X-ray Powder Diagrams Research Articles

Röntgenographische und spektroskopische Untersuchung einiger Strontium-und Zink-substituierten Calcium-Fluorapatite / X-Ray and Spectroscopic Investigation of Some Strontium and Zinc Substituted Calcium Fluoroapatites

Simultaneous strontium and zinc substitution for calcium in the fluoroapatite lattice was investigated. Crystallographic data for different members of the series Cain10-x-ySrxZny(PO4)6F2 were obtained from X-ray powder diagrams. The effects of the substitutional process on the strength of the phosphate P -O-bonds were checked by Raman spectroscopy. For comparative purposes, the first members of the series Sr10-xZx(PO4)6F2 were also investigated in a similar way.

Struktur und ionenleitung in festkörpern V: Struktur und eigenschaften der Verbindungen Na 3MnZr(PO 4) 3 und Na 3MgZr(PO 4) 3

Na 3MgZr(PO 4) 3 and Na 3MnZr(PO 4) 3 exist in the NASICON structure (space group R 3 ̄ c — D 6 3d ) with the lattice constants a 0 = (890.7 ± 0.6) pm, c 0 = (2222 ± 4) pm or a 0 = 900.0 pm, c 0 = 2239.3 pm, respectively. Intensity calculations of X-ray powder diagrams based on different models and 31P-MAS-NMR measurements indicate random distribution of Zr IV and Mg II or Mn II on the octahedral sites. The Na + ions are suggested to be equally distributed one on the Na I site and three on the Na II sites of the lattice. The compounds show incongruent melting at 1075 °C or 1025 °C, respectively. The conductivity of the manganese compound is about three times higher than for the magnesium compound. However, in comparison with Na 3Zr 2(SiO 4) 2(PO 4) the Na + ion conductivity at 300 °C is about three orders of magnitude lower, which is assumed to be caused by the highly irregular structure of the compounds.

α,ω-Alkanediammonium Tetrachlorocobaltates: Influence of the Hydrocarbon Chain on the Properties of These Compounds

Abstract In a previous paper10 a description was made of the preparation and characterization of compounds with a general formula of [NH3(CH2)nNH3]CoCl4, where n = 3,5,6,7,8,9 and 10. The diffuse reflectance spectra and magnetic moments10 revealed the presence of the tetrahedral CoCl2- 4 ion in all the compounds. In the present work the structure and properties of these compounds are studied in greater depth. The compound (enH2)2(CoCl4)Cl2 prepared according to the method of Smith and Stratton13, also shows the presence of the CoCl2- 4 ion. The parameters of the tetrahedral crystal field were calculated for CoCl2- 4 from the visible spectra and magnetic moment data. The X-ray powder diagrams of the long chain compounds (n= 6–10) indicate a layer structure and they exhibit thermal properties that are similar to those of certain lipids and liquid crystals. The conductivities in several solvents indicated different degrees of solvolysis of the CoCl2- 4 ion.

Cobalt(II) and nickel(II) halide coordination compounds with 1,6-bis(benzimidazol-2-yl)-2, 5-dithiahexane and 1,7-bis(benzimidazol-2-yl)-2, 6-dithiaheptane. The crystal and molecular structure of dibromo(1,6-bis(benzimidazol-2-yl)-2,5-dithiahexane)nickel(II)

