scholarly journals NON-INVASIVE CHEMICAL ANALYSES OF PIGMENT AND SOME ARCHAEOLOGICAL IMPLICATIONS IN ROUFFIGNAC CAVE (DORDOGNE, FRANCE)

2019 ◽  
Author(s):  
F. Plassard
Keyword(s):  
Chemical Analysis ◽  
Fluorescence Analysis ◽  
X Ray Diffraction ◽  
Raman Spectrometry ◽  
Organic Pigment ◽  
X Ray ◽  
Non Invasive ◽  
Long Time ◽  
New Research

The analysis of pigment the Palaeolithic artists used in cave art has interested the archaeologists very soon (Moissan, 1902). Nevertheless, the necessity of the preservation of the prehistoric artworks has limited the analysis on long time, because this research implied samples which could damage the artworks. The recent development of new equipment allowing non-invasive in situ chemical analysis has conducted to quick increasing of the research in this field. The pigment the prehistoric artists used in Rouffignac cave is strongly studied for fifteen years. After methodological tests, ambitious archaeological programs give nowadays new elements about our knowledge of the wall artworks. Research history. The Rouffignac cave is known for long time because its entrance was never closed. Nevertheless, the prehistoric interest of the site was understood only the 26 june 1956 when L.-R. Nougier and R. Robert identified the first artworks (Barrire, 1982 Plassard, 1999). A strong polemic was born around the authenticity of these documents during the summer 1956 and found a conclusion in an international commission meeting. In this context, the first chemical analysis of pigment in Rouffignac cave was carried out by P. Graziosi (Firenze University, Italy). He concluded the artworks were done with manganese dioxide (Graziosi, 1956). For nearly 50 years, no new research was carried out on the pigments used by the Magdalenians. In 2004, the CEA (Commissariat lEnergie Atomique) made a transportable experimental device for the X-ray fluorescence analysis which opened up new possibilities. A brief analysis campaign was held in November 2004. It aimed to test the feasibility of this type of research in cave, to confirm the Graziosi analyses and to look for black pigments which would not produce any fluorescence spectrum and could be suspected to contain organic matter. The first two objectives were achieved but the presence of organic pigment could not be detected anywhere (De Sanoit et al., 2005). Between 2009 and 2015, a new program expended, first as part of an ANR framework (MADAPCA) and then as part of a PhD project. Several methods were again tested: X-ray fluorescence, X-ray diffraction and Raman spectrometry. Several publications document this research (Beck et al., 2012 AND 2014 Lalhil et al., 2012). However, it quickly became apparent that X-ray fluorescence was the most effective Электронная библиотека ИА РАН: https://www.archaeolog.ru/ru/el-bib 26 method combining short scan times, guaranteed (or nearly) results and reproducibility of measurements. This option was therefore developed by Marine Gay as part of her PhD (Gay et al., 2016).

Chemistry and structural modulations in Bi2Sr2CuO6

1992 ◽  
Vol 7 (4) ◽  
pp. 844-852 ◽  
Author(s):  
Y. Shen ◽  
D.R. Richards ◽  
D.G. Hinks ◽  
A.W. Mitchell
Keyword(s):  
High Temperature ◽  
Oxygen Content ◽  
Metal Ion ◽  
Ion Concentration ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Time ◽  
Structural Modulation

A series of samples along the composition lines Bi2+xSr2−xCuOy, and Bi2Sr2−xCuOy have been used to study the structural modulation, chemistry, and superconducting properties of pseudo-tetragonal Bi2Sr2CuO6 (2201). The 2201 phase can be formed from crystallization of thin glassy platelets. The sample displayed a strong crystallographic (00l) orientation which made it possible to determine incommensurate modulations near (00l) reflections using a conventional x-ray θ-2θ scan. From the crystallization of the 2201 phase, it was found that structural modulation was intrinsic to the phase, and ordering of the structure required a long time at high temperature. High temperature in situ x-ray diffraction of a 2201 Bi2Sr1.85CuOy platelet showed that the modulation existed at 875 °C in O2 (Tmelt ≍ 892 °C in O2). These suggest that the structural modulation cannot be caused solely by oxygen ordering and that metal-ion displacement must be involved. By removing 0.04 to 0.05 oxygen atom per formula unit from Bi2Sr2CuOy and Bi2Sr1.85CuOy, the c* components of the modulation changed from 0.31 to 0.26 and from 0.38 to 0.31, respectively, while the b* component of the modulation remained approximately 0.2. This demonstrates that oxygen, while not the sole cause, does play a role in the formation of the structural modulation. However, the invariance of bmod with respect to the change in oxygen content does not support the model that explained the modulation by inserting extra oxygen in the BiO plane. By varying metal-ion concentrations of Bi and Sr we found that both the lattice parameters and the modulation vectors depended more on the Bi/Sr ratio than on the Sr concentration alone. As the Bi/Sr ratio increased from 1.0 to 1.35, the modulation lines moved toward the (00l) reflections. The corresponding superstructural periodicities were calculated to vary from ∼1/5b* + 0.32 c* to ∼1/5 b* + 0.63 c*. Effects of oxygen content and metal-ion concentration on the 2201 phase formation and the superconducting properties will also be discussed.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Microdomains in BaFeO3-y (0.35 < y < 0.50)

1990 ◽  
Vol 48 (4) ◽  
pp. 780-781
Author(s):  
M. Vallet-Regí ◽  
M. Parras ◽  
J.M. González-Calbet ◽  
J.C. Grenier
Keyword(s):  
Electron Diffraction ◽  
Chemical Analysis ◽  
Monoclinic Phase ◽  
Orthorhombic Phase ◽  
Total Iron ◽  
Zone Axis ◽  
Electron Micrograph ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compositional Variations

