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.

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 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.

The structure of a high-pressure polymorph of glycine (the β′-polymorph formed reversibly at 0.8 GPa from the β-polymorph) was determined from high-resolution X-ray powder diffraction data collected in situ in a diamond anvil cell at nine pressure points up to 2.6 GPa. X-ray powder diffraction study gave a structural model of at least the same quality as that obtained from a single-crystal diffraction experiment. The difference between the powder-diffraction and the single-crystal models is related to the orientation of the NH3-tails and the structure of the hydrogen-bonds network. The phase transition between the β- and β′-polymorphs is reversible and preserves a single crystal intact. No transformations were observed between the β-, α-, and β′-polymorphs on compression and decompression, although the α- and β′-polymorphs belong to the same space group (P21/c). The instability of the β- and γ-forms with pressure can be predicted easily when considering the densities of their structures versus pressure. The direction of the transformation (i.e., which of the high-pressure polymorphs is formed) is determined by structural filiation between the parent and the high-pressure phases because of the kinetic control of the transformations.

K2Zn3(P2O7)2 was synthesized by solid state reaction and its crystal structure was determined by ab initio method from powder X-ray diffraction (XRD) data. The title compound was determined to be orthorhombic with space group P212121, Z=4, and lattice parameters a=12.901(8) Å, b=10.102(6) Å, and c=9.958(1) Å. Values of lattice parameters from 303 to 573 K were measured by temperature-dependent XRD. Thermal expansion coefficients α0, lattice parameters, and cell volume at 0 K were determined to be α0(a)=1.62327×10−4/K, a0=12.855(4) Å, α0(b)=1.17921×10−4/K, b0=10.070(8) Å, α0(c)=2.62364×10−4/K, c0=9.880(4) Å, and α0(V)=6.599×10−2/K, V0=1278.967(0) Å3. The specific heat equation as a function of temperature was determined to be Cp=0.77115+0.00231T−1241.60027T−2−1.4133×10−6T2 (J/K g), for temperatures from 198 to 710 K. The melting point estimated from the μ-DTA heating curve is 795 °C.

Time-resolved synchrotron powder diffraction was used to follow the thermal transformation of cement-asbestos. Thermal transformation of asbestos fibers into nonfibrous crystalline phases is a promising solution for the elimination of these hazardous minerals. Time resolution offered by the use of an imaging plate detector with a high-brightness X-ray source allowed for the observation of metastable phases, commonly not detectable with conventional instrumentation. In addition, the use of a closed capillary as a sample holder mimicked the real, novel industrial reactor where cement-asbestos slates are sealed in a tunnel kiln. The changing gas atmosphere in the closed system was shown to affect the final composition of the recrystallized product. This study demonstrates the importance of advanced powder diffraction techniques in this field of applied research.

Isothermal sections at 1100 and 1500 °C were determined by X-ray powder diffraction method to reveal stable phases and chemical pathways in the Co–Si–C system. There is no ternary compound present in either isothermal. Cobalt silicides are formed in the Co-rich region at temperatures lower than those in the Si-rich region. CoSi2 reacts with carbon to form CoSi and SiC at 1500 °C, and Co2Si and CoSi are more stable in equilibrium with carbon. The results are also discussed in terms of thermodynamics and binding energy of the reacting substances.

MgB2 superconductors were synthesized at high pressure and high temperature (HPHT) using pure Mg and B as raw materials. The effects of the experimental conditions such as pressure and temperature on phase evolution were studied using X-ray diffraction (XRD), scanning electron microscope (SEM), and DC magnetization techniques. Results showed that high pressure and high temperature are two important factors for synthesizing the MgB2 phase. Stable MgB2 can be most effectively obtained in a pressure-temperature region from 3 to 6 GPa and between the melting points of Mg up to 1100 to 1300 °C. MgB2 starts to decompose into MgB4 at higher temperatures and pressures. The decomposition temperature of MgB2 increases with increasing pressure. The superconducting transition temperature Tc(bulk) was measured to be 38.0 to 38.8 K for MgB2 prepared at 900 to 1000 °C under 3 GPa. The larger grains and better crystalline perfection contribute to the higher Tc(bulk) and the narrower ΔT.

Four new derivatives of N-aryl-2,4-dichlorophenoxyacetamide, 2-(2,4-dichlorophenoxy)-N-(4-fluorophenyl)acetamide, N-(4-bromophenyl)-2-(2,4-dichlorophenoxy)acetamide, N-[4-chloro-3-(trifluoromethyl)phenyl]-2-(2,4-dichlorophenoxy)acetamide, and N-(3-chloro-4-fluorophenyl)-2-(2,4-dichlorophenoxy)acetamide, and two of N-alkyl-2,4-dichlorophenoxyacetamide, N-dodecyl-2,4-dichlorophenoxy-acetamide and 2-(2,4-dichlorophenoxy)-N-hexadecylacetamide, have been characterized by X-ray powder diffraction. These organic compounds are potential pesticides. Experimental 2θ peaks positions, relative peak intensities, values of d and Miller indices, and unit cell parameters are presented.

X-ray powder diffraction data collected in transmission and high-throughput geometries were used to analyze form I of atorvastatin. The X-ray wavelength of the synchrotron radiation used in this study was determined to be λ=1.3771 Å. Form I of atorvastatin was found to be triclinic with space group P1 and unit cell parameters a=5.4568(2) Å, b=9.8887(4) Å, c=30.3091(9) Å, α=76.801(3)°, β=99.177(5)°, γ=105.318(5)°, V=1527.1(1) Å3, Z=1, and M=1209.41 g mol−1 Alternatively, another unit cell dimension can be used to describe the same P1 crystal with a=5.4564(2) Å, b=9.8883(4) Å, c=29.6555(8) Å, α=95.745(3)°, β=94.297(5)°, γ=105.327(5)°, and V=1526.8(1) Å3.

Ternary Al–Cu–Ir phases, isostructural to the Al–Cu–Rh ω and C2 phases, were found to be around the Al70Cu20Ir10 and Al60Cu15Ir25 compositions, respectively. Using powder X-ray diffraction, the former was found to have a tetragonal structure (space group P4/mnc) with a=6.4142(9) Å and c=14.842(4) Å, and the latter has a cubic structure (space group Fm3) with a=15.3928(6) Å.

Two ternary phases, designated τ4 and τ5, were revealed in Al–Ti–Pt. The τ4-phase with equiatomic composition (i.e., AlTiPt) was found to have a hexagonal structure with a=4.3908(9) Å and c=5.4823(10) Å (space group P63/mmc), and the τ5-phase, forming in a compositional range between ∼ Al14Ti58Pt28 and Al21Ti63Pt16, has a tetragonal structure (possible space groups P42nm, P-4n2, and P42/mnm). The refined lattice parameters for Al15Ti60Pt25 are a=9.7019(20) Å and c=5.0231 (13) Å.