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Nanoscopic characterization of Pr 2 Zr 2 O 7 at Zr sites
Author(s) -
Martínez J. A.,
Caracoche M. C.,
Rivas P. C.,
Rodríguez A. M.,
Bondioli F.,
Manfredini T.,
Ferrari A. M.
Publication year - 2005
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200461761
Subject(s) - pyrochlore , oxygen , electric field , activation energy , materials science , characterization (materials science) , nanoscopic scale , fluorite , diffusion , crystallography , chemical physics , chemistry , nanotechnology , thermodynamics , physics , organic chemistry , quantum mechanics , metallurgy , phase (matter)
By using Perturbed Angular Correlation Spectroscopy, a suitable technique to explore internal fields at nanoscopic scale, the electric field gradients at Zr 4+ sites in the Pr 2 Zr 2 O 7 compound have been determined as a function of temperature. Three nonequivalent nanoconfigurations are present, which have been interpreted with the aid of point charge model calculations. Two of them correspond to pyrochlore – oxygen defective and perfect structures –, and the third one to the pyrochlore‐related defect fluorite structure. The most abundant interaction is a disordered and fluctuating electric field gradient, which describes the oxygen defective pyrochlore. As temperature increases, its gradual and reversible transformation towards the perfect form is observed. Below 750 °C the oxygen vacancies movement, which exhibits an activation energy of 0.14 eV, is assumed to be due to vacancies jumping among 48f equivalent sites. At higher temperatures the movement is interpreted as the fast diffusion of oxygen vacancies involving 48f and 8b sites, thus giving place to anionic disorder. The activation energy for this movement has been determined to be of 0.85 eV. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)