New organosols of nickel sulfides,palladium sulfides,manganese sulfide,and mixed metal sulfides and their use in preparation of semiconducting polymer-metal sulfide composites

Organosols of NiS, PdS, and MnS in N,N-dimethylformamide were prepared by reaction of the metal acetate with H₂S. Organosols of mixed-metal sulfides (Zn _x Cd_1–x S, Hg _x Cd_1–x S, Hg _x Cu_1–x S, Cd _x Mn_1–x S, Hg _x Mn_1–x S, Hg _x Cd_1–x S, and Mn _x Zn_1–x S) were similarly obtained by reaction of mixtures of the metal salts with H₂S. The organosol of Zn_0.5Cd_0.5S contained particle with two particle size distributions centered at 6.5 nm and 29 nm, as revealed by Ar laser-scattering analysis. The metal sulfides are recovered by addition of Et₂O to the organosols. Zn _x Cd_1–x S thus obtained shows magnetic susceptibility in the range 0.5×10^–6–2.3×10^–6 emug^–1 depending on thex value. Addition of polymers to the organosols affords semiconducting films of metal sulfide-polymer composites.     

Determination of the stoichiometry of semiconductor systems of the type CdvHg1?vSe and CdxHg1?xTe by X-ray fluorescence spectrometry

Summary Semiconductors of the composition Cd _v Hg_1–v Se and Cd _x Hg_1–x Te are gaining growing industrial interest. The energy gap between the bands of such systems depends significantly on the magnitude of the mole fractions v and x. X-ray fluorescence analysis of acid solutions of these crystals is a simple and precise procedure to determine the stoichiometry. Sample preparation, calibration series and results are discussed.

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Bestimmung der Stöchiometrie von Halbleitersystemen des Typs Cd_vHg_1–vSe und Cd_xHg_1–xTe, durch Röntgenfluorescenz-Spektrometrie

Zusammenfassung Halbleiter der Typen Cd _v Hg_1–v Se und Cd _x Hg_1–x Te gewinnen zunehmend industrielles Interesse. Der Energieabstand der Bänder in solchen Systemen hängt entscheidend von der Größe der Molenbrüche v und x ab. Ein einfaches und sicheres Analysenverfahren zur Ermittlung der Stöchiometrie ist die Röntgenfluorescenzanalyse von sauren Lösungen dieser Kristalle. Die Probenvorbereitung, Eichreihen und Resultate werden diskutiert.

Delegated to Central Institute of Analytical Chemistry, Nuclear Research Establishment (KFA), Jülich, FRG.     

Nucleation of Titania Nanocrystals in Silica Titania Waveguides

SiO_{2(1 – x)}-TiO_2(x) monomode waveguides at 632.8 nm, with x in the range 0.07–0.2 and thickness of about 0.4 m, were deposited on silica substrates by a dip-coating technique. Nucleation of TiO₂ nanocrystals and the growth of their size by thermal annealing up to 1300°C were studied by waveguided Raman scattering in the SiO_2(0.8)-TiO_2(0.2) composition. In the low frequency region (5–50 cm^–1) of the VV and HV polarized Raman spectra the symmetric and quadrupolar acoustic vibrations are observed. The mean size of the titania particles are obtained from the frequencies of the Raman peaks. The results are compared with those obtained from the measure of the linewidths in the X-ray diffraction spectra. Nanocrystals with a mean size in the range 4–20 nm are obtained by thermal annealing in a corresponding range of 700–1300°C.     

Extension of the misfit series to the mercury-based cobaltites

The exploration of the Hg–Sr/Ca–Co–O system using EDS and electron microscopy has shown the possibility to incorporate mercury and excess cobalt in the middle rock salt layer of the misfit cobaltite structure, leading to the new series [Hg_1−xCo_xSr_2−yCa_yO₃]^RS[CoO₂]_b1/b2 with 0.6x0.90, 0y2, and b₁/b₂ ranging from 1.63 to 1.79. These new composite oxides, built up from [CoO₂]_∞ layers of the CdI₂-type stacked with triple [Hg_1−xCo_xSr_2−yCa_yO₃]. rock salt layers are remarkable by their large thermopower S values similarly to the thallium and lead misfit cobaltites. More importantly, the S value is sensitive to the composition of the triple rock salt layer, increasing as the calcium content increases, so that an enhancement of the figure of merit of the pure calcium compound is expected.     

