τf = −68.7 ppm/ °C have been garnered.
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Self-assembled porous ZnGa2O4 ceramics are promising millimeter-wave ceramic materials.
Co-reporter: Songping Wu;Dr. Cuiping Han;James Iocozzia;Mingjia Lu;Rongyun Ge;Rui Xu; Zhiqun Lin
Angewandte Chemie 2016 Volume 128( Issue 28) pp:8028-8054
Publication Date(Web):
DOI:10.1002/ange.201509651
Abstract
Germaniumbasierte Nanomaterialien haben sich wegen ihrer einzigartigen chemischen und physikalischen Eigenschaften zu wichtigen Kandidaten für die nächste Generation von Energiespeichersystemen entwickelt. In diesem Aufsatz stellen wir den aktuellen Stand der Forschung hinsichtlich des Designs, der Synthese, der Verarbeitung und der Anwendung von germaniumbasierten Materialien in der Batterietechnologie vor. Außerdem fassen wir die jüngsten Fortschritte im Bereich der Ge-basierten Nanokomposit-Elektrodenmaterialien und Elektrolyte für Festkörperbatterien zusammen. Schließlich diskutieren wir die Grenzen von Ge-basierten Materialien für Energiespeicheranwendungen und stellen – mit Schwerpunkt auf kommerziellen Produkten und theoretischen Untersuchungen – Überlegungen an, in welche Richtung sich die Forschung weiterbewegen könnte.
Co-reporter: Songping Wu;Dr. Cuiping Han;James Iocozzia;Mingjia Lu;Rongyun Ge;Rui Xu; Zhiqun Lin
Angewandte Chemie International Edition 2016 Volume 55( Issue 28) pp:7898-7922
Publication Date(Web):
DOI:10.1002/anie.201509651
Abstract
Germanium-based nanomaterials have emerged as important candidates for next-generation energy-storage devices owing to their unique chemical and physical properties. In this Review, we provide a review of the current state-of-the-art in germanium-based materials design, synthesis, processing, and application in battery technology. The most recent advances in the area of Ge-based nanocomposite electrode materials and electrolytes for solid-state batteries are summarized. The limitations of Ge-based materials for energy-storage applications are discussed, and potential research directions are also presented with an emphasis on commercial products and theoretical investigations.
Co-reporter:Songping Wu;Rui Xu;Mingjia Lu;Rongyun Ge;James Iocozzia;Cuiping Han;Beibei Jiang;Zhiqun Lin
Advanced Energy Materials 2015 Volume 5( Issue 21) pp:
Publication Date(Web):
DOI:10.1002/aenm.201500400
Graphene-containing nanomaterials have emerged as important candidates for electrode materials in lithium-ion batteries (LIBs) due to their unique physical properties. In this review, a brief introduction to recent developments in graphene-containing nanocomposite electrodes and their derivatives is provided. Subsequently, synthetic routes to nanoparticle/graphene composites and their electrochemical performance in LIBs are highlighted, and the current state-of-the-art and most recent advances in the area of graphene-containing nanocomposite electrode materials are summarized. The limitations of graphene-containing materials for energy storage applications are also discussed, with an emphasis on anode and cathode materials. Potential research directions for the future development of graphene-containing nanocomposites are also presented, with an emphasis placed on practicality and scale-up considerations for taking such materials from benchtop curiosities to commercial products.
Co-reporter:Songping Wu, Rongyun Ge, Mingjia Lu, Rui Xu, Zhen Zhang
Nano Energy 2015 Volume 15() pp:379-405
Publication Date(Web):July 2015
DOI:10.1016/j.nanoen.2015.04.032
•Graphene-based nanomaterials for energy-storage device (Li–S battery and SIB).•Electrochemical principles and performances of graphene-based materials are considered.•Key obstructions and future development of novel materials were reviewed.Graphene-based nano-materials have provided an opportunity for next-generation energy storage device, particularly for lithium–sulfur battery and sodium-ion battery (SIB), due to their unique properties. This review comprehensively summarizes the present achievements and the latest progress of inorganic nano-materials/graphene composites as the electrode materials for Li–S battery and SIBs. Electrochemical principles, performances and key obstructions of graphene-based materials in the actual application are considered. This review gathers and classifies updated knowledge about Li–S battery and SIB nanomaterials related to graphene, with the aim of offering a wide view of those systems. It is concluded that cost-effective SIBs and Li–S battery are promising next-generation battery candidates in the near future, but require further investigation and improvement to deal with some critical scientific issues.Graphene-based nano-materials have aroused considerable interest as electrode materials for lithium–sulfur battery and sodium-ion battery (SIB) due to their unique properties. The excellent electrochemical performances of graphene-based nanomaterials suggested that they are promising candidates for electrode materials in next-generation energy storage device. This article is a timely and powerful report, which comprehensively elaborates the present achievements, the latest progress and future advancement of graphene-based electrode materials for Li–S battery and SIBs.
