skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Molybdenum-Suboxide Thin Films as Anode Layers in Planar Lithium Microbatteries
In this paper, we investigate the effects of operational conditions on structural, electronic and electrochemical properties on molybdenum suboxides (MoO3-δ) thin films. The films are prepared using pulsed-laser deposition by varying the deposition temperature (Ts), laser fluence (Φ), the partial oxygen pressure (PO2) and annealing temperature (Ta). We find that three classes of samples are obtained with different degrees of stoichiometric deviation without post-treatment: (i) amorphous MoO3-δ (δ < 0.05) (ii) nearly-stoichiometric samples (δ ≈ 0) and (iii) suboxides MoO3-δ (δ > 0.05). The suboxide films 0.05 ≤ δ ≤ 0.25 deposited on Au/Ti/SiO2/flexible-Si substrates with appropriate processing conditions show high electrochemical performance as an anode layer for lithium planar microbatteries. In the realm of simple synthesis, the MoO3-δ film deposited at 450 °C under oxygen pressure of 13 Pa is a mixture of α-MoO3 and Mo8O23 phases (15:85). The electrochemical test of the 0.15MoO3-0.85Mo8O23 film shows a specific capacity of 484 µAh cm−2 µm−1 after 100 cycles of charge-discharge at a constant current of 0.5 A cm−2 in the potential range 3.0-0.05 V.  more » « less
Award ID(s):
1827745
PAR ID:
10227598
Author(s) / Creator(s):
; ; ; ; ; ; ;
Date Published:
Journal Name:
Electrochem
Volume:
1
Issue:
2
ISSN:
2673-3293
Page Range / eLocation ID:
160 to 187
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, Journal of Vacuum Science & Technology A)
    Among ABO3 perovskites, SrMoO3 possesses the lowest electrical resistivity in addition to having high optical transparency in the visible spectrum. This unusual combination of material properties allows it to be a potential replacement for indium tin oxide as a transparent electrode. Thus far, its thin film synthesis has been challenging and limited primarily to pulsed laser deposition and sputtering. Here, we report the growth of SrMoO3 thin films by suboxide molecular beam epitaxy. We demonstrate that optically transparent and conductive SrMoO3 films can be grown by supplying elemental strontium via a conventional effusion cell and thermally evaporating MoO3 pellets as a molybdenum source. The direct supply of a molecular oxygen flux to the MoO3 charge was utilized to prevent reduction to lower oxidation states of the charge to ensure congruent evaporation and, thus, a stable MoO3 molecular flux. The optimal growth conditions were found by varying the Sr to MoO3 flux ratio determined from quartz crystal microbalance measurements and monitoring the growth by reflection high-energy electron diffraction. SrMoO3 thin films with 21 nm thickness were confirmed to be optically transparent with transmission between 75 and 91% throughout the visible spectral range and electrically conducting with a room temperature resistivity of 5.0 × 10−5 Ω cm. This realization of this thin film growth method can be further expanded to the growth of other transition metal perovskites in which cations have extremely low vapor pressure and cannot be evaporated in elemental forms. 
    more » « less
  2. ; ; ; ; ; ; (, Journal of materials science Materials in engineering)
    Abstract This study reports a pulsed laser deposition-assisted synthesis of highly metallic titanium nitride (TiN) and a series of semiconducting titanium oxynitride (TiNxOy) compounds in thin film form with tunable plasmonic properties by carefully altering the nitrogen (N)-oxygen (O) ratio. The N/O ratio was controlled from 0.3 (highest oxygen doping of TiN) to ~ 1.0 (no oxygen doping of TiN) by growing the TiN films under nitrogen pressures of 50, 35, and 10 mTorr and high vacuum conditions of 2 × 10−6 Torr with no external gas introduced. The presence of nitrogen in the deposition chamber during the film growth affects the gas phase oxidation of TiN to TiNxOyby increasing the mean free path-dependent N and O inter-collisions per second by two to three orders of magnitudes. The evidence of increased oxidation of TiN to TiNxOywith an increase in nitrogen deposition pressure was obtained using X-ray photoelectron spectroscopy analysis. While the TiN samples deposited in high vacuum conditions had the highest reflectance, TiNxOythin films were also found to possess high reflectance at low frequency with a well-defined edge around 20,000 cm−1. Furthermore, the vacuum-deposited TiN samples showed a large negative dielectric constant of -330 and the largest frequency of zero-crossing at 25,000 cm−1; the TiNxOysamples deposited in the presence of nitrogen ambient also showed promising plasmonic applications at the near-mid infrared range. A comparison of the dielectric constant and loss function data of this research with the literature values for noble metals seems to indicate that TiN and TiNxOyhave the potential to replace gold and silver in the visible and near-infrared spectral regions. 