Characterization of native and heterooxide layers on compound semiconductors by combined use of surface analysis methods

Summary Structure, formation and interface reactions of anodic oxides and SiO₂ on Cd_xHg_1–xTe have been studied by means of SIMS, AES, XPS, TDMS and the electron microprobe as an example for the application of surface analysis to compound and semiconductor passivation systems.

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Charakterisierung von Eigenoxid- und Heterooxidschichten auf Mehrkomponentenhalbleitern durch kombinierten Einsatz oberflächenanalytischer Verfahren

Zusammenfassung Aufbau, Bildungsmechanismus und Grenzflächenreaktionen von anodischen Oxiden und Quarz auf Cd_xHg_1–xTe wurden mit SIMS, AES, XPS, TDMS, SNMS und der Elektronenstrahlmikrosonde untersucht.

     

Dielectric and Raman studies on the solid solution (1−x)BaTiO3/xNaNbO3 ceramics

In order to elucidate the correlation between the relaxor type of phase transition and the percent of the A and B site substitution in the Ba_1−xNa_xTi_1−xNb_xO₃ solid solution, the dielectric permittivity was carried out in the temperature range 80–600 K. All ceramics of these solid solutions present a ferroelectric–paraelectric phase transition with relaxor and classical character depending on the value of x. With increasing x the three phase transition of pure BaTiO₃ are pinched into one rounded dielectric peak, and there is evidence for Vogel–Fulcher type relaxational freezing. Raman spectra of the x=0.3 and x=0.7 compositions taken at various temperatures and measured over the wavenumber range 100–1200 cm⁻¹ confirm that the first order scattering is dominant in phonon bands resulting from both ordered region and disordered matrix.     

Dielectric proprieties of ferroelectric ceramics derived from the system BaTiO3NaNbO3-based solid solutions

Dielectric studies performed on the solid solution Ba_1−xNa_xTi_1−xNb_xO₃ (BNTN) show that all compositions (x= 0.1, 0.15, 0.2, 0.4, 0.5 and 0.025, 0.05, 0.6, 0.7, 0.8) exhibit a ferroelectric–paraelectric phase transition where the Curie temperature is a function of the composition. The specimens with composition BNTN (x= 0.05, 0.1, 0.15, 0.2) have been refined by the Celref method from X-ray powder diffraction data. The evolution of dielectric constant as a function of temperature and frequency in the range 77–500 K and 20–2 × 10⁵ Hz, respectively, show that these ceramics present the classical ferroelectric character when 0x<0.075 and 0.55<x1 and relaxor character when 0.075x0.55.     

Magnetische Untersuchungen der Carbide TiC,ZrC, HfC,VC, NbC und TaC

Zusammenfassung Die magnetische Suszeptibilität an sehr reinen Mono-Carbidproben wird in Abhängigkeit vom Kohlenstoffdefekt gemessen. Mit zunehmendem Kohlenstoffdefekt werden TiC_1–x , ZrC_1–x , HfC_1–x und VC_1–x paramagnetischer. Extrapolation auf stöchiometrisches TiC führt auf Diamagnetismus. NbC_1-x und TaC_1–x zeigen einen davon abweichenden Verlauf; deren Suszeptibilitäten nehmen im wesentlichen mit steigendem C-Defekt ab und erreichen diamagnetische Werte. Eine Vorstellung zur Deutung des Suszeptibilitätsverlaufes bei TiC_1–x , ZrC_1–x , HfC_1–x und VC_1–x unter Berücksichtigung der Bindungsenergie, bei Übergangsmetallen wird entwickelt und eine Erklärung für das magnetische Verhalten von Mischcarbiden gegeben.Mit 2 Abbildungen     

