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An overview of the techniques used in art and archaeology is presented and the applicability of X-ray radiography, X-ray fluorescence (XRF), and X-ray diffraction analysis (XRD) as a tool for nondestructive investigations of objects of art and archaeology is discussed. X-ray radiography, for example, is a standard technique widely used and accepted by art historians, archaeologists, curators, and conservators as this method enables information about the manufacturing process and the condition of an object without “touching” the artifact. XRF and XRD enable a nondestructive determination of the material composition of artifacts and the determination of the crystalline structure of the components too. Air path systems and instruments with the micro-beam of X-ray and synchrotron radiation were applied for the analysis of easel paintings, pigments in paint layers, glass artifacts, and coins.
The transition between tetragonal and cubic phases in nanostructured ZrO2-Sc2O3 solid solutions by high-temperature X-ray powder diffraction using synchrotron radiation is presented. ZrO2-8 and 11 mol% Sc2O3 nanopowders that exhibit the t′- and t″-forms of the tetragonal phase, respectively, were synthesized by a stoichiometric nitrate-lysine gel-combustion route. The average crystallite size treated at 900°C was about 25 nm for both compositions. Our results showed that t′-t″ and t″-cubic transitions take place for the 8 and 11 mol% Sc2O3 samples, respectively.
The neutron diffraction technique was applied to measure strain distributions in a rebar in a reinforced concrete. At first, absorption coefficients of several kinds of concrete with different compounding ratios of water, cement, and aggregate were measured, and it was confirmed that the absorption coefficient of concrete was affected by the amounts of water and aggregate. In addition, it was also clarified by measuring strain change of the rebar under tensile loading that accuracy of the strain measurement in the rebar in the reinforced concrete was not affected by the neutron absorption by the concrete. Second, the size of the anchorage zone was evaluated by measuring strain distributions in the rebar under pull-out loading. The length of the anchorage zone measured by neutron diffraction was shorter than that measured by strain gauges. Moreover, detailed strain distributions in the rebar around cracks in the concrete were measured under tensile loading, and it was confirmed that the bond condition between rebar and concrete around cracks could be evaluated using the neutron diffraction technique.
This paper deals with the implementation of a theoretically described method to determine residual stresses in real space directly by means of small gauge volumes. For this purpose, beam limiting masks were designed, manufactured, and investigated in first experiments. Image series taken with a position sensitive CCD camera demonstrate the ability to detect interferences from gauge volumes beneath the sample surface by defined slit geometries. The experiments show that due to the highly absorbing masks the amount of detectable photons is poor, and thus long exposure times are necessary to receive suitable data. For increasing measurement depths (altering masks) a decrease in the intensity can be detected which leads to the assumption that the diffracted photons originate from deeper regions in the material. A model was developed to simulate the diffraction conditions with different mask layouts and material properties. Modeling yields consistent results with experimental data, and thus provides a basis for further improvements of the experimental setup and the realization and assessment of residual stress measurements.
The effects of chromium or nickel oxide additions on the composition of Portland clinker were investigated by X-ray powder diffraction associated with pattern analysis by the Rietveld method. The co-processing of industrial waste in Portland cement plants is an alternative solution to the problem of final disposal of hazardous waste. Industrial waste containing chromium or nickel is hazardous and is difficult to dispose of. It was observed that in concentrations up to 1% in mass, the chromium or nickel oxide additions do not cause significant alterations in Portland clinker composition.
Thin polycrystalline ZnO films were grown on silicon substrates by dc reactive magnetron sputtering using zinc oxide targets. The quality of the ZnO layers was assessed by X-ray diffraction (XRD), atomic force microscopy, Raman scattering, and photoluminescence measurements. The XRD studies and Raman studies revealed that the ZnO films crystallize in the wurtzite structure. Room temperature photoluminescence spectra consisted of a narrow near-band-edge ultraviolet band and a broad defect-related green band with peak positions at 380 and 516 nm, respectively. The main goal of the work was to define the growth conditions to prepare zinc oxide films with adequate properties to be used in electroluminescent devices. The films exhibited the best surface appearance with a 40:1 argon/oxygen flow rate, a total pressure of 1.5×10−3 mbar, and a substrate temperature of 230 °C. The structural and luminescence properties improved noticeably with the thermal annealing processes at 800 °C for 1 h.
Synchrotron X rays were used to perform nondestructive transmission diffraction and fluorescence experiments on a group of 24 European and Islamic astrolabes dated between 1350–1720 A.D. in order to determine their compositions. A group of six astrolabes produced in Lahore between 1601–1662 A.D. were found to contain a mixed α+β brass microstructure, proving that the brass was produced by a comelting technique rather than the traditional cementation process. The results also show evidence of dezincification, attributed to heavy annealing of the brass during astrolabe manufacture. This effect was so severe that an accurate analysis of the bulk Zn composition could not be determined from the fluorescence results alone; transmission X-ray diffraction gives a more accurate measurement of the bulk Zn composition.
