The formation of the solid solutions in the (La1−xGdx)OCl series was studied by X-ray powder diffraction (XPD) at room temperature in the 2θ region between 6.5 and 120°. The Rietveld profile refinement analyses of the XPD patterns were carried out with the background, unit cell, atomic position, isotropic temperature, and Gaussian profile form parameters refined freely. All (La1−xGdx)OCl samples possessed the tetragonal PbFCl-type structure with P4/nmm as the space group (Z=2). The unit cell parameters a and c evolve smoothly through the series and no clustering of the Gd3+ ions was observed according to Vegard's law. The solid solubility exists throughout the whole series. The valence bond model was used to estimate the relative stabilities of the different (La1−xGdx)OCl solid solutions. The global instability index (GII) which equals to the deviation between the formal valence and the sum of the calculated valence bonds of each atom in the asymmetric unit was used as a tool in the assessment. In the (La1−xGdx)OCl series, GII increases both from the end and the beginning of the series toward the middle indicating diminishing stability. No breakdown of the La–Gd solid solution could be verified experimentally although the GII value for the (La0.4Gd0.6)OCl composition exceeds the limit of 0.2 which should mean the collapse of the structure. However, the diffraction reflections were found somewhat broader in the middle of the series indicating possible local distortion or disorder.

Tabular untwinned crystals of colorless transparent armstrongite from the Strange Lake Alkalic Complex, on the Quebec – Labrador boundary, Canada are monoclinic, space group choices I2/m, I2, Im (diffraction aspect I*/*), with refined unit-cell parameters a = 13.599 (9), b = 14.114(9), c = 7.833 (4) Å, β = 103.41 (5)°, V = 1462.4 (±3.0) Å3. a:b:c = 0.9635:1:0.5550, Z = 4 and D(x) = 2.696 g/cm3. A fully indexed X-ray powder pattern is presented. Averaged electron-microprobe analyses suggest a theoretical formula of CaZrSi6O15 · 3 H2O. The Strange Lake armstrongite is biaxial negative, α = 1.567 (1), β = 1.576 (1), γ = 1.577 (1), 2V (meas.) = 39 (1)°, 2V (calc.) = 37°, Z∥b, X Λc = +4°, with no absorption and weak dispersion r < v.

Zr(MoO4)2 molybdate has been synthesized by solid state reaction. Single crystals were obtained by hydrothermal synthesis. Corrected crystal data are: monoclinic, a = 11.4309 (3), b = 7.9376 (2), c = 7.4619 (2) Å and β = 122.323 (2)°, V = 572.13 (6) /cm3 (5), Dx = 4.770 g/cm3. Powder diffraction data are reported.

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.

The program FAULTS has been used to simulate the X-ray powder diffraction (XRD), neutron powder diffraction (NPD), and electron diffraction (ED) patterns of several structural models for LiNi1/3Mn1/3Co1/3O2, including different types of ordering of the transition metal (TM) cations in the TM slabs, different amounts of Li+/NiII+ cation mixing and different amounts of stacking faults. The results demonstrate the relevance of the structural information provided by NPD and ED data as compared with XRD to characterize the microstructure of NMC (LiNi1−y-zMnyCozO2) compounds.

The X-ray diffraction powder patterns were prepared and the crystal structures were refined for the double-perovskite series of compounds, Sr2RSbO6 (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, and Lu). We found the structures of the entire Sr2RSbO6 series to be monoclinic with space group P21/n (no. 14), and Z = 2. From R = Lu to Pr, the lattice parameters “a” range from 5.7779(2) to 5.879 05(8) Å, “b” range from 5.7888(2) to 5.969 52(9) Å, “c” range from 8.1767(3) to 8.369 20(12) Å, “β” range from 90.112(2)° to 90.313(1)°, and “V” range from 273.483(4) to 293.714(7) Å3. These lattice parameters follow the well-established trend of “lanthanide contraction”. The R 3+ and Sb5+ ions are found to be fully ordered in the double-perovskite arrangement of alternating corner-sharing octahedra in a zigzag fashion. The SrO12, RO6, and SbO6 cages are all found to have distorted coordination environments. Powder diffraction patterns of these compounds have been prepared, submitted, and published in the Powder Diffraction File.

