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1995[X]
81Author    A. Schirmer, P. HeitjansRequires cookie*
 Title     
 Abstract    iffu siv e M o tio n in S ta g e -1 a n d S ta g e -2 L i-G r a p h ite I n te r c a la tio n C o m p o u n d s: R e s u lts o f ß -N M R a n d Q u a s ie la s tic N e u tr o n S c a tte r in g Dedicated to Professor Werner Müller-Warmuth on the occasion of his 65th birthday Investigations of Li diffusion in stage-1 and stage-2 Li graphite intercalation compounds with neutron time-of-flight and backscattering techniques and ^-radiation detected nuclear magnetic resonance/relaxation (/J-NMR) with the nucleus 8Li(T1/2 = 0.8 s) are reviewed and compared. De­ pending on temperature, the spin-lattice relaxation-rate T{1 of 8Li is governed by different pro­ cesses. Above 300 K, T f1 (T) shows maxima induced by long-range Li+ diffusion. Jump correlation times are estimated. Inspection of the B field dependence of T f1 revealed two-dimensional diffusion behaviour. The neutron spectra showed a quasielastic line broadening above 500 K, which was used to obtain diffusion coefficients and to trace jump vectors of the in-plane motion. The diffusion parameters observed with both techniques are compared, and differences that show up are dis­ cussed. In addition, the low-temperature spin-lattice relaxation rates, being due to coupling to conduction electrons, are used to explore electronic properties. 
  Reference    Z. Naturforsch. 50a, 643—652 (1995); received November 3 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0643 
 Volume    50 
82Author    EdwardH. PoindexterRequires cookie*
 Title      
 Abstract    Dedicated to Prof. W . Müller-Warmuth on the occasion of his 65th birthday Research on hydrogenous species in the Si-Si02 system is reviewed and examined. Some aspects of thermal silica on silicon are explained by comparison with crystalline quartz or bulk amorphous fused silica. Hydrogen behavior in the Si-Si02 system is complicated by the unique features of device processing technology, an electrified interface, and high electric fields. An electrochemical model of the negative-bias-field-induced degradation of the system is used as a starting point for discussion of diffusion and solubility, atomic H disposition, thermochemical phenomena, and radiation damage. It is thereby hoped to provide new approaches for complete modeling of hydro­ gen physical chemistry in the Si-Si02 system. P h y s ic a l C h e m is try o f H y d r o g e n o u s S p e c ie s in th e S i -S i 0 2 S y s te m 
  Reference    Z. Naturforsch. 50a, 653—665 (1995); received February 6 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0653 
 Volume    50 
83Author    U. KretschmerRequires cookie*
 Title      
 Abstract    The rotational spectrum of the 33S dimethylsulfoxide in natural isotopic abundance has been studied using molecular beam Fourier transform microwave spectroscopy. Rotational and qua­ drupole coupling constants could be extracted from the spectra. They were found to be A = 7017.5456(16) MHz, ß = 6894.5117(17) MHz, C=4218.14115(84) MHz, -15.720(18) MHz, X hh= -17.045(23), and X cc = 32.765(25) MHz. T h e 33S N u c le a r Q u a d r u p o le H y p e r fin e C o u p lin g in th e R o ta tio n a l S p e c tr u m o f 33S D im e th y ls u lfo x id e 
  Reference    Z. Naturforsch. 50a, 666—668 (1995); received February 15 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0666 
 Volume    50 
84Author    Ivan Gutmana, Tamás KörtvélyesiaRequires cookie*
 Title      
 Abstract    A correlation between the Wiener index (W) and the molecular surface of the respective alkane is established for the first time. This correlation is curvilinear and not particularly good. W is only weakly correlated to molecular volume of saturated hydrocarbons and does not reflect at all their surface-to-volume ratio. By this a long-existing controversy concerning the physico-chemical inter­ pretation of W is resolved. 
