G. Liang

Sam Houston State University, Huntsville, Texas, United States

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Publications (111)243.86 Total impact

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    ABSTRACT: Cadmium-incorporated Li2FeSiO4/C composites have been successfully synthesized by a solid-state reaction assisted with refluxing. The effect and mechanism of Cd-modification on the electrochemical performance of Li2FeSiO4/C were investigated in detail by X-ray powder diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectra, transmission electron microscopy, positron annihilation lifetime spectroscopy and Doppler broadening spectrum, and electrochemical measurements. The results show that Cd not only exists in an amorphous state of CdO on the surface of LFS particles, but also enters into the crystal lattice of LFS. Positron annihilation lifetime spectroscopy and Doppler broadening spectrum analyses verify that Cd-incorporation increases the defect concentration and the electronic conductivity of LFS, thus improve the Li(+)-ion diffusion process. Furthermore, our electrochemical measurements verify that an appropriate amount of Cd-incorporation can achieve a satisfied electrochemical performance for LFS/C cathode material.
    Scientific reports. 01/2014; 4:5064.
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    ABSTRACT: Double-perovskite Sr-deficient Sr2−xMgMoO6−δ (x = 0–0.15) samples were prepared via a sol–gel route and evaluated as anode materials for solid-oxide fuel cells. The effects of Sr-site deficiency on lattice structure, electrical conductivity, thermal expansion coefficient (TEC) and electrochemical performance were systematically investigated. It is found that Sr-site deficiency within 0 < x < 0.10 increases the degree of B-site ordering but decreases the TEC value. The electrical conductivity increases with increasing x and reaches the maximum at x = 0.10. The Sr-site deficiency also increases the ratio of Mo6+, leading to enhanced oxygen vacancy concentration and reduced polarization resistance. With La0.8Sr0.2Ga0.83Mg0.17O3−δ as electrolyte and Ba0.5Sr0.5Co0.8Fe0.2O3−δ as cathode, the single cells with Sr2−xMgMoO6−δ (x = 0, 0.05, 0.10 and 0.15) anodes show the maximum power densities of 527, 551, 659 and 573 mW cm−2, respectively, in H2 at 800 °C. The x = 0.10 anode exhibits the highest power density due to its high conductivity, low overpotential and good catalytic activity. Single-cell tests indicate the potential application of the deficiency in Sr-site for Sr2−xMgMoO6−δ as SOFC anode material.
    Journal of Power Sources 01/2014; 270:441–448. · 5.26 Impact Factor
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    ABSTRACT: Here we report on a unique nanohybrid made of a molybdenum oxysulfide (MoOxSy) layer on porous TiO2 nanospheres, which has been fabricated in large quantities through a facile photochemical-assembly process. The as-formed core–sheath TiO2@MoOxSy nanocomposite not only inherits the features of the interior TiO2 nanospheres with high porosity and high surface area, but also possesses enhanced conductivity from the external MoOxSy layer. When evaluated as an anode material for lithium ion batteries, such a unique TiO2@MoOxSy nanohybrid exhibits superior lithium storage performances with high specific capacity and excellent rate capability. The synergetic effects of the enhanced electrical conductivity of uniform MoOxSy coating and the porously nanoarchitectured TiO2 nanocrystal assemblies may endow the TiO2@MoOxSy electrode with remarkable lithium-storage performances.
    J. Mater. Chem. A. 11/2013; 1(47).
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    ABSTRACT: Reduced graphene oxide modified Li2FeSiO4/C (LFS/(C+rGO)) composite is successfully synthesized by a citric acid-based sol-gel method and evaluated as cathode material for lithium ion batteries. The LFS/(C+rGO) shows an improved electronic conductivity due to the conductive network formed by reduced graphene oxide nanosheets and amorphous carbon in particles. Electrochemical impedance spectroscopy results indicate an increased diffusion coefficient of lithium ions (2.4×10-11 cm2 s-1) for LFS/(C+rGO) electrode. Compared with LFS with only amorphous carbon, the LFS/(C+rGO) electrode exhibits higher capacity and better cycling stability. It delivers a reversible capacity of 178 mAh g-1 with a capacity retention ratio of 94.5% after 40 cycles at 0.1 C, and an average capacity of 119 mAh g-1 at 2 C. The improved performance can be contributed to the reduced crystal size, good particle dispersion, and the improved conductive network between LFS particles.
    ACS Applied Materials & Interfaces 11/2013; · 5.01 Impact Factor
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    ABSTRACT: Li3V2(PO4)3/C composite is prepared by a novel refluxing-assisted solid-state reaction and compared with hydrothermal synthesis.
    ChemInform 08/2013; 44(32).
