Z. Naturforsch. 68a, 315 – 316 (2013)
Comment on “Oxidation of Hafnium and Diffusion of Hafnium Atoms in Hexagonal Close-Packed Hf; Microscopic Investigations by Perturbed Angular Correlations” by Chandi C. Dey, Z. Naturforsch. 67a, 633 (2012)
Tilman Butz
Institut für Experimentelle Physik II, Fakultät für Physik und Geowissenschaften, Linnéstr. 5, 04103 Leipzig, Germany
Received November 10, 2012 / revised January 4, 2013 / published online March 6, 2013
Reprint requests to: T. B.; E-mail: butz@physik.uni-leipzig.de
In his paper, Chandi C. Dey reports on the measurement of the nuclear quadrupole interaction of 181Hf(β)181Ta in α-Hf metal with a few percent zirconium heated in air by perturbed angular correlation (PAC) of γ-rays. Since he did not observe the formation of HfO2 up to 773 K and during initial heating at 873 K for one day, he concluded that no oxygen is absorbed. The time dependent hyperfine interaction was therefore attributed to the diffusion of hafnium atoms. The transformation from α-Hf to HfO2 did not follow an Arrhenius-law, contrary to his expectations. Furthermore, he attributed the time dependent hyperfine interaction in HfO2 to the diffusion of hafnium atoms.

This interpretation is in sharp conflict with existing data as will be discussed below.

Key words: Perturbed Angular Correlations; Nuclear Quadrupole Interaction; Oxidation of Hafnium Metal.
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