The Effect of Partial Substitution of Bi on Colour Properties and Thermal Stability of BixPr1-xFeO3 Pigments

Abstract

The samples of BixPr1-xFeO3 (x = 0-0.3) were prepared by conventional ceramic method. The main aim of this work was to focus on determination of influence of partial Bi substitution for Pr on chromaticity and thermal stability. The formation temperature of the orthoferrites was chosen according to the results of DTA/TG analysis. X-ray powder diffraction analysis showed that solid solutions with orthorhombic structure were created. Results of the work proved that Bi substitution for Pr in PrFeO3 has significant impact on colour properties and thermal stability. Start of sintering of PrFeO3 was detected at 1086 °C and due to substitution of Bi3+ decreased to 956 °C (for x = 0.3). Thermal stability of the samples with x = 0.2 and x = 0.3 was limited at 1371 °C and 1360 °C, respectively. However, final colour was positively affected by the addition of Bi3+. Colour shades of powder shifted from yellowish brown to reddish brown with increasing amount of Bi ions. Very interesting colours of different deep yellowish and reddish brown shades were obtained after their application into organic binder. Mean particle size for all milled compounds prepared at 1000 °C was around 1 micrometer and for samples calcined at 1100 °C ranged between 1 and 1.6 micrometer.