  Reference    Z. Naturforsch. 50a, 669—671 (1995); received February 20 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0669 
 Volume    50 
85Author    Anna Corrias, Guido Ennas, Giorgio Paschina, Daniela ZeddaRequires cookie*
 Title    A n X -R a  
 Abstract    y D if f r a c tio n S tu d y o n A m o rp h o u s T r a n s itio n M e ta l-B o r o n A llo y s O b ta in e d by D if fe r e n t P r e p a r a ti o n M e th o d s The metal-metal structure of amorphous metal-boron alloys prepared by melt spinning, chemical reduction and mechanical alloying is compared. The general features of the structure functions and radial distribution functions obtained from X-ray diffraction data are similar. The first peak of the radial distribution function, mainly due to metal-metal nearest neighbours, has been simulated by a peak shape function. In all the investigated samples the best fit was obtained using two slightly different metal-metal distances, which suggests the presence of an asymmetric distribution. 
  Reference    Z. Naturforsch. 50a, 672—676 (1995); received Feburary 20 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0672 
 Volume    50 
86Author    T. T. Chia, B. L. Tan, S. Lima, I. C. Moreira, A. M. SerraRequires cookie*
 Title    Accumulation and bifurcation points ofthe discontinuous logistic map  
 Abstract    For most values of xde(— 1,1), the logistic map with a sectional discontinuity at jc = jtd possesses at least one inverse cascade. By using the property that, when xd is positive or zero, every first cascade accumulates at a parameter a = aacc immediately at the end of a 2-cycle, we explain the functional dependence of aacc on Jtd. Further, we derive hitherto unknown, general analytical expressions for aacc when xd lies in the range (0,0.9); in particular, these expressions give values of aacc identical to those previously found by a computational technique for selected values of xd in the same range [B. L. Tan and T. T Chia, Phys. Rev. E 47, 3087 (1993)]. We also present a method for calculating the values of the bifurcation points within any inverse cascade for this map and for the TB map which consists of two piecewise linear portions [A. A c c u m u la tio n a n d b ifu r c a tio n p o in ts o f th e d is c o n tin u o u s lo g is tic m a p 
  Reference    Z. Naturforsch. 50a, 677—683 (1995); received February 4 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0677 
 Volume    50 
87Author    Uwe Hoppe3, Günter Walter8, Dörte Stachelb, AlexC. HannoncRequires cookie*
 Title     
 Abstract    h o r t-R a n g e O r d e r D e ta ils o f M e ta p h o s p h a te G la s s e s S tu d ie d b y P u ls e d N e u tr o n S c a tte r in g Details of the short-range order of the binary metaphosphate glasses A1P30 9 and PbP2Oe and the ternary glass system ZnO-MgO-2P2Os have been studied by pulsed neutron scattering which provides a measuring range up to about ß m ax = 500 nm-1. The splitting of the P-O peak in the distance correlation functions attributable to the different bond lengths for the non-bridging and bridging oxygens was found to decrease with increasing field strength of the network-modifier cations. For the ternary system ZnO-MgO-2P2Os the peak in the distance correlation function, T(r), produced by the first oxygen neighbours around Zn2+ and Mg2+ was separated by the additional use of the X-ray structure factor. The distances rZn0 and rM gQ extracted from the separated peaks are slightly different from those obtained from the binary glasses ZnP20 6 and MgP20 6. The metal-oxygen coordination numbers were found to be NZn0=4.5 and NM g0 = 5.5. For the two binary systems the coordination numbers Al-0 and Pb-0 were obtained to be 7 and 5, respectively. 
  Reference    Z. Naturforsch. 50a, 684—692 (1995); received March 6 1995 
  Published    1995 
  Keywords    Pulsed neutron scattering, phosphate glasses, short-range order 
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 Identifier    ZNA-1995-50a-0684 
 Volume    50 
88Author    PeterH. Richter8, Andreas Wittek8, MikhailP. Kharlamovb, AlexejP. Kharlamov0Requires cookie*
 Title      
 Abstract    Dedicated to Professor Siegfried Großmann on the occasion of his 65th birthday Integrable billiards in ellipsoidal and related shapes are discussed. The emphasis is on the computation and graphic presentation of energy surfaces in the space of action variables. Explicit results, including figures, are given for spheres, circular cylinders, planar ellipses, prolate and oblate ellipsoids. A c tio n I n te g r a ls f o r E llip s o id a l B illia rd s Ich habe vorgestern die geodätische Linie für ein Ellipsoid mit drei ungleichen Achsen auf Quadraturen zurückgeführt. Es sind die ein­ fachsten Formeln von der Welt, Abelsche Inte­ grale, die sich in die bekannten elliptischen verwandeln, wenn man zwei Achsen gleich setzt. Königsberg, 28. Dezember 1838 
  Reference    Z. Naturforsch. 50a, 693—710 (1995); received February 28 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0693 
 Volume    50 
89Author    Michael Baakeal, PeterA B PleasantsbRequires cookie*
 Title      
 Abstract    Dedicated to Wolfram Prandl on the occasion of his 60th birthday The coincidence problem is analyzed in an illustrative fashion for some lattices and modules in two and three dimensions which are important for crystals and quasicrystals. We give a complete description of the groups of coincidence rotations with their associated indices and encapsulate their statistics by means of generating functions. 
