ISSN:
1573-4846
Keywords:
dehydroxilation in sol-gel ZrO2
;
paramagnetic point defects
;
tetragonal zirconia stabilization
;
nanocrystalline tetragonal ZrO2
;
nanocrystalline monoclinic ZrO2
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The formation and evolution with temperature of the crystalline phases in sol-gel ZrO2 was analyzed by using X-ray powder diffraction, refinement of the crystalline structures, ESR, and UV-Vis spectroscopy. The precursor phase of crystalline zirconia was amorphous Zr(OH)4 with the same local order as the tetragonal crystalline phase. This amorphous phase dehydroxylated with temperature, generating nanocrystalline tetragonal zirconia, and producing point defects that stabilized the tetragonal structure, generated a paramagetic ESR signal with g values like the free electron, and had a light absorption band at 310 nm. When the sample was annealed at higher temperatures, it continued dehydroxilating, and the point defects disappeared, causing the transformation of the nanocrystalline tetragonal phase into nanocrystalline monoclinic zirconia. The two crystalline nanophases coexisted since the beginning of crystallization.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008666531404
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