The powder pattern of Rb3Ta5O14 is reported here for the first time. Single crystals of Rb3Ta5O14 of 0.1–0.2 mm in size were grown using a RbCl flux at 1100 °C. The Rb3Ta5O14 powders were synthesized at 1200 °C by firing the Rb2CO3 and Ta2O5 raw materials with starting Rb/Ta ratios ranging from 0.450 to 0.800. The products with Rb/Ta ratios between 0.550 and 0.633 contained almost pure Rb3Ta5O14 with Rb/Ta ratio of 0.600, while those with Rb/Ta ratio larger than 0.677 also contained the α form of Rb4Ta6O17 with the Rb/Ta ratio of 0.677. Past studies of the synthesis and characterization of Rb4Ta6O17 should be carefully examined in the light of possible coexistence with Rb3Ta5O14, because the former structure has not been completely solved, and thus the powder pattern is inaccurate, while the presence of the latter had not been known until the present study.

Hydrothermal formation reaction of tobermorite in the autoclaved aerated concrete (AAC) process has been investigated by in situ X-ray diffraction. High-energy X-rays from a synchrotron radiation source in combination with a newly developed autoclave cell and a photon-counting pixel array detector were used. XRD measurements were conducted in a temperature range 100–190°C throughout 12 h of reaction time with a time interval of 4.25 min under a saturated steam pressure. To clarify the tobermorite formation mechanism in the AAC process, the effect of Al addition on the tobermorite formation reaction was studied. As intermediate phases, non-crystalline calcium silicate hydrate (C-S-H), hydroxylellestadite (HE), and katoite (KA) were clearly observed. Consequently, it was confirmed that there were two reaction pathways via C-S-H and KA in the tobermorite formation reaction of Al containing system. In addition, detailed information on the structural changes during the hydrothermal reaction was obtained.

The structures of anhydrous nickel, niobium, and tantalum chlorides have been investigated in situ in acidic and basic ionic liquids (ILs) of 1-methyl-3-ethylimidazolium chloride (EMIC)/AlCl3 with X-ray absorption spectroscopy (XAS). The coordination of NiCl2 changes from tetrahedral in basic solution to octahedral in acidic solution. The NiCl2 is a strong Lewis acid in that it can induce the AlCl3 to share its chlorides in the highly acidic IL, forming a structure with six near Cl− ions and eight further distant Al ions which share the chloride ions surrounding the Ni2+. When Nb2Cl10, a dimer, is added to the acidic or basic solution, the dimer breaks apart and forms two species. In the acid solution, two trigonal bipyramids are formed with five equal chloride distances, while in the basic solution, a square pyramid with four chlorides forming a square base and one shorter axial chloride bond. Ta2Cl10 is also a dimer and divides into half in the acidic solution and forms two trigonal bipyramids. In the basic solution, the dimer breaks apart but the species formed is sufficiently acidic that it attracts two additional chloride ions and forms a seven coordinated tantalum species.

Si–SiC composite (reaction bonded SiC) with a submicron SiC microstructure (starting SiC particle size: 0.22 μm) was examined by XRD analysis to determine the amount and phase composition of the secondary SiC formed by the reaction between silicon and carbon during the sintering process. It was found that the secondary SiC has grown onto the original hexagonal α-SiC grains as well as into the porosity of the green body. An increase of 3C–SiC was found within the microstructure after infiltration (from 2.6 wt. % before infiltration to 8.8 wt. % after infiltration) whereas the 4H-ploytype content was reduced. This behavior may be explained by the very small original SiC grains which acted as seeds for disoriented SiC growth and were assumed to force the nonepitaxically deposition of secondary SiC. Solid state and fast transportation processes caused the observed transformation of the SiC. Examinations of the silicon source (infiltrant) after the infiltration procedure showed that most of the carbon was converted to SiC with cubic modification (3C stacking sequence)

To minimize waste, improve process safety, and reduce costs, modifications were implemented to a method for quantifying gallium in plutonium metal using wavelength dispersive X-ray fluorescence. These changes included reducing sample sizes, reducing ion exchange process volumes, using cheaper reagent grade acids, eliminating the use of HF acid, and using more robust containment films for sample analysis. Relative precision and accuracy achieved from analyzing multiple aliquots from a single parent sample were approximately 0.2 and 0.1%, respectively. The same precision was obtained from analyzing a total of four parent materials, and the average relative accuracy from all the samples was 0.4%, which is within programmatic uncertainty requirements.

A computer program for refining anomalous scattering factors using x-ray powder diffraction data was revised on the basis of the latest version of a versatile pattern-fitting system, RIETAN-2000. The effectiveness of the resulting program was confirmed by applying it to simulated and measured powder-diffraction patterns of Mn3O4 taken at a synchrotron light source.