Co-reporter:Songping Wu, Juanjuan Xue, Rui Wang, Jianhui Li
Journal of Alloys and Compounds 2014 Volume 585() pp:542-548
Publication Date(Web):5 February 2014
DOI:10.1016/j.jallcom.2013.09.176
•Spinel MgGa2O4 ceramics were synthesized with solid-state method.•Spinel MgGa2O4 particles were characterized with XRD, SEM, XPS, FT-IR, Raman spectra and HRTEM.•Microwave properties of MgGa2O4 ceramics were: εr = 9.54, Q × f = 117,000 GHz, and τf = −4.0 ppm/°C.•Large relative density, uniform microstructures and cation ordering produced high Q × f values.•Crystal distortion from the oriented growth was advantageous to produce nearly zero τf value.Spinel MgGa2O4 ceramic materials were synthesized by solid-state method. MgGa2O4 powders were investigated with X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectrum, Raman spectrum, X-ray photoelectron spectrum (XPS), and high resolution transmission electron microscopy (HRTEM). The spinel-structured MgGa2O4 ceramics sintered at 1410 °C exhibited excellent microwave dielectric properties: a dielectric constant (ɛr) of 9.54, a quality factor (Q × f) of 117,000 GHz (at 14.7 GHz frequency) and a temperature coefficient of resonant frequency (τf) of −4.0 ppm/°C. MgGa2O4 ceramics have a wide sintering temperature region (∼150 °C) and nearly zero τf value. The large relative density, uniform microstructure and cation ordering resulted in high Q × f values. Crystal distortion from the oriented growth was advantageous to produce nearly zero τf value. MgGa2O4 ceramics are promising candidate materials for millimeter-wave devices.
Co-reporter:Rui Wang, Songping Wu, Yichao Lv, and Zhiqun Lin
Langmuir 2014 Volume 30(Issue 27) pp:8215-8220
Publication Date(Web):2017-2-22
DOI:10.1021/la501830r
Zn2GeO4 nanorod/graphene composites (ZGCs) were yielded by a two-step hydrothermal processing. Crystalline and amorphous regions were found to coexist in a single Zn2GeO4 nanorod. The surface of the Zn2GeO4 nanorod was compactly covered and anchored by graphene sheets. The ZGCs were then utilized as anodes for lithium ion batteries (LIBs). Intriguingly, partially crystalline ZGC containing 10.2 wt % graphene possessed excellent electrochemical performance, namely, high reversible capacity (1020 mA h g–1 in the first cycle), favorable cyclic performance (768 mA h g–1 after 50 cycles), and commendable rate capability (780 mA h g–1 at the current density of 0.8A g–1). The amorphous region in partially crystalline Zn2GeO4 nanorods and the elastic graphene sheets provided the accommodation of volume change during the charge and discharge processes. These advantageous attributes make ZGCs the potential anode materials for LIBs.
Co-reporter:C.X. Chen, S.P. Wu, Y.X. Fan
Journal of Alloys and Compounds 2013 Volume 578() pp:153-156
Publication Date(Web):25 November 2013
DOI:10.1016/j.jallcom.2013.05.038
Orthorhombic Mg2GeO4 ceramics were synthesized by solid-state reaction method. When stoichiometric compositions were employed, the phase transition produced under low temperature and pure orthorhombic Mg2GeO4 phase appeared at 1000 °C. B2O3 was employed as sintering aid to lower the sintering temperature of Mg2GeO4 ceramics and improve their relative densities. The B2O3-doped Mg2GeO4 ceramics have a low sintering temperature of 1250 °C and a small negative τf value. Microwave dielectric properties of B2O3-doped Mg2GeO4 ceramics were: εr = 6.76, Q × f = 95,000 GHz and τf = −28.7 ppm/°C. They could be considered as promising candidate materials for microwave/millimeter-wave devices.