  • G. Liang, M. Croft, Z. Zhong
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    ABSTRACT: This study demonstrates the feasibility of using energy dispersive X-ray diffraction (EDXRD) to characterize the internal structure and chemical composition of coin cell type Li-ion batteries. CR2032 coin cell batteries containing Li1–xMn1.42Ni0.42Co0.16O4 cathode were studied and profiled by collecting 70 EDXRD patterns collected at equal spatial intervals between top and bottom of charged and discharged coin cells of about 3.2mmthickness. Diffraction profiling of the discharged cell manifests the spinel structure with essentially constant Li content across the entire cathode. In contrast, the Bragg lines of the charged cathode cell shift to higher energy, consistent with a lattice contraction with decreased Li content. The charged-cell spectrum Bragg lines are also broadened due to two phase behavior and exhibit a distinct Li-content gradient across the cathode. The detailed electrochemical phases of the cathode materials and other layers of materials in these prototype LiMn2O4-based coin cells have been profiled, using EDXRD, as a function of z-position in the interior of the cells. Our results demonstrate that EDXRD characterization of the crystal structures and phase distribution of coin cell batteries in space and under different charge/discharge conditions should be routinely feasible.
    Journal of The Electrochemical Society 06/2013; 160(8):A1299-A1303. · 2.59 Impact Factor
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    ABSTRACT: Spherical Li3V2(PO4)3/C (LVP/C) composites are successfully synthesized via two different spray-drying processes. XRD results reveal that some impurities, such as Na3V2(PO4)3, Li2NaV2(PO4)3 and Li4(P2O7), appear when sodium salt of carboxy methyl cellulose (CMC) acts as carbon source. SEM images show two different morphologies: solid spherical particles for LVP/C(A) prepared by adding CMC after pre-sintering, and hollow for LVP/C(B) prepared by adding CMC before pre-sintering. Compared to LVP/C(B), LVP(A) presents higher tap density and better electrochemical performance at any C-rate. Remarkably, another charge/discharge plateaus or anodic/cathodic peaks around 3.85 V are detected for both LVP/C(A) and LVP/C(B) electrodes, which is attributed to the formation of Li3−xNaxV2(PO4)3 or some other electrochemically active composites containing Na+. CMC addition sequence has a significant influence on morphology of Li3V2(PO4)3. Furthermore, acting as carbon source and Na dopant, CMC shows a notable effect on electrochemical behavior of Li3V2(PO4)3 cathode material.
    Electrochimica Acta 12/2012; 90:433-439. · 4.09 Impact Factor
  • Journal of The Electrochemical Society 08/2012; · 2.59 Impact Factor
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    ABSTRACT: Li3V2(PO4)3/C (LVP/C) coated with various amounts of SiO2 has been synthesized, and the effect of surface modification by SiO2 on the performance of LVP has been systematically investigated with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), magnetic susceptibility, Raman spectroscopy, and electrochemical measurements. Based on the analysis of XRD, XPS, and TEM, it is confirmed that SiO2 coating on the surface of LVP particles does not change the monoclinic structure of LVP. The XAS, XPS, and magnetic susceptibility results indicate that the valence of V in both the pristine and SiO2-coated LVP are close to +3. Furthermore, our results reveal that the electrochemical performance of LVP/C can be significantly improved by the SiO2 coating, which is due to the enhanced structural stability and reduced charge-transfer resistance.
    Journal of Physical Chemistry C. 06/2012; 116(23).
  • G.liang, R. S.liu, L. V.wang
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    ABSTRACT: Near-edge x-ray-absorption spectra at the Cu K-edge has been measured for (Tl0.5Pb0.5)Sr2Ca1-xYxCu2O7-δ compound series. It is found that both the intensity of the quadruple 1s → 3d transition feature and the edge-energy decrease with increasing x. Our results show that the Cu valence decreases slightly with the substitution of Ca+2 by Y+3. This result, together with recent O K-edge result the O-2p holes are reduced by the substitution, indicates that electronic charge is transferred into the entire CuO2 layers by the Y+3 for Ca+2 substitution.
    International Journal of Modern Physics B 01/2012; 12(29n31). · 0.46 Impact Factor
  • G.liang, R. S.liu, L. V.wang
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    ABSTRACT: Near edge x-ray-absorption spectra at Pb L3-edges have been measured for (Tl0.5Pb0.5)Sr2Ca1-xYxCu2O7-δ compound series. It is found that the intensity of the 2p→6s transition feature decreases with the substitution of Ca+2 by Y+3. This result indicates that some electronic charges have been transferred into the Pb(Tl)-O layers by this substitution. Detailed analysis suggests that the valence value of Pb in this compound series is close to +4 and it decreases with the increase of the Y-doping level x.
