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Atkinson I.,Romanian Academy Bucharest | Atkinson I.,University of Warwick | Smith M.E.,University of Warwick | Zaharescu M.,Romanian Academy Bucharest
Ceramics International | Year: 2012

The effects of additions of zircon (5-17 wt%) to conventional single firing ceramic glazes is examined. The structural and morphological characteristics of the glazes were determined by Scanning Electron Microscopy, X-ray diffraction, infra-red spectroscopy, as well as 27Al and 29Si magic angle spinning (MAS) NMR. The presence of zircon microcrystals was revealed by X-ray diffraction (XRD) combined with scanning electron microscopy (SEM) and EDAX microanalysis. The chemical durability of the glasses is revealed to be acceptable for certain practical applications. The color characteristics of the glazes obtained were estimated in the HunterLab system (L*C*h* , emission spectra). The outcomes of the study established correlations between composition, structure and some of the physical properties. © 2011 Elsevier Ltd and Techna Group S.r.l.


Atkinson I.,Romanian Academy Bucharest | Atkinson I.,University of Warwick | Teoreanu I.,Polytechnic University of Bucharest | Mocioiu O.C.,Romanian Academy Bucharest | And 2 more authors.
Journal of Non-Crystalline Solids | Year: 2010

The influence of the additives (10 wt.% rutile, anatase and zirconia) on the atomic-scale structure and microstructure of a base glaze (60 wt.% feldspar, 15 wt.% quartz, 8 wt.% kaolin, 12 wt.% dolomite and 5 wt.% zinc oxide) is investigated. The morphology and structure of the glazes were determined by Scanning Electron Microscopy, X-ray diffraction, infra-red spectroscopy, as well as 27Al and 29Si magic angle spinning (MAS) NMR. Microscopy and X-ray diffraction revealed that the opacity was caused by crystals formed during thermal treatment. Although there are clearly crystalline phases present NMR shows that the heat treated glazes are dominated by the glassy component meaning the opacity is largely conveyed by the added oxide. The relationship between composition, structure and thermal expansion coefficient of the glazes is examined. © 2010 Elsevier B.V. All rights reserved.


Atkinson I.,Romanian Academy Bucharest | Anghel E.M.,Romanian Academy Bucharest | Munteanu C.,Romanian Academy Bucharest | Voicescu M.,Romanian Academy Bucharest | Zaharescu M.,Romanian Academy Bucharest
Ceramics International | Year: 2014

Glass-ceramics raw glazes in the Na2O-K2O-CaO-Al 2O3-ZnO-SiO2 system with low ZrO2 additions (0, 3 and 5 wt%), used as nucleating agent, were synthesised and thermally treated at 1250 C. Willemite (Zn2SiO4), sanidine (K0.831 Na0.169Al Si3O8), gahnite (ZnAl2O4) and zircon (Zr2SiO4) were the main crystalline phases identified by X-ray investigations in the resulting glazes. An increase of the ZrO2 content from 0 to 5 wt% trigged an increase of the crystallinity degree from 71.34% to 83.73% and gahnite crystallite size from 176 to 336 Å. Further, morphological and structural data of these glass-ceramics were supplementary determined by SEM, MAS-NMR of 27Al and 29Si and Raman Spectroscopy. The structural modifications in terms of the glass ceramic compositions, especially small ZrO2 additions to the expense of the SiO2 and the relationship between composition and colour characteristics of the glazes are investigated and presented in this paper. © 2013 Elsevier Ltd and Techna Group S.r.l.All rights reserved.

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