Farbe und Konstitution bei anorganischen Feststoffen, 14. Mitt.: Die Lichtabsorption des zweiwertigen Kupfers in oxidischen Wirtsgittern

Zusammenfassung Um die Beziehungen zwischen der Lichtabsorption des zweiwertigen Kupfers nach isomorphem Einbau in ein oxidisches Wirtsgitter und dessen Konstitution aufzufinden, wurde Cu²⁺ in oktaedrischer (Cu _x Mg _1–x TiO₃, Cu _x Cd _1–x TiO₃, Cu _x Mg _1–x CaSiO₄, Cu _x Mg _1–x CaGeO₄, Cu _x Mg _2–x SiO₄, Cu _x Mg _2–x GeO₄) und tetraedrischer Koordination (Cu _x Zn_2–x SiO₄, Cu _x Mg _1–x Cr₂O₄) spektralphotometrisch untersucht. Die Farbkurven besitzen mindestens 2 Absorptionsbanden (Kristallfeldbanden) im längerwelligen und eine oft gut ausgeprägte Elektronenübergangsbande (charge transfer) im kürzerwelligen Spektralbereich. In einigen Fällen ist noch eine zweite Elektronenübergangsbande als Schulter zu erkennen. Es wurden auch Cu-haltige 2,3- und 2,4-Spinelle spektralphotometrisch untersucht (Cu _x Mg _1–x Al₂O₄, Cu _x Mg _1–x Ga₂O₄, Cu _x Cd _y Zn _1–x–y Al₂O₄, Cu _x Mg _2–x SnO₄, Cu _x Mg _2–x TiO₄, Cu _x Zn _1–x MgTiO₄, Cu _x Mg _1–x Cd _y TiO₄). Es zeigte sich, daß Cu²⁺ immer auf Tetraeder- und Oktaederlücken verteilt ist. Eine Aufweitung des Wirtsgitters durch isomorphen Einbau größerer Kationen bewirkt nicht immer eine IR-Verschiebung der Banden, sondern in einigen Fällen (Spinellphasen) auch eine UV-Verschiebung. Eine Sonderstellung nimmt das ägyptisch-Blau CuCaSi₄O₁₀ ein, da hier das Cu²⁺ von 4 O_2– in planarer Anordnung umgeben ist. Die Farbkurve weist 3 Maxima auf im Einklang mit der Kristallfeldtheorie.

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In order to find out relations between the lightabsorption of bivalent copper isomorphously incorporated into an oxidic host lattice and the constitution of this lattice, the spectrum of Cu²⁺ has been investigated in octahedral (Cu _x Mg_1–x TiO₃, Cu _x Cd _1–x TiO₃, Cu _x Mg _1–x CaSiO₄, Cu _x Mg _1–x CaGeO₄, Cu _x Mg _2–x SiO₄, Cu _x Mg _2–x GeO₄) and tetrahedral coordination (Cu _x Zn _2–x SiO₄, Cu _x Mg _1–x Cr₂O₄). The colour curves show at least 2 absorption bands within the region of longer wave length and a charge transfer band often well developed in the range of shorter wavelength. In some cases also a second charge transfer band becomes conspicuous as a shoulder. Copper containing 2,3- and 2,4-spinels have been also investigated (Cu _x Mg _1–x Al₂O₄, Cu _x Mg _1–x Ga₂O₄, Cu _x Cd _y Zn _1–x–y Al₂O₄, Cu _x Mg _2–x SnO₄, Cu _x Mg _2–x TiO₄, Cu _x Zn _1–x MgTiO₄, Cu _x Mg _1–x Cd _y Zn _1–y TiO₄). From the colour curve one can infer that Cu²⁺ occupies in the spinels always tetrahedral as well as octahedral interstices. A widening of the lattice does not effect always a shifting of the absorption bands towards IR but in some cases (spinel phases) also the inverse shifting will occur. An exceptional case represents the egyptian blue CuCaSi₄O₁₀ since in this lattice the Cu₂₊ are surrounded by four O^2– in a coplanar arrangement. The colour curve shows three absorption bands in agreement with the crystal field theory.

