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Amperometric Solid-State NO2 Sensor with Ionic Liquid-Polymer Electrolyte
Nádherná, M. ; Opekar, F. ; Reiter, Jakub
A new ionic liquid-polymer electrolyte was successfully tested in the planar amperometric solid-state sensor sensitive towards nitrogen dioxide. The electrolyte consists of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) and poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) in the ratio 57:43 mol. %. The analyte, gaseous nitrogen dioxide in air, was determined using the electrochemical reduction at900 mV vs. Pt/air on gold minigrid indicating electrode with Pt/air as a reference electrode. Dependency of sensor sensitivity on the indicating electrode area and relative humidity was determined. The sensor response is linear in the NO2 concentration range 0.3 1.1 ppm and is reproducible and long-term stable.
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Magnetic properties of doped CeO.sub.2./sub. nanoparticles and CeO.sub.2./sub.-Fe.sub.2./sub.O.sub.3./sub. mixed oxides
Mantlíková, Alice ; Bittová, Barbara ; Burianová, Simona ; Vejpravová, Jana ; Nižňanský, D. ; Holec, Petr
We have investigated magnetic properties of CeO2 nanoparticles and CeO2/SiO2 nanocomposites doped by various magnetic metal oxide ions (Fe, Gd, Sm, Nd). Samples were obtained by co-precipitation and sol-gel method. Particle size has been obtained as 5 - 25 nm for nanocomposite and 25 - 100 nm for nanoparticles increasing with the increase of the annealing temperature. Detailed measurements of magnetization demonstrate paramagnetic state in the majority of the doped samples with maximum magnetization decreasing with the decrease of effective magnetic moment of the dopant ions from Gd3+ to Nd3+. It has been also observed, that the high-coercivity ε-Fe2O3 forms in CeO2-Fe2O3/SiO2 nanocomposite for higher concentration of the Fe ions (Ce/Fe/Si ratio equal to 1/2/9) and for the highest annealing temperature.
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Preparation of nanoforms of layered piezoelectric of systems BI2O3-TA(2)O(5)-AO (A=CA,SR,BA)
Štarman, S. ; Matz, V. ; Kváča, Z. ; Mohyla, M. ; Olšák, V. ; Plocek, Jiří ; Vaněk, Přemysl ; Tylš, B.
Based on the known Aurivillius phases types ABi2Ta2O9 and A2BiTaO6 ( A=Ca, Sr, Ba) were supplemented with new compositions of layered tantalates, which resulted the possibility of the existence of a new phase Sr2BiTaO6. Ternary compounds with piezoelectric structure were prepared as nanoforms by solgel reactions of homogeneous acetate Bi, Ta, A and subsequent annealing in a controlled atmosphere. Annealing temperature was determined from DSC curves based on the weight loss and phase transitions. Composition and structure of nanocrystals has been analyzed by X-ray diffraction (XRD), scanning nanomorphology (SEM) and acoustic measurements.
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The imitation of brocade fabrice in late mediavel altarpieces from Transilvania
Serendan, C. ; Hradilová, J. ; Hradil, David
The representation of rich brocade fabrics was one of the main and most striking features of European medieval paintings. What we see today is the impressive result of the artist's skills and the commissioner's preferences. To achieve this effect, medieval artists developed a large variety of materials and techniques. This paper presents the results of an integrated approach to the investigation of the techniques used by the painting workshops in Transylvania for the imitation of brocade fabrics. The investigation is carried out on a group of 12 largely unstudied Late Gothic Early Renaissance altarpieces built between 1450 1540 in German and Hungarian communities, these being some of the oldest panel paintings preserved in Romania. Over the period 2005-2010 these paintings were, for the first time subjected to an extensive technical investigation by complementary analytical methods. The in situ investigation combines visual examination and extensive non invasive point measurements by portable X-ray fluorescence. Due to their present location in various churches in Transylvania, a minimal sampling only was allowed for further elemental analysis carried out in laboratories. The laboratory investigations included light microscopy (in both visible and UV light), histochemical tests on cross-sections, scanning electron microscopy (SEM) with EDX spectrochemical microanalysis, and Fourier transform infrared spectroscopy (FTIR). The study reveals the use of at least five different types of brocade imitation, including the sophisticated technique of applied relief brocades (Pressbrokat). Most of these five types are using a combination of techniques of decorative treatment of the ground layer with paint layers, coloured glazes and application of metal leafs.
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Energy sensitive X-ray radiography for the non-destructive inspection of historical paintings
Žemlička, J. ; Jakůbek, J. ; Hradil, David ; Hradilová, J. ; Kroupa, M. ; Mislerová, H.
The technical composition of painted artworks is usually very complex and they belong to the most sophisticated cultural heritage artefacts. In the field of their inspection there is a rising demand for the non-destructive imaging and analytical methods which are able to reveal the inner composition of investigated objects. Several non-invasive methods based on the interaction of ionizing radiation with the matter have been successfully utilized during the last decades. These methods can be divided into two main groups. The better known are transmission methods (e.g. classical X-ray radiography) the less-used are emission methods (e.g. X-ray fluorescence imaging). The quality of the obtained image is highly dependent on the imaging characteristics of the used detector. The presently used ones (CCD cameras and CMOS sensors) create the image from analogue signal by the charge integration. This image is usually degraded by the presence of noise. This complication is exceeded by novel pixel detectors of Medipix family based on single particle digital counting. Furthermore these devices offer very high contrast (in principle unlimited) in the obtained image. The image can be acquired with spatial resolution better than one micrometer. Another advantage of these detectors is their ability to directly measure the energy of incident particles. This feature can be used for energy sensitive X-ray radiography (i.e. multi-channel images) and X-ray fluorescence mapping of the surface elemental composition. For the purposes of this work the laboratory ALMA in Prague prepared several multilayer samples of paints using different pigments. The results of mentioned methods applied on the test samples are summarized in this article. The first goal of these measurements is to build a comprehensive methodology for the application of these procedures in the laboratory.
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New kriteria for classification and differentiation between clay and iron oxide pigment sof various origins
Hradil, David ; Hradilová, J. ; Bezdička, Petr
Pigments containing iron, although they form a very large group, have never been considered very suitable for datation of color layers and identification of the origin of the painting, due to their abundant occurrence in nature, good availability and widespread use in all historical and pre-historical periods of time. In this paper we have verified that mineralogical composition of clay minerals in earthy pigments is a suitable tool for more detailed specification of material provenance and, in the case of ground layers, also the provenance of the artwork as such. It was obviously convenient to preferably use raw materials from a close and thus also cheaper source. For the purposes of statistical comparison we evaluated elemental composition of earthy grounds on 70 paintings from the 16(th)-18(th) centuries from Czech collections. We performed detailed mineralogical analyses for a selected representative number of grounds on 35 samples in total. We discerned 6 types of material in total 2 types of boles, 3 types of other earths, and one type representing iron-rich red from oxidized zones of hydrothermal ore deposits. We were able to distinguish between earthy pigments of Central European origin (coming from Czech and Bavarian locations) and those coming from North-Italian sources. Thus we were able to assign anonymous paintings to an appropriate place of origin.
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16th International Symposium on Intercalation Compound - ISIC16. Abstracts Book
Zima, Vítězslav ; Kavan, Ladislav ; Čejka, Jiří ; Lang, Kamil ; Vlček, Milan ; Beneš, L. ; Svoboda, Jan ; Melánová, Klára ; Frumarová, Božena ; Knotek, P. ; Jůza, Josef ; Látalová, Petra
The topic of the papers published in this proceedings is chemistry, properties and applications of intercalation compounds and related materials.
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