A BROWN ZIRCONIUM SILICATE PIGMENT

A zirconium silicate pigment in a new hue-brown-has been synthesized. Its colour is based on the perturbation principle: tellurium ions, together with lithium and molybdenum (or tungsten) ions, are incorporated into the zirconium silicate structure. A combination of disodium hexqfluorosilicate and lithium hydroxide proved useful as the mineralizer for the pigment synthesis. Alkali or ammonium tellurate (K2TeO4 was used in this work) acts as the chromophore. Further ingredients include molybdenum trioxide (ammonium molybdate can also be used) or ammonium paratungstate (WO3 is also useful), which are components of the mineralizer and also the chromophore. The effect of the K2TeO4 content in the starting mixture on the colour of the pigment has been evaluated, together with the effect of MoO3 and ammonium paratungstate. The temperature conditions of the pigment synthesis have been established and the products have been evaluated from the standpoint of their structure, conversion degree, colour hue and ability to colour ceramic glazes. © 1990.