UScholar Works
 
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CreatorTitleDescriptionSubjectDate
26 Liu, FengStrain-engineered surface transport in Si(001): complete isolation of the surface state via tensile strainBy combining density functional theory, nonequilibrium Green's function formulism and effective- Hamiltonian approaches, we demonstrate strain-engineered surface transport in Si(001), with the complete isolation of the Si surface states from the bulk bands. Our results show that sufficient tensile s...2013-01-01
27 Liu, FengEffects of Li doping on H-diffusion in MgH2: A first-principles studyThe effects of Li doping in MgH2 on H-diffusion process are investigated, using first-principles calculations. We have identified two key effects: (1) The concentration of H vacancy in the þ1 charge state ðVþ1 H Þ can increase by several orders of magnitude upon Li doping, which significantly in...2013-01-01
28 Tiwari, AshutoshRoom-temperature solid-state radiation detectors based on spintronicsIn this paper we are presenting a unique approach to solve the thermal background problem encountered in semiconductor nuclear detectors. Our approach addresses above challenge by making a shift from 'electronic detection mechanism' to 'spintronic detection mechanism'. The proposed methodology is ba...2012-01-01
29 Tiwari, AshutoshFabrication and characterization of Li7La3Zr 2O12 thin films for lithium ion batteryThin films of Li7La3Zr2O12 were deposited on SrTiO3 (100) and Sapphire (0001) substrates at room-temperature using a pulsed-laser-deposition technique. Detailed structural, compositional, optical, and electrochemical characterizations of the films were performed. The films deposited at room-temperat...2012-01-01
30 Tiwari, AshutoshCharacterization of Li7La3Zr2O 12 thin films prepared by pulsed laser depositionA pulsed laser deposition system was employed to fabricate thin films of Li7La3Zr2O12 solid electrolyte. The deposition process was carried out at room-temperature, resulting in amorphous films. These as-deposited films had a large optical band gap of 5.13 eV, and exhibited a lithium-ion conductivit...2012-01-01
31 Tiwari, AshutoshGarnet-type Li7La3Zr2O12 electrolyte prepared by a solution-based technique for lithium ion batteryHigh quality garnet-type Li7La3Zr2O12 solid electrolyte was synthesized using a solution-based technique. The electrolyte pellets were sintered at 900 oC, resulting in tetragonal phase, which then transformed to cubic phase after annealing at 1230 oC. The ionic conductivity of both phases was studie...2012-01-01
32 Tiwari, AshutoshModification of high potential, high capacity Li2FeP 2O7 cathode material for lithium ion batteriesLi2FeP2O7 is a newly developed polyanionic cathode material for high performance lithium ion batteries. It is considered very attractive due to its large specific capacity, good thermal and chemical stability, and environmental benignity. However, the application of Li2FeP2O7 is limited by its low i...2012-01-01
33 Ostafin, AgnesNanomedicine making headway across the blood brain barrierNanotechnological advances implemented by nanomedicine have allowed significant development of imaging strategies, therapeutics and theranostics for many severe and life threatening diseases such as brain tumors, Alzheimer's disease, Parkinson's disease and other neurological disorders. The Blood-Br...2012-01-01
34 Tiwari, AshutoshMid- to long-wavelength infrared surface plasmon properties in doped zinc oxidesThis work investigates properties of surface plasmons on doped metal oxides in the 2-20 μm wavelength regime. By varying the stoichiometry in pulse laser deposited Ga and Al doped ZnO, the plasmonic properties can be controlled via a fluctuating free carrier concentration. This deterministic approa...2012-01-01
35 Scarpulla, MichaelPulsed and continuous wave solid phase laser annealing of electrodeposited CuInSe2 thin filmsCu(In,Ga)Se2 (CIGS) thin film photovoltaic absorber layers are primarily synthesized by vacuum based techniques at industrial scale. In this work, we investigate non-vacuum film synthesis by electrochemical deposition coupled with pulsed laser annealing (PLA) and or continuous wave laser annealing (...2012-01-01
36 Tiwari, AshutoshElectrical transport in ultrathin NdNiO3 filmsElectrical transport properties in ultrathin NdNiO3 films grown on single crystal LaAlO3 (001) substrate were characterized. Films with thicknesses ranging from 0.6 nm to 12 nm were grown using a pulsed laser technique. Four probe resistivity as a function of temperature measurements indicated a str...2012-01-01
37 Liu, FengElectronic strengthening of graphene by charge dopingGraphene is known as the strongest 2D material in nature, yet we show that moderate charge doping of either electrons or holes can further enhance its ideal strength by up to 17%, based on first-principles calculations. This unusual electronic enhancement, versus conventional structural enhancement,...2012-01-01
38 Liu, FengInterplay between quantum size effect and strain effect on growth of nanoscale metal thin filmsWe develop a theoretical framework to investigate the interplay between the quantum size effect (QSE) and strain effect on the stability of metal nanofilms. The QSE and strain effect are shown to be coupled through the concept of quantum electronic stress. First-principles calculations reveal large ...2012-01-01
