Single-phase mullite gels doped with chromium
- Univ. of Saarland, Saarbruecken (Germany). Inst. fuer Neue Materialien
- Univ. of Zagreb (Croatia). Faculty of Chemical Engineering and Technology
The influence of chromium on homogeneity of gels and on mullite formation at 980 C was examined by DTA coupled with quadrupole mass spectrometry (QMS), X-ray diffraction (XRD), and SEM, EDX, and TEM analyses. Mullite precursors were prepared according to the method which provides completely homogeneous gels in the Al{sub 2}O{sub 3}-SiO{sub 2} system, with a constant molar ratio of (Al + Cr)/Si = 3/1 and various Al/Cr ratios (0--4 mol% Cr{sub 2}O{sub 3}). DTA and QMS analyses revealed the same processes of dehydration, combustion of organic, as well as the decomposition of nitrates independently of chromium content.The differences were observed in the crystallization path at 980 C. Only for the undoped mullite precursors was the crystallization of mullite as a sole phase determined by XRD, because chromium promotes spinel formation. The incorporation of chromium into mullite structure under nonisothermal and isothermal conditions was followed for the sample with 2 mol% Cr{sub 2}O{sub 3}, by measuring the unit cell parameters as a function of temperature.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 136510
- Journal Information:
- Journal of the American Ceramic Society, Journal Name: Journal of the American Ceramic Society Journal Issue: 11 Vol. 78; ISSN 0002-7820; ISSN JACTAW
- Country of Publication:
- United States
- Language:
- English
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