References of "Samain, Louise"
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See detailAnalytical study of “La Famille Soler” by Picasso: from the Blue Period to Cubism
Defeyt, Catherine ULg; Vekemans, Bart; Vandenabeele, Peter et al

Poster (2013, September 23)

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See detailRelationship between the Synthesis of Prussian Blue Pigments, Their Color, Physical Properties, and Their Behavior in Paint Layers
Samain, Louise ULg; Grandjean, Fernande ULg; Long, Gary J. et al

in Journal of Physical Chemistry C (2013), 117(19), 96939712

Prussian blue pigments, highly insoluble mixed-valence iron(III) hexacyanoferrate(II) complexes of typical stoichiometry Fe4III[FeII(CN)6]3·xH2O or KFeIII[FeII(CN)6]·xH2O, have been used as pigments in ... [more ▼]

Prussian blue pigments, highly insoluble mixed-valence iron(III) hexacyanoferrate(II) complexes of typical stoichiometry Fe4III[FeII(CN)6]3·xH2O or KFeIII[FeII(CN)6]·xH2O, have been used as pigments in oil paintings and watercolors for 300 years. For poorly understood reasons, these pigments often fade with time. Although the preparation methods have been recognized since the mid-eighteenth century as a contributory factor in the fading of the pigment, the spectral and physical properties of Prussian blue that vary with the type of synthesis were not precisely identified. Several Prussian blue pigments have been prepared by different methods and characterized by thermogravimetric analyses, high-energy powder X-ray diffraction, atomic absorption and flame emission, UV–visible, iron-57 Mössbauer, iron K-edge X-ray absorption, and Raman spectroscopy. The type of synthesis influences the hue, tinting strength, and hiding power properties of the Prussian blue pigments. Two major features appear to be strongly dependent on the preparative methods, the particle size and the local disorder. Both a nitrogen atmosphere and an intermediate aging step of the Berlin white, Fe2II[FeII(CN)6], during the synthesis are required to obtain a highly colored pigment through the optimization of particle size, minimization in the perturbations to the FeII–CN–FeIII intervalence electron transfer pathway, and the minimization of disordered vacancies. The potassium containing Prussian blue structure has been revisited. It can be described with the Pm3m space group, where approximately one-quarter of the [FeII(CN)6]4– sites are vacant and where the potassium cation is located at a zeolitic-like position inside the lattice cavities. The degree of ordering of the [FeII(CN)6]4– vacancies in all Prussian blues was quantified using atomic pair distribution analysis, an ordering that is consistent with the iron K-edge X-ray absorption spectra. The presence of strain in the crystals is observed by both powder X-ray diffraction and Mössbauer spectroscopy. The structural similarity between the alkali-free, improperly referred to as “insoluble”, and the alkali containing, “soluble”, Prussian blues may explain why the two varieties are almost undistinguishable by spectroscopic techniques. [less ▲]

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See detailRedox reactions in Prussian blue containing paint layers as a result of light exposure
Samain, Louise ULg; Gilbert, Bernard ULg; Grandjean, Fernande ULg et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2013)

Prussian blue, a mixed valence pigment, typically KFeIII[FeII(CN)6].xH2O, was the most widely used blue artistic pigment from ca. 1720 to the 1970's but, unfortunately, its paint layers, especially when ... [more ▼]

Prussian blue, a mixed valence pigment, typically KFeIII[FeII(CN)6].xH2O, was the most widely used blue artistic pigment from ca. 1720 to the 1970's but, unfortunately, its paint layers, especially when used in conjunction with a white pigment, tend to fade or turn green upon extended exposure to light. In order to identify the mechanism underlying these changes, paint layers have been prepared with differing amounts of these white pigments and subjected to accelerated light exposure fading. The resulting unfaded and faded paint layers as well as both the Berlin white pigment, Fe2II[FeII(CN)6], and the partially oxidized Berlin green pigment, {KFeIII[FeII(CN)6]}x{FeIII[FeIII(CN)6]}1–x, have been characterized by Raman and iron-57 Mössbauer spectroscopy. The results indicate that, upon fading, the Prussian blue pigment painted with a linseed oil binder and (PbCO3)2Pb(OH)2 or ZnO, and to a lesser extent with TiO2, undergoes a reduction at the exposed paint surface and an oxidation in the bulk of the paint layer. This combined reduction and oxidation disrupts, at least in part, the FeIII–N–C–FeII intervalent electron transfer pathways in Prussian blue thus leading to pigment fading through a reduction in the intervalent electron transfer absorbance at about 700 nm. [less ▲]

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See detailInvestigation of eighteenth-century Prussian blue pigments by PDF analysis
Samain, Louise ULg; Martinetto, Pauline; Bordet, Pierre

