High-pressure forms of intermetallic compounds with the composition CaZn2, SrZn2, SrAl2, and BaAl2 were synthesized from CeCu2-type precursors (CaZn2, SrZn2, SrAl2) and Ba21Al40 by multi-anvil techniques and investigated by X-ray powder diffraction (SrAl2 and BaAl2), X-ray single-crystal diffraction (CaZn2), and electron microscopy (SrZn2). Their structures correspond to that of Laves phases. Whereas the dialuminides crystallize in the cubic MgCu2 (C15) structure, the dizincides adopt the hexagonal MgZn2 (C14) structure. This trend is in agreement with the structural relationship displayed by sp bonded Laves phase systems at ambient conditions.

During metabolism of the fungicide 2-(2-furyl)benzimidazole (FB) in mammals, an optically active compound, metabolite A, was isolated. This compound, a principal metabolite in the biological degradation of FB, was isolated from the urine of horse and dog. When studied by IR, NMR, MS, CD and electrophoretic techniques, the metabolite proved to be the zwitterionic form of (S)-(-)-4-(2-benzimidazolyl)-4-hydroxybutyric acid. The synthesized optical active compound was in every respect identical with metabolite A. The suggested structure has been completely verified by the current investigation of its crystal structure, based on single crystal diffraction data collected at the synchrotron MAX II in Lund, Sweden. In an earlier determination, a related compound, 3-benzimidazolylpropionic acid (Ercan et al. 1996) was suggested to be non-zwitterionic. The present studies have shown that the latter compound too is zwitterionic and that the conclusions presented were apparently based on some erroneously proposed hydrogen positions.

This thesis is focused on two intermetallic systems Bi1-xSbx and CaAl2-xZnx. Bi and Sb transform into a peculiar incommensurate composite structure under pressure and our intention was to examine the structure and how alloying influences this incommensurate structure. Our investigation was obscured by the occurrence of a phase separation, which accompanied the transition A7 → Bi III. Most remarkable is the finding that structural parameters of phases with the Bi III composite structure were observed to be almost unaffected by pressure and composition effects. Secondly, phase and structural stability relations within the AB2 pseudo-binary system CaAl2-xZnx was studied. In CaAl2-xZnx, the C36-type Laves phase was observed for the first time, but not the C14-type, and a VEC induced structural transition C15-type → C36-type takes place with increasing x. The exchange of Al by Zn decreases the size of the B-type atom network surrounding Ca and at concentrations x > 0.95, the Laves phase structure is succeeded by the CeCu2 type structure, which tolerates a larger size ratio A/B. The C15-type → C36-type transformation in the CaAl2-xZnx system is induced by the valence electron concentration VEC. Through the analysis of MEM/Rietveld from synchrotron powder X-ray diffraction data, the total charge distributions and deformation charge densities were obtained for cubic and 4H hexagonal Laves phases in CaAl2-xZnx and also for orthorhombic CaZn2. The overlap electrons, which take an important role in stabilising the crystal structures, are clearly observed in the Kagome-net between B-net atoms. The Ca atoms are located in the space formed by the B-net atoms. From the high-pressure experiments it was concluded that at elevated temperatures, 1000-1500 °C, the hexagonal C36 structure type transforms to the C15 structure type between 6.2 and 9.4 GPa, and the orthorhombic CeCu2 phase to a hexagonal Laves phase between 7.5 and 15.5 GPa.

