Synthesis And Characterization Of Cobalt Blue And Pr-zircon Yellow Nano Pigments Powder

Ceramic pigment precursor was synthesized by the homogeneousprecipitation method combined with CO₂supercritical fluid drying technology,and the precursor was calcinated at different calcinations temperatures. for thepigment precursor and ceramic pigment samples were characterized by XRD,FT-IR, TG/DTA, SEM and TEM test means. Meanwhile, The color ofceramic pigments were characterized by CIE-L*a*b*and diffuse reflectivespectrum （DRS）.Cobalt blue precursor sediment was prepared by the urea homogeneousprecipitation, and the precipitate was dried at room temperature. Theprecursor was made of amorphous hydroxide and carbonate mixture. XRDresults showed that precursor calcinated at700in the air appear spinelphase, and get a good crystallinity of cobalt blue pigments at1000. FT-IRdisplayed that vibrations at about650,550,540,520,500,490cm-1, whichwere ascribed to the spinel structure. SEM showed that the pigment powderparticle size was uneven, and powder presented severe agglomeration.CIE-L*a*b*system and DRS determination, L*a*b*value was not affectedby the mineralizer HBO3, which only promoted solid state reaction and madecolor Co²⁺ions enter ZnAl2_O4lattice. Diffuse spectra of sample CoxZn1-xAl2O4showed that there was a strong absorption yellow, orange andred light range from540nm to630nm. Therefore, cobalt blue pigmentsshowed the color of sky blue.Co_0.3Zn_0.7Al₂O₄precursor was synthesized by the homogeneousprecipitation combined with CO₂supercritical fluid drying technology. XRDresults show that the precursor calcinated at800directly appeared purespinel phase. SEM results show that pigment powder calcinated at1000and1100can take on good dispersion, and particles were kind of ballshape, which size distribution between35and60nm. Compared with naturaldrying results, CO₂supercritical drying alleviated agglomeration, andpigments presented good dispersion with high sintering activity. Two dryingmethods have an effect on the L*a*b*value, especially to the b*value. Thecolor of pigments prepared by supercritical drying calcinated at700¹000was weaker than those of pigments synthesized by conventional dryingmethod. However, the color of the sample prepared by supercriticaldrying,which calcining temperature higher than1000, was brighter andmore exquisite.Pr-zircon precursor sediment was prepared by the urea homogeneousprecipitation, and the precipitate was dried at room temperature. Theprecipitate was calcinated at different temperature to obtain Pr_xZr_1-xSiO₄yellow pigments. XRD results showed that when calcining temperature of900, the main crystalline phase was the single monoclinic zirconium dioxide. Meanwhile, the curve of XRD presented Pr₂Zr₂O₇and Pr_9.33Si₆O₂₆featuresdiffraction peak, which demonstrated that Pr4+have entered in the ZrSiO4lattice, thus it explained that we have prepared the Pr_xZr_1-xSiO₄solid solutiontype of Pr-zircon yellow pigments. When Pr content between0.03and0.07and calcining temperature of800and1200, we can get high yellowcolor of Pr-zircon yellow pigments.