Stabilization of metastable tetragonal zirconia nanocrystallites by surface modification
Metastable tetragonal zirconia nanocrystallites were studied in humid air and in water at room temperature (RT). A stabilizing effect of different surfactants on the tetragonal phase was observed. Furthermore, the phase stability of silanized metastable tetragonal zirconia nanocrystallites was tested by prolonged boiling in water. The samples were analyzed with X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Changes in the monoclinic volume fraction in the samples were calculated. A number of surfactants were screened for their ability to stabilize the tetragonal phase upon exposure to humidity. Only silanes and phosphate esters of these were able to stabilize the tetragonal phase in water. Even as small amounts of silanes as 0.25 silane molecule per nm2 are able to stabilize the tetragonal phase in water at RT. Aminopropyl trimethoxy silane and γ-methacryloxypropyl trimethoxy silane were even capable of preventing phase transformation during boiling for 48 h in water.
- 5.Zhang X, Kolb BU, Hanggi DA et al (2001) WO 01/30305 A1Google Scholar
- 8.Sato T, Shimada M (1985) Am Ceram Soc Bull 64:1382Google Scholar
- 11.Yoshimura M (1988) Am Ceram Soc Bull 67:1950Google Scholar
- 18.Toraya H, Yoshimura M, Somiya S (1984) J Am Ceram Soc 67:C119Google Scholar
- 21.Van Lelieveld A, Nielsen MS, Almdal K et al (2007) EP1996144-A2, US2010016465-A1Google Scholar