Analysis of the effect of different mineralizers in the ceramic synthesis of the 'pink coral' iron-zircon pigment

摘要

The addition of several mineralizing agents (alkalineor alkaline-earth halides, KNO_3, etc.) in the traditional ceramicsynthesis of the "coral pink" iron-zircon (Fe-ZrSiO_4) ceramicpigment has been analysed, using two different Fe precursors(sulphate and goethite). FeSO_4.7H_2O employment as Feprecursor allows us to obtain a better reddish colour than withgoethite (FeO(OH)). Results let us to classify the studiedmineralisers in two major groups: i) primary or zircon-formingmineralisers, which activate somehow zircon formation with agood occlusion efficiency of hematite into the zircon matrix (NaF,NaCl and BaF_2 when using FeSO_4 and Na_2SiF_6 andNaAl_3F_6 with goethite),. And ii) secondary or modifyingmineralisers, that have a collateral effect on the pigment synthesisregulating both hematite crystallisation and occlusion (KNO_3,Na_2SiF_6 and NaAl_3F_6 with FeSO_4 and KI and KNO_3with goethite). With regard to the color yield, those compositionsmineralised with the binary systems NaF_Na_2SiF_6, NaF-NaAl_3F_6 and NaF_KNO_3 have been found to develop the best red color.