The effect of calcination temperature during the formation of the solid solution Sn0.9Ti0.1O2 doped with 1.00 mol % CoO and 0.05 mol % Nb2O5 is presented. The structural characteristics of this system were studied using X-ray diffraction, and the changes in phase formation were analyzed using the Rietveld method. With an increase in calcination temperature, there is increasing miscibility of Ti into the (Ti,Sn)O2 phase and near 1000 °C, and the remaining TiO2 (anatase) was transformed into the rutile phase. The sintering process, monitored using dilatometry, suggests two mass transport mechanisms, one activated close to 900 °C associated with the presence of TiO2 (anatase) and the second mechanism, occurring between 1200 and 1300 °C, is attributed to a faster grain boundary diffusion caused by oxygen vacancies.
Crystal structure of Ca1-x/2AlSi(N3-xOx):Eu2+ (x ∼ 0.11) has been characterized using an X-ray powder diffractometer and a transmission electron microscope equipped with an energy dispersive X-ray analyzer (EDX) and an electron energy loss spectrometer (EELS). The title compound is orthorhombic with space group Cmc21, Z = 4, unit-cell dimensions a = 0.979780(7) nm, b = 0.565197(4) nm, c = 0.506356(3) nm, and V = 0.280404(3) nm3. The atom ratio Al:Si was determined to be 1:1 by EDX, and the presence of O atoms in the crystal structure was confirmed by EELS. The x-value and the atomic coordinates of the final structural model were determined by the Rietveld method. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the structural model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from MPF are Rwp = 9.18%, S = 1.17, Rp = 6.77%, RB = 1.91%, and RF = 0.86%. Atomic arrangements of the final structural model are in an excellent agreement with the three dimensional electron-density distributions determined by MPF.
Local layer structures and their formation process in a half-V-shaped switching ferroelectric liquid crystal (HV-FLC) were investigated by means of synchrotron X-ray microdiffraction. The HV-FLC is a FLC that has a cholesteric–chiral smectic C (Ch–SmC*) phase transition sequences. X-ray microdiffraction measurements revealed that the SmC* phase in the HV-FLC was composed of asymmetric chevron and inclined-bookshelf structures. In addition, temperature-controlled X-ray diffraction measurements showed that the transient layer structures appeared during the Ch to SmC* phase transition.
Four manganese carbonyl complexes: CpMn(CO)3 (1) and its phenylvinylidene derivatives Cp(CO)2Mn=C=CHPh (2), [Cp(CO)2Mn]2(μ-C=CHPh) (3), and Cp(CO)2Mn=C=C(Ph)–C(Ph)=C=Mn(CO)2Cp (4) have been studied by X-ray powder diffraction and their unit cell parameters are reported. The monoclinic cell parameters found for complex (1) are a=12.0479(7) Å, b=7.0614(5) Å, c=10.9172(6) Å, β=117.626(2)°, Z=4, space group P2(1)/a (No. 14). The orthorhombic cells parameters for complex (2) are a=10.5240(12) Å, b=33.1105(48) Å, c=7.5007(9) Å, Z=8, space group PCCN (No. 56); for complex (3) are a=15.3545(17) Å, b=15.3966(18) Å, c=8.0033(7) Å, Z=4, space group P21212121 (No. 19). The parameters found for complexes (1–3) are in good agreement with those obtained from single crystal X-ray diffractometry. The single crystal structure of complex (4) has not been studied. The orthorhombic cell parameters for complex (4) found by X-ray powder diffraction method are a=10.0986(9) Å, b=33.2937(27) Å, c=7.4139(5) Å, Z=4, space group P21 (No. 4).
The 7-methyl-cis-2-(1’-naphthyl)-2,3,4,5-tetrahydro-1H-benzo[b]azepin-4-ol (chemical formula C21H21NO) was prepared via the reductive cleavage of the bridged N-O bond of the corresponding 7-methyl-2-exo-(1′-naphthyl)-1,4-epoxytetrahydro-1-benzazepine. The X-ray powder diffraction pattern for the new compound was analyzed and found that the title compound crystallizes in a monoclinic system with space group P2/c (No. 13) and refined unit-cell parameters a = 11.012(2), b = 18.613(5), c = 7.316(4) Å, β = 102.88(3) ° and V = 1461.8(7) Å3.
The new heteropoly blue compound (MoO2)0.5PMo14O42, which is relevant in the context of catalytic activity of heteropoly-molybdates, was prepared by controlled thermolysis of (NH4)3PMo12O40 at 730 K in a nitrogen atmosphere. Powder X-ray diffraction analysis showed that this compound has a cubic unit cell, space group Pn3m (No. 224), with ao=11.795(2) Å, Z=2 and DXR=4.2466 g cm−3. Computer modeling and Rietveld analysis of powder diffraction patterns led to a proposed structure of the corresponding Keggin-cage unit PMo14O42.
Improved X-ray powder diffraction data for orthorhombic phosphorus, S.G. C mca (64) obtained in situ at synthesis conditions of 1.2 GPa and 1100 K, are described. Representative, as synthesized, data include 2.552X, 3.3204, 2.5953, 5.1912, 1.6302, for least-squares unit-cell a=3.3182(6) Å, b=10.3744(18) Å and c=4.3227(9) Å. As an illustration of the quality of the data, the structure was solved from powder XRD and Rietveld refined to give a=3.3199(2) Å, b= 10.3678(4) Å, c=4.3154(2)Å, and V=148.535(12) Å3 with the P atom on 8f (1/2, y,z) with y=0.1044(22) and z=0.9179(7).