Exploration And Research Of Silicate Matrix Pigments

The language of color is the code information,which is the translation of the language that the color conveys.Nowadays,looking for new,environmentally safe,economically workable pigments with excellent physicochemical properties has now become a permanent challenge in the pigment industry.Pigments are divided into two categories:organic pigments and inorganic pigments.Although organic pigments are bright in color,they are inferior to inorganic pigments in heat resistance and hiding power.For glass,ceramics,enamel,architecture and other applications,only inorganic pigments can be used.Yellow-orange inorganic pigments mainly include lead chrome yellow(lead chromate),zinc chrome yellow(zinc chromate),cadmium yellow(cadmium sulfide),cadmium red(cadmium selenide)and iron yellow(hydrated iron oxide).Therefore,yellow-orange inorganic pigments containing toxic heavy metals or transition metals(such as Pb2+,Cr6+,Cd2+)are harmful to human body and environment during production and use.Inorganic pigments adjust the color change according to their intrinsic bandgap absorption and reflection.The absorption range of yellow-orange pigment must reach the blue-green zone.Most of the intrinsic band gap absorption of inorganic materials are located in the ultraviolet zone,and there are very few kinds of materials whose band gap absorption reaches the blue-green region.Therefore,it is very difficult to find new inorganic colored pigments.In view of the above situation,we propose a new method to realize the absorption of blue-green light region by doping the rare earth ion electronic transition.Thus,a yellow-orange inorganic pigment is achieved in the intrinsic band gap absorbing conventional inorganic material in the ultraviolet region.Silicate materials have the advantages of good chemical and thermal stability,low cost and easy access.It is a good matrix material.In this paper,inorganic environmentally friendly yellow and orange-red pigments are synthesized using Sr2SiO4 and Sr3SiO5 as matrix materials by traditional preparation methods.The phase and crystal structure of samples were analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM).The reflectance of samples was measured by ultraviolet-visible-near infrared(UV-Vis-NIR)spectrophotometer.A model formula was established by Van-Uitert to calculate the relationship between doped ions.The color purity and brightness of samples were characterized by CIELab color coordinate data.?.Yellow pigment was prepared by high temperature solid phase reaction using SrCO3 as a ruthenium source and SiO2 as a silicon source.The results show that(Sr1-xEux)2SiO4(x=0,1,2,4,8,16,32,64,100 mol%)series of pigments crystallize at 1250?,the sample has a uniform particle size and its size is about 5.5?m.As Eu ions increases in Sr2SiO4,the color of the sample transitions from white to pale yellow to yellow.The visible light reflectance(20%-75%)of the pigment sample decreases with the increase of Eu2+ion concentration,while the near-infrared reflectance is maintained at about 90%.The type of interaction between ions is calculated by Van-Uitert's model as electric dipole-electric quadrupole interaction.?.Powdered pigments are prepared by conventional high temperature solid phase method using barium carbonate and silica as raw materials.The results show that:(Sr1-xEux)3SiO5(x=0,1,2,4,8,16,32,64,100 mol%)series of pigments were successfully synthesized at 1250?for 3h,and the samples were uniform in particle size and the particle size was about 8 ?m.With the increase of the Sr ion content in the Eu-substituted Sr3SiO5,the color of the powder sample transitioned from white to orange and then to pale yellow and gray.The corresponding CIE coordinates of these samples were regularly shifted from(0.345,0.355)to(0.490,0.427)and return(0.324,0.348).The visible light reflectance(65%-80%)and near-infrared reflectance(85%-95%)of the pigment samples showed a trend of decreasing first and then increasing with the increase of Eu2+ ion concentration.When the concentration of doped cerium ions is 16%,the color rendering performance of the pigment is the best,L*value is 96.28,a*value is 32.82,b*value is 87.89,C*value is 93.79,and chromaticity angle ho is 68.75°.?.Similarly,cesium carbonate and silica were used as raw materials,and NH4CI,H3BO3,BaF2,MgF2,CaF2 and other cosolvents were added.The powder sample of(Sr0.92Eu0.08)3SiO5 was successfully synthesized by high temperature solid phase reaction.The results showed that the color,particle morphology and particle size of the pigment samples changed greatly after the addition of the cosolvent.The powder samples of the co-solvent such as NH4CI,H3BO3,BaF2,MgF2,and CaF2 were respectively 6.01?m,5.29?m,9.66?m,10.08?m,and 3.08?m,and the corresponding pigment samples were pale yellow.Light pink,yellow,orange,grayish white.The visible light reflectance of the pigment samples was 72%,60%,70%,65%,and 75%,respectively,and was substantially around 70%,In terms of color rendering performance,the color of the cosolvent is NH4CI,BaF2,MgF2,the L*values are 95.27,95,79,90.09,respectively,the a*values are 29.56,35.24,30.38,respectively,and the b*values are 77.84,86.08,78.12,respectively,and the C*values are 83.26,93.01,83.82,respectively,and the chromaticity angle h° are 69°,67°,68°.