Introduction: Phase transition has been recently observed in Cs2CdI4 (Touchard, Louër, Auffrédic & Louër, 1986). Thermal analysis has shown that the transformation occurs at 122°C. By quenching, the high temperature phase (β) can be stabilized at room temperature. In the present work we report the X-ray diffraction powder data, at room temperature, for the two phases α- and β-Cs2CdI4. Both phases have been indexed automatically by using powder indexing methods.

The crystal structures of marialite (Me6) from Badakhshan, Afghanistan and meionite (Me93) from Mt. Vesuvius, Italy were obtained using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and Rietveld structure refinements. Their structures were refined in space groups I4/m and P42/n, and similar results were obtained. The Me6 sample has a formula Ca0.24Na3.37K0.24[Al3.16Si8.84O24]Cl0.84(CO3)0.15, and its unit-cell parameters are a=12.047555(7), c=7.563210(6) Å, and V=1097.751(1) Å3. The average ⟨T1-O⟩ distances are 1.599(1) Å in I4/m and 1.600(2) Å in P42/n, indicating that the T1 site contains only Si atoms. In P42/n, the average distances of ⟨T2-O⟩=1.655(2) and ⟨T3-O⟩=1.664(2) Å are distinct and are not equal to each other. However, the mean ⟨T2,3-O⟩=1.659(2) Å in P42/n and is identical to the ⟨T2′-O⟩=1.659(1) Å in I4/m. The ⟨M-O⟩ [7]=2.754(1) Å (M site is coordinated to seven framework O atoms) and M-A=2.914(1) Å; these distances are identical in both space groups. The Me93 sample has a formula of Na0.29Ca3.76[Al5.54Si6.46O24]Cl0.05(SO4)0.02(CO3)0.93, and its unit-cell parameters are a=12.19882(1), c=7.576954(8) Å, and V=1127.535(2) Å3. A similar examination of the Me93 sample also shows that both space groups give similar results; however, the C–O distance is more reasonable in P42/n than in I4/m. Refining the scapolite structure near Me0 or Me100 in I4/m forces the T2 and T3 sites (both with multiplicity 8 in P42/n) to be equivalent and form the T2′ site (with multiplicity 16 in I4/m), but ⟨T2-O⟩ is not equal to ⟨T3-O⟩ in P42/n. Using different space groups for different regions across the series implies phase transitions, which do not occur in the scapolite series.

A novel hexaborate, Na2ZnB6O11, has been successfully synthesized by solid-state reaction and ab initio crystal-structure analysis has been completed using powder X-ray diffraction data. The compound crystallizes in the monoclinic space group Cc with lattice parameters a=10.7329(2) Å b=7.4080(3) Å, c=11.4822(2) Å, and β=112.16(2)°. The number of chemical formula per unit cell is Z=4 and the calculated density is 2.768(3) g/cm3. It represents a new structure type in which double-bridge-ring [B6O11]4− groups were found as fundamental building units. The infrared spectrum confirms the presence of both [BO3]3− groups and [BO4]5− groups.

X-ray powder diffraction patterns for 18 phases of 14 well-known explosives have been developed in our laboratory. Experimental patterns were obtained with an automated diffractometer for those phases for which samples were available. For phases with known crystal structures, patterns were calculated from the lattice and atomic positional parameters for comparison with the experimental patterns. Eleven of the experimental patterns have been included in Powder Diffraction File (PDF) Sets 40 and 42; four have been accepted but not yet issued. A final experimental pattern shall be submitted this year. In two other instances, since samples of sufficient quantity and/or quality were not available, calculated patterns alone are considered here. A review of the development of the crystallographic knowledge of these substances is given here together with a critique of the patterns and other known patterns of these phases.

X-ray powder diffraction data for a new calcium zirconium phosphate Ca7Zr(PO4)6 are reported. The sample was prepared by heating mixtures of CaCO3, ZrO2, and NH4H2PO4 in prescribed molar ratios at 1623 K. Powder diffraction data were collected with a laboratory X-ray source (Cu Kα) for refinement of unit-cell parameters and intensity measurement of individual reflections. Crystallographic data were Ca7Zr(PO4)6, cubic, I-43d (No. 220), a=0.98338(1) nm, V=0.95097(3) nm3, Z=2, and Dx=3.29 Mg m−3. This compound is most probably isomorphous with eulytite.

Structural measurements have been performed on the La0.7Sr0.3Mn3+ 0.85Nb5+ 0.15O3 compound with oxidation state of manganese close to +3. The composition undergoes a structural transition from rhombohedral to orthorhombic symmetry below room temperature. The calculated structural parameters show that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The compound is ferromagnetic with a Curie point of around 150 K and a magnetic moment of 3.1 μ B/Mn. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder leads to suppression of ferromagnetism.

