A system enabling X-ray diffraction patterns under controlled conditions of relative humidity and temperature has been devised and combined with an X-ray powder diffractometer. Relative humidity in the sample space is controlled by mixing dry N2 gas with saturated water vapor. Temperatures of the sample and inner wall of the sample chamber are monitored by two attached thermocouples and the information was fed back to the control unit. Relative humidity between 0% and the 95%, and temperature between room temperature and 60 °C can be controlled. All parameters including those for XRD are programmable and the system runs automatically. The function of the system was checked by recording the XRD patterns of montmorillonite (a clay mineral) and NaCl under increasing and decreasing relative humidity.

A straightforward intuitive user-friendly compact graphical interface, PreDICT (Premier DICVOL Tool) has been developed to take full advantage of the new capabilities of the most recent version of the DICVOL14 Indexing Software. The latter, an updated version of DICVOL04, includes optimizations, e.g. for monoclinic and triclinic cases, a detailed review of the input data from the indexing solutions, cell centering tests, as well as the handling of a moderate number of impurity peaks. Among the most salient features of PreDICT, one can mention the ability (1) to use 2θ non-equistepped input 1D X-ray powder diffraction patterns as can be obtained from 2D detectors, (2) to strip laboratory data from its Kα2 contribution when present, (3) to generate 2θ equistepped output 1D X-ray powder diffraction patterns in both the “.XY” and “.GSA” formats. In addition, PreDICT allows for the following features: (1) full access to the native DICVOL14 input/output ASCII file system is retained, (2) for any selection of a DICVOL14 suggested unit cell, all predicted Bragg peaks up to a certain 2θMAX value are clearly displayed and indicated, thereby emphasizing the contribution of the unaccounted peaks (if any) to the 1D X-ray powder diffraction pattern under current investigation.

Results of crystal structure refinements and phase quantification for samples of Co-doped lanthanum chromites with nominal composition LaCr1−xCoxO3, for x=0.00, 0.10, 0.20, and 0.30, prepared by combustion synthesis are presented. The resulting powders were characterized by scanning electron microscopy and X-ray diffraction (XRD). The XRD patterns were obtained with Cu Kα radiation for non-doped lanthanum chromite sample and additionally with Cr Kα radiation for Co-doped lanthanum chromites samples, in order to enhance the signal from scattering. Rietveld analysis of XRD data showed that the studied samples presented the lanthanum chromite with an orthorhombic structure (Pnma), except for the composition with x=0.30, in which the space group was found to be R3c.

This is a second and considerably expanded edition of the RIR table. We are pleased that considerable interest is now being generated in the RIR table; several contributors have provided measured data for this second edition. We have also added many entries of common minerals and simple compounds from the JCPDS data base and will continue to add more from this source with each succeeding table published. In this regard where we receive requests for a particular class of RIR's (alloys, or rare earth oxides, for examples) we can give higher priority to extracting these values from the JCPDS data base.

The reader should refer to the text explanation of the first published table in Vol. 3, No. 4 of this journal. In the first text two important errors are noted here; Equation (3) should have read RIRcorr = RIRobs/Wj; and the second sample preparation category of section 4 Specific Parameters should read “(w) Methods including well mounts with side or back loading or similar process”.

Crystalline phases present in pigments scratched off the surfaces of some decorated ceramic sherds belonging to the Cucuteni Neolithic culture were successfully identified using synchrotron radiation X-ray diffraction at Daresbury Laboratory. The ceramic sherds were selected from a collection of the National Museum of Romanian History in Bucharest. The synchrotron radiation X-ray diffraction analysis revealed that the black-color pigments on the surface of a number of sherds were produced by a variety of jacobsite (Fe2MnO4) phases; magnetite (Fe3O4) was also found in one of the sherds. The red color was derived from clay slips with a high content of hematite (Fe2O3). Calcite (CaCO3) was found in the white pigments; its presence was explained as being related to postburial deposition processes. Conclusions on technological aspects, provenance, and conservation issues are given.

Crystal data and results of structure refinements for MnSi are reported. The material is cubic, P213, with a = 4.5603(2) Å, Vd = 94.84(1) Å3, Z = 4, Dx = 5.815 Mg/m3. Intensity data were obtained from a Stoe transmission type diffractometer equipped with a position sensitive detector. CuKα1 radiation, λ = 1.5405981 Å was employed. Germanium was used as an internal standard for the determination of the lattice constant (aGe= 5.6582 Å). The structure was refined by the Rietveld method by aid of three different programs.

High-resolution powder X-ray diffraction has been used to determine the crystal structure of silver behenate, [Ag(O2C(CH2)20CH3]2. Using CASTEP density functional plane wave pseudopotential techniques to obtain an optimized structural model, Rietveld refinement of the structure gives Rwp = 8.66%. The unit cell is triclinic, space group P1, with cell dimensions of a = 4.1769(2) Å, b = 4.7218(2) Å, c = 58.3385(1) Å, α = 89.440(3)°, β = 89.634(3)°, γ = 75.854(1)°. The structure is characterized by an 8-membered ring dimer of Ag atoms and carboxyl groups with a fully extended all-trans configuration of the alkyl side chains. The dimers are joined by four-membered Ag-O rings creating a polymeric network, giving rise to one-dimensional chains along the b-axis. This structure is supported by EXAFS measurements of the local structure around the silver atoms and IR measurements.

