Measurements of Hand D diffusion in Ti0 2 • using the isotope exchange technique described in the preceding paper. are reported. Use of this technique resulted in diffusion which was accurately described by Fick's law with a constant diffusion coefficient, as predicted theoretically. in sharp contrast to single ion diffusion, where dramatic departures from classical diffusion theory were observed. The measured diffusion coefficients for H were 1.8X 10-3 exp( -O.5geV/kT) and 3.8X 10-1 exp( -1.28eV/kT) cm 2 /sec for diffusion II and 1 to the c axis, respectively. Ionic conductivity measurements are reported. which agree well with the bulk diffusion measurements. and permitted us to extend the temperature range of the measurements for c -axis diffusion from 125 to 750"C, corresponding to a range of more than four orders of magnitude in D. The measured diffusion parameters were found to be essentially independent of sample purity. although it was observed that significant concentrations of lattice defects sharply inhibited H diffusion.

Results of a precise determination of the ir absorption strength of H and D in rutile are presented, which permit determination of H or D concentration to an accuracy of 3%. The integrated absorption per ion was (2.51±0.09)×10−17 and (1.33±0.05)×10−17 cm for H and D, respectively. The procedure for calculating the H or D concentration in a particular sample from the ir absorption peaks is illustrated. Used in conjunction with the results of the theoretical analysis of the preceding paper, this technique makes possible the accurate determination of the energy and density of all electron trapping levels in TiO2 crystals. We also describe results showing that heat treatment in a dry H2 atmosphere at ∼800 °C results in the introduction of Ti intersititials but negligible H in the crystal, as predicted by the preceding paper. A technique for measuring diffusion parameters of H and D under conditions of strict chemical equilibrium, thus avoiding the large departures from Fick's law which usually plague such measurements in materials such as TiO2, is also described.

Electrical conductivity mechanisms in single crystal rutile (TiO2) between 6 and 40 K have been studied in Nb-doped and Nb+H-doped material by means of electrical resistance and Hall effect measurements. In this range, three scattering mechanisms were found to be important: neutral and ionized impurities and acoustic phonons. In the region from approximately 12 to 25 K the electrical conductivity was found to be strictly exponential in 1/T, indicating acoustic phonon limited scattering, and yielding the donor trapping energies for Nb and H (20.0±0.1 and 4.4±0.1 meV, respectively). With the acoustic phonon limited mobility written as μ=μ0/T3/2, μ0 was found to be (1.2±0.1)×104 and (3.9±0.4)×10−4 cm2(K)3/2/V s in the ‘‘a’’ and ‘‘c’’ directions, respectively. Although qualitative agreement with existing theories on neutral and ionized impurity scattering is obtained, quantitative agreement requires an improved theory taking anisotropy into account. It was also found that the ratio of ‘‘c’’ to ‘‘a’’ mobility is a function of temperature and doping. The electron effective mass was estimated to be ∼12.5 m0.

Cadmium and gold of 99.999% purity were irradiated to an integrated flux of 7.5 X10 17 electrons/cm* using 3-MeV electrons. The resistivity increase was 8.5 X10 -9 Q-cm in gold and 2.32X 10 -9 O-cm in cadmium. The resistivity versus integrated flux curve is linear. Isothermal annealing measurements were made in the region from 8 to 51°K. The resistivity annealing spectrum of gold was derived directly from the isothermal annealing curves. The spectrum consists of at least nine peaks, with 22% of the damage annealing out up to 51°K. These results confirm earlier suggestions that the radiation damage in gold is basically different from that of copper and silver. It is thought that the interstitial in gold differs from that in copper and silver. In connection with the amount of low-temperature annealing, it is thought that focusing and interstitial clustering are important. Deviations from Matthiessen's rule for gold and cadmium are in qualitative agreement with theory. Only qualitative agreement with an earlier experiment on the annealing of cadmium can be confirmed.

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