Co-reporter:Youxian Mei and Songping Wu
RSC Advances 2013 vol. 3(Issue 29) pp:11888-11894
Publication Date(Web):25 Apr 2013
DOI:10.1039/C3RA41671B
Single-crystalline YMn2O5 was successfully synthesized through a tunable hydrothermal route. The pH value of the growth solution was a crucial factor for the control of the size and morphology of YMn2O5. A low pH value led to the formation of nanorods. Both the final size of the nanocrystals and their aspect ratio increased drastically with decreasing pH value. A relatively high temperature and low metallic salt concentrations favored the formation of one-dimensional nano-crystalline YMn2O5. Magnetic measurement indicated the crystalline YMn2O5 showed a weak ferromagnetic ordering, which was explained by uncompensated spins at the surface. The magnetic susceptibility indicates that the ferromagnetic transition temperature increases from 39 to 42 K with increasing grain size from 80 to 600 nm. With the decrease in the particle size, the coercivity increases while the exchange bias decreases.
Co-reporter:Qing Ma, Songping Wu, Chan Jiang, Jianhui Li
Ceramics International 2013 Volume 39(Issue 3) pp:2223-2229
Publication Date(Web):April 2013
DOI:10.1016/j.ceramint.2012.08.066
Abstract
SnO2-doped CaSiO3 ceramics were successfully synthesized by a solid-state method. Effects of different SnO2 additions on the sintering behavior, microstructure and dielectric properties of Ca(Sn1−xSix)O3 (x=0.5–1.0) ceramics have been investigated. SnO2 improved the densification process and expanded the sintering temperature range effectively. Moreover, Sn4+ substituting for Si4+ sites leads to the emergence of Ca3SnSi2O9 phase, which has a positive effect on the dielectric properties of CaO–SiO2–SnO2 materials, especially the Qf value. The Ca(Sn0.1Si0.9)O3 ceramics sintered at 1375 °C possessed good microwave dielectric properties: εr =7.92, Qf =58,000 GHz and τf=−42 ppm/°C. The Ca(Sn0.4Si0.6)O3 ceramics sintered at 1450 °C also exhibited good microwave dielectric properties of εr=9.27, Qf=63,000 GHz, and τf=−52 ppm/°C. Thus, they are promising candidate materials for millimeter-wave devices.
Co-reporter:S.P. Wu, D.F. Chen, C. Jiang, Y.X. Mei, Q. Ma
Materials Letters 2013 Volume 91() pp:239-241
Publication Date(Web):15 January 2013
DOI:10.1016/j.matlet.2012.09.065
The monoclinic CaSnSiO5 phase could be synthesized with a conventional solid state method. The molar ratio of Ca:Sn:Si=1:1.05:1 was employed to synthesize pure CaSnSiO5 ceramics through non-stoichiometric effect. The CaSnSiO5 ceramics sintered at 1525 °C exhibited microwave dielectric properties: a dielectric constant (εr) of 9.08, a quality factor (Q×f) of 61,000 GHz and a temperature coefficient of resonant frequency (τf) of 35 ppm/°C. They are promising millimeter-wave ceramic materials.Highlights► Monoclinic CaSnSiO5 ceramics were synthesized with a solid-state method. ► Pure CaSnSiO5 ceramics were synthesized by non-stoichiometric effect. ► High relative density and normal microstructure resulted in excellent properties.► Microwave properties of CaSnSiO5: εr=9.08, Q×f=61,000 GHz and τf=35 ppm/°C. ► CaSnSiO5 ceramics are promising millimeter-wave ceramic materials.
