X-ray Powder Photographs Research Articles

Polymorphism of cephaloridine

Abstract Infrared spectra of Nujol mulls and X-ray powder photographs have shown that cephaloridine can exist in at least six different crystalline forms. The preparation, interconversion and properties of these forms are discussed. Proton magnetic resonance spectroscopy has been used to check their chemical identity.

Dimorphism in a 2,2,2-terpyridyl compound

Chloro-(2,2′,2″-terpyridine)platinum(II) chloride dihydrate, [Pt(terpy)Cl]Cl · 2H2O, crystallizes from aqueous EtOH (1:1) as a yellow dimorph, but from dilute (1 M) HCl as its less stable red dimorph. X-ray powder photography shows that, above 100 °C, the red form converts into the yellow form.

Crystal structure of pentazirconium tetratelluride, Zr5Te4

Te4Zr5, tetragonal, 74/m (No. 87), a = 10.766(1) Â, c = 3.8420(5) Â, V = 445.3 Â , Z= 2, RgiF) = 0.015, R^F) = 0.035, Τ = 293 Κ. Source of material Crystals of air-sensitive ZrsTe4 were synthesized in a sealed, argon-filled tantalum tube (4.5 d, 1470 K, cooling rate 100 K/h) from a mixture of zirconium ditelluride and zirconium (nzr : ητe = 5 : 4 ) with the use of iodine to promote crystal growth. The selected crystal was mounted in an argon-filled glass capillary. Discussion Zr5Te4 is isotypic with TI5Te4 [1]. The compound was first reported and characterized through X-ray powder photographs by Brattâs and Kjekshus [2]. Opposed to the isostructural niobium telluride [3], and the monoclinic niobium and vanadium tellurides [4,5], the metal sites are fully occupied. The tetragonal structure of Zr5Te4 is built up by three crystallographically distinct atoms situated in mirror planes perpendicular to the short c axis at ζ = 0, 1/2. The structure can be seen as being composed of columnar fragments of bcc-Zr (high temperature modification, stable above 1139 K). The Te atoms cap four of the six faces of each centred Zr9 cuboid, according to „[ZrZr8/2Te4]. The distances from the Te atoms to the central Zr atom are 3.086 Â, and 2.925 Λ to the peripheral Zr atoms of the Zr9 cuboid. The Zrl-Zr2 distance is 3.155A and the Zr2-Zr2 waist contacts in the ab-plane are 3.539 A. Alternatively, in compliance with Simon's concept of condensed clusters [6], the columnar fragments also represent chains of octahedral ZreTes clusters sharing /rani-positioned Zr 1, resulting in ,L[Zr4Zr2/2Te8/2]. The octahedral clusters are compressed (23%) along the fourfold axis. The extended clusters are linked via Zr2-Tel (2.922 Â) andZr2-Zr2 (3.424 Â) interactions to four adjacent columns of the same type. The surrounding columns are shifted by c/2 with respect to the central one. The columns are rotated about the fourfold axis by 10.3° relative to the tetragonal a, b vectors. Tel is asymmetrically coordinated by five Zr2 and one Zrl. The coordination figure can be seen as a hypho fragment of an interstitially stabilized tetrakaidecahedral TeZr9 cluster. Table 1. Data collection and handling. Crystal: silver lustre, needle-like, size 0.015 χ 0.015 χ 0.225 mm Wavelength: Mo Ka radiation (0.71073 Â) μ: 184.11 cm 1 Diffractometer, scan mode: Siemens P4, ω 26max: 63.8° WiW)measured, N(hkl)unique: 3133,442 Criterion for Iobs, N(hkl)$: /obs > 2 <7(/obs), 404 N(param) refined: 16 Programs: SHELXS-86 [6], SHELXL-93 [7], DIAMOND [8] Table 2. Atomic coordinates and displacement parameters (in A). Atom Site Un U22 U33 Un U13 C/23 Te(l) 8/1 0.05132(2) 0.28206(2) 0 0.0059(1) 0.0070(1) 0.0081(1) -0.00071(7) 0 0 Zr(l) 2a 0 0 0 0.0040(2) Un 0.0093(3) 0 0 0 Zr(2) 8A 0.30885(3) 0.36773(3) 0 0.0060(2) 0.0056(2) 0.0085(2) 0.0002(1) 0 0 Unauthenticated Download Date | 3/9/16 10:07 AM 6 Pentazirconium tetratelluride Acknowledgments. Support by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie is appreciated.

