Comparison of solution combustion and co‐precipitation methods in synthesis of iron zircon coral pigment Available to Purchase

It is essentially valuable to use simpler methods for making the protected pigment by inclusion of hematite in a transparent zirconium silicate crystal. The purpose of this paper is to compare solution combustion and co‐precipitation methods as two different routes for synthesis of zircon‐based coral pigment.

X‐ray diffraction, scanning electron microscopy and simultaneous thermal analysis were used to characterise and evaluate the precipitated zircon and Fe₂O₃ phases. The synthesised samples were incorporated into a suitable ceramic glaze and then their L*, a* and b* colour parameters were measured via Commission Internationale de I'Eclairage colorimetric method.

The results revealed that partial reduction of hematite (α‐Fe₂O₃) to maghemite (γ‐Fe₂O₃) destroyed the quality of the pigment obtained from the combustion processing method. Nevertheless, it is found that co‐precipitation would be an appropriate method for synthesis coral pigment.

It is found that the solution combustion method is not able to directly synthesise a zircon‐based coral pigment during combustion reaction. Furthermore, the presence of carbon has led to partial reduction of hematite resulting in unwanted crystalline maghemite phase. This reveals that solution combustion method is not suitable to obtain zircon‐based coral pigment.

The conventional method to synthesise ceramic pigments is a solid‐state reaction that requires high temperature and long processing time. The products are usually coarse and inhomogeneous so this method requires further processing like wet or dry milling in order to produce fine powders. Diffusion barrier in solid‐state processing prevents the control of the microstructure and the reactivity of the system. Soft‐chemical routes such as solution combustion and co‐precipitation methods are better choices to get finer powders and to achieve the desired phases at lower temperatures in shorter time as well.

Co‐precipitation synthesis of iron‐zircon coral pigment using sodium silicate (water glass) as Si source and its comparison with solution combustion method is valuable and has not been reported until now.