Co-reporter:Song-Ping Wu
Rare Metals 2013 Volume 32( Issue 4) pp:425-430
Publication Date(Web):2013 August
DOI:10.1007/s12598-013-0070-9
Solvent extraction of palladium (II) from hydrochloric acid solution with 2-n-octyl-4-isothiazolin-3-one (OIT)/cyclohexane was studied. Effects of different parameters on extraction efficiency were evaluated. 99.96 % and 98.26 % palladium (II) could be effectively extracted with 0.018 mol·L−1 OIT/cyclohexane of 0.1 and 4.0 mol·L−1 HCl medium, respectively. Nonpolar solvent and low acidity could improve the extracting efficiency, and successfully strip palladium (II) from the loaded organic phase was achieved with 0.5 mol·L−1 (NH2)2CS solution. It was proposed that the extraction of Pd complexes from HCl medium proceeded through the ion-association mechanism by slope method, NMR and FT-IR spectra.
Co-reporter:Weishuang Ni, Songping Wu, and Qun Ren
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 40) pp:13157
Publication Date(Web):September 11, 2012
DOI:10.1021/ie302249v
Surface modification of TiO2 nanoparticles with 3-methacrylic acyloxy propyl trimethoxysilane (KH570) was carried out in the liquid phase. The modified TiO2 nanoparticles, as charge control agents (CCAs), were added to toner. Infrared and X-ray photoelectron spectroscopies provided strong indications of the formation of organic links between the TiO2 and the KH570. The thick coating layer of KH570 deposited on the surface of TiO2 nanoparticles was determined to be about 2–5 nm by transmission electron microscopy. The hydrophobicity of the modified toner decreased when the amount of coated KH570 reached 5.28 wt % and then increased with further increasing amount of coated KH570. The charge-to-mass ratio (Q/M) of the modified toner shifted in the negative direction with increasing amount of coated KH570; however, with increasing amount of modified TiO2, the value of Q/M shifted in the positive direction. The reason for this difference is that the OH groups existing on the surface of TiO2 transferred from the toner to the carrier after friction.
Co-reporter:S.P. Wu, Q.Y. Zhao, L.Q. Zheng, X.H. Ding
Solid State Sciences 2011 Volume 13(Issue 3) pp:548-552
Publication Date(Web):March 2011
DOI:10.1016/j.solidstatesciences.2010.12.024
The ZnO-doped silver paste with good thixotropy was prepared and its cofiring characteristics with ferrite green tapes were studied. The sheet resistivity of silver film decreased with an increasing temperature because of larger grain size and denser film. 2 wt.% ZnO-doped silver thick film showed low sheet resistivity (0.97 mΩ/□ (mΩ/mm2)), high adhesive strength (0.85 kgf·mm−2) and excellent compatibility. ZnO scattered at the silver grain boundaries according to SEM photographs. The pinning effect led to a decreased grain size when the amount of ZnO increased. A grain growth exponent n = 3.0–4.58 was evaluated by minimizing the deviation in the function Dn − D0n = k (T) t to the experimental data. The average activation energy (47 kJ/mol) indicated that surface diffusion mass transportation was the mechanism of silver grain growth.
Co-reporter:C. Jiang, S.P. Wu, W.P. Tu, L. Jiao, Z.O. Zeng
Materials Chemistry and Physics 2010 Volume 124(Issue 1) pp:347-352
Publication Date(Web):1 November 2010
DOI:10.1016/j.matchemphys.2010.06.045
(Zn0.8Mg0.2)TiO3–xTiO2 composite ceramics has been prepared via the solid-phase synthesis method. TiO2 was employed to tone temperature coefficient of resonant frequency (τf) and stabilize hexagonal (Zn, Mg)TiO3 phase. 3ZnO–B2O3 was effective to promote sintering. The movement of grain boundary was obvious because of the liquid phase sintering. The scanning electron microscope (SEM) photographs and energy dispersive spectrometer (EDS) patterns showed that segregation and precipitation of dissociative (Zn, Mg)TiO3 grains occurred at grain boundary during sintering. SnO2 was used as inhibitor to prevent the grain boundary from moving. The dielectric behaviors of specimen strongly depended on structural transition and microstructure. We found that 1.0 wt.% 3ZnO–B2O3 doped (Zn, Mg)TiO3–0.25TiO2 ceramics with 0.1 wt.% SnO2 additive displayed excellent dielectric properties (at 1000 °C): ɛr = 27.7, Q × f = 65,490 GHz (at 6.07 GHz) and τf = −8.88 ppm °C−1. The above-mentioned material was applied successfully to make multilayer ceramic capacitors (MLCCs), which exhibited an excellent electrical property. The self-resonance frequency (SRF) and equivalent series resistance (ESR) of capacitor decreased with capacitance increasing, and the quality factor (Q) of capacitor reduced as frequency or capacity increased.