The synthesis and characterization by spectroscopic techniques of compounds with general formulae MX 2(bbdh) and MX 2(bbdhp) is described. In these formulae M = Co(II), Ni(II); X = Cl, Brbbdh = 1,6-bis(benzimidazol-2-yl)-2,5-dithiahexane and bbdhp = 1,7-bis(benzimidazol-2-yl)-2,6-dithiaheptane. The compounds have been characterized by chemical analysis, infrared spectra, ligand field spectra, X-ray powder diagrams and in one case by a single crystal structure analysis. The metal ions are octahedrally (all Ni compounds and the Co compound of bbdh) or tetrahedrally (Co compounds of bbdhp) coordinated by the ligands and the anions. The detailed structure of NiBr 2(bbdh) was determined by X-ray methods at 290 K. Crystals of C 18H 18Br 2N 4NiS 2, M r = 572.995, crystallized in the orthorhombic space group Pnc2, with a = 8.502(3), b = 13.748(2), c = 8.794(3) Å, V = 1027.96(57) Å 3, Z = 2, D x = 1.851 Mg/m 3, were studied with CuKα radiation (using monochromator, λ = 1.54178 Å), μ(CuKα) = 7.931 mm −1, F(000) = 568. The final conventional R-factor = 0.064, (R w = 0.083) for 1600 “observed” reflections and 122 variables. The structure was solved using Patterson and DIRDIF techniques and refined by SHELX. The coordination around Ni(II) is octahedral with a cis-geometry of the two bromide anions (NiBr = 2.543(2) Å), a trans-arrangement of the benzimidazole ligands (NiN = 2.132(8) Å) and a cis-geometry of the thioether groups (NiS = 2.441(3) Å). The packing in the crystal results in hydrogen bond interactions between the N-H groups of the imidazoles and bromine atoms of nearby units. The structures of the nickel compounds and the isomorphous Co(II) bbdh compound are believed to be essentially the same, as deduced from spectroscopic analysis. The Co(II) compounds of bbdhp, however, appear to be tetrahedrally coordinated, as deduced from ligand field spectra. It seems that in this case the thioether groups are not coordinated to the Co(II) ion.

X-ray diffraction analysis of the auditory ossicles in chronic otitis.

An X-ray diffraction analysis was carried out on 10 healthy mallei and incudes which were taken from cadavers and on 50 diseased mallei and incudes taken peroperatively from patients with atticoantral otitis. X-ray powder diagrams of normal ossicles were shown as a granular hydroxyapatite. In diseased ossicles, changes were found in the crystallinity of hydroxyapatite which can be divided into four groups: (i) with characteristics of a diagram of normal bones giving peaks of maximum intensity of a granular hydroxyapatite; (ii) with less hydroxyapatite crystallinity; (iii) characterized by the occurrence of an amorphous phase of bone; (iv) characterized by the absence of all types of crystallization. The occurrence of different phases of crystalline hydroxyapatite in various forms of atticoantral otitis does not depend on the type of pathological process, i.e., with or without cholesteatoma.

Characterization of a low-temperature form of InVO 4

A low-temperature form of InVO 4, belonging to the α-MnMoO 4 structural type, was characterized. The unit cell parameters were determined from X-ray powder diagrams. The infrared spectrum was discussed with the aid of a “site-symmetry analysis.” The results were discussed in comparison with those of the corresponding high-temperature form (CrVO 4 type) and with some other related compounds.

De nouveaux isotypes de U2Co3Si5 ou Lu2Co3Si5 dans les systems R-T-Ge (R = Elements Des Terres Rares; T = Ru, Co, Rh, Ir). Supraconductivite de Y2Ir3Ge5

New ternary germanides R2T3Ge5 have been prepared at 1173 K. From their X-ray powder diagrams, some of them are isostructural with U2Co3Si5: R2Ru3Ge5 (R = Y, La-Sm, Gd-Tm), Ce2Co3Ge5, R2Rh3Ge5 (R = La-Pr) and R2Ir3Ge5 (R = Y, La-Sm, Gd-Dy); others crystallize with the Lu2Co3Si5 - type structure, a monoclinic deformation variant of the U2Co3Si5 type: R2Co3Ge5 (R = Y, Pr-Sm, Gd-Er) and R2Rh3Ge5 (R = Y, Nd, Sm, Gd-Tm). The Lu2Co3Si5-type structure of Ho2Rh3Ge5 was refined from single-crystal X-ray data to a conventional R value of 0.034 for 371 independent reflections (Rw = 0.034). Superconductivity above 1.3 K was found only in Y2Ir3Ge5.

Complexes of lanthanoid salts with macrocyclic ligands. Part 25. Lanthanoid trifluoroacetate complexes with 12-crown-4, 15-crown-5, and 18-crown-6 ethers

