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Raman microscopy is used in the analysis of glaze on a number of samples that include blue and white ceramic shards, a tile from the Citadel of Algiers and intact Ming plates. The use of the glaze depth profiling method for the study of interfacial pigments on these samples [J. Raman Spectrosc. 2007; 38: 1480] prompted the study of the glaze on the same set of samples to determine glaze type dependence of this method. Using the index of polymerization ( Ip) which is closely correlated with glaze composition and processing temperature, it is shown that processing temperature could be estimated from a low of about 600 °C for some of the unknown archaeological shards to about 1000 °C or above for the Ming porcelain shards. Two intact porcelain plates from the Hongzhi (1488 - 1505) and Wanli (1573 - 1620) Ming imperial periods from the J. A. van Tilburg Museum of the University of Pretoria have been studied, and glaze/glass transition temperature was estimated to be above 1000 °C, consistent with historical data. A SnO2-based glaze tile shard from the Citadel of Algiers was also successfully probed, and results indicated a much lower sintering temperature. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Raman spectroscopy and multivariate calibration techniques are used to determine the percentage conversion of zircon (ZrSiO4) to plasma-dissociated zircon, ZrO2.SiO2 (PDZ). The integrated area of a consistent ZrO2 (monoclinic) Raman band at 477 cm-1 assigned to the Ag symmetry type from different conversion percentages of the PDZ spectra is used in a multivariate analysis scheme (partial least squares) to develop a predictive model for the subsequent determination of percentage dissociation of zircon to PDZ. In contrast to wet chemical methods, this approach eliminates the use of corrosive acids, e.g. hydrofluoric acid, thus leading to significant reductions in analysis time and material wastage, and it is a quick method that can be used online in a PDZ production facility. These results show best correlation with determination coefficient ( R2) values in the range between 99.45 and 99.99% for zircon percentage dissociation in cross-validation tests. This illustrates not only the versatility of the Raman technique in industrial applications but also the importance of noninvasive testing in the study of zircon and related materials. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The structure of LiPF6 has been probed using Raman scattering as well as pXRD and the results are compared and contrasted. The conventional Bragg angle scattering pXRD determines that dry LiPF6 crystallizes in a trigonal structure (Space Group R-3 (148)), while Raman data suggests that the observed structure is close to cubic (Space Group Fm-3m (225)), similar to NaPF6 and KPF6. DFT heat capacity calculations using ab-initio methods for both R-3 and Fm-3m structures show better correlation with the Raman observations. The differences between Raman and pXRD data in LiPF6 appear to be in common with that observed in other materials that are close to phase transitions at the temperature where order/disorder and phase transition processes are known to occur. In these circumstances, Raman spectroscopy emerges as a more sensitive probe of local structural changes than pXRD, which is known to probe the overall average long range order of crystalline materials. The results are interpreted through the relationship between the local symmetry, internal energy and the heat capacity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A micro-Raman spectroscopy study of a multi-coloured (yellow, blue, white, redish-brown and brown-black) tile shard from the Citadel of Algiers was undertaken. XRD and EDX were used as complementary techniques. The study shows that the heterogeneous three-shade yellow pigment on the tile is composed largely of the ancient ternary (Pb-Sn-Sb) pyrochlore oxide with a dominant Pb-O vibration at 127 cm(-1) consistent with the Pb2SnSbO6.5 structure as verified by XRD. The literature assignment of this band at 132 cm(-1) probably comes from a mixture of pigments. The redish-brown and the brown-black pigments are found to be Naples yellow (Pb2Sb2O7) and lead(II) stannate (Pb2SnO4), respectively, while cobalt blue (CoAl2O4) gives the blue colour and cassiterite (SnO2) is the origin of the white colour. The bulk of the tile body is composed mainly of hematite (alpha-Fe2O3), maghemite (gamma-Fe2O3), magnetite (Fe3O4) and Quartz (alpha-SiO2) with traces of calcite (CaCO3) and amorphous carbon. Micro-Raman spectroscopy proved to be very useful in the characterization of pigments as well as the tile body. These results further establish Raman spectroscopy as a technique of choice for the analysis of pigments on archaeological artifacts. The results obtained here could be used in the restoration and preservation programme of the Citadel itself which stands today as a symbol of pre-colonial Algerian heritage.