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.

Calcium carbonate crystals were prepared via a simple precipitation reaction of sodium carbonate with calcium chloride from mixed solutions of various amphiphilic organic solvents and water in the presence of cetyltrimethylammonium bromide at 25 and 60 °C. Our analysis shows that amphiphilic organic solvents and temperature have large influences on the structure and morphology of CaCO3. X-ray diffraction patterns show that single-phase hexahedral calcite was formed at 25 °C, and orthorhombic aragonite was obtained at 60 °C. Mixtures of major amounts of long aragonite crystals and minor amounts of calcite particles were also obtained at 60 °C in the methanol and the acetone solutions. Scanning electron microscopy images show that CaCO3 particles and aggregates with various morphologies, such as large solid and hollow hexahedral crystals and small round granules of calcite as well as glass-like and wheat-like aggregates of aragonite, were obtained depending on the experimental conditions. Based on the experimental results, a conclusion on the effects of temperature and amphiphilic organic solvents on the crystal structure and morphology are made.

The status of the solid materials and mineralogical and petrological results of the Stardust mission to comet 81P/Wild 2 are presented. This mission became the first successful sample-return mission since the Apollo project. This time the challenges were much less related to the availability of state-of-the-art analytical capabilities. Still, dedicated tools had to be developed to manipulate the samples that were all firmly embedded in the tracks they made when decelerating in the silica aerogel tiles of the collector. The comet particles were loosely bonded aggregates that shed their grains along the entire length of these tracks. It appears that most of the original comet minerals survived but interactions of debris with melted aerogel occurred and new minerals were made, adding to the incredibly, and unanticipated, diversity of the comet minerals, including some that so far were known only in meteorites. The latter alone showed that transport distances in the solar nebula extended all the way out to beyond Pluto into the Kuiper Belt of icy, comet-like, bodies. The full extent of the scientific yield of this mission is still unknown, promising but stressing current models of the formation of solar systems.

X-ray powder diffraction data for two ionic salts containing imidazole (Him) complexes of the magnesium(II) ion, [Mg(Him)4(H2O)2]Cl2 and [Mg(Him)6](NO3)2, are reported. Their crystal and molecular structures were determined by simulated annealing and full-profile Rietveld refinement methods. [Mg(Him)4(H2O)2]Cl2 was found to crystallize in the monoclinic system with space group C2/c, a=12.3980(3) Å, b=11.0234(2) Å, c=14.4691(3) Å, and β=107.024(1)°. [Mg(Him)6](NO3)2 crystallizes in the trigonal R-3 space group with a=b=12.4631(4) Å and c=14.9449(6)Å. Both species contain centrosymmetric complexes, and Mg is octahedrally coordinated by six imidazoles, as in [Mg(Him)6](NO3)2, or by four imidazoles and two water molecules, as in [Mg(Him)4(H2O)2]Cl2. Additional analytic, thermogravimetric, calorimetric, and spectroscopic characterizations were also performed.

New compounds Li6MB3O9 (M=Nd,Sm,Eu,Tm,Er) were synthesized by solid-state reaction. The crystal structure of Li6NdB3O9 was analyzed from both powder and single crystal X-ray diffraction data. The results obtained by powder diffraction analysis and Rietveld refinement are a=7.2725(4) Å, b=16.6398(9) Å, c=6.7529(5) Å, β=105.398(8)°, and space group P21/c, which agree with the results obtained by single crystal diffraction analysis: a=7.2712(4) Å, b=16.6268(9) Å, c=6.7484(4) Å, β=105.411(1)°, and space group P21/c. This compound is isostructural with Li6YB3O9. Single crystal structure analysis showed that the fundamental building unit of these isostructural compounds comprises three isolated [BO3]3− triangles, one distorted [NdO8]13− triangulated dodecahedron, four distorted [LiO5]9− five-coordinated polyhedra, and two [LiO4]7− tetrahedron. An analysis of the infrared spectrum of Li6NdB3O9 confirmed the presence of isolated [BO3]3− triangles in Li6NdB3O9. The remaining four Li6MB3O9 (M=Nd, Sm, Eu, Tm, and Er) compounds were found to be isostructural with Li6NdB3O9. Their unit cell dimensions decrease with an increase in the atomic number of the rare-earth atoms. DTA and TGA measurements of Li6MB3O9 (M=Nd, Sm, Eu, Tm, and Er) revealed that these borates congruently melt from 800 °C to 860 °C.

