bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal growth, pyroelectric, piezoelectric, and elastic properties of monoclinic bis (nitrilotriacetato) zirconates X[C(NH2)3] Zr(N(CH2COO)3)2 ⋅ yH2O (y=2 for X=Rb, Tl, NH4; y=1 for X=Cs; y=1.5 for X=CH3NH3)
Authors: Haussühl E. , Haussühl S. , Tillmanns E. 
Published: December 2003

Abstract
Large single crystals of optical quality and with dimensions up to 50 mm of double salts of the type X[C(NH2)3] Zr(N(CH2COO)3)2 ⋅ y H2O (X = Rb, Tl, NH4, Cs, CH3NH3) have been grown from aqueous solutions. They crystallize in the space group P21 and exhibit quasi-isotypic structures. Complete elastic and thermoelastic tensors have been derived from ultrasonic resonances of plane-parallel plates. In addition, thermal expansion, pyroelectric, dielectric and piezoelectric properties have been measured. The maximum longitudinal piezoelectric effects d
222 exceed d
111 of α-quartz roughly by a factor of 7. The pyroelectric constants π
2 surmount π
3 of tourmaline by about a factor of 9. The structural and physical properties are closely related to those of the constituent salts.
Thermal induced transformations on completely Zn2+ exchanged zeolites A and Y
Authors: Weidenthaler C. , Schmidt W. 
Published: December 2003

Abstract
The thermal stability of completely Zn2+ exchanged zeolites A and Y during calcination is studied from R.T. to 1350°C. The phase formation processes are analysed by in situ X-ray diffraction experiments as well as by quenched samples analysed and quantified by Rietveld refinements. The framework structures of the exchanged zeolites A and Y are observed to collapse above 850°C. At higher temperatures the crystallisation of Zn-β-quartz, mullite, and gahnite is initiated from the amorphous phase. Above 1050°C quartz appears and Zn-β-quartz disappears. The crystallisation of willemite is only observed for ZnA, mullite is not stable above 1150°C in both systems. Further increase in temperature leads to the crystallisation of cristobalite accompanied by the disappearance of quartz. The final crystalline components at 1350°C are, for both zeolite precursors, gahnite and cristobalite. Differences between the zeolite precursors are the amounts of amorphous phase formed, indicating a suppression of the formation of a crystalline SiO2 phase in the ZnY samples.
Topological analysis of ionic packings in crystal structures of inorganic sulfides: the method of coordination sequences
Authors: Blatov V. A. 
Published: December 2003

Abstract
Using the concept of coordination sequences and the uniformity criterion the method of topological analysis of atomic packings and of their classification at any degree of metric distortions is implemented in the computer program IsoTest. The criterion is based on the search for packings topologically similar, but not equal to close packings. The topological analysis of ionic sublattices was employed for the crystal structures of 781 inorganic sulfides. It was shown that no less than in the third of cases the sulfides are constructed on the basis of a distorted close packing, and such packings are constructed with sufficiently large cations, as a rule. The examples of forming close packings by complex thioanions contained in a number of thiosalts were drawn.
Are the compressive effects of encapsulation an artifact of the bond valence parameters?
Authors: Krivovichev Sergey V. , Brown I. D. 
Published: December 2003

Abstract
The large bond valence sums found for O2– en-capsulated by Pb2+ ions are shown to result from the use of inappropriate bond valence parameters. New values of r
o = 1.963 Å and b = 0.49 Å are recommended for Pb2+-O bonds.
Structural phase transition of GdGa2 at high pressure
Authors: Schwarz U. , Bräuninger S. , Burkhardt U. , Syassen K. , Hanfland M. 
Published: December 2003

Abstract
Structural properties of the intermetallic compound GdGa2 were investigated under hydrostatic pressures up to 20 GPa using angle dispersive x-ray powder diffraction in combination with the diamond anvil cell technique. At 7.7(5) GPa the onset of a first order phase transition from the AlB2 type structure into a hexagonal high-pressure phase is observed. The transformation is associated with a 2.5 % elongation of the lattice parameter a and an 8 % shortening of c. TB-LMTO bandstructure calculations reveal that the two-dimensional character of the gallium partial structure is preserved in the high-pressure modification.
Elastic and thermoelastic properties of selected organic crystals: acenaphthene, trans-azobenzene, benzophenone, tolane, trans-stilbene, dibenzyl, diphenyl sulfone, 2,2´-biphenol, urea, melamine, hexogen, succinimide, pentaerythritol, urotropine, malonic acid, dimethyl malonic acid, maleic acid, hippuric acid, aluminium acetylacetonate, iron acetylacetonate, and tetraphenyl silicon
Authors: Haussühl S. 
Published: December 2003

