Characterization of Iranian Ancient Colored Glazed Ceramic Tiles of Safavid Era

Investigation of the chemical compositions of pigments in glazed ancient ceramic tiles is of great importance from the monuments restoration point of view. In this regard, the current research aimed to investigate the chemical compositions and color charactristics of pigments in six glazed ancient ceramic tiles (Samples B1-B6) collected from Abdolazim Hasani Shrine (Safavid era), Ray, Iran. The results from X-ray Probe Micro Analyzer (XPMA), X-Ray Diffraction (XRD) patterns, and Energy Dispersive X-ray Spectroscopy (EDS) spectra revealed that the glazes were silica-based, containing 38.85 to 50.89 wt. % silicon in Samples B3 and B1, respectively, with lime, quarts, wollastonite, and cristobalite as the main phases. Raman spectroscopy also confirmed the presence of quartz, wollastonite, and tridymite along with chalk, gypsum, calcite, copper oxide, and green earth. The particle sizes of the pigments measured through Scanning Electron Microscopy (SEM) varied from 0.6 μm in Sample B1 to 5.5 μm in Sample B3. High intensity reflectance was also observed in the range of 490-560 nm, confirming the green color of the samples with different shades. In addition, CIE L*a*b* parameters clearly showed the correlation between the green color and concentration of Cu2+ ions within the silica-rich amorphous phase. Therefore, the presence of wollastonite, tridymite, and copper oxide in the samples under study was obviously indicative of presence of Egyptian green pigments in the glazes.