Developments in Ceramic Materials Research

In: Developments in Ceramic Materials Research ISBN 978-1-60021-770-8
Editor: Dena Rosslere, pp. 261-279 © 2007 Nova Science Publishers, Inc.
Chapter 9
COLOURED ZrSiO4 CERAMIC PIGMENTS
S. Ardizzone 1 , C. L. Bianchi 1 , G. Cappelletti 1 ,
P. Fermo 2 and F. Scimè 1
1 Department of Physical Chemistry and Electrochemistry,
University of Milan, Via Golgi 19, 20133 Milan, Italy
2 Department of Inorganic, Metallorganic and Analytical Chemistry,
University of Milan, Via Venezian 21, 20133 Milan, Italy
ABSTRACT
A sol-gel reaction starting from Si and Zr alkoxides, in water-ethanol mixtures, was
employed to obtain praseodymium, vanadium and iron doped zirconium silicate powders
(zircon). The reactions were performed by modulating both: a) the amount of metal salt
in the starting mixture (Me/Zr molar ratio in the range 0.05-0.1) and b) the temperature of
firing (600-1200°C). In the case of V-doped pigments, samples were synthesized also in
the presence of a constant amount (0.26 salt/Zr molar ratio) of mineralizers (LiF, LiCl,
NaF, NaCl, KF, KCl).
The samples were characterised by X-ray diffraction, SEM micrographs, specific
surface area determinations and UV-Vis diffuse reflectance spectroscopy. XPS analyses
were performed on V-doped zircon pigments by studying in particular the Zr 3d, Si 2p
and V 2p regions. The colour of the pigments was characterized on the grounds of the
CIE (Commission Internationale de l’Eclairage) standard procedure (CIE L*a*b*
measurements). Results from the structural, morphological and optical characterisations
are examined and cross-compared to produce a consistent picture of the key factors
leading to the formation, growth and optical properties of the reaction products.
Keywords: ceramic materials, metal doped-zircon pigments, mineralizers, sol-gel
processes, optical properties, X-ray methods, XPS.