The diffraction pattern of nanocrystalline Ce0.9Zr0.1O2 was analyzed by whole powder pattern modeling, a recently proposed method for the study of line broadening. The main result in this typical case of study—the crystalline domain size distribution—matches closely the corresponding information obtained by transmission electron microscopy. Further information on nature and content of lattice defects is also discussed.

Weight fractions of four dominant phases (C3S, C2S, C4AF and C3A) present in the NIST Reference Portland clinkers 8486, 8487 and 8488 were estimated by a series of Rietveld refinements. Calculated powder patterns were derived from the structural data for monoclinic C3S and C2S, orthorhombic C4AF and cubic C3A. X-ray diffraction data were collected in two laboratories with two diffractometers, a reflection and a transmission one. There were no significant differences between the results of the refinements based on the data sets collected on the machines with different experimental arrangements. Estimated phase compositions were compared to the reference values found by optical microscopy (MPC). Median agreement between refined and reference values within ±5% (absolute) was found only for 8488 clinker; for 8486 and C3A-rich 8487 it was within ±10% (absolute). In the majority of the refinements numerical instabilities were detected, leading to large correlations between FWHM and temperature parameters of some phases. The results obtained for C4AF were probably influenced by the presence of possible solid solutions with the structures close to that of C4AF. Weight fractions of low abundant C3A were estimated with the largest relative errors reaching in several cases ∼100%.

The thermal behavior and decomposition reaction of Prussian blue (PB) (Fe43+[Fe2+(CN)6]3·xH2O) was studied under inert atmosphere of argon by simultaneous thermogravimetry and differential scanning calorimetry, from room temperature up to 900 °C, with a heating rate of 5 K min−1. Parallel to the thermogravimetric measurements, the thermal process was monitored by in situ X-ray powder diffraction (XRD) technique under nitrogen atmosphere. The thermogravimetric data show six steps, corresponding to different stages of the decomposition reaction; comparable results are also obtained by in situ XRD. In addition, a set of PB samples heated up to selected temperatures (190, 300, 370, 540, 680, and 790 °C) were ex situ analyzed by powder XRD and Mössbauer spectroscopy. It is found that PB exhibits a negative thermal expansion prior to the water release from its crystalline lattice. Above 300 °C, the decomposition is based on the release of cyanogen gas from the PB structure. At 370 °C, a cubic iron cyanide compound is formed, while at higher temperatures several iron carbides were found. The subsequent thermal treatment of these carbides leads to the formation of metallic iron and graphite.

The decomposition reactions of two zirconium hydroxide nitrates Zr(OH)2(NO3)2·(4+x)H2O and α-Zr(OH)2 (NO3)2·(1+x)H2O (0≤x≤1) have been studied by thermogravimetric analysis and high-temperature X-ray powder diffractometry (HTXRD), in nitrogen gas environment. The decomposition reaction sequences were clearly displayed by the HTXRD technique. They are different for the two precursors, except the formation of amorphous zirconia at low temperature (200 °C) and crystalline zirconia at about 390 °C. Three modifications of Zr(OH)2(NO3)2·H2O (α,β,γ) were identified. Their X-ray powder diffraction patterns were indexed by the successive dichotomy method. The unit cells are triclinic and present some parametric and volumetric similarities from each other and also with that of their precursor. Moreover, the thermal decomposition sequences of Zr(OH)2(NO3)2·(4+x)H2O and α-Zr(OH)2(NO3)2·(1+x)H2O include the formation of anhydrous oxide nitrate ZrO(NO3)2 and anhydrous hydroxide nitrate Zr(OH)2(NO3)2, respectively.

The analysis of the distribution of pharmaceutical materials in tablet formulations, such as drugs and matrix elements, is critical to product performance and is used in such areas as quality control, impurity testing, and process monitoring. Recently imaging techniques, such as Raman, near-IR, and fluorescence imaging, have become popular for “visualization” of pharmaceutical formulations, allowing for spatial and chemical composition information to be obtained simultaneously. These methods have been primarily focused on molecular imaging, or spatial analysis of the molecular characteristics of the tablet formulation. However, elemental species are also an important part of pharmaceuticals. Micro X-ray fluorescence (MXRF) elemental imaging offers complementary information to molecular imaging techniques. In this study, MXRF was used for the elemental imaging of various commercial pharmaceutical drug and vitamin supplements. Specifically, elemental composition and heterogeneity were monitored for each different tablet.

