The transition metal fluorides KMF3 (M = Mn, Co, and Ni) were synthesized through a simple solution route. The crystal structure, morphology and electrical transport property of the resulting products were investigated. The compound KMF3 crystallizes in a cubic perovskite structure with space group Pm-3m (No. 221). A crystal structure of KMF3 was refined by the Rietveld method based on the X-ray powder diffraction data. The unit-cell parameters are 4.189 46(4), 4.075 58(4), and 4.025 70(2) for KMnF3, KCoF3 and KNiF3, respectively. A metal–insulator transition was observed in temperature-dependent electrical transport characterization in the temperature range from 250 to 280 K for these three compounds, which is considered to be related to spin-exchange in this kind of material.

Nuclear fuel plates based on a γU-Mo/Al mixture are proposed for research reactors. In this work their thermal behavior in the [425; 550°C] temperature range has been studied mainly by neutron and high energy X-ray diffraction. Even if complementary studies will be necessary, the kinetics of first the growth of the interaction layer between γU-Mo and Al and second of the γU-Mo destabilization have been accurately measured. This basic work should be helpful for defining manufacturing conditions for fuel plates with optimized composition.

Powder diffraction data were collected for a synthetic zinc molybdate of composition Na(OH)Zn2(MoO4)2·2.5H2O. The material is monoclinic, space group C2/m, with a=9.4543(12), b=6.3492(7), c=7.6453(11), β=115.899(13), and V=412.83 Å3.

A model for the long awaited crystal structure of metastable NaAlF4 is established from the powder diffraction pattern of a partly disproportionated sample. Orthorhombic, Cmcm, a=3.6121(3), b=14.952(1), c=5.2692(4) Å, Z=4, V=284.58(4) Å3. Sodium atoms are in NaF6 trigonal prisms interconnected by edges in compact layers. AlF6 octahedra are both cis- and trans-corner connected forming a layer structure similar to that observed in the NaNbO2F2 (P21/c) and BaZnF4 (Cmc21) structure types. NaAlF4 is ideally simple and symmetrical, isostructural with BiReO4 (Cmcm), representing the aristotype of the NaMIIIF4 and BaMIIF4 series.

A natural olivine sample from a mantle peridotite xenolith has been studied by in situ high-temperature powder diffraction. The structure has been successfully refined from powder data at three temperatures (25, 600, and 800 °C) using the Rietveld method. The study shows that the full-profile technique is well suited for the structure analysis of high-temperature powder diffraction data. The results indicate that, in this temperature range, there is no significant ordering of the Fe,Mg cations in the two crystallographically independent octahedral sites. This has implications for the thermodynamic modeling of olivine at upper mantle conditions. The present experiments allowed measurement of the lattice thermal expansion of olivine in the temperature range 25–800 °C, and assessment of the temperature dependence of the isotropic atomic displacement parameters.

A new occurrence of the poorly characterized mineral, yukonite, (Ca6.44K0.13Mg0.23)(Fe14.68Al0.36)(AsO4)9O15.78·25.5H2O, is described. New powder X-ray diffraction and electron microprobe data are provided for type material from Tagish Lake, Yukon Territory, Canada, and that from the new locality, Saalfield, Thuringen, Germany. New chemical formulae are proposed. The strongest reflections are at 14.1(100), 2.79(60), 3.25(57), 5.58(37), 2.61(20), 1.63(20), and 2.24(11) Å.

A new polymorph of HfMo2O8 (β-form) is synthesized under high pressure and high temperature conditions. The powder X-ray diffraction (XRD) data could be explained based on a monoclinic lattice (Space Group: C2/c No. 15) with the unit cell parameters as: a=11.415(3), b=7.906(2), c=7.438(2) Å and β=122.37(2)°, V=566.9(2) Å3. The detailed powder XRD data and analysis are reported herein.

PLZT of the compositions 0≤L≤12, and 0≤T≤10 was studied in order to describe the structure of the phases as a function of composition. This range contains a mixed region with PLZT+La2Zr2O7, an orthorhombic, a rhombohedral (hexagonal) phase, a tetragonal phase, and a mixture of different PLZT phases. Each phase pure composition is described by X-ray diffraction.

Besides statistical and graphical measures, many structural features can be used to assess the quality of a Rietveld refinement. These include the metric symmetry of the lattice (which can assist in determining the true symmetry and in identifying isostructural compounds), bond distances and angles (which should fall within normal ranges), displacement coefficients, refined stoichiometry, the absolute values of the standard uncertainties of the fractional coordinates, the hydrogen bonding pattern, the presence of approximate symmetry, the presence of unindexed peaks in the pattern, and whether the refinement converges at all. Chemical knowledge can be built into a Rietveld refinement though the use of restraints and rigid bodies. A knowledge of chemical reasonableness proved important in refining the correct structures of [Fe(H2O)6](BF4)2, (Ba1.5Sr0.5)TiO4, and (Ba1.25Sr0.75)TiO4.