AbstractElastic and thermoelastic properties of the 21 title crystalline species have been determined from ultrasonic resonant frequencies of plates and their shift upon variation of temperature, respectively. In addition, the tensors of thermal expansion have been measured by the aid of a Fizeau interferometer. An analysis of the elastic behaviour of organic crystals, including earlier elastic data of other organic compounds taken from the literature, revealed common features of organic crystals and organic liquids in respect to the scalar invariantsC= (c11+c22+c33+c44+c55+c66+c12+c13+c23)/9 and d logC/dT,Ttemperature, especially in the case of Van-der-Waals crystals. Contrary to ionic crystals the invariantCincreases in these crystals with larger molecular volume. Crystals with strong hydrogen bonds like dicarboxylic or sulfonic acids behave rather like ionic crystals. The influence of a small molecular elastic stiffness, as observed in plastic crystals, is clearly recognizable in the elastic properties. The impact of structural details on the invariantCand its logarithmic temperature derivative is surprisingly small.
Polytypism in xonotlite Ca6Si6O17(OH)2
Authors: Hejny C. , Armbruster Th. 
Published: December 2003

Abstract
Occurrence, chemistry, crystal growth, technical applications, structure and polytypism of xonotlite Ca6Si6O17(OH)2 are reviewed. Atomic coordinates of the three simplest ordered polytypes in modified Gard notation: Ma2bc (space group P2/a, a = 17.032, b = 7.363, c = 7.012 Å, β = 90.36°), Ma2b2c (space group A2/a, a = 17.032, b = 7.363, c = 14.023, β = 90.36°), and M2a2bc (space group P1̅, a = 8.712, b = 7.363, c = 7.012 Å, α = 89.99° β = 90.36°, γ = 102.18°) were modeled from geometric principles based on the known structure of the M2a2b2c polytype (space group A1̅, a = 8.712, b = 7.363, c = 14.023, α = 89.99 β = 90.36, γ = 102.18°). Unique reflection arrangements in the reciprocal lattice, characteristic of each polytype, were defined as criteria to identify xonotlite polytypes on X-ray single-crystal photographs. Precession- and Weissenberg-photographs of a xonotlite from the Kalahari manganese field (Republic of South Africa) indicated the predominance of the (100) twinned M2a2b2c polytype, followed by the Ma2b2c polytype, and very low concentrations of the Ma2bc polytype. The M2a2bc polytype could not be identified which agrees with previous electron diffraction experiments on xonotlites from other localities. Diffuse streaks parallel to a* and less intensive ones parallel to c* on single-crystal photographs suggest the presence of additional disordered polytypes.
The structure of Co(NH3)6CuCl5 at 10 K
Authors: Bernal I. , Yufit D. S. , Howard J. A. K. 
Published: December 2003

Abstract
The structure of the title compound was determined at 10 K using the Fddd diffractometer equipped with a Mo-target rotating anode. The object of the study was to determine the geometrical parameters of the cation and anion at what we assume is their resting state geometry, given the temperature of data collection. The cation is es-sentially unchanged in geometry from 294 K to 10 K. The anion is considerably distorted, having changed from a trigonal bipyramid (site symmetry 32) to a “T-shaped” or “seesaw” structure, sitting at a two-fold axis. During the cooling process, the space group changed from Fd3̅c to F41/adc. The shape of the anion is, interestingly, similar to that of XeO2F2.
Self-intersecting three-periodic minimal surfaces forming one-periodic tubes or finite polyhedra
Authors: Koch Elke 
Published: December 2003

Abstract17 families of three-periodic minimal surfaces with straight self-intersections have been derived that subdivideR3into an infinite number of one-periodic 'tubes' and/or finite 'polyhedra'. Their Euler characteristics vary between -3 and -18. Ten of these families show non-orientable minimal surfaces. They subdivideR3either into congruent tubes (eight families), into congruent polyhedra, or into two different kinds of congruent polyhedra. The minimal surfaces of seven families are orientable. All of them cause two different kinds of spatial subunits: two kinds of tubes (one family), tubes and polyhedra (three families), or two different kinds of polyhedra (three families).
The crystal structure of FeInGe2O7
Authors: Bucio J. , Ruvalcaba-Sil J. L. , Rosales I. , García-Robledo J. , Orozco E. 
Published: December 2003

