Influence of pH on the incorporation and growth of Pb2CrO5 crystallites in silica matrix

Pb2CrO5 nanoparticles were embedded in an amorphous SiO2 matrix by the sol-gel process. The pH and heat treatment effects were evaluated in terms of structural, microstructural and optical properties from Pb2CrO5/SiO2 compounds. X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), and diffuse reflectance techniques were employed. Kubelka-Munk theory was used to calculate diffuse reflectance spectra that were compared to the experimental results. Finally, colorimetric coordinates of the Pb2CrO5/SiO2 compounds were shown and discussed. In general, an acid pH initially dissolves Pb2CrO5 nanoparticles and following heat treatment at 600 A degrees C crystallized into PbCrO4 composition with grain size around 6 nm in SiO2 matrix. No Pb2CrO5 solubilization was observed for basic pH. These nanoparticles were incorporated in silica matrix showing a variety of color ranging from yellow to orange.