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Title: Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode

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Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Journal of Power Sources
Additional Journal Information:
Journal Volume: 275; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-06-01 03:25:23; Journal ID: ISSN 0378-7753
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Citation Formats

Jung, WooChul, Kim, Jae Jin, and Tuller, Harry L. Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode. Netherlands: N. p., 2015. Web. doi:10.1016/j.jpowsour.2014.11.084.
Jung, WooChul, Kim, Jae Jin, & Tuller, Harry L. Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode. Netherlands. doi:10.1016/j.jpowsour.2014.11.084.
Jung, WooChul, Kim, Jae Jin, and Tuller, Harry L. 2015. "Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode". Netherlands. doi:10.1016/j.jpowsour.2014.11.084.
title = {Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode},
author = {Jung, WooChul and Kim, Jae Jin and Tuller, Harry L.},
abstractNote = {},
doi = {10.1016/j.jpowsour.2014.11.084},
journal = {Journal of Power Sources},
number = C,
volume = 275,
place = {Netherlands},
year = 2015,
month = 2

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.jpowsour.2014.11.084

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Cited by: 17works
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  • Highlights: • HfTiO{sub 4} thin films were deposited by magnetron co-sputtering. • As-prepared and annealed at 800 °C thin films were nanocrystalline. • Optical properties and hardness were investigated in relation to thin films structure. • Hardness was 3-times higher in the case of as-deposited thin films. • HfTiO{sub 4} thin films are suitable for use as optical coatings with protective properties. - Abstract: Titania (TiO{sub 2}) and hafnium oxide (HfO{sub 2}) thin films are in the focus of interest to the microelectronics community from a dozen years. Because of their outstanding properties like, among the others, high stability, highmore » refractive index, high electric permittivity, they found applications in many optical and electronics domains. In this work discussion on the hardness, microstructure and optical properties of as-deposited and annealed HfTiO{sub 4} thin films has been presented. Deposited films were prepared using magnetron co-sputtering method. Performed investigations revealed that as-deposited coatings were nanocrystalline with HfTiO{sub 4} structure. Deposited films were built from crystallites of ca. 4–12 nm in size and after additional annealing an increase in crystallites size up to 16 nm was observed. Micro-mechanical properties, i.e., hardness and elastic modulus were determined using conventional load-controlled nanoindentation testing. the annealed films had 3-times lower hardness as-compared to as-deposited ones (∼9 GPa). Based on optical investigations real and imaginary components of refractive index were calculated, both for as-deposited and annealed thin films. The real refractive index component increased after annealing from 2.03 to 2.16, while extinction coefficient increased by an order from 10{sup −4} to 10{sup −3}. Structure modification was analyzed together with optical energy band-gap, Urbach energy and using Wemple–DiDomenico model.« less
  • Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H{sub 2} plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at. % and O contents typically below 0.2 at. % as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of ∼0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase δ-ZrH{sub 2} (CaF{submore » 2} type structure) at H content >∼55 at. % and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5–7 GPa for the δ-ZrH{sub 2} films that is slightly harder than the ∼5 GPa determined for Zr films and with coefficients of friction in the range of 0.12–0.18 to compare with the range of 0.4–0.6 obtained for Zr films. Wear resistance testing show that phase-pure δ-ZrH{sub 2} films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of ∼100–120 μΩ cm for the δ-ZrH{sub 2} films, which is slightly higher compared to Zr films with values in the range 70–80 μΩ cm.« less
  • Coatings of tantalum nitride with various compositions were deposited on silicon substrates using unbalanced reactive magnetron sputtering. An optical emission spectrometer was used to monitor the ratio of tantalum to nitrogen particles in the plasma in real time. The coatings were characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). The primary nitride phases (Ta, Ta{sub 2}N, TaN) in the films were determined using XRD and XPS. The elemental composition was revealed from XPS measurements. The refractive indices were deduced from analysis of the SE data, which were subsequently simulated using the Drude-Lorentz model. The resistivitymore » and electron mean free paths were deduced from this simulation and were correlated to the film composition and microstructure. The resistivity increased whereas the electron mean free path decreased with an increase in nitrogen content or a decrease in grain size.« less
  • Structure, magnetic and electrical transport properties of the reactive sputtered iron nitride films fabricated at different substrate temperatures (T{sub s}) and nitrogen flow rates (F{sub N{sub 2}}) were investigated systematically. The single-phase polycrystalline {gamma}'-Fe{sub 4}N film was obtained at F{sub N{sub 2}} = 20 sccm and T{sub s} = 450 deg. C. The films are soft ferromagnetic at room temperature. The electrical resistivity ({rho}) of the films fabricated at different F{sub N{sub 2}} and T{sub s} decreases with the decreasing temperature, showing a metallic behavior. Meanwhile, a variety of magnetoresistance (MR) behaviors were observed depending on the applied magnetic fieldmore » and measuring temperature. It can be deduced that the complex MR behaviors are dominated by Lorentz force, spin-orbit interaction, and weak localization effect.« less
  • This paper presents the photocatalytic and photoelectrochemical (PEC) properties of Ta{sub 3}N{sub 5} microcolumn films. The highlights include (1) overcoming the fundamental barrier of standard reactive sputtering for fabricating microcolumns; (2) preventing unnecessary complexity from complicating facile sputtering; (3) an alternative but effective approach for fabricating Ta{sub 3}N{sub 5} without using caustic NH{sub 3} gases; (4) investigating morphology tuning for favorable photocatalysis and PEC reactions; and (5) elucidating the relationships of the structures, morphologies, and properties of Ta{sub 3}N{sub 5} microcolumns. High-resolution transmission electron microscopy and selective-area electron diffraction verified the polycrystallinity of Ta{sub 3}N{sub 5} microcolumns, of which themore » elemental compositions and stoichiometry were measured using electron-probe energy dispersive spectroscopy, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. The corresponding band gap was determined to be approximately 2.1 eV. The sample exhibited a superior photodegradation capability; the photodegradation rate constant k was determined to be approximately 1.4 times higher than that of P25 under UV irradiation. A photocatalytic and PEC cycling test indicated the photodegradation reusability and photostability of the Ta{sub 3}N{sub 5} microcolumns. The incident photon-to-current efficiency performance reached 6%, suggesting that these microcolumns hold potential for application in PEC devices.« less