The atomic displacement parameters of individual ions in SrO have been determined from the Rietveld analysis of high-resolution powder neutron diffraction data. As the neutron velocity is smaller than the sound velocity in SrO, the intensity data was not corrected for the effect of thermal diffuse scattering. The room temperature value of overall isotropic thermal displacement parameters was B=0.57(2) Å2; which corresponds to Debye temperature, Θ of 242(4) K. The results are compared with experimental and theoretical estimates.

The method of high-energy total elastic X-ray scattering to determine the atomic structure of nanocrystalline, highly disordered, and amorphous materials is presented. The current state of the technique, its potential, and limitations are discussed with two successful studies on the pressure induced phase transition in mackinawite (FeS) and the high-pressure behavior of liquid gallium.

The cause of birefringence in several garnet-group minerals with general chemical formula, [8]X3 [6]Y2 [4]Z3 [4]O12, which was observed over 100 years ago, is unknown, although many different reasons were proposed, including symmetry lower than cubic. In this study, electron microprobe analyses (EMPA) were obtained for a Ti-rich andradite, ideally Ca3(Fe2 3+)Si3O12, from Magnet Cove, Arkansas, USA, and the results show that the sample is inhomogeneous with two distinct compositions. The crystal structure was refined by the Rietveld method, cubic space group $Ia\overline 3 d$ , and monochromatic synchrotron high-resolution powder X-ray diffraction (HRPXRD) data, which shows a mixture of three distinct cubic phases that are intergrown together and cause birefringence because of strain arising from small structural mismatch. This mixture of three cubic phases was not observed by any other experimental technique. These results have many implications, including garnet phase transitions from cubic to lower symmetry in the mantle, which has important geophysical consequences.

Crystal structure of 4H-SiC was refined from room-temperature X-ray powder diffraction data using the Rietveld refinement method. The refined lattice constants were determined to be a=b=3.079 93(0) Å, c=10.082 22(2) Å, and the refined overall temperature factor B=0.383(3) Å2. Using the Debye approximation, the Debye temperature was successfully determined to be 1194.8 K.

Nanocrystals of Zn1−xMxO (M=Mn, Co, or Ni) were grown using proteic sol-gel process, and the crystalline phases were identified by X-ray diffraction and Rietveld refinement. The nanocrystals have hexagonal wurtzite structure, with space group P63mc. The insertion of Mn2+ in the place of Zn2+ provoked an increase in the size of the nanocrystals, and the insertion of Co2+ or Ni2+ caused a reduction in the sizes of the nanocrystals, as compared to pure ZnO. This occurred because these three transition metals have very different ionic radii (Co2+=0.58 A˚, Mn2+=0.66 A˚, Ni2+=0.55 A˚, and Zn2+=0.60 A˚).

A direct method is described for determining depth profiles (z-profiles) of diffraction data from experimentally determined τ-profiles, where z is the depth beneath the sample surface and τ is the 1/e penetration depth of the X-ray beam. With certain assumptions, the relation between these two profile functions can be expressed in the form of a Laplace transform. The criteria for fitting experimental τ-data to functions which can be utilized by the method are described. The method was applied to two τ-data sets taken from the literature: (1) of residual strain in an A1 thin film and (2) of residual stress in a surface ground A12O3/5vol% TiC composite. For each data set, it was found that the z-profiles obtained were of two types: oscillatory and nonoscillatory. The nonoscillatory profiles appeared to be qualitatively consistent for a given data set. The oscillatory profiles were considered to be not physically realistic. For the data sets considered, the nonoscillatory z-profiles were found to lie consistently above the corresponding τ-profiles, and to approach the τ-profiles at large z, as expected from the relation between the two.

X-ray imaging techniques based on Compton backscatter permit inspection and screening of sea containers, a wide variety of vehicles, luggage, and even people. In contrast to more commonly used transmission images, backscatter imaging involves positioning both source and detection apparatus on only one side of a target object. This presents the user with inspection opportunities in situations that may be extremely difficult, if not impossible, for transmission systems that require access by the detector subsystem to the opposing side of the target. The backscatter image is somewhat akin to a photograph of the contents of a closed container, taken through the container walls. Techniques for producing X-ray images based on Compton scattering will be discussed, along with wide-ranging examples of how systems based on these principles are used to perform inspections for both security applications and for the detection of contraband materials at ports and borders. Potential applications in the area of nondestructive evaluation will also be considered. Differences in the type of information displayed by transmission and backscatter images will be highlighted, and tradeoffs between backscatter image quality and interpretability, scan speed, effective penetration, and X-ray tube voltage will also be discussed. The method used in scanning the target object results in an extremely low radiation dose, a result that significantly broadens the application spectrum for this imaging technique.