Abstract
A new iron indium germanate has been prepared as polycrystalline powder material which crystallizes in the monoclinic system (S.G. C2/m, No. 12). The structure was characterized by X-ray powder diffraction and Rietveld refinement of the resulting diffraction pattern. The cell parameters are a = 6.5124(4) Å, b = 8.5914(5) Å, c = 4.8936(3) Å, β = 102.683(2)°, V = 267.12(3) Å3 and Z = 2. The structure contains R+3 cations (R=Fe, In) almost equally distributed in distorted RO6 octahedral sites. These octahedra are joined by edge sharing forming a hexagonal arrangement on the ab planes. The RO6 octahedra layers are held together by sheets of isolated Ge2O7 diorthogroups constituted by a double tetrahedra sharing a common vertex. This compound has the thortveitite structure and keeps a strong relationship with the FeYGe2O7 germanate, which presents two R+3 sites with six-coordinated (R=Fe) and seven-coordinated (R=Y) oxygens, corresponding to the different symmetry given by the monoclinic space group P21/m (No. 11)
Prediction of crystal structure of a rare monosaccharide – influence of model geometry
Authors: Ďurík M. , Smrčok L. 
Published: December 2003

Abstract
Crystal structure of a hexagonal monosaccharide, C11H18N2O4, was succesfully predicted by potential energy minimisation. Four starting molecular models differing in ring conformations were based on similar structures and the positions of two substituents (-NH2, -CN) were found by semiempirical AM1 calculations. Generated structures were ranked according to both potential energy values and corre-sponding Rwp
´s. Calculated potential energy was sensitive to changes in the geometries of the sachcharide rings as well as to the positions of substituents. Rigid body Rietveld refinements did not improve accuracy of the crystal structures with low Rwp
´s and high potential energy.
Theoretical analysis and empirical manifestation of the distortion theorem
Authors: Urusov Vadim S. 
Published: December 2003

Abstract
The distortion theorem is analyzed by the use of the Bond Valence Model for the case of an isolated coordination polyhedron with bonds of different lengths. It is shown that a correlation should exist between the average bond length increase and the mean-square deviation of individual bond lengths from the average one, at least for nonstrained crystal structures. It is proved that the correlation parameters are strongly dependent on a mode of distortion (symmetry of coordination environment). These conclusions are in general and sometimes in quantitative agreement with available experimental data, although in most cases the distortion of coordination polyhedra results from a variety of factors of chemical, geometric and electronic origin. It is assumed that an observed correlation between the average bond distance and the distortion degree may be taken as a measure of relative role of intrinsic bond strengths and influence of crystalline environment.
Structure of iron-rich compounds in the Yb–Fe–Al system
Authors: Černý Radovan , Pacheco Vicente , Yanson Tamara , Manyako Michail , Bodak Oxana 
Published: December 2003

Abstract
X-ray diffraction studies on eleven single crystals having compositional ratios close to Yb/(Fe,Al) = 2:17 revealed four distinctly different structures, two having hexagonal symmetry (LuFe9.5 and TbCu7 type) at low and intermediate Al and Yb contents (0–7.5 at Al; 9.6–10.6 at Yb and 11.2–12.5 at Al; 10.5–10.9 at Yb), respectively, and two having rhombohedral symmetry (PrFe7(A) and PrFe7(A + B) types) at high Al and Yb contents (9.8–19.8 at Al; 10.7–11.6 at Yb). All have a common hexagonal TbCu7 type subcell and contain chains made up of Yb and Fe(Al)2 dumbbells running along the c-axis that substitute for each other with various ordering schemes and concentrations. The subcell ratio c/a depends on both the concentration of Fe(Al)2 dumbbells, for which it generally increases, and the structure type (dumbbell order). We define an order parameter capable of describing the dependency of the subcell ratio c/a on the Fe(Al)2 dumbbell ordering, irrespective of structure type, as the probability of finding two Fe(Al)2 dumbbells within a chain that are separated by one Yb atom only. Aluminium substitutes for iron mainly on non-dumbbell sites at low Al contents (LuFe9.5 and TbCu7 type) and enters Fe2 dumbbell sites only at high Al contents (TbCu7 type and PrFe7 type derivatives). The bond distances in the mixed Fe(Al)2 dumbbells increase with increasing Al content. Those in the Fe2 dumbbells depend on the dumbbell order (within one or between different structure types), and less on the Al content of the crystal.
The crystal structure of CaSiO3-walstromite, a special isomorph of wollastonite-II
Authors: Joswig Werner , Paulus Erich F. , Winkler Björn , Milman Victor 
Published: December 2003