The lanthanoid trifluoroacetates, Ln(TFA) 3, react with 12-crown-4, 15-crown-5, and 18-crown-6 ethers to give complexes with various metal:ligand ratios, 1:1, 3:2, and 2:1. The following complexes have been isolated and characterized: Ln(CF 3CO 2) 3· (C 8He 16O 4), Ln = La, Ce, Pr; [Ln(CF 3CO 2) 3] 3· (C 8H 16O 4) 2, Ln = Pr, Eu, Er; [Ln(CF 3CO 2) 3] 2· (C 8H 16O 4), Ln = Pr, Nd, Sm; [Ln(CF 3CO 2) 3] 2· (C 10H 20O 5), Ln = LaEu; Ln(CF 3CO 2) 3·(C 12H 24O 6), Ln = LaEu; [Ln(CF 3CO 2) 3] 2·(C 12H 24O 6), Ln = Y, EuEr, Yb. Thermogravimetric data show that the 2:1 complexes are usually thermally more stable. The 2:1 complexes with the 15-membered polyether undergo a slow hydrolysis in the presence of traces of water, which yields the hydroxo complex [Ln 2(CF 3CO 2) 3(OH)(C 10H 20O 5) 2] [Ln 2(CF 3CO 2) 8]. The vibrational spectra confirm the coordination of the coronands; the Δν as(CCO) shifts are not large, which point to a moderate interaction between the polyethers and the metal ions. Magnetic susceptibilities and X-ray powder diagrams have been measured. High-resolution excitation and emission spectra have been analysed for the europium-containing compounds. The spectrum of Eu(CF 3CO 2) 3·3H 2O indicates the presence of a single species with low symmetry, in agreement with the crystal structure data for the isostructural Pr-salt. The anhydrous salt Eu(CF 3CO 2) 3 generates an emission spectrum with broad bands and probably contains several, closely related polymeric species. The spectrum of [Eu(CF 3CO 2) 3] 2(C 10H 20O 5) is consistent with the presence of two chemically different sites for Eu(III); the emission bands are broad. The double salt AgEu(CF 3CO 2) 4·3CH 3CN has also been investigated; the observed transitions point to the presence of a species with idealized D 2 d symmetry. The emission spectrum of [Eu(CF 3CO 2) 3] 2(C 12H 24O 6) displays sharp bands and reveals the presence of two different sites for the metal ion with efficient energy transfers between them. One of the species may have a relatively high symmetry. In solution, all the complexes are non-electrolytes in acetonitrile and propylene carbonate and close to 1:1 electrolytes in methanol. Some dissociation occurs in acetonitrile for the 2:1 complexes with 18-crown-6 ether. On the other hand, 1H NMR spectra of the lanthanum 1:1 complexes with 12- crown-4 and 18-crown-6 ethers indicate no dissociation of the complexed polyether. Log β 1 is greater than 6 for both complexes; it is equal to 4.4 for the samarium 1:1 complex with 18-crown-6 ether.

Study of binary systems TlVO3-MVO3 : M = Li, Na

Using DTA and X-ray diffraction, two new compounds TlNa2V3O9 and TlLi2V3-O9 have been found in these systems. The thallium metavanadate TlVO3, did not exist under two allotropic forms as found before, in the binary system Tl2O-V2O5. Besides, the interpretation of the thermal effects in the binary system TlVO3-NaVO3 was completely different from a previous one. This may arise from the difference of compounds Synthesis methods used in the two studies. TlNa2V3O9 and TlLi2V3O9 showed a solid state decomposition; their X-ray powder diagrams did not allow to characterize them, because of the continuous presence of the initial compounds TlVO3, and MVO3. The examination of the pyroxene structures types occured in the alkaline metavanadates agreed with the existence of such defined mixed compounds : TlLi2(VO3)3 and TlNa2(VO3)3.

Spectroscopic and structural studies of the hexagonal perovskite Ba 2CoTeO 6

In a previous study of the hexagonal 12-layer perovskites Ba 2B IITeO 6 with B IINi and Zn, we observed a somewhat different X-ray powder diagram and infrared (i.r.) spectrum for the cobalt compound. In the present paper, we point out how vibrational spectroscopy and X-ray powder diffraction can be used to propose an ordered hexagonal six-layer perovskite structure for Ba 2CoTeO 6.

