The structures of γ- and δ-K4P2O7 are solved by X-ray powder diffraction (conventional laboratory X-ray and synchrotron data, respectively), both in hexagonal symmetry (aγ = 5.9645(3) Å, cγ = 14.4972(8) Å, Vγ = 446.64(4) Å3 at 300 °C, Zγ = 2, space group P63/mmc; aδ = 10.211 45(7) Å, cδ = 42.6958(4) Å, Vδ = 3855.59(7) Å3 at room temperature, Zδ = 18, space group P61) with cell–supercell relations $a_\delta \approx a_\gamma \sqrt{3}$ and cδ ≈ 3 cγ. In the experimental conditions, the expected β/γ transition previously announced at 486 °C is not observed; the γ-form is stable at least up to the maximum temperature of our measurements (700 °C). In the γ-form, similar to the orthorhombic form of Na4P2O7, idealized, the pyrophosphate group is in eclipsed conformation, the K+ cations occupying three different coordinations. In the δδ-form, two of the three different [P2O7]4− groups are staggered and one eclipsed, the K+ cations occupying 12 independent sites.

The (Ag,Pd)22Se6 phase was synthesized from individual elements by silica glass tube technique and structurally characterized from powder X-ray diffraction data. The (Ag,Pd)22Se6 phase crystallizes in Fm$\overline3$m symmetry, unit-cell parameters: a = 12.3169(2) Å, V = 1862.55(5) Å3, Z = 4, and Dc = 10.01 g/cm3. The crystal structure of the (Ag,Pd)22Se6 phase represents a stuffed 3a.3a.3a superstructure of the Pd structure (fcc), where only 4 from 108 available octahedral holes are occupied. Its crystal structure is related to the Cr23C6 structure type.

Eighty specimens of cellulosic materials were analyzed over a period of several years to study the diffraction characteristics resulting from polymorphism, crystallinity, and chemical substitution. The aim of the study was to produce and verify the quality of reference data useful for the diffraction analyses of cellulosic materials. These reference data can be used for material identification, polymorphism, and crystallinity measurements. Overall 13 new references have been characterized for publication in the Powder Diffraction File (PDF) and several others are in the process of publication.

Phase diagrams and X-ray powder diffraction patterns provide critical information for thermoelectric (TE) research. We have conducted a survey of phase diagrams and powder diffraction patterns of TE systems in the ASM (American Society for Metals) Metal/Alloy database and ICDD (International Centre for Diffraction Data) PDF (Powder Diffraction File), respectively, for their availability and crystal systems. In this report, we focus on TE materials that have the half-Heusler XYZ structure, and related compounds, based on a set of materials selection rules. We found that among 306 potential XYZ compounds that we have surveyed, 234 have powder diffraction patterns in the PDF, but only 28 have phase diagram information, and 67 do not have any crystallographic information. Among the 234 phases with powder patterns, 84 were reported to have cubic F43m half-Heusler type structure, and the remainder have hexagonal, orthorhombic or other structure types. Some XYZ compounds have both cubic and hexagonal phases. This information will provide the basis for future activities for the improvement of the databases. These activities include filling the missing gaps in both phase equilibria database and the PDF, as well as adding TE and pertinent physical properties to the PDF.

Chitin is a natural polysaccharide found in many diverse phyla and almost always occurs in association with protein. In this study the chitin polymer is characterized by X-ray diffraction from its naturally occurring unprocessed state through various steps used in the purification procedure. In addition, the effect of different treatments on the final product is examined. These studies show that native chitin has a characteristic diffraction pattern that is not altered by the mild treatments used to isolate relatively pure chitin. Chitins prepared from different sources exhibit the same characteristic diffraction pattern. In addition, chitin films prepared using non-degrading solvents retain most of the characteristic patterns. De-acylation of chitin to produce chitosan results in large changes to the diffraction pattern. To a very limited extent features present in the diffraction pattern of native chitin can be recovered by re-acylation of chitosan.

The stereoselective synthesis of 7-fluoro-2-exo-(2-methylpropen-1-yl)-2,3,4,5-tetrahydro-1,4-epoxybenzo[b]azepine was developed by intramolecular 1,3-dipolar cycloaddition of the nitrone derived from the corresponding 2-allyl-4-fluoro-N-(3-methylbut-2-enyl)aniline. The X-ray powder diffraction (XRPD) pattern for the new compound was analyzed and found to crystallize in a monoclinic system with space group P21/m (No. 11) and refined unit-cell parameters a = 11.655(5) Å, b = 5.850(2) Å, c = 18.314(4) Å, β = 104.27(3) and V = 1210.1 (6) Å3.