Percleveite-(Ce), (Ce, La, Nd)(2)Si2O7, is a new mineral species from the Bastnas Fe-Cu-REE deposit, Skinnskatteberg, Vastmanland, Sweden. It occurs closely associated with mainly cerite-(Ce), bastnasite-(Ce) and quartz. The colour is greyish and the luster greasy to resinous. The anhedral crystals, up to 0.5 mm in size, are colourless in thin section and optically uniaxial (+). Happroximate to6. Cleavage is imperfect parallel to {001}. Electron-microprobe analyses give: La2O3 14.66, Ce2O3 31.36, Pr2O3 3.41, Nd2O3 12.97, Sm2O3 2.69, Gd2O3 2.26, Dy2O3 0.53, Ho2O3 0.07, Er2O3 0.21, Yb2O3 0.04, Y2O3 2.93, CaO 0.10, FeO 0.01, SiO2 26.55, sum 97.79, yielding the empirical formula (Ce0.87La0.41Nd0.35Y0.12Pr0.09Sm0.07Gd0.06Dy0.01Ca0.01)(Sigma=1.99)Si2.01O7 based on 7 O atoms. The mineral is shown to be isostructural with the synthetic, low-temperature lanthanide disilicates (general formula Ln(2)Si(2)O(7)) with tetragonal symmetry (space group P4(1)). Unit-cell parameters are a=6.7805(8) and c=24.689(4) Angstrom (refined from powder data) with Z=8. The structure has been refined from single crystal data to a weighted Rw value of 0.036. All four symmetry independent Ln positions are slightly differently occupied by the lanthanide ions. Percleveite is formed at conditions with slightly higher SiO2 activities, and lower concentrations of Ca and Mg, than conditions favourable for the crystallization of cerite-(Ce).

The high-pressure behavior of the heavier group 15 elements As, Sb, and Bi was investigated by means of ab initio density functional calculations employing pseudopotentials and a plane wave basis set. The high-pressure structural sequence of these elements is distinguished by the occurrence of the Bi-III structure, which is a complex, incommensurately modulated, host-guest structure. We approximated this structure by a supercell which reproduced the experimentally established pressure stability ranges of the host-guest structure for the different elements extremely well. With pressure we find an increasing admixture of d states (s-d hybridization) in the occupied levels of the electronic structure of As, Sb, and Bi. However, the s-d mixing remains at a low level. Thus, the emergence of a complex intermediate pressure structure cannot be explained by a pressure-induced altered valence state for these elements. Instead, it is argued that the Bi-III structure is a consequence of a delicate interplay between the electrostatic and the band energy contribution to the total energy. In the intermediate pressure range of heavier group 15 elements, both important parts of the total energy account equally for structural stability.

A previously unreported urolith is presented. The concrement was found in the bladder of four Persian cats and one collie dog. It contained potassium, magnesium and phosphorus, all determined by chemical analysis. The infrared spectrum of the X-ray-dense urolith displayed absorption bands in the phosphate region. A single absorption maximum at 930 cm–1 indicated the presence of inorganic pyrophosphate. A single crystal structure determination of the urolith has been performed. The results obtained are consistent with the formula [K1.0Mg1.5]4+[P2O7]4–.(H2O)5, which corresponds to 11.5% K, 10.7% Mg and 18.2% P. The structure contains negatively charged slabs of composition MgP2O7·(H2O)2 2– alternating with positively charged, hydrated Mg2+ and K+ ions. The observed P2O7 is that of a distorted eclipsed syn conformation, which is the most common geometry in the solid state according to a statistical analysis of known structural data. A simple numerical descriptor has been derived, classifying observed X 2O7 conformations. It is suggested that some genetic enzymatic dysfunction of pyrophosphate-hydrolysing alkaline phosphatase might cause the formation of this unusual urolith.