BaFeO3-y compositions (0.35<y<0.50) have been investigated by means of electron diffraction and microscopy to resolve contradictory results from powder X-ray diffraction data.The samples were obtained by annealing BaFeO2.56 for 48 h. in the temperature range from 980°C to 1050°C . Total iron and barium in the samples were determined using chemical analysis and gravimetric methods, respectively.In the BaFeO3-y system, according to the electron diffraction and microscopy results, the nonstoichiometry is accommodated in different ways as a function of the composition (y):In the domain between BaFeO2.5+δBaFeO2.54, compositional variations are accommodated through the formation of microdomains. Fig. la shows the ED pattern of the BaFeO2.52 material along thezone axis. The corresponding electron micrograph is seen in Fig. 1b. Several domains corresponding to the monoclinic BaFeO2.50 phase, intergrow with domains of the orthorhombic phase. According to that, the ED pattern of Fig. 1a, can be interpreted as formed by the superposition of three types of diffraction maxima : Very strong spots corresponding to a cubic perovskite, a set of maxima due to the superposition of three domains of the monoclinic phase along [100]m and a series of maxima corresponding to three domains corresponding to the orthorhombic phase along the [100]o.

In-situ Investigation of Bainite Formation with fast X-Ray Diffraction (iXRD)

2017 ◽  
Vol 72 (6) ◽  
pp. 355-364
Author(s):  
A. Kopp ◽  
T. Bernthaler ◽  
D. Schmid ◽  
G. Ketzer-Raichle ◽  
G. Schneider
Keyword(s):  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Investigation

New Coordination Compounds of Fe(III) with Organic Ligands

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihaela Flondor ◽  
Ioan Rosca ◽  
Doina Sibiescu ◽  
Mihaela-Aurelia Vizitiu ◽  
Daniel-Mircea Sutiman ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Complex Compounds ◽  
Organic Ligands ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Chemical Analysis ◽  
Structural Formulae ◽  
Paramagnetic Properties

In this paper the synthesis and the study of some complex compounds of Fe(III) with ligands derived from: 2-(4-chloro-phenylsulfanyl)-1-(2-hydroxy-3,5-diiodo-phenyl)-ethanone (HL1), 1-(3,5-dibromo-2-hydroxy-phenyl)-2-phenylsulfanyl-ethanone(HL2), and 2-(4-chloro-phenylsulfanyl)-1-(3,5-dibromo-2-hydroxy-phenyl)-ethanone (HL3) is presented. The characterization of these complexes is based on method as: the elemental chemical analysis, IR and ESR spectroscopy, M�ssbauer, the thermogravimetric analysis and X-ray diffraction. Study of the IR and chemical analysis has evidenced that the precipitates form are a complexes and the combination ratio of M:L is 1:2. The central atoms of Fe(III) presented paramagnetic properties and a octaedric hybridization. Starting from this precipitation reactions, a method for the gravimetric determination of Fe(III) with this organic ligands has been possible. Based on the experimental data on literature indications, the structural formulae of the complex compounds are assigned.

Texture Evolution Under Fast Heating and Cooling Rates of Zirconium Alloys Studied In-Situ by Synchrotron X-Ray Diffraction

2020 ◽  
Author(s):  
Chi-Toan Nguyen ◽  
Alistair Garner ◽  
Javier Romero ◽  
Antoine Ambard ◽  
Michael Preuss ◽  
...  
Keyword(s):  
Texture Evolution ◽  
Zirconium Alloys ◽  
X Ray Diffraction ◽  
Fast Heating ◽  
Cooling Rates ◽  
X Ray ◽  
Heating And Cooling

STRUCTURAL EVOLUTION OF EXCEPTIONALLY IRON-DEFICIENT HEMATITE NANOCRYSTALS AS OBSERVED BY IN SITU SYNCHROTRON X-RAY DIFFRACTION

2019 ◽  
Author(s):  
Si Athena Chen ◽  
◽  
Peter Heaney ◽  
Jeffrey E. Post ◽  
Peter J. Eng ◽  
...  
Keyword(s):  
Structural Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Iron Deficient

Hydrolytic products of Fe(III) after oxidation of Fe(II) by chlorate

1982 ◽  
Vol 47 (4) ◽  
pp. 1069-1077 ◽  
Author(s):  
Karel Mádlo ◽  
František Hanousek ◽  
Antonín Petřina ◽  
Jaroslav Tláskal
Keyword(s):  
Electron Microscopy ◽  
Ir Spectroscopy ◽  
Chemical Analysis ◽  
Ferrous Sulphate ◽  
Reaction Medium ◽  
Potassium Chlorate ◽  
X Ray Diffraction ◽  
X Ray

Ferrous sulphate was oxidized by potassium chlorate in the pH region 2-7 and at temperatures ranging from 298.1 to 323.1 K and various hydrolytic products of Fe(III) were separated and indentified. The separated solid ferric products were analyzed using a combination of the chemical analysis, IR spectroscopy, X-ray diffraction, and electron microscopy. The following substances were found as major components of the products: Fe2O3.n H2O ("ferric gel"), Fe2O3.n H2O with bound SO2-4 ions ("sulphogel"), α-FeO(OH), γ-FeO(OH) and Fe3O4. Their amount depends particularly on the pH temperature of the reaction medium.

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