Preparation and properties of InAs 50 mol%-CuInSe 2 50 mol% alloy

Continuing our search on semiconducting compounds and alloys, the InAs 50 mol%-CuInSe 2 50 mol% alloy was investigated. Both InAs and CuInSe are adamantine which satisfies the four electron per atom rule. A large single crystal ingot was carefully prepared using the vertical Bridgmans method. The specimen was examined by room temperature and temperature dependence X-ray powder photography, Electron Probe Microanalysis (EPMA), Differential Thermal Analysis (DTA), and Vickers hardness test.

Preparation and Reactivity of Some Phenyl-bismuth(III) Quinolin-8-olate Derivatives

The bimetallics [ PhBi (Ox)2( NaX )n] (Ox- = quinolin-8-olate: X = Cl , Br or I), containing variable amounts of sodium halides, have been prepared by reaction of PhBiX2 with Na(Ox) (mole ratio 1 : 2) or of Ph2BiX with Na(Ox) (mole ratio 1 : 1) in ethanol. A similar preparation has given [ PhBi ( MeOx )2( NaI )n] ( MeOx - = 2-methylquinolin-8-olate) . The bimetallics have been characterized by X-ray powder photography, f.a.b . mass spectrometry and 1H n.m.r. and electronic spectroscopy. Sodium halide-free PhBi (Ox)2 was obtained from the reaction of Ph2BiCl with Na(Ox) in the presence of 15-crown-5, or from treatment of PhBiI2 or Ph2BiI with NBu4(Ox). Reaction of equimolar amounts of PhBiI2 and Na(Ox) gives Bi(Ox)2I, which can also be obtained from BiI3 and Na(Ox) in a 1:1 or 1:2 stoichiometry. Treatment of PhBiI2 with M(0x) (M = Na or K) in a 1:3 mole ratio yields [ MPhBi (Ox)3] bimetallics, which appear to contain both chelating and unidentate Ox ligands from their electronic spectra.

Caesium hexachlororhodate(IV): An authentic compound of rhodium(IV)

The green solid Cs 2[RhCl 6], generated in aqueous media using acidic ammonium hexanitrocerate(IV), (NH 4) 2[Ce IV(NO 3) 6], is as formulated. It has the d 5 configuration for rhodium. Evidence for the Rh IV ions in the freshly prepared solid—and for Rh III ions in the solid and aqueous solution after decomposition—is given using X-ray powder photographs, vibrational spectra (IR and Raman), ESR, magnetic susceptibility and elemental analysis. The definitive properties of Cs 2[RhCl 6] are compared with those for various chlororhodium(III) compounds. Previous data concerning it, often apparently conflicting, are rationalized.

Complexation with diol host compounds. Part 20. Kinetics of desolvation of inclusion compounds of 2,2′-bis(2,7-dichloro-9-hydroxy-9-fluorenyl)biphenyl with 1,4-dioxane and 1,3-dioxolane

The structures of the inclusion compounds of 2,2′-bis(2,7-dichloro-9-hydroxy-9-fluorenyl)biphenyl with 1,4-dioxane and 1,3-dioxolane, with host : guest ratios of 1: 3.5 and 1: 2 respectively, have been elucidated. Their kinetics of desolvation have been studied and the dioxane inclusion compound desolvates in two distinct steps, each following the first-order kinetic model. The dioxolane inclusion compound desolvates in one step and follows a contracting area model. X-Ray powder photography shows that the dioxane inclusion compound forms a stable intermediate γ-phase before final desolvation to a non-porous α-phase.

Synthetic, Structural, and Magnetic Studies of Strontium Copper(II) Borates with the Composition Sr1-xMxCU2(BO3)2, M = Ba or Ca

Studies of the new type of alkaline earth copper(II) borates, represented by SrCu2(BO3)2, have been performed by high temperature techniques. In the parent structure of SrCu2(BO3)2, the strontium content can be partially substituted by calcium or barium. A series of such phases with the composition Sr1-xMxCu2(BO3)2 where M = Ca or Ba and 0 ≤ x < 0.4 have been prepared. X-ray powder photographs verify that these phases are isostructural to SrCu2(BO3)2. The crystal structure of Sr1-xMxCu2(BO3)2 can be regarded as consisting of slightly puckered layers with the composition [CuBO3]- stacked along [001], with eight coordinated alkaline earth atoms located between the layers. Estimated bond valence sums for all atoms indicate normal bond length distributions in the structure. The structure possesses a pseudo-mirror symmetry but the deviations (<0.2 Å) from this symmetry (space group I4/mmm) are statistically highly significant. The substitution of strontium for smaller calcium or larger barium atoms has a pronounced effect on the interlayer separation. Measured magnetic susceptibilities of SrCu2(BO3)2 indicate a transition to an antiferromagnetic state below 14 K.

