Showing papers by "Claes-Göran Granqvist published in 2004"
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TL;DR: In this paper, a study of spattered Nitrogen-doped Titanium Dioxide thin film in aqueous electrolyte was conducted in order to study the properties of the thin film.
73 citations
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TL;DR: Nanomaterials for Environmental Applications: Novel WO3-based Gas Sensors made by Advanced Gas Deposition as discussed by the authors, is a novel WO 3-based gas sensor made by advanced gas deposition.
63 citations
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TL;DR: Gas Sensing Properties of Nanocrystalline WO3 Films made by Advanced Reactive Gas Deposition as discussed by the authors, which are made by advanced reactive gas deposition, are discussed in Section 2.
Abstract: Gas Sensing Properties of Nanocrystalline WO3 Films Made by Advanced Reactive Gas Deposition
60 citations
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TL;DR: In this paper, an alternative high-temperature route employing advanced reactive gas deposition for structure engineering of WO 3 nanoparticles in making nanocrystalline films, especially, for gas sensing applications, is considered.
Abstract: Fine-grained crystalline or amorphous thin films are normally produced by atomistic deposition of species under conditions giving a low adaton mobility. Here we consider an alternative high-temperature route employing advanced reactive gas deposition for structure engineering of WO 3 nanoparticles in making nanocrystalline films, especially, for gas sensing applications. For instance, structure engineering may be necessary in the case of very fine-grained n-type semiconductor oxide films in order to increase the electrical conductivity of the films. The crystal structure of WO 3 together with its different phases makes possible structure engineering of its nanoparticles by high-temperature processes such as the reactive gas deposition. Produced nanocrystalline WO 3 films in metastable tetragonal crystal structure were found to be very sensitive to H 2 S in air already at room temperature.
36 citations
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TL;DR: In this paper, the authors report measurements and analysis of non-Gaussian components in nanoparticle Pdz(WO3)1-z film gas sensors, with z being 0.01 or 0.12, in different ambients.
Abstract: It has previously been shown that resistance fluctuations in resistive sensors provide enhanced sensitivity and selectivity for gas detection. We report measurements and analysis of non-Gaussian components in nanoparticle Pdz(WO3)1-z film gas sensors, with z being 0.01 or 0.12, in different ambients. These components can be characterized by higher-order spectra. Contour plots are given of bispectra, and plots of integrated bispectra and trispectra. The phase of the integrated higher-order spectra is analyzed as well.
16 citations
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7 citations
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TL;DR: In this article, the authors introduce materials for energy efficiency and solar energy utilization and discuss some current trends for basic research and development, which involve thin surface coatings, such as solar absorber surfaces, transparent infrared reflectors and transparent conductors, large area chromogenics for transmittance control in smart windows, and transparent convection-suppressing materials, whereas solar cell materials are not included.
Abstract: This paper introduces materials for energy efficiency and solar energy utilization and discusses some current trends for basic research and development. Most of the materials involve thin surface coatings. Overviews are given for solar absorber surfaces, transparent infrared reflectors and transparent conductors, large-area chromogenics for transmittance control in “smart windows”, and transparent convection-suppressing materials, whereas solar cell materials are not included. The paper also treats a few examples of specific coatings that are presently being investigated; data are given for angular-selective transmittance through porous Cr films with oblique columnar microstructure, transparent and conducting non-stoichiometric SnO2 films, and chromogenic effects in Li-intercalated VO2 films.
5 citations
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25 May 2004TL;DR: Highly Sensitive and Selective WO3 Nanoparticle Gas Sensor Operating in Thermally Modulated Dynamic Mode (TDDM) as mentioned in this paper, which operates in TMD mode.
Abstract: Highly Sensitive and Selective WO3 Nanoparticle Gas Sensor Operating in Thermally Modulated Dynamic Mode
4 citations
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25 May 2004TL;DR: In this article, a dual-beam gas deposition of PdxWO3 nanoparticle films was used to detect ethanol and hydrogen gas in the presence of resistance noise and dc resistance.
Abstract: Nanoparticle films of PdxWO3, with x being 0.01 or 0.12, were made by dual-beam gas deposition. Resistance noise as well as dc resistance were measured during exposure to ethanol and hydrogen gas. For ethanol concentrations exceeding 50 ppm, changes in the resistance noise gave 300 times larger detection sensitivity than changes in the dc resistance. This sensitivity reached a maximum at 250 °C and was very reproducible for ethanol sensing.
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25 May 2004TL;DR: In this paper, WO3 nanoparticles were generated by gas deposition and the size distribution of the agglomerates was found to be log-normal, i.e., similar to the size distributions of the gas-phase nanoparticles forming the deposit.
Abstract: WO3 nanoparticles were generated by gas deposition. Deposits on Al substrates were studied by scanning force microscopy operated in the intermittent-contact (tapping) mode. At low surface coverage (< 0.5 %), we observed single nanoparticles with a mean size of ~ 1.5 nm. An increase of the amount of particles led to agglomerates, which appeared at surface coverages as low as 2 to 4 %. At full coverage the mean agglomerate size was ~ 5 nm. This value did not change as the sample was annealed at temperatures up to 250 °C. The size distribution of the agglomerates was found to be log-normal, i.e., similar to the size distribution of the gas-phase nanoparticles forming the deposit. For explaining the obtained log-normal size distribution of the agglomerates simulations of the agglomeration process were also carried out.