5 resultados para NB-DOPED TIO2

em Université de Lausanne, Switzerland


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The present study discusses the effect of iron doping in TiO2 thin films deposited by rf sputtering. Iron doping induces a structural transformation from anatase to rutile and electrical measurements indicate that iron acts as an acceptor impurity. Thermoelectric power measurement shows a transition between n-type and p-type electrical conduction for an iron concentration around 0.13 at.%. The highest p-type conductivity at room temperature achieved by iron doping was 10(-6) S m(-1).

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The Lower Carboniferous Baralacha La basaltic dykes were emplaced along transtensional faults. The basalts exhibit tholeiitic and alkaline affinities. The tholeiites are TiO2-poor, moderately enriched in light rare earth (LREE), and display Nb and Ta negative and Th positive anomalies. The alkali basalts, compared to the tholeiites, have higher TiO2, rare earth and highly incompatible trace element contents and greater LREE enrichments. The Nd and Pb isotope compositions of the Baralacha La basalts suggest that they derive from the partial melting of an enriched OIB mantle source. characterized by a HIMU component, and contaminated by the lower continental crust. The Baralacha La dyke swarm represent the remnants of an early rifting event on the northern Indian passive margin.

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Late Triassic submarine alkali basalts and hawaiites were collected from two superimposed tectonic slices belonging to the Kara Dere - Sayrun unit of the Middle Antalya nappes, southwestern Turkey. New determinations on conodont faunas allow to date this sequence to the Lower Carnian (Julian). The volcanic rocks show rather homogeneous compositions, with high TiO2 and relatively low MgO and Ni contents which suggest olivine fractionation. Their primitive mantle-normalised multi-elements plots show Nb and Ta enrichments relative to La, Pb negative anomalies and heavy rare earth element and Y depletions typical of intraplate ocean island basalts. These characteristics are consistent with the major and trace element compositions of their primary clinopyroxene phenocrysts, which do not show any feature ascribable to crustal contamination. The studied lavas display a restricted range of epsilon Nd (+4.6 to +5.2) which falls within the range of ocean island basalts. Their initial (Nd-143/Nd-144)i ratios are too low to be explained by a simple mixing line between depleted MORB mantle (DMM) and HIMU components. Their Pb and Nd isotopic compositions plot along a mixing line between HIMU component and an enriched mantle, the composition of which could be the result of the addition of about 5 to 8% of an EM2 component (recycled marine sediments) to DMM. The lack of evidence for any continental crustal component. in their genesis could be consistent with their emplacement in an intra-oceanic setting.

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We find that even very low Ni doping levels of high-quality Bi2Sr2Ca1Cu2O8 single crystals strongly affect the transition temperature T(c). We also observed that T(c) is not related to the total Ni concentration, but only to that of Ni engaged in NiO-type bonds. By controlling the temperature during crystal growth, one can modify the relative weight of Ni in NiO-type bonds with respect to other configurations-and therefore T(c).

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The story Numbers of 25 which reports the incident of Baal Peor is one among several texts in the book of Numbers focusing on divine wrath, its cause and its consequences. The present article offers a detailed analysis of the account which is difficult to understand because of certain jumps in the plot and because of its allusive style. Scholars mostly agree with the idea that the story grew in two or three stages. A lot of commentators believe that the original story contains only the apostasy of Peor caused by the Moabites (vv. 1-5). A subsequent story would focus on Pinchas' action against Zimri and Kospi, and a third layer is linked to the story of the war between Israel and Midian (Numbers 31). The problem of this theory however is that it seems impossible to reconstruct an original story about the matter of Peor; one does not find a satisfying end within vv. 1-5. Furthermore, v. 5, which belongs to the first, "Moabite", section, is already linked to the theme of Midian which dominates the second and the third passage. Moreover, the assemblage of different themes and motifs seem having been done with care: Regarding the two abuses of Israel reported in the story--idolatry and intermarriage--, they often go together in late polemical Deuteronomistic and post-Deuteronomistic layers (Ezra-Nehemiah). The double focus on Midian and Moab could both be polemically directed against certain Moses traditions found in the books of Exodus and Deuteronomy (concerning Moses' marriage with a Midianite women on the one hand and his stay and death and burial in Moab - in the vicinity of Beth Peor - on the other hand). As in several ANE traditions also in the Hebrew Bible the motif of "divine wrath" serves to interpret fatal historical events; in Num 25 as in other Biblical stories however it is doubtful whether the alleged incident (the plague) really have taken place and the story's plot is anchored in ancient Israel's history.