Phase structure and thermal evolution in coating films and powders obtained by sol-gel process: Part II. ZrO{sub 2}{minus}2.5mole {percent} Y{sub 2}O{sub 3}

Journal Article · Wed Oct 01 00:00:00 EDT 1997 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1997.0345· OSTI ID:554343

Caruso, R; Benavidez, E; de Sanctis, O ^[1]; Caracoche, M C; Rivas, P C ^[2]; Cervera, M ^[3]; Caneiro, A; Serquis, A ^[4]

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1. Laboratorio de Materiales Ceramicos, FCEIyA, IFIR, Av. Pellegrini 250, 2000 Rosario (Argentina)
2. Programa TENAES, Departamento de Fisica, FCE, Universidad Nacional de La Plata, c.c. 67, 1900 La Plata (Argentina)
3. Departamento de Ciencia y Tecnologia, Universidad Nacional de Quilmes, R.S. 184, 1864 Bernal (Argentina)
4. Centro Atomico Bariloche, CNEA, 8400 Bariloche (Argentina)

Powders and coatings of zirconia doped with 2.5 mole {percent} yttria have been produced via the sol-gel route. The phase structure and subsequent thermal evolution in heating and cooling cycles have been investigated using mainly perturbed angular correlations spectroscopy. Thermal analyses and XRD as a function of temperature have also been performed to obtain complementary information. Upon heating, the amorphous gels crystallized into the tetragonal structure and showed the same hyperfine pattern and thermal behavior as observed in tetragonal zorconia obtained by the ceramic route: the two configurations vacancies around zirconium ions denoted as t{sub 1} and t{sub 2} forms and their mutual t{sub 1}{r_arrow}t{sub 2} transformation. While the powder sample exhibited an incipient thermal instability above 1000{degree}C and underwent completely the t{sub 2} form to m{endash}ZrO{sub 2} transition during subsequent, gradual cooling below 500{degree}C, the coating retained the tetragonal phase within the whole temperature range investigated. Hyperfine results suggest that the tetragonal phase stabilization is favored by the highly defective nature of the t{sub 1} form and consequently hardened by the availability of oxygen. The PAC derived activation energy for the fast diffusion of the oxygen vacancies inherent to the t{sub 2} form was determined as 0.54{plus_minus}0.14eV. {copyright} {ital 1997 Materials Research Society.}

• OSTI ID: 554343
• Journal Information: Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 10 Vol. 12; ISSN JMREEE; ISSN 0884-2914
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CERAMICS
COATINGS
CRYSTAL DEFECTS
HYPERFINE STRUCTURE
PERTURBED ANGULAR CORRELATION
PHASE STUDIES
POWDERS
SOL-GEL PROCESS
THERMAL ANALYSIS
YTTRIUM OXIDES
ZIRCONIUM OXIDES