39 Liu, FengAnisotropic strain enhanced hydrogen solubility in bcc metals: the independence on the sign of strainWhen an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, strain can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to strain ‘‘monotonically,'' increasing (decreasing) with...2012-01-01
40 Scarpulla, MichaelPulsed laser processing of electrodeposited CuInSe2 photovoltaic absorber thin filmsIn this report we investigate the effects of pulsed laser annealing (PLA) on both as-electrodeposited (ED) and electrodeposited-furnace annealed (EDA) CuInSe2 (CIS) samples by varying the laser fluence (J/cm2) and number of pulses. Results for as-ED samples indicate that liquid CIS-phase formation d...2011-01-01
41 Liu, FengTopological and electronic transitions in a Sb(111) nanofilm: the interplay between quantum confinement and surface effectWhen the dimension of a solid structure is reduced, there will be two emerging effects, quantum confinement and surface effect, which dominate at nanoscale. Based on first-principles calculations, we demonstrate that due to an intriguing interplay between these two dominating effects, the topologica...2012-01-01
42 Scarpulla, MichaelTemperature dependent conductivity of polycrystalline Cu 2ZnSnS 4 thin filmsThe temperature-dependent conductivity of Cu2ZnSnS4 (CZTS) thin films prepared by sulfurization of different sputtered ZnS/Cu/Sn stacks and also of the same stack annealed for different times was investigated from 30-300 K. Fitting of the through-thickness conductivity requires a model including Mot...2012-01-01
43 Liu, FengSpatial and energy distribution of topological edge states in single Bi(111) bilayerBy combining scanning tunneling microscopy and spectroscopy, angle-resolved photoemission spectroscopy, and density functional theory band calculations, we directly observe and resolve the one-dimensional edge states of single bilayer (BL) Bi(111) islands on clean Bi2Te3 and Bi(111)-covered Bi2Te3 s...2012-01-01
44 Smith, Grant D.Molecular dynamics of a 1,4-polybutadiene melt. Comparison of experiment and simulationWe have made detailed comparison of the local and chain dynamics of a melt of 1,4-polybutadiene (PBD) as determined from experiment and molecular dynamics simulation at 353 K. The PBD was found to have a random microstructure consisting of 40% cis, 50% trans, and 10% 1,2-vinyl units with a number-av...Polybutadiene melt; Molecular dynamics1999
45 Smith, Grant D.; Bedrov, Dmitro; Borodin, OlegQuantum-chemistry-based potential for poly(ester urethane)We have carried out extensive high-level quantum chemistry studies of the geometry, charge distribution, conformational energies, and hydrogen-bonding energies of model compounds for a family of Estane thermoplastic urethanes (TPUs). Upon the basis of these studies, we have parametrized a classical ...Estane thermoplastic urethanes; TPU; Charge distribution; Confromational energy2003
46 Pugmire, Ronald J.Investigation of the structural conformation of biphenyl by solid state 13C NMR and quantum chemical NMR shift calculationsThe principal values of the 13C chemical-shift tensor (CST) for biphenyl have been determined with the FIREMAT experiment. The internal dihedral angle between the benzene rings in biphenyl is estimated to fall between 10 and 20° on the basis of quantum mechanical calculations of the CST principal v...Carbon-13; Chemical-shift tensor; biphenyl; FIREMAT2001
47 Smith, Grant D.Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquidsAtomistic molecular dynamics simulations were performed on 1-butyl-3-methyl-imidazolium azide [bmim][N3], 1-butyl-2,3-dimethylimidazolium azide [bmmim][N3], and 1-butynyl-3-methylimidazolium azide [bumim][N3] ionic liquids. The many-body polarizable APPLE&P force field was augmented with parameters ...2012-01-01
48 Bedrov, Dmitro; Borodin, Oleg; Smith, Grant D.Comment on "On the accuracy of force fields for predicting the physical properties of dimethylnitramine"Zheng and Thompson have recently reported a comparison of three atomistic force fields for prediction of physical properties of dimethylnitramine (DMNA) from molecular dynamics (MD) simulations.1 Specifically, they compared the rigid molecule force field by Sorescu, Rice, and Thompson (SRT);2 the ge...2007
49 Scarpulla, MichaelDetection of ZnS phases in CZTS thin-films by EXAFSCopper zinc tin sulfide (CZTS) is a promising Earthabundant thin-film solar cell material; it has an appropriate band gap of ~1.45 eV and a high absorption coefficient. The most efficient CZTS cells tend to be slightly Zn-rich and Cu-poor. However, growing Zn-rich CZTS films can sometimes result in ...2011-01-01
50 Smith, Grant D.; Borodin, Oleg; Bedrov, Dmitro13C NMR spin-lattice relaxation and conformational dynamics in a 1,4-polybutadiene meltWe have performed molecular dynamics (MD) simulations of a melt of 1,4-polybutadiene (PBD, 1622 Da) over the temperature range 400?273 K. 13C NMR spin?lattice relaxation times (T1) and nuclear Overhauser enhancement (NOE) values have been measured from 357 to 272 K for 12 different resonances. The T...Polybutadiene melt; 13C NMR; Spin-lattice relaxation; Conformational dynamics; Molecular dynamics simulation2001
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