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57Fe Mössbauer and electronic spectroscopy study on a new synthetic hercynite-based pigment

2003; Elsevier BV; Volume: 24; Issue: 5 Linguagem: Inglês

10.1016/s0955-2219(03)00329-7

1873-619X

Giovanni B. Andreozzi, Giovanni Baldi, Gian Piero Bernardini, Francesco Di Benedetto, Maurizio Romanelli,

Dyeing and Modifying Textile Fibers

AbstractA new blue hercynite-based pigment,stable at the processing temperatures for the ceramic application,has been synthesized. It isconstituted by corundum and Ti-bearing hercynite. In order to clarify the complex Fe distribution evidenced by Baldi et al. [Proc.CIMTEC 2002(2003)],a 57 Fe Mo¨ssbauer and diffuse reflectance spectroscopy study has been undertaken. Fe was found to be dis-tributed between corundum,as trivalent,and hercynite,both as Fe(II) and Fe(III). Moreover,Fe(II) occupies both tetrahedral andoctahedral sites in the latter mineral,according to a temperature dependent disorder. UV–VIS investigation revealed the presence ofa broad band in the blue region,the shape and position of which was found to be due to an intervalence charge transfer mechanismbetween Fe(II) and Ti(IV) in two edge-sharing octahedra of hercynite.# 2003 Elsevier Ltd. All rights reserved. Keywords:Al 2 O 3 ; Colour; Pigment; Spectroscopy; Spinels 1. IntroductionCeramic pigments are white or coloured crystallinematerials with high thermal stability and high chemicalresistance. These properties are strategic for their use inhigh temperature treatments. In recent years the devel-opment of new ceramic materials has fostered theresearch of pigments stable at application temperaturesover 1200 C. The crystalline coloured substances thatremain unaltered in such conditions belong to a restric-ted number of structures: zirconium silicate ZrSiO