Synthesis and thermal stability of zirconia and yttria-stabilized zirconia microspheres.
J Colloid Interface Sci
; 448: 582-92, 2015 Jun 15.
Article
em En
| MEDLINE
| ID: mdl-25796070
ABSTRACT
HYPOTHESIS:
Zirconia microparticles produced by sol-gel synthesis have great potential for photonic applications. To this end, identifying synthetic methods that yield reproducible control over size uniformity is important. Phase transformations during thermal cycling can disintegrate the particles. Therefore, understanding the parameters driving these transformations is essential for enabling high-temperature applications. Particle morphology is expected to influence particle processability and stability. Yttria-doping should improve the thermal stability of the particles, as it does in bulk zirconia. EXPERIMENTS Zirconia and YSZ particles were synthesized by improved sol-gel approaches using fatty acid stabilizers. The particles were heated to 1500 °C, and structural and morphological changes were monitored by SEM, ex situ XRD and high-energy in situ XRD.FINDINGS:
Zirconia particles (0.4-4.3 µm in diameter, 5-10% standard deviation) synthesized according to the modified sol-gel approaches yielded significantly improved monodispersities. As-synthesized amorphous particles transformed to the tetragonal phase at â¼450 °C with a volume decrease of up to â¼75% and then to monoclinic after heating from â¼650 to 850 °C. Submicron particles disintegrated at â¼850 °C and microparticles at â¼1200 °C due to grain growth. In situ XRD revealed that the transition from the amorphous to tetragonal phase was accompanied by relief in microstrain and the transition from tetragonal to monoclinic was correlated with the tetragonal grain size. Early crystallization and smaller initial grain sizes, which depend on the precursors used for particle synthesis, coincided with higher stability. Yttria-doping reduced grain growth, stabilized the tetragonal phase, and significantly improved the thermal stability of the particles.
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Base de dados:
MEDLINE
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article