Kristallzüchtung und Einkristallstrukturverfeinerungen der Rhodium(III)-phosphate RhPO4 und RhP3O9

Abstract By means of chemical vapour transport reactions (transport agent: 1 atm Cl2 at room temperature) dark red, transparent crystals of RhPO4 (1323 K → 1223 K) and orange crystals of RhP3O9 (1223 K → 1123 K) were obtained with edge length up to 1 mm. The structures of both compounds were refined from x-ray single crystal data (RhPO4: α-CrPO4 structure type, Imma, Z = 12, a = 10.3967(8) Å, b = 13.1124(9) Å, c = 6.3929(5) Å, 1249 independent reflections with |F| ≥ 3σ(F), 50 variables, R = 0.026; RhP3O9: C-MP3O9 structure type, Cc, Z = 12, a = 13.002(8) Å, b = 19.065(9) Å, c = 9.296(4) Å, β = 127.04(3)°, 4541 independent reflections with |F| ≥ 3σ(F), 119 variables, R = 0.033). The crystal structures of RhPO4 and RhP3O9 are described and compared to isotypical compounds. Temperature dependent x-ray powder photographs gave no evidence for a phase transition for RhPO4 neither then for RhP3O9 up to 1223 K.

Phase Diagram, Lattice Parameter, and Optical Energy Gap Values for the Cd2x(CuGa)yMn2zTe2 Alloys

The T vs composition phase diagram of the alloy system Cd2xCuGa)yMn2xTe2 (x + y + z = 1) was investigated in the range 0 < z < 0.8 by differential thermal analysis and X-ray diffraction measurements. Samples were prepared for various lines of constant x/y ratio and the T(z) data were determined for each line. X-ray powder photographs were used to determine equilibrium conditions, to give lattice parameter values, and to determine the limits of single-phase solid solution. In addition to the various phase field boundaries, the zinc-blend-chalcopyrite and Mn-ordered-Mn-disordered transition lines were determined, these fields being the ones of interest in the measurements of optical energy gap and magnetic properties. Room-temperature values of the optical energy gap Eo were determined for all of the single-phase samples and the variations of Eo with z were investigated.

T(z) diagrams and lattice parameter values for the Hg 2x(CuIn) yMn 2zTe 2 and Hg 2x(AgIn) yMn 2zTe 2 systems

Polycrystalline samples of Hg 2 z (CuIn) y Mn 2 x Te 2 and Hg 2 x (AgIn) y Mn 2 z Te 2 alloys were prepared by the melt and anneal technique. Differential thermal analysis measurements were carried out on the alloys, and sections of the T( z) diagram of each alloy system were determined. Guinier X-ray powder photographs were used to show the equilibrium conditions and to give lattice parameter values. Room temperature optical energy gap values were determined for some sections of the CuIn alloys.

Synthesis of MO 2Cl 2(N,N,N',N'-tetramethylethylenediamine) (M = Mo and W) and crystal structure of WO 2Cl 2(N,N,N',N'-tetramethylethylenediamine) —an unprecedented coordination geometry in the WO 2Cl 2 Core

WO 2Cl 2(tmen) and MoO 2Cl 2(tmen) (tmen N,N,N'N'-tetramethylethylenediamine) have been prepared and the X-ray structure of WO 2Cl 2(tmen) determined. WO 2Cl 2(tmen) is built of distorted octahedral molecules with cis-dioxoligands, d(WO) = 1.705 and 1.711 Å and an angle OWO of 103.3dg, cis-chloroligands and cis bound tmen nitrogen atoms resulting in an all cis configuration which is unique among complexes of MO 2 2+ (M = Mo, W). The trans influence of the oxo-ligands, as demonstrated by two different WCl distances (2.336 Å trans to N and 2.440 Å trans to O) and two different WN distances (2.249 Å trans to Cl and 2.458 Å trans to O) in the molecule, is discussed in relation to other multiply-bonded ligands. X-ray powder photographs show that MoO 2Cl 2(tmen) is isostructural with the tungsten complex. 13C and 1H NMR, IR and Raman data are presented for both complexes.