Poster (2012, October 30)

Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704. Because of both its highly intense color and its low cost, Prussian blue was widely ... [more ▼]

Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704. Because of both its highly intense color and its low cost, Prussian blue was widely used as a pigment in paintings until the 1970's. The early preparative methods were rapidly recognized as a contributory factor in the fading of the pigment [1], a fading already known by the mid-eighteenth century. The eighteenth-century methods are based on the calcination of dried blood to produce a potassium hexacyanoferrate complex, which is the first of two essential reactants for synthesizing Prussian blue. The second reactant is an iron salt. We successfully reproduced two typical eighteenth-century empirical recipes [2]. The resulting pigments were of variable color quality, ranging from intense blue to blue-gray or blue-green, and exhibit broadened or inexistent Bragg peaks. High-energy powder X-ray diffraction experiments were performed at the ID11 beamline at ESRF, Grenoble, France. The pair distribution function (PDF) of the pure Prussian blue pigments was refined with a three-phase model, in order to take into account the vacancy distribution in the unit cell of Prussian blue. In certain ancient Prussian blues, the PDF analysis revealed the presence of nanocrystalline ferrihydrite, Fe10O14(OH)2, and also identified the presence of alumina hydrate, Al10O14(OH)2, with a particle size of ca. 15 Å. Paint layers prepared from these ancient pigments subjected to accelerated ageing showed a tendency to turn green, a tendency that was often reported in eighteenth- and nineteenth-century books. The presence of particles of hydrous iron(III) oxides was also observed in a genuine Prussian blue sample obtained from an eighteenth-century polychrome sculpture. [1] Kirby, J.; Saunders, D. The National Gallery Technical Bulletin 2004, 25, 73. [2] Dossie, R. The Handmaid to the Arts; Nourse, J.: London, 1758; Le Pileur d'Apligny, M. Traité des couleurs matérielles et de la manière de colorer relativement aux différents arts et métiers; Saugrain et Lamy: Paris, 1779. [less ▲]

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See detailStudy of the alteration processes of Prussian blue in laboratory-prepared and genuine paint layers
Samain, Louise ULg; Sanyova, Jana; Strivay, David ULg

Conference (2012, July 09)

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is complex because of the highly ... [more ▼]

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is complex because of the highly heterogeneous character of an ancient paint layer. In this context we focus on a particular pigment, Prussian blue. Prussian blue is a hydrated ferric ferrocyanide complex, first synthesized in 1704 in Berlin. It has been widely used by artists until the 1970s. However, the permanence of Prussian blue had already been questioned by the mid-eighteenth century, because it exhibits a tendency to fade in light and to turn green. To date, little attention has been devoted to the understanding of the degradation processes of Prussian blue in paint layers. We induced discoloration upon light exposure in commercial and laboratory-synthesized Prussian blue watercolor and oil paint layers by accelerated ageing. Pure Prussian blue painted in a dark shade appears to be extremely light fast but fades when either painted in a lighter shade or mixed with white pigments. We analyzed the paint layers by various techniques, i.e., UV-visible, Fourier transform infrared, Raman, Mössbauer and X-ray absorption spectroscopy. We attributed the fading of Prussian blue to a reduction of the iron(III) ions at the surface of the paint layers. We also observed a partial oxidation of Prussian in the entire paint layer. Finally we confirmed these results by analyzing works of art containing Prussian blue, i.e., a polychrome sculpture, wallpapers and mural decoration sample. [less ▲]

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See detailCrystal Structure and Local Disorder in Modern and Ancient Prussian Blue Pigments
Samain, Louise ULg; Martinetto, Pauline; Bordet, Pierre et al

Poster (2012, June 06)

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is however complex because of the highly ... [more ▼]

The necessity of understanding degradation and alteration processes in a painting's materials is well established for preservation and art history issues. The task is however complex because of the highly heterogeneous character of a paint layer, which consists of a mixture of pigments and a binder on a support. In this context we focus on a particular pigment, Prussian blue. Prussian blue is a hydrated ferric ferrocyanide complex, first synthesized in 1704 in Berlin. It has been widely used by artists until the 1970's. However reports of discoloration had already appeared in eighteenth and nineteenth century books. To date, little attention has been devoted to the understanding of the degradation processes of Prussian blue in paint layers. The preparation methods of Prussian blue were rapidly recognized as a contributory factor in the fading of the pigment because they lead to the introduction of impurities in its structure. The crystal structure of Prussian blue is notoriously complex because of the presence of vacancies and local disorder. Unresolved questions about the crystal structure of the soluble variety of Prussian blue, i.e., Prussian blue containing alkali cations, are still found in the literature. We reproduced modern and ancient preparation methods of Prussian blue and analyzed the obtained pigments by high-energy powder diffraction at the beamline ID11, ESRF, Grenoble and at the beamline CRISTAL, Soleil, Paris. The crystal structure of soluble Prussian blue was reviewed by Rietveld refinement and appears to contain approximately a quart of iron(II) sites vacant, similarly to the well-known insoluble crystal structure. The refinement of the pair distribution function extracted from the total scattering signal revealed a local structure different from the average one. The local arrangements are best described by combining three different substructures with different numbers of vacancies and vary upon the type of synthesis. The PDF analysis also evidenced the formation of nanocrystalline ferrihydrite and alumina hydrate in Prussian blue pigments synthesized according to eighteenth-century recipes. The local disorder and the presence of an undesirable iron compound in Prussian blue can help to better understand the degradation mechanisms in paint layers containing this pigment. [less ▲]

