Showing papers by "R. B. van Dover published in 2006"
TL;DR: In this article, the authors describe methodologies for the generation and screening of combinatorial libraries of electrocatalyst materials for fuel cell applications, generated by cosputtering of three elements onto a Si substrate coated with a Ta adhesion underlayer.
Abstract: We describe methodologies for the generation and screening of combinatorial libraries of electrocatalyst materials for fuel cell applications, generated by cosputtering of three elements onto a Si substrate coated with a Ta adhesion underlayer. Screening was carried out via a fluorescence assay as well as by scanning electrochemical microscopy. Whereas the former provided rapid qualitative screening with limited spatial resolution, the latter provided high spatial resolution. The fluorescence screening method was tested on Pt, PtBi, PtPb, and PtRu nanoparticles, while both methods were tested on a film containing a Pt–Bi–Pb ternary composition spread.
63 citations
TL;DR: In this article, it was shown that the temperature coefficient of the resonant frequency of the tetragonal ceramics, τf, correlates to the measured tetragonality ratio (c/a).
Abstract: We show that the temperature coefficient of the resonant frequency of the tetragonal ceramics, τf, correlates to the measured tetragonality ratio (c/a). This is based on a previously established relation between c/a and the oxygen positional parameter u. As the c/a ratio approaches its ideal value, the value of u also approaches its ideal value and the distortion of the oxygen octahedral decreases, leading to an increase of τf to a positive value. Theses relations were confirmed by experimental measurements using three dielectric compositions, with varying c/a ratio near ideal.
10 citations
TL;DR: In this paper, the dependence of the octahedral bond valence on the microwave dielectric properties of (1-x)Al 0.5 Ta 0.6, Mg 0.33Ta 0.67 O 2 transformed into a tetragonal structure was investigated.
Abstract: The dependence of the octahedral bond valence on the microwave dielectric properties of (1-x)Al 0.5 Ta 0.5 O 2-x Mg 0.33 Ta 0.67 O 2 (0.6≤x≤ 1.0) ceramics was investigated. As x increased beyond 0.6, (1-x)Al 0.5 Ta 0.5 O 2 -xMg 0.33 Ta 0.67 O 2 transformed into a tetragonal structure. As x increased, the dielectric constant (e r ) increased from 25.8 to 27.4 due to an increase in ionic polarizability, and the discrepancy between the observed dielectric polarizabilities (α obs. ) and the theoretical ones (α theo. ) increased from 4.02% to 4.68% with the decrease of the octahedral bond valence from 3.759 to 3.726 due to the increase of the unit cell volume. The temperature coefficients of the resonant frequencies (τ f ) were found to depend on the octahedral bond valence and dielectric mixing rule.
1 citations
21 May 2006
TL;DR: In this paper, the maximum photoluminescence of erbium-containing oxides was evaluated using a composition spread approach, and the results showed that the Er:Zn-Ge-SiO system is particularly promising.
Abstract: The composition-spread approach provides a means for evaluating the maximum photoluminescence in new systems of erbium-containing oxides. Hundreds of combinations of zinc-, bismuth-, gadolinium-, and aluminum-substituted SiO 2 are evaluated; the Er:Zn-Ge-Si-O system is particularly promising.