Transformation behaviors of the technologically important polycrystalline Ti50.75Ni47.75Fe1.50 shape memory alloy were investigated using differential scanning calorimeter (DSC) and powder diffraction techniques. DSC revealed that there are two-stage (i.e., cubic→trigonal→monoclinic) martensitic phase transformations on cooling and a one-step transformation (monoclinic→cubic) on heating. In situ structural refinement of cubic→trigonal→monoclinic on cooling was carried out using the D1A high-resolution neutron powder diffractometer at the Institut Laue-Langevin Neutrons for Science in Grenoble, France. Results showed that the phases involved during the phase transition are consistent with the differential scanning calorimeter cooling curve, and the refined crystal structure parameters obtained from Rietveld refinements with the generalized spherical harmonic description agreed reasonably well with X-ray single-crystal data. Subsequently, a combined neutron and synchrotron structural refinement for each phase was conducted because the trial refinements initially using only the synchrotron data of trigonal phase yielded a false minimum with a somewhat high goodness-of-fit χ2. Results obtained from the combined neutron and synchrotron data of the cubic, trigonal, and monoclinic phases show that the same minimum goodness-of-fit indices were always obtained.

Several benzothiophene-based compounds, including 1-benzothiophene-2-carboxylic acid, exhibit a wide variety of pharmacological activities. They have been extensively used to treat various types of diseases with high therapeutic effectiveness. In this contribution, the crystal structure of a new polymorph of 1-benzothiophene-2-carboxylic acid (BTCA) was determined from laboratory X-ray powder diffraction data with DASH, refined by the Rietveld method with TOPAS-Academic, and optimized using DFT-D calculations. The new form of 1-benzothiophene-2-carboxylic acid crystallizes in space group C2/c (No. 15) with a = 14.635(4), b = 5.8543(9), c = 19.347(3) Å, β = 103.95(1)°, V = 1608.8(6) Å3, and Z = 8. The structure is a complex 3D arrangement which can be described in terms of hydrogen-bonded dimers of BTCA molecules, joined by the acid–acid homosynthon, which interact through C–H⋯O hydrogen bonds to produce tapes further connected through head-to-tail π⋯π and edge-to-face C–H⋯π interactions. A comparison with a previously reported triclinic polymorph and with the related 1-benzofuran-2-carboxylic acid (BFCA) is also presented.

The deflection (curvature) of embedded single-crystal silicon chips was investigated by rocking curve X-ray diffraction techniques at two significant manufacturing stages in the process chain of printed circuit boards with embedded components. An overview of the curvature deduction by two different approaches was presented: (1) the measurement of the variation of the rocking curve maximum as a function of the lateral sample position along a specific traverse; the slope in such a diagram is then proportional to the corresponding curvature in that direction. (2) The evaluation of the rocking curve width; here the peak width is inversely proportional to the curvature at known beam diameter, diffraction angle, and beam divergence. It was shown that the rocking curve method is applicable to determine the curvature inside single crystalline chips. Furthermore, the method is also suitable to determine the curvature of fully embedded or encapsulated chips. Additionally the absorption of the radiation in the embed medium was quantitatively discussed. The curvature of two different prepared samples was determined at temperatures up to 200 °C in a heating stage attached to the diffractometer device.

The crystal structure of the mullite in a commercial material was refined by the Rietveld method using laboratory X-ray powder diffraction data. In this one refinement, most of the common challenges—including variable stoichiometry (partially occupied sites), multiple impurity phases, amorphous material, constraints, restraints, correlation, anisotropic profiles, microabsorption, and contamination during grinding—are encountered and the thought processes during the refinement are described step-by-step. Interpretation of the refinements includes bulk chemical analysis, chemical composition of the mullite, assessment of the geometry, bond valence sums, the displacement coefficients, crystallite size and microstrain, comparison to similar structures to assess chemical reasonableness, and the nature of the amorphous phase.

In this paper, grandite core with Grs64±1Adr36±1Sps2 composition was crystallographically studied. This core represents zone A of the macroscopically visible five A–E zones of the optically anisotropic Grs58–64Adr36–42Sps2 grandite. The applied procedure includes the detailed analysis of the powder diffraction patterns, and the Rietveld refinements of the crystal structures in a series of 18 space groups and two mixtures, which were followed by the comparative analysis of the R-values, site occupancy factors, and the bond lengths and angles. Synthesis of all of the presented results allows us to undoubtedly conclude that studied grandite is not cubic, neither as monophase nor as multiple phases in a mixture. Namely, it was established that structural dissymmetrization occurred and that it crystallized in the disordered rhombohedral $R\bar{3}c$ or orthorhombic Fddd space groups, whereby the first one is more probable. Beside the established lower symmetry of the studied grandite, which could be treated as the primary cause, the residual strain is also not excluded as the second possible cause for its slight optical anisotropy.

