On the precipitation of coherent spinel nanoparticles in Ti-doped MgO

Journal Article · Tue Mar 15 04:00:00 EST 2005 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2004.12.019· OSTI ID:20725821

Yang, K C ^[1]; Shen, P ^[1]

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1. Institute of Materials Science and Engineering, National Sun Yat-sen University, Number 70, Lien-Hai Road, Kaohsiung, Taiwan (China)

The Mg{sub 2}TiO{sub 4}/MgO composites prepared by reactive sintering of MgO and TiO{sub 2} powders (9:1 molar ratio) at 1600 deg. C and then air-cooled or further aged at 900{sup o}C were studied by X-ray diffraction and analytical electron microscopy in order to characterize the microstructures and formation mechanism of nanosized Mg{sub 2}TiO{sub 4} spinel precipitated from Ti-doped MgO. Expulsion of Ti{sup 4+} during cooling caused the formation of (001)-specific Guinier-Preston zone under the influence of thermal/sintering stress and then the spinel precipitates, which were about 30nm in size and nearly spherical with {l_brace}111{r_brace} and {l_brace}100{r_brace} facets to minimize coherency strain energy and surface energy. Secondary nanosized spinel was precipitated and became site saturated during aging at 900 deg. C, leaving a precipitate-free zone at the grain boundaries of Ti-doped MgO. The intergranular spinel became progressively Ti-richer upon aging at 900 deg. C and showed <110>-specific diffuse scatter intensity likely due to short-range ordering and/or onset decomposition.

• OSTI ID: 20725821
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 3 Vol. 178; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
DECOMPOSITION
DOPED MATERIALS
ELECTRON MICROSCOPY
GRAIN BOUNDARIES
GUINIER-PRESTON ZONES
MAGNESIUM OXIDES
NANOSTRUCTURES
PRECIPITATION
SINTERING
SPHERICAL CONFIGURATION
SPINELS
STRAINS
STRESSES
SURFACE ENERGY
TITANATES
TITANIUM IONS
TITANIUM OXIDES
X-RAY DIFFRACTION