Solid-state Features Research Articles

Morphology and mechanical properties of blends of polycarbonate and segmented copolyetherester

The solid state features and the mechanical properties of melt mixed polycarbonate (PC)/segmented copolyetherester (CPEE) blends were investigated over the full composition range. The partially crystallized blends were composed of two amorphous phases but with only small composition differences in most blend compositions. The specific interactions, and the free volume decreases observed, gave rise to a decrease in the γ relaxation strength. The dependence on composition of both the decreases in the γ relaxation strength and in the free volume, as well as that of the modulus of elasticity and yield stress, were very similar to those of miscible blends. The nature of the amorphous phases of the blends at room temperature, changed from glassy to partially rubbery as the CPEE content was increased. As a consequence, to discuss the plots of the properties against composition at room temperature, the properties of the rubbery materials in the glassy state had to be determined. The synergistic modulus and yield stress behaviors appeared to be mainly determined by the γ relaxation strength and specific volume decrease, and that of ductility additionally by the Tg change.

ISO Observations of Solid-State Features in Circumstellar Disks

ISO has opened new infrared windows for spectroscopy, enabling detailed studies of the composition of the dust particles present in circumstellar disks. For oxygen-rich dust, and in particular for silicates, a forest of new features has been discovered, and comparison with laboratory data has enabled the identification of most of them. Of special relevance is the detection of crystalline silicates, which present themselves as a new diagnostic for studying the formation of comets and planetesimals in the disks surrounding young and, surprisingly, also evolved stars.

GEOCHEMISTRY OF S, CU AND NOBLE METALS (PGE+AU) IN THE SOUTHWESTERN PART OF THE RONDA PERIDOTITE MASSIF, SOUTHERN SPAIN

Thirty peridotites and eleven pyroxenites collected in the southwestern part of the Ronda peridotite massif have been analysed by iodometric titration, XRF and ICPMS to investigate the effect of the regional porous flow percolation process documented by Van der Wal and Bodinier (1996) on chalcophile/siderophile elements. The peridotites come from the different petro-structural domains now recognised within the Ronda peridotite. These are garnet/spinel peridotites (fertile lherzolites to harzburgites) from the Spinel Tectonite domain, the old (presumably middle Proterozoic; Reisberg and Lorand, 1995) sub-continental lithospheric protolith, lherzolites, harzburgites and dunites from the Granular Domain that extensively recrystallized during a young (Cainozoic?) regional melt percolation and lithospheric erosion event and plagioclase lherzolites from the Plagioclase Tectonite domain, which is a solid-state recrystallization feature resulting from the crustal emplacement of the massif. Each of the three sub-domains defined by Van der Wal and Bodinier (1996) in the Granular Domain has been investigated, i.e. the Coarse-Granular domain (CGD), where melt accumulation below the Recrystallization Front generated extensive recrystallization and silicate grain growth, the Fine-Granular domain (FGD), an area of melt entrapment and cpx-producing reactions (cpx2), and the Layered Granular domain (LGD) which display elongated bodies or layered-like olivine-rich lherzolites, harzburgites and dunites, sometimes rich in chromite, cpx2 and low Ti magmatic amphibole maybe present around spinel. Such olivine-rich lithologies (Mg#=0.88-0.9) may represent channels where percolating melts were focused at high-T, producing olivine by reaction with the pyroxenes (e.g., Bodinier et al., 1999). Our analyses reveal a much greater complexity in the Cu, S and PGE patterns than previously reported in the Ronda peridotites. This diversity clearly results from the superimposition of several magmatic processes in the mantle. All the lherzolites show S (150-250 ppm), Cu (20-30 ppm) and PGE concentration ranges (0.004-1.2 x CI-chondrites) mostly inherited from the ancient melting event that affected the protolith. Like many orogenic and oceanic lherzolites, they are light PGE-enriched (RuN/IrN = 1.6-2.6; RhN/IrN = 0.38- 0.48; PdN/IrN = 1.3-2.4; N = chondrite-normalised). Rather good positive correlations are preserved between S, Cu and fertility indices (r = 0.9) in cpx2-free samples. Palladium and fertility indices behave sympathetically; negativelyslopping CN normalised PGE patterns have survived in some CGD cpx-poor lherzolites and FGD harzburgites. Meanwhile coupled Pd, Cu and S enrichments are observed in cpx2-bearing samples, The olivine-rich LGD peridotites display the greatest diversity of PGE contents and PGE relative abundances. Chrome spinel dunites are strongly impoverished in all chalcophile/siderophile elements but Ru (Ir = 0.001 x CI chondrites; S 1; SN/PdN > 1 ;N = protolith normalised). Type D Cr-rich clinopyroxenites, the latest pyroxenite type, are richer in PGE (up to 55 ppb) but much lower in S and Cu (CuN/PdN < 0.2; SN/PdN < 0.04). A peculiar Au-, Pd- and As-enrichment trend proportional to the distance from the Recrystallization Front is observed in the harzburgites from the Spinel Tectonite domain. It is ascribed to upward-migration of S-poor but volatile-rich small-melt fractions that escaped from the Granular Domain. Local concentrations of these small-melt fractions could have probably given rise to the PGE-rich Cr- As-Ni mineralizations of magmatic origin that characterise the Ronda peridotite massif (Gervilla and Leblanc, 1990). The type D pyroxenites are likely precursor of these mineralizations. However, another Au enrichment trend (up to 6 x protolithic values) uncorrelated to the other noble metals also characterise lherzolites and harzburgites from both sides of the recrystallization front. Gold abundances in these rocks would record a widespread circulation of late-magmatic (oxidising) fluids through the south-western part of the Ronda peridotites during the latest stages of the melt percolation process. Because of numerous analogies between our Ronda data and similar rocks in ophiolitic complexes, our study could provide clues to understand the behaviour of chalcophile/ siderophile elements in fossil oceanic lithospheres submitted to melt/rock reactions above subduction zone.

