Micro-Raman, XRD and THM-Py-GC/MS analysis to characterize the materials used in the Eleven-Faced Guanyin of the Du Le Temple of the Liao Dynasty, China

A Multi-Analytical Approach to Investigate the Polychrome Clay Sculpture in Qinglian Temple of Jincheng, China

“…For the sample XSND-16 and SJD-29, the main elements being Pb and O, their characteristic Raman bands ( Figure 10 b) at 122, 152, 227/231, 313/316, 392 and 549 / 551cm − 1 , were attributed to minium (Pb 3 O 4 ). The Raman results combined with SEM-EDS analysis indicated that the red pigment samples XSND-13, 16, 17 and SJD-29 were thus minimum or a mixture of minium and cinnabar: this is reasonable, as using mixed materials made from two or more pigments in one colour layer to achieve the desired hue is a common traditional technique in Chinese artworks [ 2 , 4 , 27 ].…”

“…The characteristic Raman bands at 219, 341, 418, 510/511, 824, 834, 913, 925, 977, 3345/3347 and 3434/3436 cm − 1 , were ascribed to atacamite (Cu 2 (OH) 3 Cl). In particular, the Raman bands at 824, 834, 913, 925 and 977 cm − 1 were attributed to the bending vibration of O-H and Cu-OH, while the peaks in the range of 219 and 511 cm − 1 were assigned to the vibration modes of O-Cu-O and Cl-Cu-Cl [ 4 , 28 ], and the bands at 3345/3347 and 3434/3436 cm − 1 were assigned to OH stretching [ 29 ].…”

“…The light green pigment (XSBD-3) was confirmed as malachite (Cu 2 (OH) 2 CO 3 ) based on its Raman spectra (seen in Figure 11 b) of 166, 349, 435, 1078, 1355, 1492 and 3374 cm − 1 , which are the characteristic Raman peaks of malachite [ 4 , 30 , 31 ]. Its high C, Cu and O content as assessed by SEM-EDS is essentially also in accordance with malachite.…”

“…It was also commonly used in polychrome clay sculptures, based on evidence from sites such as the Qianfoya Grottos [ 33 ]. Atacamite, another representative pigment used for green colouration, was also widely used in ancient Chinese polychrome clay sculptures and murals after the time of the Five Dynasties (CE709-960) due to the advancements of synthetic technology in that period [ 4 , 34 ]. In ancient China, atacamite was a relatively scarce mineral, with natural green copper ore only been found in the Kangjiltag gold deposits in Xinjiang province [ 35 ].…”

“…Certain analytical methods have already been proven to be effective in the scientific analysis of the various structures of ancient polychromic artworks, including surface or cross-section observation using optical microscopy [ 3 ], digital microscopy [ 4 ] and scanning electron microscopy (SEM) [ 5 ]; X-ray diffraction (XRD) [ 6 ] and SEM [ 7 ] are particularly beneficial for accurately identifying the crystalline structures and microstructure of the clay ground layer while a combination of Herzberg stain and optical microscopy is commonly used to identify the fibre sources in ground clay layers [ 8 ]; particle induced X-ray emission spectroscopy (PIXE) [ 9 ], X-ray fluorescence (XRF) [ 10 ] or energy dispersive spectroscopy (EDS) [ 11 ] have also been used to analyse the elements of the relevant mineral pigments, and a combination of Raman spectroscopy (RS) [ 12 , 13 ], Fourier transform infrared spectroscopy (FT-IR) [ 12 , 13 ] and XRD [ 7 ] have also been found to be beneficial for accurately identifying pigments.…”