  Reference    Z. Naturforsch. 50a, 711—717 (1995); received March 27 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0711 
 Volume    50 
90Author    Scott Rader, DiekW. Wheeler, W. C. Schieve, Pranab DasRequires cookie*
 Title      
 Abstract    Hübler's technique using aperiodic forces to drive nonlinear oscillators to resonance is analyzed. The oscillators being examined are effective neurons that model Hopfield neural networks. The method is shown to be valid under several different circumstances. It is verified through analysis of the power spectrum, force, resonance, and energy transfer of the system. Key words: Nonlinear resonance, Hopfield model, two-neurons, slaving. N o n lin e a r R e s o n a n c e in N e u r o n D y n a m ic s 
  Reference    Z. Naturforsch. 50a, 718—726 (1995); received May 9 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0718 
 Volume    50 
91Author    D. CamposRequires cookie*
 Title      
 Abstract    , 1994 C O The time-independent perturbation theory is developed for an arbitrary operator ft(X)= £ which can be expanded in powers of the perturbation parameter A . A unified formulation allows the establishment of a formal interrelation between the methods of Rayleigh-Schrödinger and of Bril­ louin-Wigner. We introduce a nonunitary transformation operator to connect the nth eigenket of #(0) with the nth eigenket of and it is proven that this operator satisfies a Lippmann-Schwinger type equation. A perturbation method based on this equation is proposed, and it is applied to describe an electron moving in a Yukawa potential. 
  Reference    Z. Naturforsch. 50a, 727—736 (1995); received July 14 
  Published    1995 
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 Identifier    ZNA-1995-50a-0727 
 Volume    50 
92Author    Noriaki Okubo, Mutsuo Igarashi, Ryozo YoshizakiRequires cookie*
 Title      
 Abstract    The 81 Br nuclear spin-lattice relaxation time in AlBr3 has been measured between 8 K and room temperature. The result is analyzed using the theory of the Raman process based on covalency. A Debye temperature of 67.6 K and covalency of0.070 and 0.072 for terminal and 0.022 for bridging bonds are obtained. The correspondence of the latter values to those obtained from the NQR frequencies is low, in contrast to the previously examined compounds. 81 B r N u c le a r Q u a d r u p o le R e la x a tio n in A lu m in iu m T rib ro m id e 
  Reference    Z. Naturforsch. 50a, 737—741 (1995); received February 20 1995 
  Published    1995 
  Keywords    Aluminium tribromide, Nuclear quadrupole relaxation, Raman process, Debye temper­ ature, Covalency 
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 Identifier    ZNA-1995-50a-0737 
 Volume    50 
93Author    M. Grottel3, A. Kozakb, Z. PająkRequires cookie*
 Title    l H a n  
 Abstract    d 19F N M R S tu d y o f C a tio n a n d A n io n M o tio n s in G u a n id in iu m F lu o r o a n tim o n a te s Proton and fluorine NMR linewidths, second moments, and spin-lattice relaxation times of polycrystalline [C(NH2)3]2SbF5 and C(NH2)3SbF6 were studied in a wide temperature range. For the pentafluoroantimonate, C3-reorientation of the guanidinium cation and C4-reorientation of the SbF5 anion were revealed and their activation parameters determined. The dynamical inequivalence of the two guanidinium cations was evidenced. For the hexafluoroantimonate, two solid-solid phase transitions were found. In the low temperature phase the guanidinium cation undergoes C3 reorien­ tation while the SbF6 anion reorients isotropically. The respective activation parameters were derived. At high temperatures new ionic plastic phases were evidenced. 