    International Journal of Modern Physics B 01/2012; 13(29n31). · 0.46 Impact Factor
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    ABSTRACT: To further study the charge carrier concentration in electron doped cuprate superconductors. a systematic x-ray absorption near edge structure (XANES) measurement has been carried out on Th-doped superconductor system R2-xThxCuO4-δ (R=Nd, Sm, and Gd). The XANES results show that, similar to the Ce-doped compounds, while the intensity of the Cu1+4pπ feature increase with the increase of the Th doping level x, the intensities of the Cu2+4pπ and 4pσ features decreases. This clearly indicates that the electrons doped by the Th atoms are injected into the local Cu 3d-orbitals. The normalized Cu1+4pπ intensity data show that the Cu1+ concentration in the Th-doped compound series with different R-elements is linearly proportional to the Th doping-level x. The data suggest that both Ce and Th donate the same fraction of electrons into the Cu sites.
    International Journal of Modern Physics B 01/2012; 13(29n31). · 0.46 Impact Factor
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    ABSTRACT: Single crystals Nd2-xCexCuO4-δ with x=0.0 and 0.2 are studied by polarized X-ray absorption measurements at Cu K-edge. The positions and intensities of the 1s→ 4pσ transition features in the K-edge spectra are analyzed with a modified cluster model and functional curve fitting procedure. All of the experimental results including the energies of the spectral features, the energy separations between features and the variation of feature intensities, can be well explained by the cluster model parameters obtained from the curve fitting. Particularly, it is found that the charge transfer energy gap Δ in the Nd2-xCexCuO4-δ system decreases from about 1.4 eV at x=0 to 0.5 eV at x = 0.2. Our analysis in this paper provides a method for quantitative X-ray absorption spectroscopy (XAS) study of the charge transfer gap for electron-doped cuprate superconductors and related materials.
    International Journal of Modern Physics B 01/2012; 12(29n31). · 0.46 Impact Factor
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    Journal of The Electrochemical Society 01/2012; 159(10):A1573-A1578. · 2.59 Impact Factor
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    ABSTRACT: Image-guided thermal ablation of tumors is becoming a more widely accepted minimally invasive alternative to surgery for patients who are not good surgical candidates, such as patients with advanced head and neck cancer. In this study, multifunctional superparamagnetic iron oxide coated with gold nanoshell (SPIO@Au NS) that have both optical and magnetic properties was conjugated with the targeting agent, C225 monoclonal antibody, against epidermal growth factor receptor (EGFR). C225-SPIO@Au NS have an average a diameter of 82 ± 4.4 nm, contain 142 ± 15 antibodies per nanoshell, have an absorption peak in the near infrared (~800 nm), and have transverse relaxivity (r(2)) of 193 and 353 mM(-1) s(-1) versus Feridex™ of 171 and 300 mM(-1) s(-1), using 1.5 T and 7 T MR scanners, respectively. Specific targeting of the synthesized C225-SPIO@Au NS was tested in vitro using A431 cells and oral cancer cells, FaDu, OSC19, and HN5, all of which overexpress EGFR. Selective binding was achieved using C225-SPIO@Au NS but not with the non-targeting PEG-SPIO@Au NS and blocking group (excess of C225 + C225-SPIO@Au NS). In vivo biodistribution on mice bearing A431 tumors also showed selective targeting of C225-SPIO@Au NS compared with the non-targeting and blocking groups. The selective photothermal ablation of the nanoshells shows that without laser treatment there were no cell death and among the groups that were treated with laser at a power of 36 W/cm(2) for 3 min, only the cells treated with C225-SPIO@Au NS had cell killing (p < 0.001). In summary, successful synthesis and characterization of targeted C225-SPIO@Au NS demonstrating both superparamagnetic and optical properties has been achieved. We have shown both in vitro and in vivo that these nanoshells are MR-active and can be selectively heated up for simultaneous imaging and photothermal ablation therapy.
    Biomaterials 10/2011; 32(30):7600-8. · 8.31 Impact Factor
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    ABSTRACT: In this study, extensive structural and magnetic characterizations have been carried out on the silica, gold, and C225 antibody triply coated iron oxide nanoparticles for image-guided laser ablation of head and neck tumors. X-ray absorption and x-ray diffraction results show the phase of the uncoated and coated nanoparticles to be in the γ-Fe2O3 structure. The nanoparticles are studied by transmission electron microscopy and it is found that these nanoparticles have an average diameter of 82 nm and contain 142 antibodies per nanoshell. The magnetization measured at 500 Oe indicates that coating of the iron oxide nanoparticles by silica/gold/C225 decreases blocking temperature from 160 K to about 55 K, which can be explained by the spin-disorder induced change in the effective volume of the γ-Fe2O3 core. The blocking temperature decreases from 95 K to 55 K with an increase of magnetic field from 100 Oe to 500 Oe. It is found that the coercivity of the triply coated nanoparticles decreases from 195 to 25 Oe with an increase of temperature from 5 K to 300 K.