The human eye is continuously exposed to the environment yet little is known about how much of toxins, specifically heavy metals are present in its different parts and how they influence vision and acuity. To shed light into this subject, aqueous humor and lens samples were collected from 14 cataract patients to study the presence and concentration of selected metals in the eye. Subjects undergoing routine cataract surgery were consecutively enrolled for study by simple random sampling. Prior to surgery, subject demographic were compiled. The surgical procedure involved small incision cataract removal using phacoemulsification. During the procedure, a small aliquot of aqueous humor was retained for analysis, whereas homogenized lens fragments were obtained during phacoemulsification. A balanced salt solution was used as control for each set of samples. Both ocular specimens were analyzed by total reflection X-ray fluorescence spectrometry after dilution and addition of an internal standard. The data obtained show substantial variations in elemental signature between the two media (aqueous humor and lens) and the patients themselves. Most commonly found heavy metals in both types of media were chromium and manganese. Barium was found in the lens, but not in aqueous tissue, whereas nickel was found only in the aqueous humor. Concentrations were generally higher in aqueous samples. Further study and increased sample size are required to more accurately elucidate the relationship between systemic and ocular metal accumulation and the impact of metal accumulation on measures of visual function and ocular disease.

A number of synchrotron X-ray fluorescence microprobes (XFMs) around the world offer synchrotron X-ray microdiffraction (μXRD) to enhance mineral phase identification in geological and other environmental samples. Synchrotron μXRD can significantly enhance micro X-ray fluorescence and micro X-ray absorption fine structure measurements by providing direct structural information on the identity of minerals, their crystallinity, and potential impurities in crystal structures. The information is useful to understand the sequestration of metals in mineral deposits, mineral processing residues, soils, or sediments. Synchrotron μXRD was employed to characterize a surficial calcrete uranium (U) ore sample and to illustrate its usefulness in conjunction with U LIII μXANES analysis. μXRD and U LIII μXANES revealed that the mineral carnotite [K2(UO2)2(V2O8)·nH2O, n = 0, 1, 2, or 3] was not the sole U bearing mineral phase present and that surface complexes and or an amorphous precipitate were present as well. Unit-cell analysis from the μXRD patterns revealed that the interlayer spacing of carnotite was not uniform and that significant unit-cell volume expansions occurred likely because of variable cations (K+, Rb+, and Sr2+) and variably hydrated interlayer cations being present in the interlayer. Oriented specimen, single crystal effects, and the fixed orientation of the sample relative to the incident beam and the charge-coupled device camera limit the number of visible reflections and complicate mineral phase identification. With careful analysis of multiple structural analysis tools available at XFMs, however, a strong link between X-ray amorphous and X-ray crystalline materials in geologic and environmental samples can be established.

A specially designed specimen holder employing a beryllium dome has been fabricated for collection of X-ray diffraction (XRD) data from highly reactive materials. The specimen holder has a robust O-ring type seal (<10−9Torr) and no observed intensity artifacts in the 1° to 150° 2θ range. The design also minimizes specimen displacement errors and allows for analysis of both powders and bulk specimens (i.e., pellets). The simple design makes for straightforward assembly of the holder within the confines of a glove box. XRD analysis of hygroscopic LaBr3 powders collected with this holder are suitable for Rietveld structure refinement, yielding unit cell lattice parameters of a=7.9703(6) Å and c=4.5122(6) Å; cell volume=248.44(6) Å3; Rp=7.70%.

A specimen containing nanograms of sulfur, calcium, and 3d transition metal elements was measured by incident X-ray beams of various sizes restricted by a waveguide placed in a portable TXRF spectrometer. The signal to background ratios of spectra decreased with an increase in incident X-ray beam size. The portable spectrometer was also applied to rainwater and a specimen containing antimony and rare earth elements. Nanograms of elements in these specimens were detected by K-line or L-line excitation.

A computer program for analysing two-component interstratified structures by two different Fourier transform methods is described. The first method consists of the calculation of the X-ray diffraction intensity function, and in the second one (direct method) the distribution function of interlayer distances is calculated. The programs have been written in compiled GWBASIC for an Olivetti M-24 microcomputer (MS-DOS operating system), and they may also be run on any IBM compatible personal computer. As an example, this program is applied for the analysis of a chlorite-smectite interstratified mineral.