  Reference    Z. Naturforsch. 50a, 742—748 (1995); received March 2 1995 
  Published    1995 
  Keywords    NMR, Molecular Motions, Phase transitions 
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 Identifier    ZNA-1995-50a-0742 
 Volume    50 
94Author    A. Pojtinger, R. Bellissent, P. Lamparter, S. SteebRequires cookie*
 Title     
 Abstract    h e m ic a l a n d T o p o lo g ic a l S h o r t R a n g e O r d e r o f A m o rp h o u s T i-S i A llo y s Amorphous Ti10p_xSL alloys (13<x<60) were produced by sputtering. Their partial structure factors were determined by X-ray and neutron diffraction. The Bhatia-Thornton density-concentra-tion correlation function GNC(R) was calculated by a cluster relaxation model. Three-dimensional atomic clusters were produced by the Reverse Monte Carlo method. These clusters were analyzed in terms of trigonal prismatic arrangements as a structural unit. In amorphous Ti75Si25 and Ti87Si13 those Si-atoms which are surrounded by 9 Ti-atoms in the first coordination shell prefer trigonal prismatic arrangements. In the atomic clusters of amorphous TiS9Si41, Ti49Si51, and Ti40Si60, however, no preference of trigonal prisms was found. 
  Reference    Z. Naturforsch. 50a, 749—757 (1995); received March 11 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0749 
 Volume    50 
95Author    M.R S Tu D, Karin Eckardt3, Hartmut Fuess3, Masakazu Hattoric, Ryuichi Ikeda0, Hiroshi Ohkic, Alarich Weiss, Fachbereich Materialwissenschaft, Fachgebiet StrukturforschungRequires cookie*
 Title     
 Abstract    tr u c tu r e a n d D y n a m ic s o f C r y s ta l S o lv a te s H e x a p h e n y ld itin • 2 X , X = B e n z e n e , T o lu e n e , F lu o ro b e n z e n e , C h lo ro b e n z e n e , a n d A n ilin e . A n X -R a y , P (y a p o r)= /(T)> a n d 2H N The crystal structures of the hexaphenylditin (hpdt) solvate compounds, (C6H5)3Sn-Sn (C6H5)3 • 2X, solvent X = aniline (an), chlorobenzene (cb), fluorobenzene (fb), and toluene (to), were determined. They are isomorphous with the known benzene (be) crystal solvate compound hpdt • 2be, crystallizing in the trigonal space group R3, with Z=3 formula units per unit cell. The lattice constants (in pm), from X-ray powder diffraction, are: hpdt • 2an (1): a= 1170.01 (9), c = 2641.49 (20), c/a = 2.2577; hpdt • 2be (2): a = 1165.45 (5), c = 2641.30 (9), c/a = 2.2663; hpdt • 2cb (3): 0=1175.88(5), c = 2661.66(10), c/a = 2.2635; hpdt • 2fb (4): 0 = 1167.69(5), c = 2643.21 (9), c/a = 2.2636; hpdt • 2to (5): <7=1182.24 (7), c = 2649.13(l 1), c/a = 2.2408. The single crystal structure determination of 5 leads to a = 1180.2(2), c = 2651.4 (5). The decomposition of 5 results in the monoclinic phase of hexaphenylditin. Vapor pressure measurements p=f,T), 260 < T/K <350, of the compounds have been performed and the heats of vaporization A/fv/kJmole_ 1 were determined: 52.44 (1), 46.65 (2), 34.52 (3), 43.08 (4), 55.30 (5). The dynamics of the host molecules C6D6, C6D5CD3 and C6H5ND2 were studied by 2H NMR in the range 295 < T/K < 118. The rotation of the benzene molecule about its threefold axis is maintained till 118 K; in the case of toluene the rotation of the phenyl ring about the pseudo-threefold axis freezes in below 180 K, while the methyl group still rotates about its threefold axis till 123 K. 