Co-reporter:S.P. Wu, L.Q. Zheng, Q.Y. Zhao, X.H. Ding
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 372(1–3) pp:120-126
Publication Date(Web):3 December 2010
DOI:10.1016/j.colsurfa.2010.09.038
Conductive silver terminal paste for multilayer chip inductances (MLCIs) was prepared. Surfactant could decrease the apparent viscosity of silver paste and improve the densification of the fired silver films, however, surplus surfactant would worsen the levelability of silver paste because of the decrease in the surface tension of the printed thick films. Suitable dosage of lead-free glass and sintering temperature are also very important to obtain the qualified thick films. Silver thick films containing 5 wt.% frit/silver have high adhesion strength (119 Kgf cm−2), low sheet resistance (5.4 mΩ/□), dense microstructure and excellent electroplating behavior at the fired temperature of 850 °C. MLCIs with as-synthesized silver terminal paste have excellently electrical and mechanical properties.Graphical abstractSilver thick films (MLCI CB3216B700) have high adhesion strength (119 Kgf cm−2), low sheet resistance (5.4 mΩ/□) and dense microstructure under 5 wt.% glass/silver condition at the fired temperature of 850 °C.Research highlights▶ 1–1.5 wt.% surfactant was ideal for the rheological properties of silver pastes. ▶ 5 wt.% glass gave films dense microstructures and excellent electroplating behaviors. ▶ MLCIs with the silver paste have excellently electrical and mechanical properties.
Co-reporter:S.P. Wu, R.Y. Gao, L.H. Xu
Journal of Materials Processing Technology 2009 Volume 209(Issue 3) pp:1129-1133
Publication Date(Web):1 February 2009
DOI:10.1016/j.jmatprotec.2008.03.010
The preparation of flake micron-sized copper powders with the chemical–mechanical method was investigated. Reaction of [Cu(NH3)4]2+ complex with hydrazine hydrate at 85 °C produced monodispersed fine spherical copper powders, which were used as precursor to synthesize flake copper powders by the ball milling process. The flake copper powders having an excellent dispersibility and a uniform size of 9 ± 2 μm could be achieved. Thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) of the flake copper were investigated with thermal analyzer. The results showed that the oxidizing temperature increased with a decreasing specific area. The flake copper powder particles were employed as functional conductive materials in copper thick film paste for base-metal-electrode multi-layer ceramic capacitors (BME-MLCCs). Excellent connection between internal and terminal electrode and even distribution of glass in copper thick film can be observed by polarized light photograph. The dense thick films were also found by scanning electron microscopy (SEM) analysis, and the high densification of the fired films could be attributed to the “framework” effects.
Co-reporter:S.P. Wu, J. Ni, J.H. Luo, X.H. Ding
Materials Chemistry and Physics 2009 Volume 117(Issue 1) pp:307-312
Publication Date(Web):15 September 2009
DOI:10.1016/j.matchemphys.2009.06.005
In this paper, the microwave dielectric behavior of ZnNb2O6–TiO2 ceramics synthesized at different conditions was studied. ZnNb2O6–1.75TiO2 ceramics, sintered at 1050 °C, exhibited a good dielectric behavior. CuO and B2O3 were used as sintering aids to decrease the sintering temperature of the above materials. According to XRD analysis, the reaction between columbite ZnNb2O6 and rutile occurred, resulted in new phase ZnTiNb2O8 and Zn0.17Nb 0.33Ti0.5O2. The change of crystal grain and densification was also observed with SEM. Results indicated that the dielectric behavior of samples strongly depended on structural transitions and microstructure of materials. We found that 2.0 wt.% CuO doped ZnNb2O6–1.75TiO2 ceramics with 2.0 wt.% B2O3 additive sintered at 975 °C exhibited good dielectric properties: ɛr = 40, Q × f = 17,000 GHz (at 5.6 GHz) and τf = −12 ppm °C−1. The high specific insulation resistance and excellent compatibility with Ag90Pd10 electrode suggested that ZnNb2O6–1.75TiO2 ceramics was suitable for manufacturing multilayer ceramic capacitors with a high reliability.