Abstract
The crystal structure of CaSiO3-walstromite has been solved and refined by a data set collected in situ from an inclusion in a diamond single crystal (1135 observed reflections, MoKα
, Nonius CAD4, R = 3.46). The crystal structure is almost identical to that of walstromite (Ca2BaSi3O9). The replacement of Ba2+ by Ca2+ causes no significant structural changes (ring silicate; according to F. Liebau: dreier single rings). The structural differences to wollastonite-II (Ca3Si3O9) are also relatively small: The Ca positions are almost the same, but the axial Si3O9-ring is isomorphously replaced by the same ring with the inverse axiality. This constitutes a new principle of isomorphous replacement. Based on density functional theory the equation of state has been predicted. This allows us to estimate the remaining pressure of the investigated CaSiO3 inclusion in the diamond to be ≈3 GPa.
The Freezing of n-Alkanes C15H32 and C17H36: An Unsual Mechanism of Homogeneous Nucleation
Authors: Weidinger Inez , Klein Juliane , Stöckel Peter , Biller E. , Baumgärtel Helmut , Leisner Thomas 
Published: December 2003

Abstract
The nucleation kinetics of n-alkane droplets with carbon numbers of 15 and 17 was observed in an electrodynamic balance. Changes in the elastic light scattering pattern of the single levitated microdroplets indicate the phase transition liquid to solid. Measurements of the nucleation rates gave information on the dynamics of the nucleation process and allow to propose a new mechanism for the nucleation. Large induction times observed for the C15H32 droplets indicate that the nucleation starts after a solid layer has been built up at the surface.
Measurement of the 129Xe NMR Chemical Shift of Supercritical Xenon
Authors: Baumer D. , Fink A. , Brunner E. 
Published: December 2003

Abstract
The measurement of the 129Xe Nuclear Magnetic Resonance (NMR) chemical shift as a function of density is reported. The apparatus used in this study enabled us to measure the 129Xe NMR chemical shift in the supercritical state up to a pressure of about 70 MPa, i.e., a density of 440 amagat1 at 298 K.
The Nonlinear Optical Response of Pt(111) Electrodes in Perchloric Acid Solution: Implications for the Potential of Zero Charge
Authors: Friedrich K. A. , Daum W. , Dederichs F. , Akemann W. 
Published: December 2003

Abstract
Second harmomic and sum frequency generation (SHG, SFG) are used to investigate the second-order non-linear optical response of a Pt(111) single-crystal electrodes in perchloric acid solution. In the potential window between hydrogen evolution and surface oxidation the SHG signal shows a pronounced minimum at 760 mVRHE and rises linearly with decreasing electrode potential. The potential of the minimum as well as the magnitude of the signal in the potential range of hydrogen adsorption depend on the pH of the electrolyte. The dependence of the SHG signal on excitation frequency in the range of 9000–1200 0cm−1 shows a continuous SHG signal increase to higher frequencies without characteristic surface resonances. The SHG signal is assigned to the excitation of a continuum of electronic levels. The maximum of the signal intensity is observed at potentials close to 0 VRHE, where hydrogen evolution takes place and the surface has a maximum of negative charge. Sum-frequency spectra of CO adsorbed on Pt(111) exhibit the known vibrational signature of terminal and bridge-like coordination and an additional resonant signal. On the same surface, the SHG signal is characterized by a high signal intensity which remains constant up to the CO oxidation potential. The potential dependence of the nonlinear response of the Pt(111)/CO surface as well as of the neat surface in perchloric acid indicates a high sensitivity to the surface charge. As a consequence, a negatively charged surface up to a potential of 600 mVRHE is deduced. Our results are at variance with a value for the potential of zero charge of 0.34 VRHE which was derived from the CO charge displacement method, but in agreement with the value based on the immersion technique (U. W. Hamm et al. , J. Electroanal. Chem. 414 (1996) 85).
Investigation of the Pressure Effects on Inclusion Equilibria of Substituted Phenols with β- and γ-Cyclodextrins
Authors: Sueishi Yoshimi , Itami Shotaro 
Published: December 2003

Abstract
The effects of pressure were examined for the inclusion complexation of β- and γ-cyclodextrins (CDs) with 4-substituted phenols. The reaction volume for the CD inclusion complexation with 4-substituted phenols, which is the change in volume accompanied by CD inclusion, was estimated from the pressure dependence of the inclusion equilibria. The reaction volumes estimated for the phenols/β-CD system were positive values in the range of 2.5 and 14.0cm3mol−1, while those for the phenols/γ-CD system were negative in the range of −11.8 and −0.8cm3mol−1. The difference in the reaction volumes for the inclusion complexation of β- and γ-CDs is explained in terms of the difference in the number of water molecules repelled from the CD cavity. Based on the results, the inclusion behavior of CD complexation is discussed.
Behaviour of Some Copper(I) and Cobalt(III) Complexes in Acetonitrile and n-Butyronitrile at 298.15K
Authors: Gill Dip Singh , Pathania Vivek , Vermani Bal Krishan , Sharma Raj Pal 
Published: December 2003