Dinuclear Oxovanadium(IV) N-(Phosphonomethyl)iminodiacetate Complexes: Na(4)[V(2)O(2){(O)(2)P(O)CH(2)N(CH(2)COO)(2)}(2)].10H(2)O and Na(8)[V(2)O(2){(O)(2)P(O)CH(2)N(CH(2)COO)(2)}(2)](2).16H(2)O(1).

The dioxovanadium(IV) complexes with pida(4)(-) ligands (H(4)pida) = N-(phosphonomethyl)iminodiacetic acid), Na(4)[V(2)O(2){(O)(2)P(O)CH(2)N(CH(2)COO)(2)}(2)].10H(2)O (1) and Na(8)[V(2)O(2){(O)(2)P(O)CH(2)N(CH(2)COO)(2)}(2)](2).16H(2)O (2), were isolated from reactions of H(4)pida with either oxovanadium(V) (i.e., NaVO(3)) or oxovanadium(IV) precursors within the pH range of 2-8. The structures of complexes 1 and 2 were investigated by X-ray diffraction methods and in contrast to expectation were both found to be dinuclear. Complex 1 crystallized in the monoclinic system: P2(1)/n, a = 10.5632(1) Å, b = 11.1868(1) Å, c = 12.6921(1) Å, beta = 106.45 degrees, V = 1438.44(2) Å(3), Z = 4, and R (wR2) = 0.0781 (0.2017). Complex 2 crystallized in the monoclinic system P2(1)/c: a = 13.9822(2) Å, b = 11.1888(2) Å, c = 18.6519(3) Å, beta = 100.88 degrees, V = 2865.51(8) Å(3), Z = 4, and R (wR2) = 0.046 (0.125). Both complexes 1 and 2 have similar dimeric frameworks where two vanadium centers are linked by two phosphonate groups of two pida(4)(-) ligands (quadridentate binucleating), bridging through their four oxygen atoms to form a V(2)O(4)P(2) eight-membered ring which possesses a crystallographic inversion center. In contrast to their solid-state features, in aqueous solution both dinuclear crystalline compounds immediately dissociate to monomeric species, as observed by EPR and UV/vis spectroscopy. Both solution-state EPR and NMR spectroscopy confirmed that redox chemistry is involved in the reaction between vanadate and H(4)pida. Studies in mixed solvent systems showed that the dinuclear complex would remain intact in the presence of sufficient organic solvent. In the absence of oxygen the mononuclear and the dinuclear complexes will reversibly interconvert, whereas, in the presence of oxygen, the complexes will oxidize. These studies document the existence of higher oligomeric vanadium compounds and surprisingly, in general, lend credibility to several emerging mechanistic proposals involving oligomeric species of vanadium compounds in catalytic processes.