Co-reporter:Jiao Li;Wu Songping;Ding Xiaohong;Ni Jing
Journal of Materials Science: Materials in Electronics 2009 Volume 20( Issue 12) pp:1186-1192
Publication Date(Web):2009 December
DOI:10.1007/s10854-008-9849-0
Mixture of zinc metatitanate and rutile (ZnTiO3 + 0.2TiO2), had been prepared via the conventional solid-state reaction method. The sintering behavior and microwave dielectric properties of ZnO–TiO2 system were investigated. The composition and microstructure of ceramics were discussed with XRD and SEM. It was found that ZnO–TiO2 ceramics, which was sintered at 900°C using 1.0 wt% B2O3 as sintering additive, had homogeneously fine microstructures and high densification. Samples possessed excellent microwave dielectric properties: εr = 26, Q × f = 34,890 GHz, and τf = −11 ppm/°C. The above- mentioned material was suitable for the tape casting process and compatible with Ag electrodes, therefore, was an excellent candidate for multilayer ceramic capacitor applications.
Co-reporter:Wu Songping, Ni Jing, Jiao Li, Zeng Zhenou
Materials Chemistry and Physics 2007 Volume 105(Issue 1) pp:71-75
Publication Date(Web):15 September 2007
DOI:10.1016/j.matchemphys.2007.04.027
Gray bimetallic copper–nickel powders were synthesized with hydrothermal–reduction method. Formic acid and glutin were employed as hydrothermal–reduction agent and dispersion agent, respectively. Nickelous carbonate, copper carbonate and sodium formate were carried out in a titanium material autoclave at 230 °C to obtain gray-black powders for 20 h. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersion X-ray (EDX), thermal analyzer and laser size distribution analyzer were applied to analyze particle behavior. Bimetallic copper–nickel particles with polyhedral shape and uniform size in the range of 0.5 ± 0.2 μm were formed in an optimal reaction condition. Influences of dispersing agent on size and shape of particles were obvious. The size of particles decreases as an increasing dosage of formic acid. Microanalysis and thermal behavior of nickel-rich Ni–Cu solid solution suggest that copper–nickel powder particle has a core–shell structure.
Co-reporter:Songping Wu
Materials Letters 2007 Volume 61(Issue 16) pp:3526-3530
Publication Date(Web):June 2007
DOI:10.1016/j.matlet.2006.11.128
In this paper, non-agglomerated monodispersed ultra-fine copper metallic powders have been synthesized with chemical reduction method. Fine lead-free glass powders were also prepared by solid synthesis process. Thick film paste prepared by above-mentioned copper metallic powders and lead-free glass powders was applied as conductive paste of MLCC. Mixture of glass and zinc oxide give the thick film a high adhesion strength which is attributed to the rough interface from interfacial reaction between glass and chip, and a good densification. Diffusion of metal between copper thick film and nickel thick film is clear. Ni–Cu solid solution appears under high temperature firing.
Co-reporter:Songping Wu
Materials Letters 2007 Volume 61(4–5) pp:1125-1129
Publication Date(Web):February 2007
DOI:10.1016/j.matlet.2006.06.068
The preparation of ultrafine copper powder with chemical reduction method was investigated. Ascorbic acid was employed as reducing agent. Reaction of CuSO4·5H2O with ascorbic acid at 70 °C gives polyhedron monodispersed ultrafine copper powder. The copper powder having excellent dispersibility was prepared when the pH value was controlled at 6 with aqueous ammonia. Influences of reaction temperature on the efficiency of copper powders were also studied. TG/DTG/DTA of copper powder was discussed with thermal analyzer. As-prepared copper powder was applied in BME-MLCC. The micro-structures of end termination and interface were discussed with SEM and polarized light microscope. The copper end termination has high adhesion force, excellent solderibility behavior and resistance behavior to soldering.
