SYNTHESIS, STRUCTURAL CHARACTERIZATION AND RAMAN-SPECTROSCOPY OF THE INORGANIC PIGMENTS LEAD-TIN YELLOW TYPE-I AND TYPE-II AND LEAD ANTIMONATE YELLOW - THEIR IDENTIFICATION ON MEDIEVAL PAINTINGS AND MANUSCRIPTS

Lead tin yellow type I (Pb2SnO4) and type II (PbSn1-xSixO3) have each been prepared in a high-temperature furnace, and the preparative conditions defined. The crystal structure of type II has been refined from powder X-ray diffraction data and indicates that the Sn and Si atoms are randomly distributed over the same type of site with Sn/Si ratio approximate to 3/1 (i.e., x approximate to 1/4). The Raman spectra of each form and also that of lead antimonate yellow (Pb2Sb2O7) have been obtained. Raman microscopy is shown:to be an effective technique whereby these inorganic yellow pigments as minute (approximate to 1 mu m) grains may be identified on medieval manuscripts and paintings.