The title compound, ∣Na6Li1.6K0.4Cl2∣[Al6Si6O24]‐SOD, is similar to sodalite proper, but the introduction of Li and K into the structure creates a reduction in unit-cell volume and additional collapse of the framework tetrahedra. Refinement of an X-ray powder diffraction pattern of a multiphase material yielded for sodalite a lattice parameter of 0.88427 (2) nm, an Al–O–Si bond angle of 137.9(3°), and Al–O and Si–O bond lengths of 0.1730(5) nm and 0.1620(5) nm, respectively. The angle of the unique Al–O–Si bond corresponds well with the 138° obtained by 29Si solid-state magic-angle-spinning nuclear magnetic resonance spectroscopy. This characterization is important since the compound constitutes an essential part of a radioactive waste form intended for a high-level waste repository.

The crystal structures of Sr2MgWO6 and Ba2SrWO6 compounds, studied by powder X-ray diffraction, were found to be distorted perovskites with a complete NaCl type ordering between Mg2+/W6+ and Sr2+/W6+ ions, respectively. The unit cells are characterized by the tetragonal (space group I4/m; a0a0a−) symmetry, with the parameters a=5.5849(10) Å and c=7.9455(10) Å, for Sr2MgWO6 and triclinic (space group F-1; a−b−b−) symmetry, with the parameters a=8.5409(10) Å, b=c=8.5860(10) Å, α=89.35(1)° and β=γ=90.31(1)°, for Ba2SrWO6. © 2004 International Centre for Diffraction Data.

The crystal structures of BaR2ZnO5, where R=La, Nd, Dy, Ho, and Y, were studied by neutron diffraction, and that of the Er analog was investigated by synchrotron X-ray diffraction. Two structure types were confirmed for this series of compounds and agreed with those reported in literature. The compounds with a smaller size of R (R=Dy, Ho, Y, and Er) are isostructural to the orthorhombic “green phase (BaY2CuO5)” compounds. The cell parameters for compounds with the R=Er to Dy range from a=7.0472(1) Å to 7.0944(1) Å, b=12.3022(1) Å to 12.3885(2) Å, and c=5.6958(1) Å to 5.7314(1) Å, respectively. R is 7-fold coordinated inside a monocapped trigonal prism. These prisms share edges to form wavelike chains parallel to the long b-axis. The Ba atoms reside in 11-fold coordinated cages. The compounds which contain a larger size R (R=La and Nd) crystallize in the tetragonal I4/mcm space group, but are not isostructural to the “brown phases” BaR2CuO5. The lattice parameters for the La and Nd analogs are a=6.9118(1) Å, c=11.6002(2) Å for BaLa2ZnO5, and a=6.7608(1) Å and c=11.5442(2) Å for BaLa2ZnO5. The structure consists of ZnO4 tetrahedral groups (instead of planar CuO4 groups as found in the brown phase) with Ba ions inserted in between. The structure can be viewed as consisting of alternate layers of Zn-Ba-O and Nd-O extending infinitely in the xy plane and perpendicular to the z-axis.

Phase transitions were found with use of an in situX-ray anvil-type of apparatus with a boron annulus at pressures up to 12 GPa. The disordering of vacancies in the In sub-structure, or α→βtransition, was found in In2Te3at p > 1.9 GPa. The next transformation from the β-form into the Bi2Te3type of structure was observed in both sesquitellurides at 2.0 GPa and 5.0 GPa for In2TGe3and Ga2Te3respectively. The In2Te3metastable phase of the Bi2Te3resulted from heating up to 200° C at p > 4.0 GPa, and it remained in a normal condition on release of the pressure. The X-ray powder diffraction data of pressure-induced phases, volume changes and bulk modulus of both sesquitellurides are given. The compressibility anisotropy of the layer pressure-induced phase was observed. The mechanism of the crystal structure transformation from the face-centered cubic structure into the Bi2Te3type is proposed to be due to the displacement of atoms from the space diagonal of the cube [111] into [112]-cubic direction and the rhombohedral distortion of the angle between these directions.

