Search results for "niobium"

Enhancement of photoconversion efficiency in dye-sensitized solar cells exploiting pulsed laser deposited niobium pentoxide blocking layers

2015

Abstract Among all the photovoltaic technologies developed so far, dye-sensitized solar cells are considered as a promising alternative to the expensive and environmentally unfriendly crystalline silicon-based solar cells. One of the possible strategies employed to increase their photovoltaic efficiency is to reduce the charge recombination at the cell conductive substrate through the use of a compact blocking layer. In this paper, we report on the fabrication and characterization of dye-sensitized solar cells employing niobium pentoxide (Nb 2 O 5 ) thin film blocking layer deposited through the pulsed laser deposition technique on conductive substrates. The careful selection of the optimal…

Investigation of the kinetics of growth of anodic oxide films on niobium by galvanostatic and tensiodynamic experiments

1990

Abstract The kinetics of growth of anodic oxide films on niobium has been investigated by interferometric methods. Tensiodynamic experiments allow the growth of the films at constant rate. Photoeffects during the growth of the films under absorbed light give additional information on the growth process.

Physical and Chemical Principles of Obtaining Thermally Resistant Containers for Treatment of High Purity Niobium and Tantalum Compounds

2011

Mathematical modelling of the distribution of strain in layered quartz ceramics with protective coating of niobium (tantalum) pentoxide from two sides is reported. It is found that fragmentation of the basic layer (decreasing the area of the continuous boarder between layers) and smoothing of sharp edges of the base fragments should reduce the strains on the boundary between the substrate and coating and, correspondingly, enhance the thermal resistance of the samples. Treatment of the niobium pentoxide coating by concentrated light induces a network of fractal micro- and nano-size fractures that compensates the difference of thermal expansion between the layers.

Amorphous semiconductor—electrolyte junction. Impedance study on the a-Nb2 O5—electrolyte junction

1990

Abstract A systematic study of the impedance behaviour of the anodic niobium oxide film/aqueous electrolyte interface was carried out using the lock-in technique at different signal frequencies. The dependence of both components of the impedance on the electrode potential and on frequency is analysed by taking into account the amorphous nature of the films. The lack of long-range order in these oxide layers modifies the physical picture in respect to the case of single crystal semiconductors. A new equivalent circuit has been assumed, based on recent theory of an amorphous semiconductor Schottky barrier. Such a new approach allows the characterization of the interface and the determination …

INTERACTION BETWEEN MECHANICAL STRESSES AND OXIDATION OF THE NIOBIUM

1998

Atomic layer deposition of ferroelectric LiNbO3

2013

The ferroelectric and electro-optical properties of LiNbO3 make it an important material for current and future applications. It has also been suggested as a possible lead-free replacement for present PZT-devices. The atomic layer deposition (ALD) technique offers controlled deposition of films at an industrial scale and thus becomes an interesting tool for growth of LiNbO3. We here report on ALD deposition of LiNbO3 using lithium silylamide and niobium ethoxide as precursors, thereby providing good control of cation stoichiometry and films with low impurity levels of silicon. The deposited films are shown to be ferroelectric and their crystalline orientations can be guided by the choice of…

ChemInform Abstract: NbNi2.38Te3, a New Metal-Rich Niobium Telluride with a “Stuffed” TaFe1+ xTe3 Structure.

2010

The authors report the synthesis, structure, and electrical properties of NbNi{sub 2.38}Te{sub 3}. The structure of the compound was determined by X-ray crystallography and the electric conductivity of the compound was measured.

Diene-Containing Half-Sandwich MoIII Complexes as Ethylene Polymerization Catalysts: Experimental and Theoretical Studies

2001

International audience; Seventeen-electron compounds of Mo III having the general formula [(h 5-C 5 R 5)Mo(h 4-diene)X 2 ] (R H, Me; diene butadiene, iso-prene, or 2,3-dimethylbutadiene; X Cl, CH 3) are a new class of ethylene polymerization catalysts. The polyethy-lene obtained shows a bimodal distribution , the major weight fraction being characterized by very long (M around 10 6) and highly linear polymer chains. The newly prepared pentamethylcyclo-pentadienyl (Cp*) derivatives are more active than the cyclopentadienyl (Cp) derivatives, but much less active than previously investigated niobium III compounds having the same stoichiometry. On the other hand, the turnover frequency of the a…

The niobium and yttrium abundances in the sedimentary gem deposits of Sri Lanka

1986

Niobium Nitride Thin Films for Very Low Temperature Resistive Thermometry

2019

We investigate thin film resistive thermometry based on metal-to-insulator-transition (niobium nitride) materials down to very low temperature. The variation of the NbN thermometer resistance have been calibrated versus temperature and magnetic field. High sensitivity in tempertaure variation detection is demonstrated through efficient temperature coefficient of resistance. The nitrogen content of the niobium nitride thin films can be tuned to adjust the optimal working temperature range. In the present experiment, we show the versatility of the NbN thin film technology through applications in very different low temperature use-cases. We demonstrate that thin film resistive thermometry can …