Use of a Hewlett-Packard ScanJet image digitizer as an X-ray powder photograph densitometer

A densitometer trace of an X-ray powder photograph is easily obtained by making a contact print and scanning this with a Hewlett-Packard ScanJet using the programs SCANGAL, IMAGE EDITOR and SCANNER on SCANNING GALLERY in the WINDOWS environment. The light in the ScanJet from a halogen lamp (50 V, 42.5 W) is reflected by the print and detected by a charge-coupled device. The instrument measures reflected light intensity. The flatbed ScanJet has an optical resolution of 2550 dots yielding 300 dots per inch (d.p.i.) over the A4 page. Output resolution is selectable and runs from 38 to 600 d.p.i. The density and mode (binary, dithered, greyscale and scaling) may be adjusted. However, when scanned, the regular negative Guinier photograph does not give clear images because the rough developed-emulsion surface scatters light indiscriminately, producing dark images and lacking in resolution.

Thermal analysis of new hydrazinium(2+) hexafluoroantimonate

Hydrazinium(2+) hexafluoroantimonate was prepared by the reaction of N2H6F2 with an excess of SbF5 in anhydrous HF as solvent. The compound was characterized by chemical analysis and vibrational spectra. The X-ray powder photograph was indexed on the basis of a monoclinic cell witha=8.22(2),b=10.04(3),c=9.51(2) Å,β=97.2(2)° andV=780 Å3. The thermal decomposition study of N2H6(SbF6)2 showed that it decomposed to gaseous components through an intermediate, a mixture of N2H5SbF6 and NH4SbF6. In the DSC curve, a strong endothermic effect and medium exothermic and endothermic effects were observed in the range 25–600°C.

Preparation and characterization of hydrazinium(1+) and (2+) hexafluorostannate(IV) and hydrazinium(2+) hexafluorostannate(IV) difluoride

Reaction between N 2H 6F 2 and Sn(OH) 4 in aqueous HF as solvent gave two new complexes, N 2H 6SnF 6 and (N 2H 6) 2SnF 6.F 2, depending on the initial molar ratio of the starting materials. In a laser beam N 2H 6SnF 6 is slowly destroyed and the product of decomposition as a mixture of the N 2H 5 + and NH 4 + compounds. Thermal decomposition of (N 2H 6) 2SnF 6.F 2 in a vacuum system yields pure (N 2H 5) 2SnF 6. Hydrazinium(1+) and (2+) flurostannate(IV) compounds were characterized by chemical analysis and vibrational spectra. An X-ray powder photograph of N 2H 6SnF 6 was indexed on the basis of a cubic cell with a=10.550(4) Ā, V=1174(1) Ā. The thermal behaviour of (N 2H 6 2SnF 6.F 2 was additionally investigated using TG, DTG and DTA measurements

Fluoro- and oxo-fluorozirconates

The preparations of (BH 2) [ZrF 6]. mH 2O, where B = ethylenediamine (m=0) and biguanide (m=1), (BH) 2 [ZrF 6].nH 2O, where B = guanidine (n=1), pyridine (n=0), (BH) [ZrF 5].H 2O, where B = α β - and γ -picoline, (BH 2) [ZrOF 3] 2.xH 2O, where B = ethylenediamine (x=5), propylene-1,2-diamine (x=3), N,N‵-dimethylethylenediamine (x=3), M I[ZrOF 3].1.5 H 2O, where M I = alkali metals, (N 2H 5) [Zr 2O 2F 5].4H 2O and (BH 2) [ZrOF 4], where B = 1,10-phenanthroline and 2,2‵-bipyridyl are described. The compounds were characterised by chemical analysis, TGA, IR spectroscopy and x-ray powder photography. (pyH) 2[ZrF 6] (py = pyridine) is unstable and undergoes slow decomposition on keeping in air. On isothermal heating at 120°C it yields (py H) [ZrF 5]. At 180°C (α -pic H) [ZrF 5].H 2O(α -pic = α -picoline) yields (α - pic H)[Zr 2F 9]. K[ZrOF 3].1.5 H 2O yields K[ZrOF 3].O.5H 2O and the anhydrous compound successively at 130°C and 225°C. The corresponding anhydrous cesium compound is produced at 220°C. IR spectra suggest the presence of Zr-O-Zr chains in the oxofluoro-compounds. From the various types of studies it appears that the oxofluorozirconates contain only a fraction of water as Zr-OH group.