La vinciennite, Cu10Fe4Sn(As,Sb)S16, une nouvelle espèce minérale. Etude paragénétique du gîte type de Chizeuil, Saône-et-Loire

Vinciennite Cu10Fe4Sn(As0.8Sb0.2)S16 was discovered in the pyrite deposit in Chizeuil, Saône-et-Loire, France. It is associated with pyrite, chalcopyrite, colusite, stannite, bornite, enargite, tetrahedrite, tennantite and other minerals in a gangue of quartz and/or barite. Other minerals include : hessite, altaite, tetradymite, cassiterite, stannoidite, kesterite, mawsonite, aikinite, cosalite, bismuthinite, wittichenite, bismuth, molybdenite, rutile, chalcocite and covellite. Vinciennite also has been found at Huaron, Peru. As small opaque grains up to 1 mm, with a metallic lustre and an orange colour ; VHN25 = 280, calculated density 4.29 g.cm-3. Very brittle with a conchoidal fracture. In polarized light, the anisotropism is weak with colours ranging from purplish-blue to greenish brown-yellow ; simple or weakly polysynthetic twins are occasionally observed. The reflectance values are (SiC standard) : 420 nm : 19.4-19.4 ; 460 nm : 21.8-20.6 ; 500 nm : 23.9-22.8 ; 540 nm : 27.7-26.5 ; 580 nm : 30.7-29.5 ; 620 nm : 33.6-32.1 ; 660 nm : 35.9-34.3 ; 700 nm : 37.8-36.0 ; 740 nm : 38.8-36.8 ; 780 nm : 39.5-36.6. Pseudo-cubic, vinciennite is in fact tetragonal P4122 (or possibly P4/mmm, P422 or P4mm) with a = b = c = 10.697(6) Å and Z = 2. Strongest lines of the X-ray powder diagram are : 4.37 (3) 211 ; 3.088 (10) 222 ; 2.676 (5) 400-004 ; 1.895 (9) 440-404 ; 1.614 (7) 622-226 ; 1.227 (4) 626-662 ; 1.091 (5) 844-448. Analytical results (mean of 6 analyses) with a cameca electron microprobe using Sb2S3, SnO2, As, Cu and Fe as standards are : Cu 40.90 ; Fe 14.63 ; Sn 7.33 ; As 3.43 ; Sb 1.60 ; S 31.85 ; total 99.74 %. The name is for Prof. Henri Vincienne (1898-1965) who first called attention to the mineral. Type material is preserved in the mineralogical collection of the Ecole Nationale Supérieure des Mines de Paris. Its description was approved by I. M. A.

Etude des profils des bandes de diffraction X d'une beidellite-Na hydratée à deux couches d'eau. Détermination du mode d'empilement des feuillets et des sites occupés par l'eau

Intensities and shapes of the (02,11), (20,13) and (04, 22) diffraction bands are calculated for model structures and are fitted to the experimental patterns, in order to describe the structural characteristics of a two-water-layer Na-beidellite (Rupsroth, Bavaria, Germany). The determined features are: the average dimensions and size distributions of coherent domains, the coordinates of the crystallographically bound water molecules, the nature and abundance of stacking defects. The localization of the water sites and the determination of their occupancy rates are obtained using a general and powerful procedure which is described. For the stacking, a quantification of the influence, on the X-ray powder diagrams, of all crystallochemically possible modes given in the literature has been done. On the basis of such a quantification, it was possible to establish the layer succession law in the studied hydrated particles.

Trimercurated acetaldehyde. The crystal structure of [OHg 3CCHO]NO 3·H 2O

The product of mercuration of acetaldehyde in aqueous mercuric-nitrate is a hydrated oxonium nitrate of tris(mercuri) acetaldehyde, [OHg 3CCHO]NO 3·H 2O, the crystal structure of which has been determined. The crystals are tetragonal, space group P4 2/ m with four formula units in the unit cell of dimensions a 10.755(3) and c 6.763(2) Å. The structure was determined by means of X-ray diffractometry and refined by full-matrix least-squares method to an R value of 0.038. Mercuration of acetylene gives the same product but in polycrystalline form as shown by X-ray powder diagrams. The Hg 3CCHO units are interconnected by oxonium oxygen atoms to a polymeric columnar [OHg 3CCHO] n n+ cation. The nitrate ions show positional disorder. The geometry of the column is defined by a flat Hg 3O oxonium pyramid and a slightly distorted Hg 3CC tetrahedron, with HgO and HgC bond distances of 2.04(1) to 2.08(1) Å.