    more » « less
  3. ; ; ; (, Journal of Vacuum Science & Technology A)
    The emerging optoelectronic material family of transition metal dichalcogenides may be useful in flexible electronics. However, only MoS2 has been grown directly as thin films on polymer substrates, owing in part to the high deposition temperatures typically required to prepare these materials. Changing vapor deposition chemistry can allow much lower film growth temperatures. We show that when using tetrakis(dimethylamido)zirconium(IV), Zr(NMe2)4, and H2S as precursors, low-temperature chemical vapor deposition affords films of zirconium(IV) sulfide (ZrS2) directly on polymer substrates. Stoichiometric and crystalline ZrS2 films can be deposited with good adhesion on polyimide (Kapton) and polyether ether ketone (PEEK) substrates at 150–200 °C. The films deposited on polydimethylsiloxane (PDMS) substrates were stoichiometric and crystalline, but not well adhered. Films on all substrates were polycrystalline with small (20–30 nm) grains, highly oriented in the [001] direction of the 1T ZrS2 phase. The films grown on PEEK have resistivities ca. 625 Ω cm, two orders of magnitude higher than ZrS2 films deposited at 800–1000 °C from ZrCl4 and sulfur. The films grown on Kapton are similarly conductive, whereas films on PDMS are not conductive. 
    more » « less
  4. ; ; ; ; (, Advanced Electronic Materials)
    Abstract This work characterizes the structural, magnetic, and ferroelectric properties of epitaxial LuFeO3orthoferrite thin films with different Lu/Fe ratios. LuFeO3thin films are grown by pulsed laser deposition on SrTiO3substrates with Lu/Fe ratio ranging from 0.6 to 1.5. LuFeO3is antiferromagnetic with a weak canted moment perpendicular to the film plane. Piezoresponse force microscopy imaging and switching spectroscopy reveal room temperature ferroelectricity in Lu‐rich and Fe‐rich films, whereas the stoichiometric film shows little polarization. Ferroelectricity in Lu‐rich films is present for a range of deposition conditions and crystallographic orientations. Positive‐up‐negative‐down ferroelectric measurements on a Lu‐rich film yield ≈13 µC cm−2of switchable polarization, although the film also shows electrical leakage. The ferroelectric response is attributed to antisite defects analogous to that of Y‐rich YFeO3, yielding multiferroicity via defect engineering in a rare earth orthoferrite. 
    more » « less
  5. ; ; (, Journal of Vacuum Science & Technology A)
    Lithium lanthanum tantalate (Li3xLa1/3−xTaO3, x = 0.075) thin films were grown via pulsed laser deposition using background gas atmospheres with varying partial pressures of oxygen and argon. The background gas composition was varied from 100% to 6.6% oxygen, with the pressure fixed at 150 mTorr. The maximum ion conductivity of 1.5 × 10−6 S/cm was found for the film deposited in 100% oxygen. The ion conductivity of the films was found to decrease with reduced oxygen content from 100% to 16.6% O2 in the background gas. The 6.6% oxygen background condition produced ion conductivity that approached that of the 100% oxygen condition film. The lithium transfer from the target to the film was found to decrease monotonically with decreasing oxygen content in the background gas but did not account for all changes in the ion conductivity. The activation energy of ion conduction was measured and found to correlate well with the measured ion conductivity trends. Analysis of x-ray diffraction results revealed that the films also exhibited a change in the lattice parameter that directly correlated with the ion conduction activation energy, indicating that a primary factor for determining the conductivity of these films is the changing size of the ion conduction bottleneck, which controls the activation energy of ion conduction. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email