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The behavior of atomic hydrogen in osmium dioxide and ruthenium dioxide is investigated through ab initio calculations using density functional theory. Interstitial hydrogen behaves as a donor in both metal oxides and only has one stable interstitial position, bonding with an O atom to form an OH O defect. The rates of diffusion parallel to the c -axis are estimated to be 3.95 × 10 − 7 exp(−0.793/ k B T ) m 2 /s and 3.64 × 10 − 7 exp(−0.659/ k B T ) m 2 /s in OsO 2 and RuO 2 , respectively. The rates of diffusion perpendicular to the c -axis are estimated to be 1.80 × 10 − 6 exp(−0.941/ k B T ) m 2 /s and 1.10 × 10 − 6 exp(−1.21/ k B T ) m 2 /s in OsO 2 and RuO 2 , respectively. Additionally, the binding energy of multiple H atoms in (O, Os, Ru) vacancies have been calculated. High binding energies of hydrogen in metal vacancies result in multiple H atoms associating with a single metal vacancy. In RuO 2 , the binding energy of multiple H atoms outweighs the formation energy of a single Ru vacancy as well as that of a Ru–O divacancy. [ABSTRACT FROM AUTHOR]

Vacancy depth profiles installed by rapid thermal annealing can be monitored either by Pt diffusion or through vacancy-assisted oxygen precipitation. The features of these profiles clearly show that the vacancy species manifested in these experiments is a 'slow vacancy', Vs. The evolution of Vs depth profiles is controlled by an exchange with another (mobile) kind of vacancy that is likely to be a 'Watkins vacancy', Vw, first observed at cryogenic temperatures. At low T the conversion of Vs into Vw is slow and practically irreversible. At higher T the two species coexist in an equilibrium ratio and diffuse as one entity with an averaged diffusivity. This model provides a good fit to the RTA-installed depth profiles of Vs. The total vacancy community includes, beside Vs and Vw, also a fast vacancy Vf that is responsible for the vacancy contribution into self-diffusion at high T. In RTA experiments, the Vf species seems to be completely annihilated by self-interstitials which leaves only two other vacancy species, Vs and Vw. [ABSTRACT FROM AUTHOR]

Suezawa et al. [Phys. Rev. B 90, 117201 (2014)] claim in their Comment that the data reported by Shimizu et al. [Phys. Rev. Lett. 98, 095901 (2007)] and Kube et al. [Phys. Rev. B 88, 085206 (2013)] on silicon selfdiffusion for temperatures between 900 and 735 °C are affected by carbon and vacancy clusters and, accordingly, do not reflect self-diffusion under thermal equilibrium conditions. We demonstrate in our Reply that an impact of carbon on self-diffusion can definitely be excluded. In addition it is rather unlikely that the self-diffusion data reported by Shimizu et al. [Phys. Rev. Lett. 98, 095901 (2007)] and Kube et al. [Phys. Rev. B 88.085206 (2013)] are affected by the dissolution of vacancy clusters since strong differences exist not only in the preparation of the samples used for the experiments, but also in the time of diffusion. Finally, the vacancy formation enthalpy deduced by Suezawa et al. [J. Appl. Phys. 110, 083531 (2011)] from quenching experiments is consistent with the value obtained from the temperature dependence of the vacancy formation enthalpy reported by Kube et al. [Phys. Rev. B 88, 085206 (2013)]. Overall we conclude that the quenching experiments of Suezawa et al. [J. Appl. Phys. 110, 083531 (2011)] cannot disprove the interpretation of the low-temperature self-diffusion data reported by Shimizu etal. [Phys. Rev. Lett. 98,095901 (2007)] and Kube et al. [Phys. Rev. B 88, 085206 (2013)]. [ABSTRACT FROM AUTHOR]