By using Perturbed Angular Correlation Spectroscopy, a suitable technique to explore internal fields at nanoscopic scale, the electric field gradients at Zr4+ sites in the Pr2Zr2O7 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 degrees 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.

Nanoscopic characterization of Pr2Zr2O7 at Zr sites / Ja, Martinez; Mc, Caracoche; Pc, Rivas; Am, Rodriguez; Bondioli, Federica; Manfredini, Tiziano; Ferrari, Anna Maria. - In: PHYSICA STATUS SOLIDI B-BASIC RESEARCH. - ISSN 0370-1972. - STAMPA. - 242:(2005), pp. 1838-1841.

Nanoscopic characterization of Pr2Zr2O7 at Zr sites

BONDIOLI, Federica;MANFREDINI, Tiziano;FERRARI, Anna Maria
2005

Abstract

By using Perturbed Angular Correlation Spectroscopy, a suitable technique to explore internal fields at nanoscopic scale, the electric field gradients at Zr4+ sites in the Pr2Zr2O7 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 degrees 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.
242
1838
1841
Nanoscopic characterization of Pr2Zr2O7 at Zr sites / Ja, Martinez; Mc, Caracoche; Pc, Rivas; Am, Rodriguez; Bondioli, Federica; Manfredini, Tiziano; Ferrari, Anna Maria. - In: PHYSICA STATUS SOLIDI B-BASIC RESEARCH. - ISSN 0370-1972. - STAMPA. - 242:(2005), pp. 1838-1841.
Ja, Martinez; Mc, Caracoche; Pc, Rivas; Am, Rodriguez; Bondioli, Federica; Manfredini, Tiziano; Ferrari, Anna Maria
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11380/309321
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