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See detailDegradation mechanisms of Prussian blue pigments in paint layers
Samain, Louise ULg

Doctoral thesis (2012)

Prussian blue is a modern synthetic pigment discovered in Berlin at the beginning of the eighteenth century. Prussian blue is a hydrated iron(III) hexacyanoferrate(II) complex and its color results from ... [more ▼]

Prussian blue is a modern synthetic pigment discovered in Berlin at the beginning of the eighteenth century. Prussian blue is a hydrated iron(III) hexacyanoferrate(II) complex and its color results from an intervalence charge transfer between the iron(II) and iron(III) ions when light is absorbed at ca. 700 nm. Because of both its highly intense color and its low cost, Prussian blue enjoyed immediate popularity among artists and was widely used as a pigment in paintings until the 1970's. However, the permanence of Prussian blue had already been questioned by the mid-eighteenth century, because it exhibits a tendency to fade in light and to turn green. The preparative methods were rapidly recognized as a contributory factor in the fading of the pigment. The main objective of this thesis is the identification of the degradation mechanisms of Prussian blue pigments in paint layers. Prussian blue was synthesized according to both ancient and modern preparation methods. A thorough analysis of the pigments revealed a dependency upon the type of synthesis, the crystallite size, and vacancy content, all properties that influence the local electronic and structural configurations of the iron ions in Prussian blue. The presence of nanocrystalline ferrihydrite as an undesirable iron containing reaction product was identified in Prussian blue pigments prepared according to eighteenth-century recipes. Discoloration upon light exposure in Prussian blue paint layers was induced by accelerated ageing. Pure Prussian blue painted in a dark shade is extremely light fast but fades when either painted in a lighter shade or mixed with white pigments. The fading of Prussian blue was attributed to a reduction of the iron(III) ions at the surface of the paint layer. A partial oxidation of Prussian blue in the entire paint layer was also observed. The analysis of works of art containing Prussian blue confirmed the combined oxidation and reduction of Prussian blue iron ions upon ageing. The study of alteration mechanisms in a painting pigment is essential both for conservation and historical studies in order to best preserve our cultural and artistic heritage with respect to an artist’s original intentions. [less ▲]

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See detailThe Pivotal Role of Mössbauer Spectroscopy in the Characterization of Prussian Blue and Related Iron Cyanide Complexes
Grandjean, Fernande ULg; Long, Gary J; Samain, Louise ULg

in Mössbauer Effect Reference and Data Journal (2012)

For 50 years, 57Fe Mössbauer spectroscopy has played a pivotal role in the characterization of Prussian blue complexes and many related iron cyanide complexes, a pivotal role that is extensively ... [more ▼]

For 50 years, 57Fe Mössbauer spectroscopy has played a pivotal role in the characterization of Prussian blue complexes and many related iron cyanide complexes, a pivotal role that is extensively illustrated in this paper. For the benefit of the young Mössbauer spectroscopists, the successes, the failures, and the pitfalls reported in the literature are discussed. The successes include the unquestionable distinction of iron oxidation and spin states in Prussian blue and the determination that Prussian blue and Turnbull's blue are the same. The failures include the distinction between low-spin FeII and high-spin FeIIIcations in Berlin green. The pitfalls include many, sometimes poorly determined, hyperfine parameters that have been reported for complexes whose stoichiometry is either unknown or unspecified and even sometimes incorrect. [less ▲]

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See detailInsights into the ancient methods of preparation of Prussian blue pigments by high-resolution powder diffraction and PDF analysis
Samain, Louise ULg; Martinetto, Pauline; Bordet, Pierre et al

Conference (2011, September 09)

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See detailCaractérisation et vieillissement accéléré de pigments de bleu de Prusse synthétisés selon les méthodes de préparation anciennes et modernes
Samain, Louise ULg; Lauricella, Melina; Silversmit, Geert et al

Conference (2011, April 11)