The low-cycle fatigue behavior of a cobalt-based superalloy was studied in situ using neutron–diffraction experiments. The alloy exhibited stress-induced formation of a hexagonal-close-packed (hcp) phase within its parent face-centered-cubic (fcc) phase at ambient temperature under strain-controlled fatigue conditions with a total strain range, Δε=2.5%. The (101) hcp peak was first observed during the 12th fatigue cycle under the given conditions following a period during which no hcp phase was detected. Subsequently, the intensity of the hcp peaks increased as fatigue progressed. Furthermore, within a single fatigue cycle, the intensity of the (101) hcp peak decreased during the compression half-cycle and increased again when the specimen was subjected to a subsequent tensile strain. The result suggests that the fcc to hcp transformation is partially reversible within one fatigue cycle.

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.

Investigation of the NiLIII band at various excitation voltages and the use of Ni and Ti thin films in the path of the NiLII,III and TiLII,III radiation, has shown that with proper electrode geometry and using target voltages of about 4 kv the effect of self absorption on emission edge shift and band shape is negligible for these elements. However, the LII/LIII intensity ratio of titanium is strongly effected by self absorption, but it is not effected for nickel and iron by self absorption.

A survey of several investigators’ soft x-ray band spectra from alloys and conducting compounds showed that the observed band changes were related to the electronegativity difference of the combining elements or the ionic character of the band. Peaks appearing on the low energy side of transition metal bands when combined with 2nd period elements appear to be a cross transition between the 2s or 2p band of the non-metal and inner level of the metal.

This paper reports the results of a detailed X-ray diffraction study of a new phase-transformation observed in SiC crystals grown by a vapour-liquid-solid mechanism involving the hydrogen-reduction of methyltrichlorosilane. The 10.ℓ reciprocal lattice rows of these crystals, as recorded on X-ray diffraction photographs, reveal sharp reflections corresponding to the hexagonal close-packed 2H (ABAB….) structure and sometimes also corresponding to the cubic close-packed 3C (ABCABC…) structure. These reflections are invariably connected by a diffuse but continuous streak whose intensity is a measure of the random faulting on the basal planes. The crystals were needle shaped and the structure sometimes varied along their length.

Several crystals were annealed in an inert atmosphere at progressively higher temperatures and their 10.ℓ reciprocal lattice row re-examined to determine the annealing behaviour as well as possible structural transformations. For a number of dark green needles having a faulted 2H structure the 2H reflections disappeared around 1400° C and the 10.ℓ reciprocal lattice row revealed only a continuous streak with increased intensity around positions for 3C reflections. On further heating the structure went over to a strongly faulted 3C. Around 1600°C the appearance of a 6H structure became discernible while highly diffuse 30 reflections still persisted. The reversible part of the transformations, if any, could not be observed. Some of the structures were, however, found to be much more stable and did not transform even up to 1650° C.

The above results, in particular the discovery of a 2H-3C phase-transformation around 1400°C, throw fresh light on the thermodynamic stability of the different SiC types. The mechanism of the 2H-3C transformation, the possible influence of faults and impurities and the thermal stability of various SiC structures are discussed on the basis of the experimental results stated above.

Methods for, and results from, x-ray diffraction analysis of large numbers of fly ash samples obtained from U.S. power plants are described. Qualitative XRD indicates that low-calcium/Class F fly ash (usually derived from bituminous coal) consists typically of the crystalline phases quartz, mullite, hematite and magnetite in a matrix of aluminosilicate glass. Highcalcium fly ash (derived from low-rank coal) has a much more complex assemblage of crystalline phases that typically includes these four phases plus lime, periclase, anhydrite, alkali sulfates, tricalcium aluminate, dicalcium silicate, melilite, merwinlte and a sodalite-structure phase. Glass compositions among the particles are more heterogeneous and range from calcium aluminate to sodium calcium aluminosilicate, Every ash studied Is mixed with an internal Intensity standard (rutile) so that Intensity ratios can be used to make comparisons of the relative amounts of crystalline phases. An error analysis was performed to define the level of uncertainty in making these comparisons. These intensity ratios will be used for quantitative XRD phase analyses when reference intensity ratios for each fly ash phase become available.