The determination of crystallite-size and lattice-strain parameters in conjunction with the profile-refinement method for the determination of crystal structures

It is shown that the current status of the least-squares profile-refinement method, for the determination of crystal structures from X-ray and neutron powder diagrams, allows the simultaneous determination of crystallite-size and lattice-strain parameters. As profile-shape functions the Voigt, pseudo-Voigt and Pearson VII functions are considered. Formulae are obtained enabling structure refinement and size-strain analysis in the same computer run.

Orotic acid sodium salt in kidney stones and urinary deposits.

Kidney stones from a plaice, Pleuronectes platessa, have been shown to consist of the sodium salt of orotic acid. Precipitation of orotic acid in human kidneys and urine samples has previously been reported but the precipitates must have been salts, most likely the sodium salt, of orotic acid and not the free acid. This reinterpretation is based on the acid strength of orotic acid and on data for the solubilities of sodium orotate and orotic acid. Sodium orotate is therefore a member on the list of compounds present in human urinary deposits and calculi. X-ray powder diagrams and d-values and IR-spectra of the sodium salt are recorded to facilitate future identifications.

R 5T 3 compounds (R ≡ rare earth; T ≡ Rh, Ir) with an Mn 5Si 3-type structure

X-ray diffraction on a single crystal was used to establish the crystal structure of Ho 5Rh 3. A hexagonal structure of the Mn 5Si 3 type with space group P6 3/ mcm and lattice constants a = 8.100 A ̊ and c = 6.337 A ̊ was determined. Gd 5Rh 3, Tb 5Rh 3, Dy 5Rh 3, Er 5Rh 3, Tm 5Rh 3 and Lu 5Rh 3 are isostructural with Ho 5Rh 3. X-ray powder diagrams taken with a Guinier camera on the high temperature phase of R 5Ir 3 compounds (R ≡ Tb, Dy, Ho, Er, Tm, Lu) were indexed using Mn 5Si 3 structure parameters. A single-crystal study of Lu 5Ir 3 and Er 5Ir 3 showed weak superstructure reflections.

The coordination chemistry ofN-vinylimidazole

The synthesis of coordination compounds of formula M(viz)n(A)2 is described, where viz. =N-vinylimidazole, M = Mn, Fe, Co, Ni, Cu, Zn or Cd, A = ClO 4 − , BF 4 − or NO 3 − , and n varies from 3 to 6, depending upon the particular combination of cation and anion. The compounds are easily prepared in ethanol from the hydrated metal(II) salts and the ligand and the products were characterized using i.r., ligand-field, far-i.r. and e.p.r. spectra in conjunction with x-ray powder diagrams and magnetic techniques. Octahedral cations [M(viz)6]2+ are formed in many cases, although square planar species Cu(viz)4(A)2 and tetrahedral species [M(viz)4]2+ for M = Co and Zn are also found.

Characterization of the monoclinic rare earth orthoarsenates

Crystallographic data for the compounds LnAsO 4 ( Ln ≡ La, Ce, Pr, Nd) which crystallize in the monazite structural type were determined from X-ray powder diagrams. Their vibrational spectra are also reported and discussed in comparison with those of some related compounds.

Characterization of the monoclinic form of praseodymium chromate(V)

Pure samples of the monoclinic (monazite-like) form of PrCrO 4 have been obtained for the first time and some of its properties are reported. The unit cell parameters, determined from X-ray powder diagrams, and the IR spectrum are discussed in comparison with those of some structurally related compounds.

Complexes of calcium(II), strontium(II) and barium(II) with heterocyclic ligands

The synthesis and characterization of new complexes of general formula ML n X 2· mH 2O, where M = Ca(II), Sr(II), Ba(II); L = N-methylimidazole (N-Meim), 3-amino-5-methylisoxazole (3-AMI), 5-amino-3,4-dimethylisoxazole (5-ADI), 2,5-diphenyloxazole (PPO); n = 1–4, 6; X = Cl −, Br −, I −, SCN − and m = 0–6, have been reported. All the derivatives are studied by chemical analysis, molar conductivity, i.r. spectra and X-ray powder diagrams in order to give information about the donor atoms' competitivity of the ligands and to elucidate the structure of the complexes. The ligands act as monodentate N-ring bonded, the compounds are generally distorted tetrahedral, only the [Ba(5-ADI) 6](SCN) 2, [Ca(N-Meim) 4Cl 2]·4H 2O and [Ca(3-AMI) 4Br 2]·3H 2O are octahedral.