Semifluorinated (SF) side chain polymers show phase separation between polymer backbone and SF side chains. Due to strong interaction between SF segments the side chains determine the structure behaviour strongly, often resulting in layered structures in which backbones and layers of SF side chains alternate. The interest in this work was directed to find out the dependence of these structures on concentration of SF side chains. Thin films of random copolymers consisting of methylmethacrylate (MMA) and semifluorinated side chain methacrylate (SFMA) segments and with different fluorine content in the perfluoroalkyl side chains (abbreviated as H10F10 and H2F8) were prepared by spin-coating. Phase separation and structure changes were initiated by external subsequent annealing. Corresponding bulk material served as basic information. Generation of ordered structures and variation of film parameters were observed using different X-ray scattering methods (XRR, GIWAXS, and GISAXS). The phase behaviour in bulk is governed by the SF side chain amount and their specific fluorine content which control the self-organization tendency of SF side chains. Additionally, the confinement in thin films generates an orientation of side chains normally to film surface.

An X-ray analysis method has been developed for the quantitative analysis of pyrite (FeS2) in coals and lignites. Requiring neither the use of external or internal references, the method linearly relates diffraction peak area in the absorption corrected X-ray diffractogram obtained from the finely powdered coal to the pyrite abundance. The [311] diffraction peak of pyrite (FeS2) has been used to develop the analysis protocol. The Argonne premium coals have been used as the experimental subjects. The abundance of pyrite in each coal has been measured from the absorption corrected diffractograms, which has been constructed from the experimentally measured diffraction intensities and the mass absorption coefficient of each coal sample. The accuracy (accessed from the figure-of-merit and the net count uncertainty associated with the 1.63 Å pyrite peak) as well as the lower limit of detection for pyrite in these coals is presented. The role of the mass absorption coefficient in the conversion of the measured intensity to the absorption corrected intensity is discussed.

Two additional forms of K2FeF5 are disclosed and characterized by powder diffraction. One (form-IV) adopts a new A2MF5 structural type, space group C2/m, a = 13.0919(2) Å, b = 5.7311(1) Å, c = 7.3114(1) Å, β = 118.241(1), and Z = 4, it is obtained from the thermal evolution of form-III, isostructural with Rb2FeF5, space group Pnma, a = 7.3964(2)  Å, b = 5.6779(1) Å, c = 11.5445(3) Å, and Z = 4. Both forms are compared to two previously reported polymorphs. The III → IV transition is topotactic, conserving the same zigzag cis-connected octahedral (FeF5)n2n− chains after an ~90° rotation and 1/2b translation of half of them.

Cadmium hydroxide nitrate dihydrate, Cd5(OH)8(NO3)2·2H2O, and zinc hydroxide nitrate diammoniac, Zn5(OH)8(NO3)2·2NH3, have been investigated by means of X-ray powder diffraction. Their unit cell dimensions were found by an indexing program and confirmed by single crystal studies. Precise data collected with strictly monochromatic radiation are reported. The figures of merit are F30=118 (0.0071,36) for the cadmium compound and F30=53 (0.015,38) for the zinc compound. A short discussion of the unit cell parameters compared to those of a related zinc hydroxide nitrate dihydrate is presented.

Single-crystal synchrotron X-ray diffraction (XRD) data were collected and refined for congruent lithium niobate crystals 8 and 6 μm in diameter, sizes that are comparable to the size of the powder particles used in powder diffraction. The motivation for using such small crystals is to minimize problems such as extinction, which decrease with crystal size. The R/wR factors were 0.011/0.014 and 0.019/0.018, for the 8 and 6 μm data, respectively, and the goodness of fit factors were 2.3(1) and 1.63(8), which compare favorably with values obtained from previous powder and single-crystal diffraction studies. Results from single-crystal XRD using crystals less than 10 μm in size may rival those obtained from powder diffraction.