Crystal structure of BaxSr3–xMgSi2O8 has been determined by Raman spectroscopy and X-ray diffraction. The solid solution series have glaserite-type layered structures made of corner-sharing SiO4 tetrahedra and MgO6 octahedra. Ba2+ and Sr2+ ions are sandwiched in between the layers. Raman spectroscopy has found that structural symmetry changes at x = 0.5 and 2.5. Structural refinement by the Rietveld method has clarified that the symmetry changes occur among C2 (Z = 4), P${\bar 3}$m1 (Z = 1), and P${\bar 3}$ (Z = 3). They originate in SiO4 tilting caused by size mismatch between alkali–earth cations and their site spaces. For x ≤ 0.5, SiO4 tilting occur every other interlayer space, whereas for x ≥ 2.5, all the SiO4 tilt.

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%.

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.

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.

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.

X-ray powder diffraction data are reported for α-brass with the composition Cu: 63.44±0.04 wt %, Zn: 36.45±0.06 wt %. No valid reference card for this material is present in the JCPDS-ICDD database. The investigated brass composition is cubic (Fm3m) with a0: 3.69612±0.00014 Å, unit cell volume: 50.4938±0.0058 Å3, density calculated: 8.44±0.05 g/cm3, density measured: 8.43±0.03 g/cm3. The X-ray diffraction pattern presented resembles that of deleted reference card 6-657 in great detail.

Quantitative phase analysis by powder diffractometry requires accurate measurement of the integrated intensities of the diffracted, lines. When lines are isolated and on simple backgrounds, count integration techniques work very well. However, when one or more lines overlap the line of interest, or a complex background is present, profile fitting techniques are required in order to eliminate interferences.

Profile fitting involves choosing a mathematical model to represent the expected profile shapes. Experience has shown that the profile shapes obtained with a parafocusing powder diffractometer are not easily described and many models have been tried with varying degrees of success. Generally the more free parameters allowed In the model the ‘setter the fits, although, aesthetically one would like to keep the number of free parameters to a minimum.

Numerous spurious X-ray peaks were encountered during grazing incidence angle diffractometer scans of ceramic and polymeric thin films on crystalline and amorphous substrate materials. At least three possible sources of spurious peaks are identified. (1) At (2θ) values greater than ∼ 10°, Laue reflections from characteristic and Bremsstrahlung continuum radiation produce spurious peaks with a (2θ) dependence on X-ray incident angle and sample orientation. At (2θ) values less than 10°, (2) specular X-ray reflection from a boundary between two media of different indices of refraction and (3) diffuse surface scattering produces spurious peaks with a dependence on X-ray incident angle and sample surface topography. From an understanding of the spurious peaks, improved experimental techniques may be developed. Because these peaks can interfere significantly with grazing incidence diffractometer scans, it is particularly important to those making studies of thin films by this asymmetric diffraction geometry to be aware of the existence and origins of these spurious peaks.

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.

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 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.

A new cobalt hydroxide carbonate Co2(OH)2CO3 was successfully synthesized by a hydrothermal method. The compound is isomorphous with malachite [Cu2(OH)2CO3] and crystallizes in a monoclinic system [space group P21/a (No. 14); a=9.448(5) Å, b=12.186(9) Å, c=3.188(4) Å, β=98.593°, V=367.143(9) Å3, Z=4, and Dc=3.786(9) g/cm3]. Crystal structure of Co2(OH)2CO3 was refined by the Rietveld method with RP=4.3%, RWP=5.7%, Rexp=5.1%, RB=1.74%, and S=1.117 on the basis of the X-ray powder diffraction data. The crystal structure of Co2(OH)2CO3 obtained by the Rietveld refinement shows that all species Co2+, CO32−, and OH− ions occupy C1 site symmetry. Two crystallographically different Co2+ and OH− ions and one type CO32− ion exist in the lattice. Co(1) is coordinated to two oxygen atoms from CO32− ions and two OH− ions; Co(2) is coordinated to two oxygen atoms from CO32− ions and four OH− ions, thus forming a distorted octahedron with (4+2) coordination.

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.

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.