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111.
Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures 下载免费PDF全文
Katharina Skaja Christoph Bäumer Oliver Peters Stephan Menzel Marco Moors Hongchu Du Manuel Bornhöfft Christoph Schmitz Vitaliy Feyer Chun‐Lin Jia Claus Michael Schneider Joachim Mayer Rainer Waser Regina Dittmann 《Advanced functional materials》2015,25(46):7154-7162
Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta2O5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta4+ and Ta5+, which takes place over the entire former Pt/Ta2O5‐x interface of the dendrite‐like structure. 相似文献
112.
In this paper, the features and the most important results of the computer model ElGreen will be presented. With the help of the computer model it is possible to simulate various promotion strategies for different technologies in all EU countries. Policies that can be selected are the most important price driven strategies (feed-in tariffs, investment subsidies, tax incentives), capacity driven instruments (tradable green certificates, national or international wide trading system) and a voluntary green pricing system.The following recommendations are derived:
- (i)Regardless of which strategy is chosen credible sources must guarantee that the promotional strategy will survive a specified planning horizon;
- (ii)The differences between either national trading, international trading or feed-in tariffs are very small if the design of the promotional system is optimised;
- (iii)When introducing a TGC system it is of paramount importance that no mix up between existing and new capacities takes place.
113.
Kalpana R. Dey Tapas Debnath Claus H. Rüscher Margareta Sundberg Altaf Hussain 《Journal of Materials Science》2011,46(5):1388-1395
Samples of nominal compositions, Cs0.25Nb
y
W1−y
O3 and Cs0.3Nb
y
W1−y
O3 with 0.0 ≤ y ≤ 0.25 and 0.0 ≤ y ≤ 0.3 were synthesized using appropriate amounts of Cs2WO4, WO3 and WO2 in evacuated and closed silica glass tubes at 800 °C. The polycrystalline products contain hexagonal shaped crystals of up
to 15 μm diameter as long as y ≤ 0.15. X-ray powder patterns of the samples reveal the formation of hexagonal tungsten bronze (HTB-I) type phase with y < 0.1. A mixture of HTB-I and an analogous less reduced hexagonal tungsten bronze (HTB-II) type phase is seen when y ≥ 0.1. HTB-II content increases with increasing y, revealing close similarity to bronzoid type phases when y = x. Results of SEM/EDX analysis also support a partial substitution of tungsten by niobium in the HTB-I type phase. Infrared
absorption and optical reflectivity data shows the effect of increasing amount of non-metallic phase for y > 0.1 and the effect of counterdoping by Nb5+/W5+ substitution in the metallic HTB-I type phase for y ≤ 0.1, respectively. Reinvestigations in the system Rb0.3Nb
y
W1−y
O3 (0.0 ≤ y ≤ 0.175) show similar results with increasing content of HTB-II type phase related with y. 相似文献
114.
115.
116.
Deriving soil critical limits for Cu, Zn, Cd, and Pb: a method based on free ion concentrations 总被引:2,自引:0,他引:2
We present a method to calculate critical limits of cationic heavy metals accounting for variations in soil chemistry. We assume the free metal ion concentration (Mfree) to be the most appropriate indicator of toxicity, combined with a protective effect of soil cations (e.g., H+, Ca2+). Because soil metal cations tend to covary with pH, the concentration of Mfree exerting a given level of toxic effect (Mfree,toxic) can be expressed as a function of pH alone. We use linear regression equations to derive Mfree,toxic in toxicity experiments from soil pH, organic matter content, and endpoint soil metal. Chronic toxicity data from the literature, for plants, invertebrates, microbial processes, and fungi are interpreted in terms of an average log Mfree,toxic together with distributions of species sensitivity. This leads to critical limit functions to protect 95% of species, of the form log Mfree,CRIT = (pH + gamma. Appreciable effects of soil pH upon log Mfree,CRIT are found, with alpha = -1.21 (Cu), -0.34 (Zn), -0.43 (Cd), and -0.83 (Pb). Critical limit functions in terms of the geochemically active soil metal (Msoil,CRIT), that pool of metal which controls the free ion concentration, have also been derived, with soil pH and organic matter content as variables. The pH effect on Msoil,CRIT is relatively small, with slopes of 0.05 (Cu), 0.19 (Zn), 0.16 (Cd), and 0.20 (Pb), since the effect of pH on Mfree,CRIT is countered by the variation of Mfree with pH. 相似文献
117.
118.
Max Müller A. Rammul K. Windisch M. Claus und A. Oelker 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1904,7(12):753-755
Ohne Zusammenfassung 相似文献
119.
120.
Johannes Prescher und Reinhold Claus 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1920,40(7-8):208
Ohne ZusammenfassungMitteilung aus dem Staatlichen Chemischen Untersuchungsamt für die Auslandsfleischbeschau in Cleve (Vorsteher: Dr. M. Fritzsche). 相似文献