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Mit 20 Abbildungen     

Molecular,thermodynamic, and kinetic parameters of iodomethanes and iodomethyl radicals: <Emphasis Type="Italic">ab initio</Emphasis> calculations

The wave functions and enthalpies of formation of the ground states of iodomethanes CH_{4– x} I_x and iodomethyl radicals CH_3–x I_x. (x = 1–3) were calculated ab initio with regard to electron correlation. The geometries of the molecules of these compounds were determined, as well as the normal mode frequencies and other parameters, which were used for calculating the thermodynamic functions in the 0–1500 K range. These functions were used for calculating the constants of the CH_4–x I_x CH_4–x I _x–1 + I and CH_4–x I_x + I CH_{4– x} I _x–1 + I₂ equilibria, which, in turn, were used for calculating the corresponding rate constants in the high concentration limit.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1812–1822.Original Russian Text Copyright © 2004 by Dymov, Skorobogatov, Tschuikow-Roux.This revised version was published online in April 2005 with a corrected cover date.     

Oxygen States in Oxides with a Perovskite Structure and Their Catalytic Activity in Complete Oxidation Reactions: System La1 – x Ca x FeO3 – y (x = 0–1)

Oxygen states in the La_{1 – x} Ca _x FeO_{3 – y} perovskites prepared using different procedures are studied by temperature-programmed reduction (TPR). Results are compared to data on the catalytic activity in the oxidation of methane and carbon monoxide. The activity of the samples in the CO and CH₄ oxidation over a wide temperature range (200–600°C) is shown to correlate with the amount of reactive surface and subsurface oxygen removable during TPR below 420°C. These oxygen states in the samples of the La_{1 – x} Ca _x FeO_{3 – y} series can be associated with the domain or intergrain boundaries. No correlation is found between the amount of lattice oxygen removable during TPR and the activity of the La_{1 – x} Ca _x FeO_{3 – y} samples in the complete oxidation of methane at temperatures of 450–600°C. It is suggested that catalytic complete oxidation is determined by the most reactive surface and subsurface oxygen states located at the interphase boundaries, whereas the lattice oxygen does not participate in these reactions.     

Apparent Dipole Moments of 1-Butanol, 1-Propanol, and Chlorobenzene in Cyclohexane or Benzene, and Excess Molar Volumes of (1-Propanol or Chlorobenzene + Cyclohexane or Benzene) at T = 298.15K

Apparent dipole moments and relative permittivities of {x1-butanol + (1 – x) cyclohexane}, {x1-propanol + (1 – x)cyclohexane or (1 – x)benzene} and {xchloro- benzene + (1 – x)cyclohexane or (1 – x)benzene} were determined for the mole fraction range of 0.0003 < x < 0.1 at a temperature of T = 298.15 K and at a frequency of f = 100 kHz. The apparent dipole moments were calculated using Frohlich equation. The molar excess volumes for {x1-propanol + (1 – x)cyclohexane or (1 – x) benzene} and {xchlorobenzene + (1 – x)cyclohexane} were determined by a vibrating-tube densimeter at T = 298.15 K.     

Specific heat and phase transition of (Li1−xKx)2SO4 single crystals

A specific heat study of (Li_1–xK_x)₂SO₄ — LKS — mixed crystals has been made in a wide concentration rangex covering the temperature range 300–800 K. The phase diagram was determined. It is shown that a variation of the Li⁺:K⁺ concentration changes the critical behaviour of the specific heat. The results are discussed in terms of scattering mechanisms of energy carriers.