NaCl1−xBrxO3 single crystals were prepared by unidirectional crystallization. The influences of the composition on structure, quality, and optical properties of NaCl1−xBrxO3 crystals were investigated. X-ray powder diffraction analysis revealed that the diffraction patterns for the NaCl1−xBrxO3 crystals have almost the same set of peaks as those of NaClO3 and NaBrO3, except that an extra very weak forbidden (100) diffraction peak was detected at about 13.3° 2θ for crystals grown from solutions of BrO3−∼15–70 at. % (i.e., x=0.15–0.70). These crystals can, therefore, be considered to have a distorted cubic structure closely related to the cubic structures of NaClO3 (x=0) and NaBrO3 (x=1). Our study also found that good-quality crystals can only be obtained in two doping ranges (x>0.75 or x<0.10). Outside these two ranges, the crystals tended to crack and even became opaque. Lattice distortions in the crystals were the probable cause as revealed by X-ray powder diffraction patterns. The optical activity of NaCl1−xBrxO3 crystals measured by a laser was found to decrease from 2.89 to 2.01°/mm with increasing value of x from 0 to 0.02. Stimulated Raman scattering of NaBr0.90Cl0.10O3 crystals was measured using a 0.532-μm ps laser as a pump source and four anti-Stokes lines plus six Stokes lines were observed. The fourth anti-Stokes emission was found to be at 454.5 nm and the sixth Stokes emission at 713.6 nm. Its Raman gain coefficient was determined to be 18.4 cm/Gw.

Samples of amorphous Se, SSe40, SSe30, and SSe20 were synthesized and were then crystallized by annealing at 373 K for 5, 20, and 120 mins. The results showed that the changes in the structural and microstructural parameters for samples SSe40, and SSe30 are different from those of sample SSe20. These discrepancies are being discussed in terms of the peak shifts in both the amorphous and crystalline state, the percentage of sulfur compositional variations, and finally in terms of the probable site occupancy of the sulfur atoms in the selenium structure.

Generating compressive stresses in aerospace materials is an important consideration for enhancing fatigue life. Shot peening and cold expansion of holes are two techniques for imparting beneficial compressive stresses. X-ray diffraction is a direct method for measuring elastic strains. Diffraction peak widths are an indication of plastic strain. Elastic and plastic strains can be used to better assess the true condition of a component. This paper presents elastic and plastic strain information from shot peened and cold expanded aerospace materials. Examination of surface data showed which shot peened samples had the deeper layer of compressive stresses. Likewise, elastic and plastic strain data enabled successful ranking of the holes in terms of the maximum amount of cold working.

The orthorhombic mineral moolooite, CuC2O4. nH2O, described by Clarke and Williams (1986) using Debye-Scherrer photographic data, has a fully-disordered stacking fault (FDSF) structure. Related monoclinic models have been reported for various synthesised samples based on Schmittler (1968). In the present study, synchrotron radiation diffraction data for moolooite and synthesised specimens have been examined with particular reference to crystallographic disorder. The moolooite data correspond to space group Pnnm, with a = 5.3064(2), b = 5.6804(2), c = 2.5630(1) Å; Vc = 77.26(1) Å3; and Z = 1; and the FDSF structure along the b-direction has been confirmed. The synthetic specimen data from the study indicate partial ordering, with space group P21/n; and the cell parameters for one specimen being a = 5.957(7), b = 5.611(5), c = 5.133(7) Å; β = 115.16(2)°; Vc = 155.27 Å3 and Z = 2. The level of zeolitic water in the materials has been considered using the approach of Schmittler based on thermogravimetry and pycnometry. The new data for natural topotype material correspond to CuC2O4.1.0H2O. It is postulated that the level of water for natural and synthetic specimens may be attributed to the conditions under which the material forms.

Reference X-ray diffraction patterns for the quarternary intermetallic superconductor phases of compositions LuNi2B2C and YNi2B2C are reported. Both materials were synthesized by the arc-melting technique. The patterns of these metallic phases exhibit preferred orientation in an ordinarily pressed sample, which was minimized through special specimen preparation. The observed intensities and the calculated values for both phases agree reasonably well with each other. Both compounds were refined in the space group I4/mmm, with a=3.4647(1) Å and c=10.6330(4) Å for LuNi2B2C and a=3.5271(1) Å, c=10.5361(7) Å for YNi2B2C.

The crystal structure of cephalexin monohydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Cephalexin monohydrate crystallizes in space group C2 (#5) with a = 27.32290(17), b = 11.92850(4), c = 16.75355(8) Å, β = 108.8661(4)°, V = 5166.99(3) Å3, and Z = 12. Although the general arrangement of molecules is similar to that in cephalexin dihydrate, the structural differences result in very different powder patterns. The crystal structure is characterized by alternating layers of hydrogen bonds and van der Waals contacts parallel to the bc-plane. The water molecules occur in clusters. Five of the six protons in the water molecules act as donors in O–H⋯O hydrogen bonds. The sixth hydrogen atom acts as a donor to two different phenyl ring carbon atoms to form bifurcated O–H⋯C hydrogen bonds. Each cephalexin molecule is a zwitterion, containing ammonium and carboxylate groups. The ammonium ions form N–H⋯O hydrogen bonds to carboxylate groups and water molecules, as well as to carbonyl groups. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1417.