Determination of Diffusion Coefficients of Hydrogen in Niobium at Low Temperatures by Resistivity Measurements after Quench*

Quenching Studies of Lattice Vacancies in High-Purity Aluminium

“…This is at least one power of ten faster than the rates reported for any previous quenching experiments on Al. 26) The quenched samples were mounted in liquid N 2 on a sample holder for electrical-resistance measurements and transferred to a liquid-helium cryostat 27,28) without warming. The standard four-point direct-current method was used to measure the resistance of the sample before and after annealing.…”

“…Here, divacancies are likely to contribute substantially to C eq V and hence to D T (T ), making it impossible to obtain H SD 1V from the radiotracer data alone. Fortunately, the 100%-abundant stable isotope 27 Al is well suited for NMR investigations of the selfdiffusivity by measuring the spin-lattice relaxation rate in a rotating frame (Γ 1ρ ).…”

“…Using the theory of the positron diffusivity as limited by phonon scattering 60,61) to extrapolate the experimentally determined D + in Al 62) to higher temperatures gives us D + (625 K) = 9.6 × 10 −5 m 2 s −1 and, with eq. (27),…”