Without experimental or predicted literature crystal structures for succinonitrile at low temperature, structure solution was attempted from powder diffraction data taken at 173 and 90 K from a solid sample. Its room-temperature plastic-crystal state makes production of a sample with good particle statistics and random orientation almost impossible. Combining constrained models, simulated annealing, and careful application of second-order spherical harmonic corrections nevertheless produced viable-looking structures at 90 and 173 K, yielding two distinct structure models with the same projection down c. VASP optimization of atom coordinates in the experimental cell agreed well with the 90 K model but poorly with the model derived from the 173 K data. The refined 90 K structure changed little on optimization and fitted all datasets from 85 to 225 K. Plots of cell data, torsion angles, and isotropic displacement parameters against temperature suggest possible phase transitions around 100, 120, and 180 K. Cell data at 90 K: monoclinic P21/a, a=9.0851(5) Å, b=8.5617(5) Å, c=5.8343(3) Å, β=79.295(2)°, and Z=4. Succinonitrile has gauche conformation, in agreement with literature spectroscopy data.

A series of synthetic calcium silicates has been produced comprising nano-sized plates. The starting calcium silicate referred to as nano-structured calcium silicate, NCS, appears itself X-ray amorphous but contains impurities of calcite. These impurities decompose during the dry thermal conversion of the material into wollastonite. NCS can be enriched with calcium or silicon, respectively. The silicon enriched NCS can be hydrothermally transformed into a sheet material related to Ca7Si16O38(OH)2. The X-ray pattern of this material was sufficient to allow the calculation of its unit cell with a comparatively high figure of merit. The calcium enriched NCS can form two very distinctly different ceramic materials upon hydrothermal treatment, one a band material (formed below 200 °C) and the other a rose petal shaped material (formed above 210 °C). The X-ray diffraction patterns could not be resolved. The fit between the observed and calculated patterns was less than 50% as expressed in comparatively low figures of merit (unusually <20), which is attributed to calcium carbonate impurities in the samples disrupting the long range order. The patterns of these calcium enriched samples could be best compared to those of tobermorite or truscotite.

The fuzzy frontiers between structure determination by powder diffractometry and crystal structure prediction are discussed. The application of a search-match program combined with a database of more than 60 000 predicted powder diffraction patterns is demonstrated. Immediate structure solution (before indexing) is shown to be possible by this method if the discrepancies between the predicted crystal structure cell parameters and the actual ones are <1%. Incomplete chemistry of the hypothetical models (missing interstitial cations, water molecules, etc.) is not necessarily a barrier to a successful identification (in spite of inducing large intensity errors), provided the search-match is made with chemical restrictions on the elements present in both the virtual and experimental compounds.

Methods using X-ray fluorescence have been developed to identify cometary material captured in aerogel during the NASA Stardust mission to Comet 81P/Wild 2. These analytical methods are necessitated by the levels of trace contaminants present in the aerogel. The cometary material disaggregates during deceleration in the aerogel, so fluorescence mapping of the entire track (which can be several millimeters long) is necessary. Distinguishing those pixels which have cometary material and aerogel from those which have only cometary material can be very challenging. We have chosen a “dual threshold” method, with some pixels clearly having only aerogel (plus contaminants) and other pixels clearly having cometary and aerogel material. Between these two threshold levels is a set of pixels which cannot be easily ascribed to one or the other. By leaving these pixels out of the analysis, the estimate of cometary material is improved.