Co-reporter:Wu Songping, Jiao Li, Ni Jing, Zeng Zhenou, Liu Song
Intermetallics 2007 Volume 15(Issue 10) pp:1316-1321
Publication Date(Web):October 2007
DOI:10.1016/j.intermet.2007.04.001
In this paper, ultrafine nickel-rich Cu–Ni bimetallic powders were synthesized with hydrothermal-reduction method. When polyethyleneglycol (PEG) was employed as protective agent, flake bimetallic powder particles, which have an excellent dispersibility and uniform size of 1.8–2.0 μm, can be prepared. Polyhedral powder particles, which have a uniform particle size in the range from 0.5 to 0.8 μm, were successfully synthesized using gelatin as protective agent. By thermal analysis, it was found that the oxidation-resistance of Cu–Ni powder particles was strong. Above-mentioned flake/polyhedral bimetallic powders were mixed with inorganic binder and vehicle to make conductive thick film. The low resistivity and high adhesion strength of thick film were attributed to high densification and rough interface from interfacial reaction, respectively.
Co-reporter:Wu Songping
Journal of Materials Science: Materials in Electronics 2007 Volume 18( Issue 4) pp:447-452
Publication Date(Web):2007 April
DOI:10.1007/s10854-006-9042-2
The preparation of micron size flake silver powders with chemical-mechanic method was investigated. Reaction of silver nitrate with ascorbic acid gives fine spherical silver powders. The spherical silver powders were processed by globe mill to make micron size flake silver powders having excellent dispersability and uniform shape. The XRD and thermal analyzer were employed to analyze as—prepared flake silver powders. The flake silver powders were employed to make polymer silver thick film and fire-type thick film. The application of small molecule surfactant in the stage of synthesizing precursor and large specific area of flake particles give a low resistivity of polymer thick film. The fire-type silver thick film was studied by SEM and EDX. SEM photograph shows that the grain boundaries of silver are prominently visible, and the densification of the fired thick film is high. The fire-type thick film has a low bulk resistivity and high adhesion strength.
Co-reporter:Wu Songping
Journal of Materials Science: Materials in Electronics 2007 Volume 18( Issue 10) pp:1031-1035
Publication Date(Web):2007 October
DOI:10.1007/s10854-007-9133-8
In this paper, the metal–ceramic composite material, i.e., silver–BaTiO3 composite powder, was prepared with chemical deposition method. Composition, dispersibility and shape of powder particles were investigated by XRD, SEM and size distribution analyzer. Coalescence of particles occurs during low sintering process, and sintering temperature has a great effect on composition and shape of single powder particles. The sintering of silver on the surface of particles increases with an increasing temperature by SEM and EDX observation. The shrinkage and softening temperature of composite powders increase and decrease as an increasing silver content, respectively, by TMA analysis. Sheet resistance 52 mΩ/□ was observed from the film corresponding to 80 wt.% silver content which was sintered at 300 °C.
Co-reporter:Wu Songping, Meng Shuyuan
Materials Letters 2006 Volume 60(Issue 20) pp:2438-2442
Publication Date(Web):September 2006
DOI:10.1016/j.matlet.2004.08.051
The preparation of micron size copper powder with chemical reduction method was investigated. The copper powder having excellent dispersibility was prepared when sodium metaphosphate was employed as dispersion agent. Reaction of CuSO4·5H2O with hydrazine hydrate at 80 °C gives spherical monodispersed micron size copper powder. The influences of dosage of dispersion agent on the size and dispersibility of powder particles were obvious. The appropriate conditions were NH4Cl/Copper (W/W) 15% and five times calculated value of hydration hydrazine. TG/DTA/DTG of the as-prepared copper powder was investigated with thermal analyzer.
Co-reporter:Yichao Lv, Songping Wu, Rui Xu
Materials Chemistry and Physics (1 March 2017) Volume 189() pp:252-257
Publication Date(Web):1 March 2017
DOI:10.1016/j.matchemphys.2016.12.044