    10/2011;
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    ABSTRACT: A series of LiFe{sub 1-x}VâPOâ/C samples have been successfully prepared using a two-step solid-state reaction route. The effect of vanadium incorporation on the performance of LiFePOâ has systematically been investigated with X-ray diffraction, Raman spectroscopy, charge/discharge measurements, and cyclic voltammetry tests. It is found that V incorporation significantly enhances the electrochemical performance of LiFePOâ. Particularly, the LiFePOâ/C sample with 5 at. % vanadium doping exhibits the best performance with a specific discharge capacity of 129 mAh g⁻¹ at 5.0 C after 50 cycles; the capacity retention ratio is higher than 97.5% at all C rates from 0.1 to 5.0 C. X-ray absorption spectroscopy results show that the valence of V in LiFe{sub 0.95}V{sub 0.05}POâ/C is between +3 and +4. It is confirmed that the samples with x ⤠0.03 are in single phase, whereas the samples with 0.05 ⤠x < 1.00 contain two impurity phases: LiâVâ(POâ)â and LiVOPOâ. A clear feature of vanadium incorporation in LiFePOâ has been specified.
    J. Phys. Chem. C. 07/2011; 115:13520-13527.
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    ABSTRACT: The effects of the grain size of the doped SiC nanoparticles on the critical current density ( J <sub>c</sub>) of the Ti-sheathed MgB<sub>2</sub> superconducting wires were studied. The concentration of the SiC dopant was 10% and the sizes of the SiC particles were 20 nm, 45 nm, and 123 nm. Contrary to the J <sub>c</sub> results reported on the SiC-doped Fe-sheathed MgB<sub>2</sub> wires, we found that the J <sub>c</sub> for the Ti-sheathed MgB<sub>2</sub> wires decreased with the size of the SiC particles. We also found that the J <sub>c</sub> is greater than that of the undoped MgB<sub>2</sub> wires only for the wires with 123 nm SiC size. This unusual dependence of J <sub>c</sub> on the size of the SiC dopant is discussed in association with the results from the magnetization, electrical resistivity, x-ray diffraction, and transmission electron microscopy measurements.
    IEEE Transactions on Applied Superconductivity 07/2011; · 1.20 Impact Factor
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    ABSTRACT: The effects of sintering temperature on the superconducting properties of Ti-sheathed MgB2 wires have been studied. The wires were fabricated by in situ powder-in-tube (PIT) method and characterized by x-ray diffraction, magnetization, scanning electron microscopy and transport measurements. Samples were sintered for 30 minutes at the following temperatures: 650° C, 700° C, 750° C, 800° C, and 850° C. It is found that the cores of these wires are almost in pure MgB2 superconducting phase, indicating that the Ti-sheath does not react with Mg or B. The superconducting transition temperature Tc decreases from 36 K to 34.2 K with the decrease of the sintering temperature from 850° C to 650° C. At 5 K and 20 K, critical current density Jc peaks up for samples sintered at 800° C, which is in sharp contrast with previously reported result that for Fe-sheathed MgB2 wires, Jc peaks up at sintering temperature of 650° C.
    04/2010;
  • H. Fang, G. Liang
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    ABSTRACT: Fe-sheathed MgB2 wires doped with C and TiC nanoparticles in the formula MgB2-xCx+yTiC (x = 0, 0.05, 0.1, 0.15, 0.2, and y = 0, 2.5 wt.%, 5 wt.%) were investigated. X-ray diffraction patterns indicate that the core materials in the wires contain small amount of Fe2B and MgO impurity phases, and the peaks shift with the variation of doping amount. It is found that the critical temperature Tc decreases with the increase of doping amount. Strong in-field current carrying capability enhancement was observed on MgB1.95C0.05+2.5 wt.% TiC.
    04/2010;

Publication Stats

619 Citations
243.86 Total Impact Points

Institutions

  • 1993–2014
    • Sam Houston State University
      • Department of Physics
      Huntsville, Texas, United States
  • 2013
    • China Three Gorges University
      Tung-hu, Hubei, China
  • 2005–2007
    • University of Houston
      • Department of Mechanical Engineering
      Houston, Texas, United States
  • 1999
    • Texas A&M University
      College Station, Texas, United States
  • 1987–1991
    • Rutgers, The State University of New Jersey
      • • Department Physics and Astronomy
      • • Department of Physics
      New Brunswick, NJ, United States