The Effect of Praseodymium Oxide Content and Substituting Iranian Rice Husk with Silica on (Pr,Zr)SiO4 Pigment

In this research various compositions of (Pr,Zr)SiO4 were synthesized and the effect of praseodymium content and replacing Iranian rice husk with silica was investigated. The samples were calcined at 1050oC and then washed and milled. One of the interesting results of the research is that the variation in praseodymium oxide content, did not considerably alter the L*a*b* coordinates. As a result, it is possible to produce more economical pigments using less amount of this oxide. Furthermore, by substituting rice husk ash with silica the yellow component of the pigments decreased, which is probably owing to the impurities of the rice husk ash, which in this case may be removed by washing with acid. The XRD results showed the formation of ZrO2 and ZrSiO4 which regarding the yellowish color of the pigments, it may be concluded that praseodymium has entered the structure as solid solution.