Anisometric Cyclometalated Palladium(II) and Platinum(II) Complexes. Structural and Photophysical Studies

The potentially tridentate ligand 4‘-[4-(dodecyloxy)phenyl]-6‘-phenyl-2,2‘-bipyridine (HL1) easily undergoes metalation at the ortho-C atom, yielding the rodlike complexes [Pd(L1)Cl] (1) and [Pt(L1)Cl] (2). The solid state features and the photophysical properties of the complexes have been studied. Crystal data for 2: PtC34H39ClN2O, triclinic, P1̄, a = 9.043(2) Å, b = 10.874(2) Å, c = 15.710(4) Å, α = 96.95(2)°, β = 92.51(2)°, γ = 102.32(2)°, V = 1494.3(6) Å3, Z = 2, and final R = 0.0387 (Rw = 0.0335) for 4333 independent reflections. The electronic spectra of complexes 1 and 2 show intense absorption bands in the UV region due to metal-perturbed ligand-centered (LC) transitions. In addition, complex 2 shows a moderately intense metal-to-ligand charge-transfer (MLCT) band in the visible region. Both complexes 1 and 2 show luminescence, although under different conditions. Strong emission has been observed for a 77 K glassy solution (highest energy feature 495 nm; τ = 74 μs) or room-temperature crystal (λmax = 490 nm) of 1. In both cases, the emission was assigned to a triplet LC excited state. Complex 2 exhibits emission from a 3MLCT level both in solution at room temperature (λmax = 590 nm; τ = 700 ns; Φ = 0.037) and in glass at 77 K (λmax = 545 nm; τ = 18 μs). The room-temperature emission of crystalline 2 (highest energy feature 590 nm) is also similar in energy to that observed in fluid solution and exhibits the typical MLCT vibrational progression, thus ruling out a contribution from either metal−metal or strong π−π interactions.

ISO-SWS observations of Planetary Nebulae

First results of the ISO1 Short-Wavelength Spectrometer on three bright planetary nebulae NGC 6543, NGC 7027 and NGC 6302 provide a wealth of information on solid-state features and spectral lines. Spectra from 2.4 to 45 μm are presented, at a reduced resolution of about 600.

Layered Cuprates

AbstractLayered copper-oxide superconductors exhibit the highest critical transition temperatures of any materials. Yet all of the known double perovskites A′A″B′B″O6 containing copper have a random or rock salt distribution of the B cations with the exception of the unique layered arrangement found in La2CuSnO6. Only the layered arrangement contains the CuO22- planes which are necessary for high-temperature superconductivity. The occurrence of layered or two dimensional structures increases markedly when vacancies are introduced on the oxygen sublattice, as evidenced in Ln2AEmCu2TimO5+3m (Ln = lanthanide, Y: AE = Ba, Ca: 2 ≤ m ≤ 4). Similarities among oxygen-deficient structures, especially those with two-dimensional solid-state features, are discussed. Combined conductivity and thermopower analysis are presented to elucidate their unique internal chemistry, defect structure, and conduction parameters. In particular, data for La2-xSrxCuSnO6 are presented and related to the crystal chemistry of the copper-oxygen layer. These data are compared with La2Ba2Cu2Sn2O11 and La2Ba2Cu2Ti2O11 to illustrate the significance of oxygen vacancies on the properties of the copper oxygen planes. New layered cuprates are discussed including the mixed A-site stoichiometries Ln′Ln″AEmCu2TimO5+3m (Ln = lanthanide, Y: AE = Ba, Ca: 2 ≤ m ≤ 4) which contain the smaller lanthanide (Ln″) ordered between the closely spaced, facing sheets of Cu-O square pyramids.