In this work, zinc oxide samples were obtained from hydroxycarbonate by thermal decomposition at 300 °C. Zinc hydroxycarbonate samples were produced by homogeneous precipitation over different periods of time. The method used to obtain zinc oxide produces different morphologies as a function of the precursor precipitation time. Among the obtained particle shapes were porous spherical aggregates, spherulitic needle aggregates, and single acicular particles. This work investigated spherulitic needle-aggregate formation and the correlation among morphology, domain size, and microstrain. Transmission electron microscopy data revealed that the acicular particles that form the spherulitic needle aggregates consist of nanometer crystallites. Apparent crystallite size and microstrain in the directions perpendicular to (h00), (h0l), (hk0), and (00l) planes were invariable as a function of precursor precipitation time. From the results, it was possible to conclude that the precursor precipitation period directly influenced the morphology of the zinc oxide but did not influence average crystallite size and microstrain for ZnO samples. Therefore, using this route, it was possible to prepare zinc oxide with different morphologies without microstructural alterations.

X-ray powder diffraction data, unit-cell parameters, and space group for a new succinylcholine iodide polymorph II, C14H30O4N2I2, are reported [a=13.908(3) Å, b=13.184(3) Å, c=11.717(2) Å, β=92.501(3)°, unit-cell volume V=2146,28 Å3, Z=4, space group P21/c]. All measured lines with the exception of one were indexed and are consistent with the P21/c space group. No detectable impurities were observed.

X-ray powder data originally published for the zeolite mineral goosecreekite are of poor quality. The new data reported here for material from Norway are compared with powder data calculated from the published structure. The cell is monoclinic (space group P21, Z=2), a=7.422(2) Å, b=17.414(4) Å, c=7.288(2) Å, β=105.43(3)°, V=907.9(3) Å3. F30=32.75(0.023,40).

An orthorhombic fully ordered structural model is proposed for vaterite [space group Ama2, a=8.4721(5) Å, b=7.1575(7) Å, c=4.1265(4) Å, Z=4, and V=250.23(4) Å3]. It is based on a microtwinning hypothesis, with three domains rotated by 120° along the orthorhombic a axis, regenerating a pseudohexagonal habit. The solution came from direct space ab initio calculations applied to the powder diffraction data. However, five weak superstructure reflections seen in single-crystal and powder diffraction experiments, leading to a six times larger unit cell, are still unexplained.

Previously unpublished powder X-ray diffraction data for potassium silver thiocyanate, AgK(SCN)2 and dipotassium silver thiocyanate, AgK2(SCN)3 are presented. F30 values for AgK(SCN)2 and AgK2(SCN)3 are 80(0.0075, 50) and 53(0.0089, 63), respectively. The Rietveld refinement of the patterns is also performed. For AgK(SCN)2Rp=6.98, Rwp=11.84, and RBragg=2.9. For AgK2(SCN)3Rp=7.22, Rwp=10.79, and RBragg=5.0.

Three polyureas with decreasing soft segment molecular weights of 1000, 650, and a 250/1000 blend were molded onto circular steel plates and then impacted with a high speed (275 m/s) conical-shaped steel cylinder. The polyurea layer of the post mortem bilayers was characterized on a molecular level by small angle synchrotron X-ray scattering (SAXS) at the Advanced Photon Source at the Argonne National Laboratory. Analysis revealed that the hard domains of the polyureas with lower molecular weight soft segments reformed and oriented over a greater area of the coating, thus increasing the polymer strain hardening and resulting in visibly less out of plane bilayer deformation. This agrees with the hypothesis that polymer strain hardening is a mechanism that retards necking failure of the metal plate.

Powder X-ray diffraction (XRD) data were collected for Pr0.7Ba0.3MnO3. This sample was prepared using the conventional solid state reaction by mixing Pr6O11, Mn2O3, and BaCO3 up to 99.9% purity at 1400 °C in air for 60 h. XRD analysis using the Rietveld method was carried out and it was found that this manganite sample has orthorhombic symmetry with Pnma space group. The lattice parameters are found to be a=5.4900 Å, b=7.7578 Å, and c=5.5227 Å.

Keeping with tradition, the 2000 MRS annual meeting again took place in Boston Copely Plaza from November 27 to December 1. The 2000 meeting was well organized and well attended, with a total of 4600 attendees representing industrial, academic, and government sectors. The rich technical program was multi-disciplinary (41 symposia) to meet the needs of the attendees. A total of 4000 papers were presented. There were a number of memorable lectures, several special seminars on policy and funding, an award ceremony, a new educational seminar series that focused on the scientific basis and practical application of commercial tools. The meeting also highlighted an elaborate exhibit, poster sessions and other well organized events. This report summarizes various events which took place at the meeting.

The powder diffraction pattern of the new cubic perovskite material La0.2Sr0.8Fe0.8Co0.1Cr0.1O3−δ is described. The compound has a unit cell parameter of a=3.875 27(1) Å with Z=1 and Dx=5.75 g/cm3.