نتایج جستجو برای: niobium

تعداد نتایج: 3152  

Journal: :Annalen der Chemie und Pharmacie 1844

Journal: :Acta Physica Polonica A 2023

In this presented work, pure and holmium, niobium, holmium–niobium co-doped titanium dioxide nanopowders were synthesized by the sol–gel method. Their morphological, structural, optical, photocatalytic properties analyzed scanning electron microscopy, X-ray diffraction, UV–visible spectrophotometer. The activities of examined using ultraviolet light. results have shown that doping both with a s...

2007
Shixiong Zhang T. Venky Venkatesan

Title of dissertation: UNUSUAL ELECTRONIC TRANSPORT AND MAGNETISM IN TITANIUM OXIDE BASED SEMICONDUCTORS AND METALS Shixiong Zhang, Doctor of Philosophy, 2007 Dissertation directed by: Professor T. Venky Venkatesan Department of Physics The main objective of this thesis was to explore the structural, electrical, magnetic and optical properties of titanium based novel oxide thin films, such as t...

2017
Yan Xin Yang-Xin Yu

The data reported in this article are structural and physicochemical properties for bare and F, O, OH and CH3O-functionalized Nb n+1C n (n = 1, 2, 3 and 4) MXenes. The structural properties are presented as top views and side views from the X direction of the optimal structures of studied MXenes. The physicochemical properties include quantum capacitances, electrostatic potentials and electroni...

Journal: :Beilstein Journal of Organic Chemistry 2005
Luiz Carlos da Silva Filho Valdemar Lacerda Júnior Mauricio Gomes Constantino Gil Valdo José da Silva Paulo Roberto Invernize

We have found that some of the usually poor dienophiles (2-cycloenones) can undergo Diels-Alder reaction at -78 degrees C with unusually high stereoselectivity in the presence of niobium pentachloride as a Lewis acid catalyst. A remarkable difference in reaction rates for unsubstituted and alpha- or beta-methyl substituted 2-cycloenones was also observed.

2001
Mauricio Gomes Constantino Valdemar Lacerda Valquiria Aragão

Epoxide ring opening is a frequently required transformation in Organic Synthesis. In this paper we describe the application of NbCl5 for this purpose using three different substrates. Chlorohydrins, 1,2-diols, products containing solvent residues as well as rearrangement products are obtained, depending on both the substrate structure and reaction conditions. Rationalizations to account for so...

Journal: :Journal of Organometallic Chemistry 1982

2011
Tina Wang Michael J. Kelley

The focus of this project was to design and construct a model controlled-flow apparatus to study electropolishing of one cm 2 niobium coupons at surface flow rates typical of cavity processing. A simulation of the apparatus was constructed using CFDesign, a flow and thermal simulation software, to ensure that the selected dimensions may be expected to provide steady-state, laminar flow across t...

2015
Lucas Janson Matthew Klein Heather Lewis Andrew Lucas Andrew Marantan Katherine Luna

We describe an experiment in superconductivity suitable for an advanced undergraduate laboratory. Point-contact spectroscopy is performed by measuring the differential conductance between an electrochemically etched gold tip and a 100-nm superconducting niobium film with a transition temperature Tc ≈ 7 K. By fitting the results to Blonder-Tinkham-Klapwijk theory using a finite lifetime of quasi...

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