Reaction of NO2(g) with NaCl(100)

The heterogeneous reaction of 2NO2(g) + NaCl(100) → NaNO3(s) + ClNO(g) has been investigated using infrared spectroscopy. Single crystals, chosen for their well-defined and almost defect-free surfaces, were exposed to NO2 at four pressures: 0.15, 0.52, 1.5, and 3.5 mbar at 298 K. The formation of NO3- ions on NaCl was quantified from the photometry as the reaction progressed. The number of NO3- ions produced indicates that the reaction is not limited to the initial NaCl(100) face, but that nitrate ions also penetrate into the upper layers of the substrate. Despite an excess of NO2, the NaCl crystal transformation to NaNO3 ceases in a few hours. Gas phase ClNO is also observed spectroscopically. The strongest solid-state feature from the reaction is a well-defined sharp doublet at 1360 and 1414 cm-1 assigned to the ν3 asymmetric stretching vibration of NO3-. Both bands grow in unison as the reaction progresses. We suggest that the doublet results from the splitting of the ν3 degenerate mode in the monomers, dimers, or small ordered arrays of NO3- ions bound to neighboring ions of the NaCl substrate. There are as many as three regions that characterize the growth of NO3- at each NO2 pressure. Two of these regions are used to measure rates of NO3- production. The order of the reaction was determined from these rates and was found to be quadratic in NO2 pressure. A solid−gas reaction probability was also obtained from these reaction rates, assuming N2O4 is the reactant, and was measured to be (1.3 ± 0.3) × 10-6. This reaction probability is smaller by nearly 2 orders of magnitude than those reported by other research groups who have used powdered NaCl substrates. Probability differences are not surprising since the kinetics of this reaction is expected to depend on the concentration of defects at the surface. A mechanism, involving fracture of the NaCl substrate and diffusion of NO2 into its interior, accounts for the different growth regions and the production of NO3-. Finally when a small amount of water vapor is introduced with NO2, the production rate of NO3- is enhanced dramatically. The possible roles of H2O in heterogeneous chemistry of NaCl are discussed.

The Ardara pluton, Ireland: deflating an expanded intrusion

The Ardara pluton, north-western Ireland, is a circular monzodiorite-granodiorite intrusion with a “tail.” It has been regarded as a typical example of a pluton emplaced entirely by expansion (“balloning”) after initial intrusion. Most of the foliation in the pluton is magmatic, with weak superimposed solid-state features, apart from a thin rind of strong solid-state deformation. The solid-state deformation in the pluton appears to be largely, if not entirely, of post-intrusive, tectonic origin. Flattened microgranitoid enclaves, a concentric magmatic flow foliation and compositional zoning in the pluton are consistent with some expansion of magma prior to crystallization. However, strains in the wall rocks indicate that only a small amount (25%–38%) of the volume of the pluton can be ascribed to ballooning. This relatively small amount of expansion could account for (a) observed structural concordance and strong syn-metamorphic deformation in the aureole, (b) flattening of microgranitoid enclaves (magma globules) in the pluton and possibly (c) a small amount of solid-state deformation in the pluton during “lock-up” of magmatic flow. Evidence of solid-state deformation superimposed on a strong magmatic flow foliation in the tail of the pluton implies that a fault was active during emplacement and may have assisted the intrusion. Further space for the pluton may have been made by a complex interaction of processes, many of which cannot be constrained from a two-dimensional cross-section through the area. These possibilities highlight the limitations of attempting to constrain emplacement mechanisms on the sole basis of structures adjacent to plutons.

On the synthesis of FeB system thin films from powder mixtures under the influence of laser radiation

This paper describes an investigation of the synthesis of films from iron and boron powder mixtute under the influence of pulse laser radiation. The investigation of the composition of phases by Mossbauer spectroscopy showed that a heterogenic structure is formed with the distribution of phase concentration being dependent on the composition of mixture. The maximum yields of the FeB, Fe 2B, Fe 3B and FeB n formed phases are moved over 1.5 times with respect to the stoichiometric mixture composition of the atoms. It was defined that through synthesis under the influence of pulse laser radiation, the maximum yield of the synthesized phase is dependent on the solid state features of the pure synthesized materials.

Why does tetramethylammonium oxalate exhibit sublimation?

Solid state features of the ionic compound [NMe4]2[C2O4] are used to explain its unexpected sublimation behaviour.