The crystal structure of one isotropic [(1) Brazil] and three birefringent spessartine samples [(2) California, (3) Tanzania, and (4) Colorado] were refined using the Rietveld method, cubic space group $Ia\overline 3 d$ , and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. The results of electron-microprobe analysis (EMPA) indicate homogeneous compositions, in terms of end-members, as follows: (1) Sps54Alm43, (2) Sps90Alm8, (3) Sps64Prp27Grs3, and (4) Sps73Alm19. Their crystal structures were modeled well as indicated by the Rietveld refinement statistics where the reduced χ 2 and overall R (F 2) values for each sample are: (1) 1.395 and 0.0329, (2) 1.082 and 0.0354, (3) 1.025 and 0.0347, and (4) 1.016 and 0.0413. Two cubic phases occur in samples 2–4, and a single cubic phase occurs in sample-1. The dominant cubic phase-1 with locality, weight fraction (%), unit-cell parameter (Å), distances (Å), and site occupancy factors (sofs) are as follows: (1) Brazil: 100%, a = 11.581 54 (1), average <Mn–O> = 2.3156, Al–O = 1.8949 (3), Si–O = 1.6376 (3) Å, Mn(sof) = 0.961(1), Al(sof) = 0.945(1), and Si(sof) = 0.936(1); (2) California: 96.67(7)%, a = 11.613 32(1), average <Mn–O> = 2.3249, Al–O = 1.8956 (4), Si–O = 1.6416 (4) Å, Mn(sof) = 0.951(1), Al(sof) = 0.946(1), and Si(sof) = 0.927(1); (3) Tanzania: 69.46(6)%, a = 11.598 45(1), average <Mn–O> = 2.3199, Al–O = 1.8964 (5), Si–O = 1.6398 (5) Å, Mn(sof) = 0.808(1), Al(sof) = 0.942(1), and Si(sof) = 0.922(1); and (4) Colorado: 98.58(6)%, a = 11.606 89(1), average <Mn–O> = 2.3204, Al-O = 1.8948 (6), Si–O = 1.6450 (6) Å, Mn(sof) = 0.949(1), Al(sof) = 0.967(2), and Si(sof) = 0.913(2). The two-phase intergrowth causes strain that arises from mismatch of the structural parameters and gives rise to strain-induced birefringence.

The compound Na2ZnV2O7 with an åkermanite-type structure has been synthesized. It has a tetragonal unit cell, a=8.2711(4), c=5.1132(2) Å, and crystallizes with P-421m symmetry, Z=2. Its crystal structure has been refined from a combination of X-ray and neutron powder diffraction data. The structure contains layers of corner-sharing VO4 and ZnO4 tetrahedra, the former in pairs forming pyrovanadate V2O7 units. The sodium atoms are positioned between the layers, with a distorted antiprismatic coordination of oxygen atoms.

Powder X-ray diffraction data are reported for La1−xSrxCo0.8Fe0.2O3 (x=0.2, 0.4) and La0.8Ba0.2Co0.8Fe0.2O3. The powders were prepared by thermal decomposition of metal-containing complex solutions. All compositions have rhombohedral unit cells. In hexagonal setting, the cell parameters are a=5.4451(2) Å, c=13.2553(2) Å for La0.6Sr0.4Co0.8Fe0.2O3; a=5.4556(3) Å, c=13.1999(2) Å for La0.8Sr0.2Co0.8Fe0.2O3 and a=5.4795(1) Å, c=13.2983(5) Å for La0.8Ba0.2Co0.8Fe0.2O3. The space group is probably R3c (167) for all three compositions.

Precise X-ray powder diffraction data are given for two germanides, CoGe and Co5Ge7. The refined unit cell parameters for CoGe are a=11.630(1) Å, b=3.8014(3) Å, c=4.9347(3) Å and β=100.889(8)° (space group C2/m, Pearson symbol mC16) with volume of the unit cell 214.24(2) Å3; the figures of merit are M20=96, F30=77 (0.0085, 46). The refined unit cell parameters for Co5Ge7 are a=7.6262(4) Å and c=5.8017(5) Å (I4mm, tI24) with volume of the unit cell 337.42(3) Å3; the figures of merit are M20=204 and F22=130(0.0068, 25). The dependence on composition of the unit cell parameters of CoGe is discussed in terms of specific defect structures.

Crystal and X-ray powder diffraction data are presented for the title compound. The powder pattern was indexed and refined on a monoclinic cell with a=17.356(6) Å, b=3.528(1) Å, c=11.285(1) Å, β=94.23(2) Å. The cell volume and Dm=1.772 g/cm3 give Z=4. The space group could not be determined with certainty. The planes of the urate anions likely are stacked parallel or nearly parallel to (010).

Recent developments in instrumentation mean that chemical analysis of large drill cores taken for geological purposes can be performed rapidly at sub-millimetre scales using core scanners equipped with energy-dispersive X-ray fluorescence spectrometers. The present study describes the development of a calibration for the Itrax Core Scanner (Cox Analytical, Sweden), intended for whole cores of coal-seam sections, without the need for sample preparation. The calibration was developed for key major elements (Al, Si, P, S, K, Ca, Ti, and Fe) based on pressed pellets of reference coals, allowing semi-quantitative and, at times, quantitative analyses. The influence of core curvature and surface roughness compared with an ideal flat-surface was also examined using model samples, and their influence on the apparent sample composition evaluated.