A Study of the Crystallization of ZrO2 in the Sol–Gel System: ZrO2–SiO2
Autor: | Tessy Lopez, Leticia M. Torres-Martínez, L. C. Torres-Gonzalez, D.H. Aguilar, Patricia Quintana |
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Rok vydání: | 2001 |
Předmět: |
Zirconium
Materials science Scanning electron microscope chemistry.chemical_element Mineralogy Condensed Matter Physics Electronic Optical and Magnetic Materials Amorphous solid law.invention Inorganic Chemistry chemistry Chemical engineering law Materials Chemistry Ceramics and Composites Cubic zirconia Crystallite Physical and Theoretical Chemistry Crystallization Thermal analysis Sol-gel |
Zdroj: | Journal of Solid State Chemistry. 158:349-357 |
ISSN: | 0022-4596 |
Popis: | ZrO2–SiO2 sol–gel powders were produced using tetraethoxysilane (TEOS) and zirconium propoxide. After gellation, the ZrO2 crystallization process was investigated using X-ray diffraction (XRD), thermal analysis (DTA/TGA), and scanning electron microscopy (SEM). Fresh gels were amorphous. Thermal treatments were carried out from 100 to 1400°C for a total annealing time of 182 h. Tetragonal zirconia, (Z(t)) was the first phase to crystallize, between 300 and 500°C. Crystallization temperature was lower for zirconia-rich compositions, increasing as silica content was raised. DTA analysis showed that Z(t) crystallization occurred in two stages. Complete tetragonal–monoclinic zirconia transformation occurred near 1000°C, and was clearly observed only in ZrO2-rich compositions (>80%). Silica remains amorphous until 1200°C, when ZrSiO4 formation took place. A metastable sol-gel phase diagram was proposed to show the crystallization process between 100 and 1400°C. |
Databáze: | OpenAIRE |
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