New low-resolution spectrometer spectra for IRAS sources

Low-resolution spectra of 486 IRAS point sources with F sub nu(12 microns) in the range 20-40 Jy are presented. This is part of an effort to extract and classify spectra that were not included in the Atlas of Low-Resolution Spectra and represents an extension of the earlier work by Volk and Cohen which covers sources with F sub nu(12 microns) greater than 40 Jy. The spectra have been examined by eye and classified into nine groups based on the spectral morphology. This new classification scheme is compared with the mechanical classification of the Atlas, and the differences are noted. Oxygen-rich stars of the asymptotic giant branch make up 33 percent of the sample. Solid state features dominate the spectra of most sources. It is found that the nature of the sources as implied by the present spectral classification is consistent with the classifications based on broad-band colors of the sources.

Bond functions in calculating X-ray structure factors for diamond-structure crystals

Much attention is now given to electron--distribution models that are fairly simple from the computational viewpoint but capable of describing the main solid-state bond features. We construct electron distributions for crystals having the diamond structure by means of localized bond functions, whose performance is evaluated by comparing the Fourier transforms with the observed structure factors for x-ray Bragg reflections for diamond and silicon. That approach to distribution description is of interest because wave-function calibration of x-ray form factors gives excellent agreement with variational calculations for the atomic density and atomic orbitals.

Solid state and solution features of amylose and amylosic fragments

An understanding of the molecular changes occurring during polymorphic transformations of amylose is sought through the use of energy calculations. Four stable families of low energy conformers are found; three of these correspond to conformations observed in linear and cyclic maltodextrins in the crystalline state. Upon change of solvent, significant variations have been shown to occur in the relative abundance of amylose conformers. This, in turn, influences properties such as chain extension. The relevance of the stable conformers with respect to helical structures of amylose is analyzed. Whereas one of the conformers would generate a V type shallow helix, another one would give rise to a 6 fold left-handed strand having a 3.6 A advance per residue. This would generate a double helical stranded structure.

Specific solid state features of transparent ferroelectric ceramics

Characteristic features of chemical composition, structure and properties of transparent ferroelectric ceramics (TFC) are revealed from the analysis of the known materials. From considerations of the microstructure of TFC, it is shown that practically no space charge accumulates on the grain boundaries. Essential physical and technological factors responsible for light transmittance are analyzed, and criteria that can be used for the search for new TFC compositions proposed. Some TFC properties are explained in terms of highly doped and compensated ferroelectrics. Specific features of TFC in comparison with electrooptic single crystals and opaque ferroelectric ceramics are discussed.

Auger Spectroscopy of Solid Surfaces: Electron versus Ion Excitation

Auger transitions involving outer electrons in free atoms and in solids are compared with particular reference to L23 deexcitation in elements Na to Si. Under electron or x-ray excitation the elemental solid state spectra are band-like in character with breadth twice that of the conduction valence band, and a shape determined in detail by matrix element, surface and electronic relaxation effects. This is in strong contrast to the L23 VV spectrum of Cu which is quasi-atomic in character and the M45 VV spectrum of various Ag alloys which show mixed atomic-band like behaviour. Under ion excitation a superposition of a solid state spectrum and an excited atom spectrum is observed. Various theories of the origin of the quasi-atomic spectrum are considered, and attempts are made to account for the energies in the atomic spectrum and the relative intensities of atomic and solid state features. Calculations of the detailed motions of atoms in the surface region following inner shell ionisation are reviewed, and the sensitivity of atomic yield to inner core lifetime and the angle of incidence of the ion beam is discussed.

Abstract: Solid state and atomic features in the valence-band Auger spectra of copper, silver, and gold

Abstract: Solid state and atomic features in the valence-band Auger spectra of copper, silver, and gold

SF System: Power Conversion

This article describes the constant current, high voltage power facilities which power the SF Submarine Cable repeaters. The overall power system description includes discussions of the power connections to the cable, and a review of overall design requirements and objectives. The circuit description is covered in a general manner to demonstrate the basic concept. Particular emphasis is given to the description of several significant circuit innovations which include automatic load sharing by two constant current sources, 20 kHz inverter operation with output wave symmetry correction, solid-state alarm detectors, automatic turn-up and turn-down features, electrical noise suppression, redundant shutdown circuits and selective alarm cutoffs. The physical design includes the extensive use of plug-in modules for ease of maintenance, convection cooling of the entire power supply including the test load, and a key interlock system which prevents access to high voltage components when the power supply is energized. A special high-voltage switch can transfer the cable from one power plant to another without interruption of service.