The crystal structure of Na3MnF6 has been investigated at high pressures by means of single-crystal x-ray diffraction, and its Mn(III) coordination environment has been studied by means of single-crystal optical absorption spectroscopy using diamond anvil techniques. Compressibility data (unit cell parameters) were collected in the pressure range from ambient to 4.06 GPa, and structural refinements based on single-crystal diffraction data were performed at 0.12, 0.91, 2.27, and 2.79 GPa. The monoclinic space group symmetry (P2(1)/n) is retained in the entire pressure range, but, at increasing pressure, a discontinuous phase transition is observed at similar to 2.2 GPa. This is interpreted as an effect of a reversible, isosymmetric phase transition with a hysteresis width of 0.5 GI)a, observed when the pressure is successively lowered. The structure refinements show that the phase transition involves a reorientation of the static prolate distortion of the coordination around manganese(III). The angle between the elongation axis (z) Of the MnF63- octahedron with [001] flips from similar to 20 degrees at ambient pressures to similar to 70 degrees at 2.79 GPa, Polarized single-crystal absorption spectra of Na3MnF6 show drastic changes of the polarization of bands due to spin-allowed d-d transitions in Mn(III) when passing the transition pressure, which confirm the results of the single-crystal structure refinements. A possible explanation for this transition is discussed in terms of structure packing arguments. The isothermal bulk modulus at ambient pressure and its pressure derivative were determined to B-0 = 47.8(1) GPa and B-0' = 1.2(1), respectively.

A series of Ru(II) compounds and salts have been synthesized: [Ru(6-carboxylato-bpy)(2)] (5), [Ru(6-carboxylato-bpy)(tpy)]PF(6) (9), [Ru(tpy)(2)](PF(6))(2) (8), and [Ru(bpy)(2)(Pic)]PF(6) (11), where 6-carboxy-bpy (1) = 6-carboxy-2,2'-bipyridine, tpy (2) = 2,2':6',2"-terpyridine, and Pic = 2-carboxylatopyridine. The compounds have been characterized by NMR, electrospray mass spectrometry (ESI-MS), cyclic voltammetry, absorption and emission spectroscopy (at 100, 140, and 298 K), and single-crystal X-ray diffraction (complex 5). Complex 5 crystallizes in the monoclinic system, space group P2(1)/n, formula RuC(22)H(14)N(4)O(4).C(2)H(5)OH, with a = 11.088(3) Å, b = 11.226(3) Å, c = 35.283(9) Å, beta = 91.41(2) degrees, and Z = 8. A linear dependence on the number of coordinated carboxylato groups and the electrochemical redox potentials was found, ca. 0.4 V lower reduction potential for the oxidation step (Ru(II/III)) per carboxylate group. Also, to the best of our knowledge, these are the first examples (9, 11) of mononuclear Ru(II) complexes containing a carboxypyridine-ruthenium moiety displaying any luminescence emission.

A redetermination of the crystal structure of ganomalite, with composition Pb9Ca5.44(1)Mn-0.56(1)Si9O33, using new single crystal X-ray diffraction data is reported. Hexagonal space group symmetry P (6) over bar, with Z = 1 and unit cell parameters a = 9.8456(3) Angstrom and c = 10.1438(4) Angstrom. The refinement of a structural model based on the Pb5Ge3O11 structure, with a partially occupied manganese position, resulted in an R-value of 0.031. The arrangement of the SiO4 tetrahedra in ganomalite is an intermediate between the nasonite and pyromorphite structure, and the structure can be described as containing "lead tunnels" based on Pb9O21 units extending through the structure.

The berate mineral Mg1.33Mn1.44Fe0.05. Sb0.17O2BO3 from the Mossgruvan mine, Nordmark, Varmland, Sweden, has been studied by a combination of single crystal X-ray diffraction and electron microscopy (HREM, EELS and EDX) techniques. The HREM investigations showed that the structure belongs to the pinakiolite family, whose other members with increasing complexity are, e.g. pinakiolite, ludwigite, orthopinakiolite, takeuchiite and blatterite. The space group is orthorhombic, Pnnm (No. 58), a = 37.384(11) Angstrom, b = 12.568(3) Angstrom, c = 6.200(2) Angstrom; Z = 32. The structural model, for which the initial coordinates could be deduced from the HREM images, has been refined versus the 2280 most significant X-ray reflection intensities with sin theta/lambda less than or equal to 0.70 Angstrom(-1) to R-value of 0.056.As for many other members of the pinakiolite family some cation positions are disordered. The disorder is obviously related to the structural effects caused by the distorted oxygen coordination octahedra around the Mn3+ ions. As revealed by HREM, some blatterite crystals contain extended planar defects that can be explained as due to irregular repeat distances between the twin planes in the [100] direction.

