Lithol reds belong to the group of azo pigments, which were popular artists’ colouring materials in the first half of the twentieth century. These pigments were also used in many branches of industry. Here, we report X-ray powder diffraction data, unit-cell parameters, and space groups for three compounds from this group: sodium (E)-2-((2-hydroxynaphthalen-1-yl)diazenyl)naphthalene-1-sulphonate monohydrate (Na lithol red), monoclinic, space group C2/c, with cell parameters a = 33.343(7), b = 6.667(2), c = 16.397(4) Å, β = 90.83°, V = 3644.51 Å3, Z = 8; barium (E)-2-[(2-hydroxynaphthalen-1-yl)diazenyl]naphthalene-1-sulphonate trihydrate (Ba lithol red), monoclinic, space group P21/m, with cell parameters a = 17.758(9), b = 6.209(4), c = 16.857(8) Å, β = 92.07°, V = 1857.39 Å3, Z = 2; and ammonium (E)-2-[(2-hydroxynaphthalen-1-yl)diazenyl]naphthalene-1-sulphonate monohydrate (NH4 lithol red), monoclinic, space group P2/c, with cell parameters a = 17.721(5), b = 6.428(3), c = 16.911(5) Å, β = 100.31(3)°, V = 1895.31 Å3, and Z = 4. In the first and third cases we synthesised the pigments in their monohydrate form, performed X-ray powder diffraction measurements, and indexed all of the obtained diffraction maxima. In the case of the barium compound, despite many efforts in the course of the synthesis procedure, the powder diffraction patterns of the obtained samples were not of the best quality. Nevertheless, we indexed the best one and found a reliable space group and cell parameters.
Among various types of cultural heritage objects, icons belong to the most interesting and not too often investigated group. Similarly to the investigations of easel paintings, only tiny amounts of samples taken from icons can be available for scientific studies. In the literature very few technical papers on icons can be found, so there is a shortage of information for comparative studies in this subject.During the medieval and post-medieval era, calcium carbonate was the most commonly used ground material in the northern regions of Europe, while gypsum was preferred in the southern ones [1]. XRPD is one of the best techniques for precise characterization of these materials. In our work, we have undertaken XRPD investigations of ground layer composition in twenty five post-Byzantine icons from the collection of the National Museum in Krakow, The Bishop Erazm Ciolek Palace (Poland). The aim of our research was to supplement the data obtained by optical microscopy (OM), scanning electron microscopy connected with X-ray spectrometry (SEM-EDX) and other methods.All XRPD measurements were performed using laboratory X-ray source; an X'PERT PRO MPD apparatus, working in θ/θ Bragg/Brentano geometry, CuKα radiation (λ=1.5418 Å), equipped with diffracted-beam graphite monochromator and a PIXcel PSD detector, in a 2θ range from 5 to 85º. Prior to each measurement the minute amount of each sample was placed on the zero-background sample holder and fixed to it with the use of propanol. Phase analysis of the obtained results was performed by X'pert HighScore software and PDF-4+ Database.In our studies on the grounds of icons from the Bishop Erazm Ciolek Palace, we have detected gypsum, anhydrite, calcite, dolomite and other compounds which were purposely added to the material of the preparation layer, or were contaminants of the raw materials. In one case we have also identified weddellite [Ca(C2O4)(H2O)2.37; PDF 04-011-6807] which is a product of the ground layer deterioration.Our results allowed us to divide the investigated icons into four groups: containing only calcite (group I -8 icons), containing gypsum and anhydrite (group II -6 icons), containing only gypsum (group III -4 icons) in the ground layer. The composition of the ground layer in the rest of the investigated objects (group IV) was more rich and contained a mixture of carbonates and/or sulfates with addition of other compounds.Given the lack of bibliographic resources, this research is one of the first integrated approaches to determine the components of artistic materials used in icons from the collection of the National Museum in Krakow. We hope that identification of the materials present in the ground layer of an icon will help in collecting historical information which is necessary for the documentation of the artwork and important for appropriate conservation strategies.[1] Mastrotheodoros, G. P. (2016). Archaeometry. 58, 5 830-847.
Two examples of transition metal molybdates were studied with the use of X-ray diraction and DC magnetometry techniques. First compound, copper dimolybdate trihydrate CuMo2O7·3H2O contains 2D layers. The second one is brillar cobalt trimolybdate octahydrate CoMo3O10·8H2O. Both compounds exhibit paramagnetic behaviour at room temperature. However, in the rst one copper ions form dimers linked by oxygen bridges, in which exchange interactions between two localized spin states occur. The second compound consists of isolated cobalt ions in the octahedral surroundings, resulting in magnetic properties deviating from the Curie law.
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