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Zusammenfassung Bei Temperaturen zwischen 300 und 800 K wurde für einen breiten Konzentrationsbereich für x die spezifische Wärme von (Li_1–xK_x)₂SO₄-Mischkristallen untersucht und das entsprechende Phasendiagramm erstellt. Es wurde gezeigt, daß eine Änderung des Verhältnisses Li⁺:K⁺ auch das kritische Verhalten der spezifischen Wärme verändert. Die Ergebnisse werden hinsichtlich von Sreuungsmechanismen der Energieträger diskutiert.

     

Neutron activation analysis of CdxHg1-xTe

A procedure has been developed for the analysis of Cd_xHg_1-xTe samples; the elements to be determined /Na, K, Cr, Mn, Cu, Co, Zn, As, La/ are separated by chromatography after neutron activation. The detection limit varies between 1×10^–5% and 5×10^–8%. A comparison of the calculation and semiempirical methods of the screening effect determination has been made.     

Phase transformations in formation of five-layer perovskites Ca5?xSrxTiNb4O17 (x=0?5) from coprecipitated hydroxocarbonate systems

We have determined the characteristic features of the formation of five-layer perovskites Ca_{5– x} Sr_xTiNb₄O₁₇ (x=0–5) from systems of coprecipitated hydroxocarbonates. We have established that the sequence of formation for their crystal structure depends on the composition and nature of the products obtained, and is different for the individual compounds Ca₅TiNb₄O₁₇, Sr₅TiNb₄O₁₇, and the phases Ca_5–x Sr_xTiNb₄O₁₇ (x=1–4).__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 50–54, January–February, 2005.     

Theoretical study of [Hg3(o-C6F4)3]n · {benzene} (n = 1, 2) complexes

The electronic structure and spectroscopic properties of [Hg₃(o-C₆F₄)₃]_n · {benzene} (n = 1, 2) were studied at the HF, MP2 and PBE levels. The interaction between [Hg₃(o-C₆F₄)₃] and benzene at the HF and MP2 levels was analyzed. Secondary π-interactions (Hg–benzene) were found to be the main contribution short-range stability in the [Hg₃(o-C₆F₄)₃] · {benzene} complex. At the MP2 and PBE levels equilibrium Hg–C distances of 338.4 and 361.4 pm; and interaction energies of 46.6 and 29.2 kJ/mol were found, respectively. The absorption spectra of these complexes were calculated by the single excitation time-dependent method at PBE level.     

Fluoride-conducting Electrolytes Based on Doped Oxyfluorides Pb1 – xAlxF2 + x–2yOy

Employing materials with fast transport of fluoride ions in chemical power sources and gas sensors requires synthesizing new materials with a wide range of electric properties. High conductivity of -PbF₂can be provided by introducing trivalent ions, which create excess concentration of fluoride ions in -PbF₂. Experimental data on the ionic conductivity of Pb_{1 – x} M _x F_{2 + x} , where M is In, Sb, or Bi, are presented in [1–3]. For the first time brief information about high ionic conductivity of doped Pb_{1 – x} Al _x F_{2 + x– 2y} O _y was reported in [4]. Here, we study in greater detail ionic conduction of neat Pb_{1 – x} Al _x F_{2 + x– 2y} O _y and that doped with fluorides of transition metals Zn, Cu, Ni, Co, Mn, Cr, V, or Ti in the temperature range 272–473 K.     

Nonlinear Impedance of Liquid In–Ga Electrode in Aqueous Solutions of a Symmetrical Surface-Inactive Electrolyte