The crystal structure of the sodium manganese(III) fluoride compound, Na5Mn3F14, has been reinvestigated. The previous structure model, assuming the non-centrosymmetric space group symmetry Pna2(1), has been transformed to the centrosymmetric symmetry Pnam. Least squares refinements, based on new collected single crystal X-ray diffraction data, converged smoothly with the new structural model and yielded an R-value of 0.022. The general structural features described earlier, as the structural relations to the chiolite structure, still applies. However, the changed space group symmetry introduces new symmetry constraints to e.g. some of the coordination polyhedra in the structure.

Plumboferrite from the type locality at Jakobsberg, Filipstad, Sweden, has been reexamined. It occurs in assemblages confined to bands in metamorphic carbonate rock and is associated with hematite, magnesioferrite-jacobsite-magnetite solid solutions, lindqvistite, calcite, andradite, phlogopite, hedyphane, svabite, hematophanite, native copper, and cuprite. Six samples investigated fall in a narrow composition range: PbO 33.9-34.6, Sb2O5 0.0-0.3, Fe2O3 62.4-63.9, MnO 0.6-1.8, TiO2 0.1-0.5, SiO2 0.0-0.2, Al2O3 0.0-0.1, MgO 0.1-0.4 (weight percent). The mineral is moderately anisotropic and optically uniaxial(-). Reflectance values obtained in air are 25.6-24.2% (470 nm), 24.5-23.5% (546 nm), 23.7-22.8 (589 nm), and 22.6-22.1% (650 nm). VHN100 = 882 and D-calc = 6.12(1) g/cm(3).Single-crystal X-ray studies show that plumboferrite is hexagonal, essentially P6(3)/mmc, with the cell dimensions a = 5.931(1), c = 23.551(2)Angstrom and V = 717.4(2) Angstrom(3) (refined from powder data). Overexposed precession X-ray photographs indicate the presence of a supercell with a' = root 3a = 10.27 Angstrom and c' = 3c = 70.7 Angstrom (hexagonal setting). The structure of plumboferrite has been refined from the 394 most significant (I > 5 sigma(I)) X-ray reflections with (sin theta)/lambda less than or equal to 0.81 Angstrom(-1) to R = 3.9%. It has a defect magnetoplumbite-type structure that can be described in terms of two basic structural units, the R and the S (spinel) blocks. The stacking sequence of such blocks along c is RSR'S', where ideally R = (Pb2Fe5O11-delta) and S = (Fe6O8) for plumboferrite. The formula (with Z = 2 for the subcell) for the investigated material approaches Pb(2)Me(0.33)Fe(10.67)O(18.33), with Me = Mn2+, Mg, rather than PbFe4O7, which is still prevalent in the literature. The departure from stoichiometry (19 O atoms per formula unit) reflects partially occupied O3 positions in the R blocks. The weak superlattice reflections observed (not included in the present refinements) probably result from the ordering of split Pb positions, O vacancies, or both.