Abstract
Molar conductances of a large number of copper(I) and cobalt(III) complexes, behaving as strong 1:1 electrolytes, have been measured in acetonitrile (AN) and n-butyronitrile (n-BTN) at 298.15K. The conductance data have been analyzed by the Shedlovsky method to evaluate Λ0 and K
A values of these electrolytes. Limiting ion conductances (λ
i

0) for various ions in AN have been calculated by using transference number data. In n-BTN, where no transference number data is available, such values have been calculated by an indirect method using Bu4NBPh4 as a reference electrolyte. The actual ionic radii (ri
) for various ions in solution have been calculated using a modified form of Stokes’ law. The ionic radii (ri
) for various complex ions have been compared with the ionic radii of two reference ions, Bu4N+ and Ph4B−, which are not solvated in dipolar aprotic solvents, to throw light on the solvation behaviour of these complex ions.
Dynamical Structure of Liquid Metals: Recent Theoretical Progress
Authors: Hoshino Kozo 
Published: December 2003

Abstract
Recently, experimental studies on the dynamical structure of liquid metals have been actively carried out by the inelastic X-ray scattering (IXS) technique using the synchrotron radiation which have stimulated theoretical studies. In this paper, recent progress in theoretical studies on the dynamical structure of liquid metals are described in two approaches, i.e. the theoretical approach based on the memory function formalism and the various kinds of computer simulations.
Static and Dynamic Structures of Expanded Fluid Mercury
Authors: Inui Masanori , Tamura Kozaburo 
Published: December 2003

AbstractX-ray diffraction, small angle X-ray scattering and preliminary inelastic X-ray scattering measurements for a metallic fluid up to the supercritical region have been carried out using synchrotron radiation at SPring-8. We obtained the structure factor,S(k), and the pair distribution functions,g(r), for expanded fluid Hg from the liquid to the dense vapour region by X-ray diffraction measurements. Change of the local structure in the metalinsulator transition in fluid Hg is discussed. To obtain information on the density fluctuation in fluid Hg near the critical point, small angle X-ray scattering measurements were carried out at SPring-8. In addition to the static structures, the dynamic structure factor of expanded fluid Hg was obtained for the first time using inelastic X-ray scattering technique newly established at a synchrotron radiation facility of the third generation source. Preliminary results of the first experiment are presented.
Conductivities, Partial Molar Volumes, and Isentropic Compressibilities of Sodium, Potassium and Ammonium Thiocyanates in Water + N,N-Dimethylformamide Mixtures at 20°C
Authors: Tsierkezos Nikos G. , Molinou Ioanna E. 
Published: December 2003

Abstract
Conductance, ultrasonic velocity, and density measurements are reported for NaSCN, KSCN and NH4SCN in water, N,N-dimethylformamide (DMF), and water + DMF mixtures at 20°C. The limiting molar conductances and association constants have been derived from the Lee–Wheaton conductivity equation. The single-ion conductances have been evaluated using Bu4NBPh4 as the “reference electrolyte”. The limiting molar volumes and apparent isentropic compressibilities have been calculated. The ion–ion and ion–solvent interactions have been discussed.
Clusters in a Saturated Vapor: Pressure-Based Temperature Enhancement of the Cluster Fraction
Authors: Slanina Zdeněk 
Published: December 2003

AbstractRecent computational findings of temperature increase of clustering degree in different saturated vapors are analyzed. A thermodynamic proof is given and a simple criterion suggested. Illustrations are presented with argon, water, and carbon vapor. Relationships to the fullerene stability island are discussed, too.
Poverty in America 1970–1990: who did gain ground? An application of stochastic dominance criteria employing simultaneous inequality tests in a partial panel
Authors: Anderson Gordon 
Published: December 2003

AbstractAtkinson (1987) proposed stochastic dominance criteria for analysing poverty which, under certain conditions, establish orderings of states for any poverty line and any poverty measure within given class, refocusing debate on the nature of the income distribution of the poor. Employing new empirical techniques, these criteria are implemented for the United States from 1970 to 1990 using the Panel Study of Income Dynamics. Results highlight the pivotal role of family size scale economies in consumption, indicate different experiences for white versus non‐white groups and suggest that optimism over the progress of the poor is not warranted. Copyright © 2003 John Wiley & Sons, Ltd.