Naslov
Crystallization pathway of sol–gel derived zinc-doped mullite precursors

Autori
Mandić, Vilko ; Tkalčec, Emilija ; Popović, Jasminka ; Kurajica, Stanislav ; Schmauch, Jörg

Izvornik
Journal of the European Ceramic Society (0955-2219) 36 (2016), 5; 1285-1292

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
γ-alumina ; Zn-doped γ-alumina metastable solidsolution ; Gahnite ; Mullite ; crystallisation

Sažetak
Zinc doped mullite precursors were sol–gel prepared in order to study the Zn influence on crystallization pathways of the spinels first formed at about 920–970◦C. Precursors were calcined at 700◦C andthermally treated at 1000–1300◦C and thereafter characterized (DTA/TG, PXRD, Rietveld refinement). Thermal treatment of precursors at 1000◦C initiates segregation of ZnAl2O4 from first formed Zn-rich gamma-alumina metastable solid solution. Remaining spinel reacts with amorphous silica yielding mullite ; thereby further enriching gamma-alumina on Zn. Thermal treatment affects Zn-doped gamma-alumina yielding crystallite size 11±3 and 28±4 nm at 1000 and 1300◦C, respectively. Parameter of inversion for ZnAl2O4, delta, increased from 0.05 to 0.20 upon heatingfrom 1000 to 1300◦C. SEM EDS analysis show the bodies sintered at 1600◦C reveal zinc deficiency due to Zn volatile nature. Electron microscopy (TEM, SEM) of sintered compacts exhibited microstructure with lower porosityhaving both elongated and equiaxial grains.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Kemijsko inženjerstvo, Temeljne tehničke znanosti

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