Two molybdates MIV (MoO4)2 (with MIV = Hf or Zr) were synthesized by solid state reaction between MIVO2 and MoO3. Zirconium molybdate undergoes a reversible phase transition at 952 K.

Hf(MoO4)2 and H.T. Zr(MoQ4)2, obtained as single crystals, are trigonal, space group with Z = 6; the cell dimensions are respectively a = 10.1005(3), c = 11.7230(5)Å; V = 1035.76(11)Å3; Dm(298 K) = 4.78(4), Dx = 4.792 Mg m−3 and a = 10.1409(3), c = 11.7097(5)Å; V = 1042.88(11)Å3; Dm (298 K) = 3.91(4), Dx = 3.926 Mg m−3.

L.T. Zr(MoO4)2, indexed by the Visser automatic indexing program (1969) was found to be monoclinic, possible space group P2, P21 or Pm with Z = 4; the cell dimensions are a = 9.7557(5), b = 7.9373(5), c = 7.4631(4)Å, β = 97.959°(5); V = 572.3(5)Å Dm(298 K) = 4.74(5), Dx = 4.770 Mg m−3. Powder diffraction data were obtained at 293 K on a counter diffractometer with Ni-filtered copper radiation ( = 1.5418 Å).

Cu-paddle-wheel-based Cu3(BTC)2 (nicknamed Cu-BTC, where BTC ≡ benzene 1,3,5-tricarboxylate) is a metal organic framework (MOF) compound that adopts a zeolite-like topology. We have determined the pore-size distribution using the Gelb and Gubbins technique, the microstructure using small-angle neutron scattering and (ultra) small-angle X-ray scattering (USAXS\SAXS) techniques, and X-ray powder diffraction reference patterns for both dehydrated d-Cu-BTC [Cu3(C9H3O6)2] and hydrated h-Cu-BTC [Cu3(C9H3O6)2(H2O)6.96] using the Rietveld refinement technique. Both samples were confirmed to be cubic Fm $\bar 3$ m (no. 225), with lattice parameters of a = 26.279 19(3) Å, V = 18 148.31(6) Å3 for d-Cu-BTC, and a = 26.3103(11) Å, and V = 18 213(2) Å3 for h-Cu-BTC. The structure of d-Cu-BTC contains three main pores of which the diameters are approximately, in decreasing order, 12.6, 10.6, and 5.0 Å. The free volume for d-Cu-BTC is approximately (71.85 ± 0.05)% of the total volume and is reduced to approximately (61.33 ± 0.03)% for the h-Cu-BTC structure. The d-Cu-BTC phase undergoes microstructural changes when exposed to moisture in air. The reference X-ray powder patterns for these two materials have been determined for inclusion in the Powder Diffraction File.

The construction and use of a captive inert atmosphere cell for the preservation of atmospherically sensitive samples during X-ray diffraction is described.

Structural and chemical changes in materials can be dynamically observed by using time resolved X-ray Powder Diffraction (XRPD) to collect patterns as these events happen. During calcination of amorphous zirconium hydroxide, Zr(OH)4, and its crystallisation to a metastable tetragonal form of zirconia, ZrO2, patterns have been collected at 10°C temperature intervals during a heating sequence to 500°C. These patterns show both the onset of ordering within the amorphous starting material and the progress of its conversion into crystalline zirconia. Events are recorded within the pattern in the form of peak growth and reduction in amorphous component of the pattern with increasing temperature.

The variables of reflection overlap, crystallinity and crystallite size, primary extinction, microabsorption, chemical substitutions, preferred orientation, and analytical procedures affect quantitative analysis by powder X-ray diffraction. The intensity of the strongest reflection (I) of 39 minerals from a typical sedimentary environment divided by the intensity of the strongest reflection (Ic) of corundum, I/Ic, may be used to determine mineral percentages. Because of the numerous variables mentioned above, the I/Ic ratios used should be taken from multi-mineral specimens that occur either in the same geological formation for quantitative analysis (±7%) or in a similar geological formation for quantitative analysis (±30%).

A powder X-ray diffraction technique has been developed to quantify the relative amounts of α-carbamazepine (A) and β-carbamazepine (B) when they occur as a mixture. The theoretical basis of this technique was developed in 1948 by Alexander and Klug (Anal. Chem., 20:886-889). The powder X-ray diffraction patterns of A and B revealed that the line with d-spacing of 10.1 Å was unique to A. The ratio of the integrated intensity of the 10.1 Å line in a mixture of A and B, to the intensity of the 10.1 Å line in a sample consisting of only A, was calculated as a function of weight fraction of A in the mixture. These ratios were also experimentally determined, and there was a good agreement between the theoretical and experimental intensity ratios. The particle size of the samples, the sample preparation technique and the experimental conditions were controlled so as to eliminate the major sources of error in powder X-ray diffractometry. In order to minimize preferred orientation of the particles, a sample holder was specially fabricated.