Showing papers by "Claes-Göran Granqvist published in 1996"
230 citations
TL;DR: In this paper, the authors measured the impedance responses of pure and fluorinated Ti oxide films in the lithium containing electrolyte, and found that the size of the charge transfer resistance was associated with the Li ion injection from the electrolyte into the film, and a modest fluorination lowered this resistance by about two orders of magnitude.
Abstract: Films of Ti oxide and Ti oxyfluoride were produced by reactive magnetron sputtering of Ti in Ar+O2(+CF4). Compositional and structural analyses were accomplished by Rutherford backscattering spectrometry, x‐ray diffraction (XRD), infrared absorption spectrometry, and atomic force microscopy (AFM). Electrochemical characterization of films immersed in a Li conducting electrolyte was performed with cyclic voltammetry and coulometric titration. Detailed impedance spectra were recorded for the 2×105–1×10−3 Hz range. The impedance responses of pure and fluorinated Ti oxide films in the lithium containing electrolyte differed significantly even if their structures, according to AFM and XRD, were very similar. One main difference was the size of the charge transfer resistance, presumably connected to the Li ion injection from the electrolyte into the film. A modest fluorination lowered this resistance by about two orders of magnitude. The voltammetric and the impedance responses, as well as the magnitude of the ...
44 citations
TL;DR: In this article, a reactive rf magnetron sputtering onto ITO-coated glass was used to make a film of Sn oxide and oxyfluoride, which was analyzed by Rutherford backscattering spectrometry, x-ray diffraction, and atomic force microscopy.
Abstract: Films of Sn oxide and oxyfluoride were made by reactive rf magnetron sputtering onto ITO‐coated glass. We analyzed the composition by Rutherford backscattering spectrometry, the structure by x‐ray diffraction, and the surface topography by atomic force microscopy. Li intercalation from a liquid electrolyte was more facile in the oxide than in the oxyfluoride, as found from cyclic voltammetry. Impedance spectra were taken for a wide range of frequencies and polarizing voltages. Nyqvist diagrams were interpreted from a circuit model with elements representing Li insertion at the electrolyte/film interface and electron insertion at the film/ITO interface. The data were consistent with a fractal surface of the Sn oxide film, with a dimension in excellent agreement with measures obtained through several independent techniques. The chemical diffusion coefficient was ∼10−13 cm2/s and slightly decreasing with increasing potential for all films.
28 citations
TL;DR: In this article, the authors measured the transmittance and reflectance of W oxide and oxyfluoride films in the 0.4-1 μm wavelength range using a newly developed instrument and found that the ratio between diffuse and total optical response was <0.2% for transmittances and <1% for the reflectance irrespective of the electrochromic absorption level.
Abstract: Films of W oxide and oxyfluoride were made by reactive sputtering, and electrochromic absorption modulation was obtained by subsequent electrochemical Li intercalation. Total and diffuse transmittance and reflectance were measured in the 0.4–1 μm wavelength range using a newly developed instrument. The ratio between diffuse and total optical response was <0.2% for the transmittance and <1% for the reflectance irrespective of the electrochromic absorption level. These magnitudes of the scattering are acceptable for practical smart windows applications and lend credence to a description of electrochromism in terms of localized absorption centers. Vector perturbation theory for light scattering by a film with rough interfaces could be reconciled with the data, assuming uncorrelated roughness.
24 citations
TL;DR: In this paper, the optical transmittance and Mossbauer spectra were recorded for progressively increased lithiation and it was likely that the lithium is located in internal double layers in the film.
Abstract: Lithiated Sn oxide films, denoted LixSnO2, were produced by reactive rf magnetron sputtering of Sn and electrochemical post‐treatment. Optical transmittance and Mossbauer spectra were recorded for progressively increased lithiation. Increasing x from zero to ∼0.1 did not have any significant effect on the optical data or Mossbauer spectra, and it is likely that the lithium is located in internal double layers in the film. Further increasing x from ∼0.1 to ∼0.2 yielded significant transmittance drops and Mossbauer spectra unambiguously showing a conversion Sn4+→Sn2+. Hence the optical absorption can be reconciled with intervalency transitions as in other cathodically coloring electrochromic oxides. Electrocrystallization appeared to dominate the electrochemistry at x≳0.2.
20 citations
TL;DR: The surface roughness of evaporated CaF2 films was studied by Atomic Force Microscopy as mentioned in this paper, where scaling exponents for kinetic roughening, α and β, were found to be close to 1 and 1 2, respectively.
20 citations
TL;DR: In this paper, the fractal dimension of a self-affine surface relief was investigated in a Li+-conducting electrolyte with reactive r.f. magnetron sputtering and cyclic voltammograms taken at different sweep rates were interpreted in terms of a unique structural parameter.
18 citations
TL;DR: In this article, a new instrument for automatic recordings of angular dependent transmittance through thin film samples is described and the output is a polar plot giving a schematic and convenient overview of the optical performance.
17 citations
TL;DR: In this article, a theoretical framework based on the Maxwell Garnett and Bruggeman effective medium theories is proposed for obliquely sputter deposited films based on Cr, Al, or Ti.
14 citations
TL;DR: In this paper, a W-oxide-based films were produced by reactive d.c. magnetron sputtering and fluorination and substrate bias were used to modify the film properties.
9 citations
TL;DR: In this paper, a review of sputter deposited Woxide-based films is presented, showing their capacity as counter electrodes in transparent electrochromic devices and showing that angular angle deposition could yield angular selectivity.