Lindqvistite is a new mineral from Jakobsberg, Filipstad, Sweden. It occurs as black crystals up to 5 mm in size with perfect basal cleavage, associated with hematite, jacobsite, plumboferrite, calcite, phlogopite, andradite, hedyphane, barite, and copper minerals. The mineral is opaque, gray in reflected light, with weak bireflectance, and it is moderately anisotropic. Reflectance values obtained in air and oil (at 589 nm) are R(o) = 22.2, R(e') = 21.5, (im)R(o) = 8.76, and (im)R(e') = 8.34%. VHN100 = 857 and D(calc) = 5.76(l) g/cm3. The idealized formula for lindqvistite is Pb2MeFe16O27, with Me = Mn2+, Mg. An empirical formula based on microprobe analyses is Pb2.04Mn1.27Mg0.71Zn0.04Fe14.84Al0.02Ti0.03Si0.05O26.51(1).X-ray studies show that lindqvistite is hexagonal, essentially P63/mmc, with a = 5.95 1 (1), c = 33.358(4) angstrom, and V = 1023.1(5) angstrom3 for Z = 2. The eight most intense reflections in the X-ray powder pattern [d in angstroms (I/I(o))(hkl)] are 4.168(55)(008), 3.334(40)(0,0,10), 3.011(60)(109), 2.975(70)(110), 2.802(95)(1,0,10), 2.779(45)(0,0,12), 2.624(100)(116), and 2.612(90)(1,0,11).Very weak diffuse extra reflections, about two orders of magnitude weaker than the substructure reflections, observed on X-ray photographs could be indexed with a tripled hexagonal unit cell (a' = a . square-root 3 = 10.31 angstrom and c' = c). The present investigation is confined to elucidating the substructure having a = 5.951 angstrom. The derived structural model of lindqvistite has been refined, with the 505 most significant X-ray reflections [I > 5sigma (I)] with (sin theta/lambda less-than-or-equal-to 0.81/angstrom to R = 0.041. It is closely related to the W-type synthetic ferrites and can be described in terms of two basic structural units, commonly denoted as the R and the S (spinel) blocks. The stacking sequence of such blocks is RSSR'SS', where R = (Pb2Fe5O11)3- and S = (Me0.5Fe5.5O8)1.5+ for lindqvistite. The two crystallographically different Pb atoms and a single O atom, all located at the central section of the R block, are positionally disordered.The mineral name honors Bengt Lindqvist of the Swedish Museum of Natural History, where the type material is deposited.

Zenzenite, ideally Pb3(Fe3+,Mn3+)4Mn3(4+)O-15, is a new mineral species from Langban, Filipstad, Sweden. It is hexagonal holosymmetric, space group P6(3)/mcm, with a 10.008(4), c 13.672(8) angstrom, V 1186(1) angstrom 3 and Z = 4. The strongest five observed reflections of the X-ray powder pattern [d in angstrom (I(obs))(hkl] are: 3.18(8)(211), 2.828(7)(114), 2.663(10)(213), 2.366(6)(222) and 1.687(8)(226). Zenzenite is black and opaque, and in polished section it appears white with a weak bireflectance (in oil). The anisotropy is strong. Calculated luminance values (Y%) based on reflectance measurements (10 nm steps) in the visible spectrum (relative to the C illuminant) are 24.8-29.2 (air) and 10.8-14.5 (oil). Cleavage parallel to {001} is prominent. VHN50 = 764. D(x) equals 6.83 g/cm3 for an empirical formula and 6.97 g/cm3 for the ideal with an Fe/Mn3+ ratio of 1.6. The structure has been determined and refined with the 372 most significant X-ray reflections with sin(theta)/lambda less-than-or-equal-to 0.65 angstrom-1 to R = 2.8% and shown to be isostructural with synthetic Pb3Mn7O15. The structure consists of, inter alia, layers perpendicular to the [001] direction of edge-sharing coordination octahedra around the Mn(Fe) positions. The Pb positions are located between the layers. Empirical bond-valences estimated from the observed bond-distances suggest that those metal ion positions containing major amounts of tetravalent Mn are located within the layers. The name of this new mineral honors Dr. Nils Zenzen (1883-1959).

La2CuO4‐Schichten mit der Breite von zwei CuO‐Oktaedern, eckenverknüpft mit den CuO‐Polyedern der trennenden „Wände”︁, kennzeichnen die Struktur der neuen LaCu‐O‐Phase La2Cu2O5, die bei 1075‐1100°C stabil ist. Dieser Aufbau führt zum Postulat einer homologen Reihe La2n+2Cun+4O4n+7, von der neben La2Cu2O5 (n = 2) bereits La8Cu7O19 (n = 3) hergestellt und strukturell charakterisiert werden konnte. magnified image