  Reference    Z. Naturforsch. 50a, 758—769 (1995); received March 24 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0758 
 Volume    50 
96Author    Y. Waseda3, K. Sugiyama3, J. M. ToguribRequires cookie*
 Title      
 Abstract    A high temperature X-ray diffraction study of molten alumina has been carried out at 2363 K (2090 °C). The local ordering parameters in molten alumina were estimated by using the interference function refining technique. Octahedrally coordinated aluminum is suggested to remain in the melt as the fundamental local structure. 
  Reference    Z. Naturforsch. 50a, 770—774 (1995); received March 18 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0770 
 Volume    50 
97Author    H. Preuß, M. PernpointnerRequires cookie*
 Title     
 Abstract    ie L ö s u n g d e r S c h rö d in g e r-G le ic h u n g a ls ein d im e n sio n ale s P ro b le m . I I . T e s t a n E in e le k tr o n a to m e n Solving the Schrödinger-Equation as a One-Dimensional Problem. II. Tests on One-Electron Atoms As announced in part I of this work, concrete calculations on the one-electron atoms H, He+, and Li2+ are presented here. The results allow a comparison between the implemented method of discretization and other methods with respect to the one-dimensional formalism. The use of a Gaussian integral kernel makes it possible to perform the spatial integration analytically. Further­ more it is shown how fast oscillations in the curve parametrization can be avoided by the use of non-integral parameters. 
  Reference    Z. Naturforsch. 50a, 775—778 (1995); eingegangen am 6 März 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0775 
 Volume    50 
98Author    B. Robers, M. StockhausenRequires cookie*
 Title      
 Abstract    Dedicated to Professor Dr. E. Wicke X-band ESR spectra of liquid solutions of Cu(II)nitrate and Cu(II)chloride in N-methyl-formamide and four N,N-disubstituted amides are reported and discussed with respect to the occurrence of ion pairs or higher ionic aggregations. Nitrate solutions allow to distinguish two complex types of moderate asymmetry at most. Chloride solutions indicate a succession of at least three complex types with strongly increasing asymmetry. 
  Reference    Z. Naturforsch. 50a, 779—784 (1995); received December 16 1994 
  Published    1995 
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 Identifier    ZNA-1995-50a-0779 
 Volume    50 
99Author    F.F H Anna\, A. H. Shafikb, M. StockhausenbRequires cookie*
 Title    Static Permittivity and Association in M ixtures of Mono-and Dihydric Alcohols  
 Abstract    The static permittivity has been measured for «-hexanol and w-dodecanol in heptane solution on admixture of a mi­ nor (fixed) fraction of a dihydric alcohol (ethanediol, 1,6-hexanediol or 1,12-dodecanediol) from low to medium total alcohol concentrations. The 20 °C dispersion steps are re­ ported. They show a more or less pronounced intensification due to the additive, which unexpectedly is smaller on addi­ tion of two diols together than of only one diol. Probably this reflects competing self-and hetero-association equi­ libria. 
  Reference    Z. Naturforsch. 50a, 785—786 (1995); received March 23 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0785_n 
 Volume    50 
100Author    A. A. Kornysheva, D. A. Kossakowskib-C, S. LeikindRequires cookie*
 Title    L a n  
 Abstract    d a u T h e o r y o f a S y s te m w ith T w o B ilin e a rly C o u p le d O r d e r P a r a m e t e r s in E x t e r n a l F ie ld : E x a c t M e a n F ie ld S o lu tio n , C r itic a l P r o p e r tie s a n d I s o th e r m a l S u s c e p tib ility We present simple description of a system with two bilinearly coupled order parameters in external field based on an exact mean-field solution of the Landau Hamiltonian. It reproduces the qualitative form of the "field-temperature" phase diagram given by a molecular-field model and by more sophisticated theories and experiments on metamagnets. The solution gives the same critical exponents as the molecular-field theory, but it is not restricted to the magnetic systems only and it is easier to handle, since it formulates the results in explicit analytical form. The susceptibility in this model does not diverge at the second order transition line (far from a higher order critical point separating the second and first order transition lines), but jumps down from the lower temperature wing to the higher temperature one. The jump amplitude is proportional to the square of the field in small fields and diverges in large fields close to the higher order critical point. PACS 05.70.Fh 
  Reference    Z. Naturforsch. 50a, 789—794 (1995); received May 23 1995 
  Published    1995 
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 Identifier    ZNA-1995-50a-0789 
 Volume    50 
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