The effect of hydrogen pressure on the kinetics of the HDDR-process of bulk Nd-Fe-B-type alloys

1994 ◽  
Vol 30 (2) ◽  
pp. 642-644 ◽  
Author(s):  
O. Gutfleisch ◽  
C. Short ◽  
M. Verdier ◽  
I.R. Harris
Keyword(s):  
Hydrogen Pressure ◽  
Kinetics Of

Bombardment by Reflection - A Novel Method to Prepare High Quality Hydrogenated Amorphous Germanium by Anodic PCVD

1997 ◽  
Vol 467 ◽  
Author(s):  
Annette Diez ◽  
Twlo P. Drüsedau
Keyword(s):  
Atomic Hydrogen ◽  
Carrier Mobility ◽  
Hydrogen Pressure ◽  
Amorphous Germanium ◽  
Hydrogen Dilution ◽  
Novel Method ◽  
Hydrogenated Amorphous ◽  
Hydrogenated Amorphous Germanium ◽  
Kinetics Of

ABSTRACTDeposition of amorphous germanium by anodic PCVD was performed changing the germane/hydrogen dilution ratio from 1/6 to 1/100. Films deposited under high dilution of germane are of a high mechanical density (92.5 % of bulk) and good optoelectronic properties (electrical conductivity at room temperature σ=10−5 (Ω cm)−1, majority carrier mobility-lifetime product at λ=1200 nm ημ=x 10−7 cm2/V). The quality of the films is increased by deposition at increasing pumping speed for hydrogen (lower hydrogen pressure) keeping the other parameters constant. It is suggested that fast atomic hydrogen originating from a backscattering process at the powered electrode bombard the growing film and contribute to the improved quality of the a-Ge:H. Also, the growth kinetics of the films is changed from linear to parabolic dependence on germane flow interchanging deposition from high to low hydrogen pressure. This effect is rationalized in terms of a contribution of energetic atomic hydrogen to the dissociation of germane.

Kinetics of Silicon Growth under Low Hydrogen Pressure

1978 ◽  
Vol 125 (4) ◽  
pp. 637-644 ◽  
Author(s):  
M. Jean‐Pascal Duchemin ◽  
M. Michel Bonnet ◽  
M. François Koelsch
Keyword(s):  
Hydrogen Pressure ◽  
Silicon Growth ◽  
Kinetics Of

Catalytic activity of rhodium(I) complexes containing poly(siloxy)alkyldiphenylphosphines

1980 ◽  
Vol 45 (7) ◽  
pp. 2100-2107 ◽  
Author(s):  
Vladimír Kavan ◽  
Martin Čapka
Keyword(s):  
Catalytic Activity ◽  
Hydrogen Pressure ◽  
Catalyst Activity ◽  
Molar Ratio ◽  
Normal Hydrogen ◽  
Kinetics Of

Kinetics of homogenous hydrogenation of 1-heptene catalysed by rhodium(I) complexes prepared in situ from di-μ.μ'-chloro-bis(dicyclooctenerhodium) and phosphine L (L = 2-(diethoxymethylsilyl)ethyldiphenylphosphine, 3-(diethoxymethylsilyl)propyldiphenylphosphine and their copolymers with diethoxydimethylsilane) have been studied at 64°C under normal hydrogen pressure. The dependence of the catalyst activity on the type of L( monomeric, polymeric, supported on silica) has been examined. The effects of Rh : P molar ratio, the concentration of phosphine groups in siloxane copolymers and of the method of catalyst fixation to support on catalyst performance are discussed.

scholarly journals The catalytic isomerization of buten-1

1941 ◽  
Vol 178 (972) ◽  
pp. 106-117 ◽  
Keyword(s):  
Double Bond ◽  
Hydrogen Pressure ◽  
Square Root ◽  
Double Bond Migration ◽  
Rate Determining Step ◽  
Catalytic Isomerization ◽  
Rate Of Reaction ◽  
Hydrogenation Reactions ◽  
Kinetics Of ◽  
Catalytic Exchange

It has been shown that butene-1 undergoes isomerization to butene-2 on a nickel catalyst in the presence of hydrogen. B y using deuterium, this double-bond migration has been examined simultaneously with the exchange and hydrogenation reactions. The kinetics of double-bond migration and hydrogenation at 65° C were found to be identical, the rate of reaction in both cases being proportional to the square root of the butene pressure and to the square root of the hydrogen pressure. Energies of activation for the three reactions were measured over the temperature range 76-126° C and the following values found: Exchange 9.0 kcal. Hydrogenation 2.5 ,, Double-bond migration 5.9 ,, At the lowest temperatures, the rate of double-bond migration was about six times that of exchange. These facts are in agreement with the theory that the catalytic exchange between olefines and deuterium takes place through the formation of an associative complex. The rate-determining step in the double-bond migration is the second, fast step of the exchange reaction, viz.

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