Reliability of Raman micro‐spectroscopy in analysing ancient ceramics: the case of ancient Vietnamese porcelain and celadon glazes

Abstract

Non-destructive Raman spectroscopy has been used to study ancient ceramics. On the basis of spectral features characteristic to the microstructures, the composition and technological processing of ceramics in ancient times could be quantitatively determined. Ceramics are heterogeneous materials composed of grains of different phases, coated by different glazes containing various pigments. The question of reliability and representation of the Raman spectra recorded from the surface of glaze or on a section of shard is discussed. As an illustration, ancient (13-14th centuries) Vietnamese (proto)porcelains made at Ha Lan (Nam Dinh) were studied with particular attention to the analysis of the SiO 4 -based glassy network: Spectral components of the Si-O stretching mode are analysed in terms of isolated (Q 0 ), more or less associated (Q 1 , Q 2 , Q 3 ) or fully-bonded (Q 4 ) SiO 4 tetrahedra. The results show the facility and reliability of Raman spectroscopy as a non-destructive technique suitable for discrimination between ancient ceramics and modern copies.

Re‐dating of Chinese celadon shards excavated on Mapungubwe Hill, a 13th century Iron Age site in South Africa, using Raman spectroscopy, XRF and XRD

“…The shift of the peak from 464 cm 1 in pure SiO 2 to lower wavenumbers (457-460 cm 1 ) has been attributed to tensile stress, which exists in small grains of quartz in the interface layer. 19 It should be noted, however, that we observed this shift also in spectra not recorded on the interface but always in association with the peak at 450 cm 1 , characteristic of silica glass, as also seen in the spectrum in Fig. 2…”

On‐site Raman analysis of Iznik pottery glazes and pigments

“…Considering the Si-O bending (~500 cm -1 ) and stretching (~1000 cm -1 ) envelopes [12,21,22], glaze signatures are rather homogeneous, both for artifacts ( (Table 1), except the shard "e" (torsade), which shows a strong 1095 cm -1 component. This last spectrum is very similar to those recorded on many Kütahya wares.…”

Porcelain shards from Portuguese wrecks: Raman spectroscopic analysis of marine archaeological ceramics

“…1400 BC) through to the fine European and Chinese porcelains of the fifteenth to nineteenth centuries. The range of materials investigated includes tin-glazed earthenwares, mediaeval terracotta roof tiles, majolica and bone Chinas from which it has been possible to deduce the salient features of the ceramic bodies, glazes and the applied pigments where appropriate [3][4][5][6][7]. The non-destructive analysis of ceramics poses several challenges for spectroscopists because of their composite nature, where the sintered grain and domain sizes range from a few microns to about 500 μ, the presence of crystalline and glassy phases along with unreacted starting components, and the inhomogeneity of the ceramic matrices arising from diverse processing technologies, firing sequences and kiln temperatures.…”