BaTiO3 powders were prepared through mechanical activation chemistry and analyzed by Rietveld refinement with X-ray diffraction data. Raw BaCO3 and TiO2 powders were dry milled for 5 and 20 h and then calcinated for 2 and 4 h at 800 °C. The milling process was found to have broken up the BaCO3 and TiO2 crystals into smaller crystals and formed only small amounts (<1.5 wt%) of BaTiO3. Subsequence calcinations for 2 and 4 h at 800 °C successfully produced large amounts (>97.7 wt%) of BaTiO3 crystals. The calcination process also generated microstrains and crystallite-size anisotropy in BaTiO3. An increase in the calcination time from 2 to 4 h increased the BaTiO3 weight percentage and the crystallite-shape anisotropy, but decreased the tetragonal distortion anisotropic microstrains in BaTiO3 crystals.

Rietveld refinement using synchrotron powder X-ray diffraction data of the ranciéite, Ca0.19K0.01(Mn4+0.91◻0.09)O2⋅0.63H2O, crystal structure reveals significant differences from that reported previously. The interlayer H2O molecules occupy sites halfway between the Mn,O octahedral sheets. The Mn sites in the octahedral sheets have 10% vacancies, and the mean Mn–O distance indicates that all Mn is tetravalent (Mn4+). The interlayer Ca cations are located above and below the Mn vacancies and are octahedrally coordinated to three O2 atoms in the octahedral sheet and three H2O molecules in the interlayer.

A practical description of the mathematics required to implement the hexagonal grid and spiral trace pole figure data collection schemes is presented. Applying the concepts of stereographic and equal area projections with geometry, spreadsheets were created to calculate the angular settings of the goniometer. Using the generated settings, the hexagonal grid and spiral trace schemes were programmed into the existing X-ray software and employed to collect data for a sample of aluminum foil. The resulting (111) pole figures were similar to those collected with the conventional 5°χ×5°ϕ grid. The hexagonal grid has been shown by others to reduce the number of data points and time needed to complete a pole figure, while providing equal area sampling. Although not optimized, the spiral method was also investigated as another alternative to the 5°χ×5°ϕ grid.

A new way of incorporating powder diffraction data into a cost function to predict the crystalline structure of inorganic solids is proposed. This approach was applied to the following series of compounds: cubic SrTiO3, tetragonal NaNbO3, TiO2 (anatase), tetragonal CaTiO3, and hexagonal BaTiO3. A tremendous increase in the efficiency of obtaining the correct structure is achieved when a cost function based upon this new approach is applied to these problems.

A general least-squares technique for X-ray diffraction line broadening analysis has been developed. The technique can be used to determine single, double, and triple line broadening effects caused by small particle sizes, microstrain, stacking faults, or all three presented in a closed-packed hexagonal nanomaterial. The technique was applied to characterize the microstructure of β-Ni(OH)2, a negative electrode material in nickel-metal hydride (NiMH) batteries. Double line broadening effects caused by both small crystallite sizes and stacking faults in β-Ni(OH)2 were detected and analyzed. Triple line broadening effects caused simultaneously by small crystallite sizes, microstrain, and stacking faults were detected in β-Ni(OH)2 after activation and charge-discharge cycle tests. The triple line broadening effects were found to be selective and most pronounced for diffraction lines with h−k=3n±1. The broadening effects were larger when l=even, but smaller when l=odd. The shape and the average size of the crystallites, microstrain, and stacking fault probability in β-Ni(OH)2 changed dramatically after activation and charge-discharge cycles. The method was also applied to characterize and investigate the microstructure of nano ZnO materials. Results indicate that no selective broadening appears in the XRD patterns of the nano ZnO materials. The average crystallite sizes were different slightly, and the stacking fault probabilities differed significantly with different dopants.