Physical Properties of the (2InAs) 1−x(CuInSe 2) x solid solution

The vertical Bridgman method was employed to prepare ten compositions of the solid solution 2 InAs −1( CuInSe 2) x ( x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.85 and 0.9)) all of which had large single crystal volumes. The specimens of composition x = 0.85 and 0.90 have a chalcopyrite structure while the rest are zinc blende in structure. All speciments were studied by X-ray powder photography which enabled the determination of the lattice parameters, the X-ray linear absorption coefficient, the mass absorption coefficient and the X-ray density.

Thermal analysis studies of the dolomite-ferroan dolomite-ankerite series. II. decomposition mechanism in flowing CO 2 atmosphere

Ankerites and ferroan dolomites [Ca(Mg,Fe)(CO 3) 2] dissociate in three stages to give characteristic three-endothermic-peaked DTA curves which correspond to three weight loss steps on TG curves. Pure dolomite decomposes in only two steps. The definition of these phenomena is greatly enhanced by determination in flowing CO 2. During this investigation a series of well-characterized minerals covering the dolomite-ferroan dolomite-ankerite series was studied using TG-DTG, DTA-EGA, TM and continuous heating X-ray powder photography (“continuous XRD”), backed up by X-ray diffractometry of products cooled from intermediate temperatures (“static” XRD). Limited Mössbauer spectroscopic determinations (reported in detail elsewhere) were also made on intermediate products. The first stage of the thermal decomposition of dolomite results in the formation of Mg-calcite ((CaMg)CO 3) and periclase (MgO), with the liberation of CO 2. In the cases of ankerite and ferroan dolomite, the initial reaction is similar except that a ferroan periclase or magnesian wustite ((Mg,Fe)O) is produced respectively. However, this phase is rapidly oxidized by CO 2 to magnesioferrite (MgFe 2O 4). A ferrous spinel (Fe 3O 4 - MgFe 2O 4 solid solution) may also be formed as an unstable transient intermediate compound during this oxidation, depending on experimental conditions. As a result, CO is liberated by reduction of CO 2. The second decomposition step arises out of a solid-state reaction between calcite and magnesioferrite to produce dicalcium ferrite (2CaO · Fe 2O 3) and periclase with the evolution of CO 2. The remaining unreacted calcium carbonate dissociates to CaO and CO 2 in the third decomposition step.

Effects of crystallographic ordering on the magnetic behaviour of (AgIn) 1-zMn 2zTe 2 and (CuIn) 1-zMn 2zTe 2 alloys

Measurements of magnetic susceptibility in the temperature range 4.2–300 K were made on polycrystalline samples of the (AgIn) 1 - z Mn 2 z Te 2 and (CuIn) 1 - z Mn 2 z Te 2 alloys, and the data used to give values of spin-glass transition te mperature T g and Curie-Weiss paramagnetic temperature θ. For any sample for which the X-ray powder photograph indicated an apparently single phase condition, either zinc-blende or chalcopyrite, the susceptibility data could show up to three separate T g values. These different magnetic conditions are attributed to crystallographic ordering of the Mn ions on the chalcopyrite and zinc-blende lattices, the three observed T g values corresponding to disordered zinc-blende, ordered zinc-blende and ordered chalcopyrite. The value of θ obtained from the 1/χ vs. T plot is shown to be a weighted mean of the separate values of θ for the phases present. The relative sizes of the T g peaks and the values of θ for any given sample gives an indication of the amount of each phase present. These amounts were varied by using different methods of heat treatment and it was shown that the magnetic behaviour was consistent with the T( z) phase diagram for the two alloy systems.

Effect of hydrogen on the magnetic properties of Ho0.85Tb0.15Fe2 and Dy0.73Tb0.27Fe2

X-ray powder photographs on Ho0.85Tb0.15Fe2Hx (x=0–3.1) and Dy0.73Tb0.27Fe2Hx (x=0–3.3) revealed that there is an expansion of the lattice upon hydrogenation. Magnetization measurements were performed using a PAR vibrating sample magnetometer in the temperature range 100–700 K. The total magnetic moment is found to decrease with increase of hydrogen content. The Curie temperature of the hydrides is considerably lowered, though the exact TC in hydrides could not be determined due to desorption. Both Ho0.85Tb0.15Fe2 and Dy0.73Tb0.27Fe2 do not exhibit any compensation, whereas Tcomp is observed and found to decreasse with x in the case of the Ho0.85Tb0.15Fe2Hx system, x=0.18–3.1. No compensation was observed even in the hydrides of the Dy0.73Tb0.27Fe2 system. The temperature variation of magnetization of Ho0.85Tb0.15Fe2Hx and Dy0.73Tb0.27Fe2Hx suggests the occurrence of a spin-reorientation transition.