Capacitance–voltage profiling of deuterium passivation and diffusion in diamond Schottky diodes

Capacitance–voltage measurements have been performed on deuterated boron-doped natural type IIb diamond. They demonstrate the electrical passivation of the boron acceptors, which was manifested by a persistent decrease in capacitance after deuteration. Bias annealing experiments have been carried out to determine the charge state of the diffusing deuterium. The differences between annealing with or without bias lead to the conclusion that boron–deuterium complexes dissociate at about 750 K and that the released deuterium is positively charged.     

Evidence of hydrogen–boron interactions in diamond from deuterium diffusion and infrared spectroscopy experiments

We report on the first experimental evidence of hydrogen–boron interactions in boron-doped diamond. Deuterium diffusion studies in homoepitaxial B-doped diamond films reveal that hydrogen diffusion is limited by the B concentration and is characterized by a low effective diffusion activation energy. Infrared spectroscopy experiments show that boron acceptor electronic transitions disappear under hydrogenation. These results are consistent with hydrogen ionization and diffusion of fairly mobile H⁺ which form pairs with B⁻.     

Separation of water–isotopes mixture in continuous-flow thermal diffusion columns for recovery of deuterium

The present study deals with the estimation of deuterium recovery from the separation of water–isotopes mixture (H₂O–HDO–D₂O) by continuous-flow thermal diffusion. First, the equations for predicting the degrees of separation for each component in H₂O–HDO–D₂O system were derived by following the same procedure performed in the previous work. The recovery of deuterium (D) was then estimated from the degrees of separation of HDO and D₂O and confirmed with the experimental results.     

Hydrogen–deuterium isotope effects in the reactions of chlorobenzene and benzene on a Pt/γ-Al2O3 catalyst

The kinetic isotope effect for combustion of a C₆H₅Cl/C₆D₅Cl mixture on Pt/-Al₂O₃ was found to be close to unity between 520 and 580 K. However, in the presence of an excess of heptane, an isotope effect of 1.5 was found between 460 and 490 K. For the combustion of a C₆H₆/C₆D₆ mixture the k_H/k_D value was around 2 between 404 and 439 K. The results show that in the combustion of chlorobenzene per se, C–H bond activation is not a rate-determining step. On Pt sites, C–Cl bond scission probably occurs already at low temperatures. The chlorine and the phenyl group cannot easily react further. Chlorine on the surface is active in chlorination, which is shown by the formation of C₆D₅Cl in an experiment with C₆H₅Cl and C₆D₆. Only at a certain temperature is the chlorine removed, partly as polychlorinated benzenes. The removal of chlorine from the catalyst allows oxygen to take part in the reaction, which determines the rate of the combustion of chlorobenzene. When heptane is present, Cl is removed from the surface and C–H bond scission can become rate determining, as is also the case in the combustion of C₆H₆/C₆D₆. Upon (partial) combustion of C₆H₅Cl/C₆D₅Cl and C₆H₆/C₆D₆ mixtures on a Pt/-Al₂O₃ catalyst, hydrogen–deuterium exchange occurs on the -Al₂O₃ support.     

A deuterium–palladium electrode as a new sensor in non-aqueous media: the potentiometric titration of weak acids in alcohols

A deuterium–palladium electrode was employed as a new indicator electrode for the titration of weak acids in tert-butanol and iso-propanol. The investigated electrode showed a linear dynamic response for p-toluenesulfonic acid in the concentration range from 0.1 to 0.001 mol L⁻¹, with a Nernstian slope of 53.0 mV per decade in tert-butanol. The potential in the course of the titration and at the titration end-point (TEP) was rapidly established. Potassium hydroxide and tetrabutylammonium hydroxide (TBAH) proved to be very suitable titrating agents for these titrations. The response time was less than 10–11 s and the lifetime of the electrode was limitless. The experimental results obtained for the proposed electrochemical sensor and a conventional glass electrode were in good agreement. The advantages of the electrode are long-term stability, fast response, reproducibility, and easy preparation.