Experimental data related to the potential dependence of nonlinear characteristics of the electrical double layer at a liquid In–Ga electrode in aqueous solutions of a symmetrical surface-inactive electrolyte are obtained for the first time. It is shown that, as opposed to polycrystalline Cd and Pb electrodes, on a liquid (atomically smooth) In–Ga electrode, as on Hg, there is a clear intersection of the potential dependences of a nonlinear signal for different concentrations of a 1–1-valence surface-inactive electrolyte at one point. The intersection point exactly corresponds to the potential of zero charge of an electrode undistorted by specific adsorption of ions. It is established that, when estimating hydrophilicity of metals by a nonlinear impedance method, most information is provided by the region of average negative charges, rather than by the region near zero charge. It is shown that, as opposed to a linear impedance method, the nonlinear impedance method makes it possible to determine, directly from experiment, quantities that directly characterize the metal–solvent chemisorption interaction in a pure form; at the same time, these quantities are criteria of lyophilic nature of metals. Quantities that characterize the metal–solvent chemisorption interaction, obtained by the linear and nonlinear impedance methods are in good agreement, which confirms the validity of the approach we proposed earlier for separating the difference between reciprocal capacitances of the inner part of the electrical double layer on Hg and metal M, ^Hg _M C ^-1 _i= 1/C ^Hg _i– 1/C ^M _iinto physical (^Hg _M C ^–1)_physand chemical constituents. This coincidence also confirms correctness of numerical values obtained earlier for quantities (^Hg _M C ^–1)_phys.     

Thermodynamic parameters of liquid ternary Fe1−x(Ni5/6Cr1/6)x alloys

Summary Computer-aidedKnudsen cell mass spectrometry is used for thermodynamic investigations on liquid ternary Fe_1–x(Ni_5/6Cr_1/6)_x alloys. The thermodynamic excess properties have been determined by means of the Digital Intensity-Ratio (DIR) method. Liquid ternary Fe_1–x(Ni_5/6Cr_1/6)_x alloys are characterized by exothermic molar heats of mixingH ^E, negative molar excessGibbs energiesG ^E, and negative molar excess entropiesS ^E. At 1850 K, the minimumH ^E value is –3120 J/mol (42.3 at.% Fe), the minimumG ^E value is –2540 J/mol (30 at.% Fe), and the minimumS ^E value is –0.44 J/(mol K) (60 at.% Fe). At 1850 K, the thermodynamic activities of Fe show slight negative deviations from the ideal behaviour for alloys with a Fe-content of less than 75 at.%, and ideal behaviour for the Fe-rich alloys (x _Fe>0.75).

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Thermodynamische Parameter flüssiger ternärer Fe_1–x(Ni_5/6Cr_1/6)_x-Legierungen

Zusammenfassung Die Thermodynamik flüssiger ternärer Fe_1–x(Ni_5/6Cr_1/6)_x-Legierungen wurde mit Hilfe der computerunterstützten Knudsenzellen-Massenspektrometrie studiert. Die thermodynamische Auswertung der experimentellen Untersuchungen erfolgte nach der digitalen Intensitätsverhältnismethode (DIR). Flüssige ternäre Fe_1–x(Ni_5/6Cr_1/6)_x-Legierungen zeigen exotherme molare MischungswärmenH ^E, negative molareGibbssche ZusatzenergienG ^E, und negative molare ZusatzentropienS ^E. Bei 1850 K sind die Minimumswerte fürH ^E –3120 J/mol (42.3 At.% Fe), fürG ^E –2540 J/mol (30 At.% Fe) und fürS ^E –0.44 J/(mol K) (60 At.% Fe). Bei 1850 K zeigen die thermodynamischen Aktivitäten von Fe bei Legierungen mit einem Fe-Gehalt von höchstens 75 At.% leichte negative Abweichungen vom idealen Verhalten, die Fe-reichsten Legierungen (x _Fe>0.75) verhalten sich hingegen nahezu ideal.

     

CdTe and anodic oxides on Hg1−xCdxTe: interface and compositional analysis using Rutherford backscattering spectroscopy

The composition and interfacial region has been studied for CdTe and anodic oxides deposited/grown on Hg_1?xCd_xTe using Rutherford backscattering spectroscopy. The interfacial region for the CdTe/Hg_1?xCd_xTe sample was found to be ～35 nm, in which out‐diffusion of Hg was observed. The interfacial region in the case of anodic oxides/Hg_1?xCd_xTe was found to be very small, <10 nm (of the order of experimental resolution), in which the Hg concentration increases steeply and the oxygen concentration decreases. Passivant and bulk compositions also have been obtained in both cases. Copyright © 2005 John Wiley & Sons, Ltd.