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See detailFading of modern Prussian blue pigments in linseed oil medium
Samain, Louise ULg; Silversmit, Geert; Sanyova, Jana et al

Poster (2011, February 04)

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See detailFading of modern Prussian blue pigments in linseed oil medium
Samain, Louise ULg; Silversmit, Geert; Sanyova, Jana et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2011), 26(5), 930

The fading of modern laboratory-synthesized and commercial Prussian blue, iron(III) hexacyanoferrate(II), based pigments in a linseed oil medium during exposure to light has been investigated. The ... [more ▼]

The fading of modern laboratory-synthesized and commercial Prussian blue, iron(III) hexacyanoferrate(II), based pigments in a linseed oil medium during exposure to light has been investigated. The Prussian blue pigments were painted from linseed oil, as a pure pigment and mixed with white lead, (PbCO3)2Pb(OH)2, zinc white, ZnO, or titanium white, TiO2, pigment. The samples were subjected to accelerated ageing for 800 hours and the light fastness of the Prussian blue pigment was evaluated by reference to blue wool standards. Pure Prussian blue is extremely light fast whilst it strongly fades when mixed with a white pigment, especially with lead white or zinc oxide. The painted samples were studied by UV-visible, iron K-edge X-ray absorption, iron-57 transmission Mössbauer, and attenuated total reflectance infrared spectroscopy. X-ray absorption results reveal a decrease in the iron coordination number in aged samples in the presence of white pigment. The Mössbauer spectra of the pure Prussian blue and the unaged and aged mixtures of Prussian blue and lead white or zinc oxide at 1:100 and 1:10 dilution ratios, respectively, indicate the presence of iron(II) and iron(III) in a ratio close to one as expected for the bulk stoichiometric KFeIII[FeII(CN)6]; no change in the spectral parameters was observed upon ageing. Combined with the X-ray near edge absorption and infrared studies, these results suggest reduction of the surface iron ions in the Prussian blue with ageing upon exposure to light. [less ▲]

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See detailStudy of the degradation mechanisms of Prussian Blue in paint layers by X-ray absorption spectroscopy
Samain, Louise ULg; Silversmit, Geert; Vekemans, Bart et al

Conference (2010)

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See detailCharacterization of modern Prussian blue pigments by Mössbauer spectroscopy and synchrotron radiation
Samain, Louise ULg; Silversmit, Geert; Sougrati, Moulay T. et al

Conference (2009, November 27)

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See detailFading of Modern Prussian Blue Pigments : Preliminary Study
Samain, Louise ULg; Sougrati, Moulay T.; Hatert, Frédéric ULg et al

Poster (2009, June)

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See detailEpitaxial growth of CdTe on Si by Molecular Beam Epitaxy
Samain, Louise ULg; Seldrum, Thomas; Dumont, Jacques et al

in Physicalia Magazine (2008), 30(3), 99-112

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See detailStrain reduction in selectively grown CdTe by MBE on nanopatterned silicon on insulator (SOI) substrates
Bommena, R.; Seldrum, T.; Samain, Louise ULg et al

in Journal of Electronic Materials (2008), 37(9), 1255-1260

Silicon-based substrates for the epitaxy of HgCdTe are an attractive low-cost choice for monolithic integration of infrared detectors with mature Si technology and high yield. However, progress in ... [more ▼]

Silicon-based substrates for the epitaxy of HgCdTe are an attractive low-cost choice for monolithic integration of infrared detectors with mature Si technology and high yield. However, progress in heteroepitaxy of CdTe/Si (for subsequent growth of HgCdTe) is limited by the high lattice and thermal mismatch, which creates strain at the heterointerface that results in a high density of dislocations. Previously we have reported on theoretical modeling of strain partitioning between CdTe and Si on nanopatterned silicon on insulator (SOI) substrates. In this paper, we present an experimental study of CdTe epitaxy on nanopatterned (SOI). SOI (100) substrates were patterned with interferometric lithography and reactive ion etching to form a two-dimensional array of silicon pillars with similar to 250 nm diameter and 1 mu m pitch. MBE was used to grow CdTe selectively on the silicon nanopillars. Selective growth of CdTe was confirmed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Coalescence of CdTe on the silicon nanoislands has been observed from the SEM characterization. Selective growth was achieved with a two-step growth process involving desorption of the nucleation layer followed by regrowth of CdTe at a rate of 0.2 angstrom s(-1). Strain measurements by Raman spectroscopy show a comparable Raman shift (2.7 +/- 2 cm(-1) from the bulk value of 170 cm(-1)) in CdTe grown on nanopatterned SOI and planar silicon (Raman shift of 4.4 +/- 2 cm(-1)), indicating similar strain on the nanopatterned substrates. [less ▲]

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