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1	Author	Tooru Hasebe, Kazuko Tanaka	Requires cookie*
	Title	7L i -N M
	Abstract	R S tu d ie s o n M o le c u la r M o tio n o f H y d r a te d L ith iu m Io n s in C o n c e n tr a te d A q u e o u s S o lu tio n s o f L iC l, L iB r , a n d L iS C N a t L o w T e m p e r a tu r e s Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Nuclear spin-lattice relaxation times, 7\, of 7Li in 13.8mol/kg LiCl-H20 and 12.3 mol/kg LiCl-D20 solutions have been measured in the temperature range 80K-313K. They showed similar temperature dependences with the same minimum values (27 ± 1 ms) which proved that the electric quadrupole interaction is dominant for the relaxation of 7Li-NMR. The Tx and T2 values of 7Li-NMR in concentrated aqueous solutions of LiCl (8-14 mol/kg), LiBr (8-10 mol/kg) and LiSCN (8-14 mol/kg) at 80 K to 300 K have been studied to obtain information concerning the dynamic properties of Li+ ions and the effect of anions. Ti at temperatures higher than the glass transition point is governed by a tumbling motion of the hydrated lithium ions.
	Reference	Z. Naturforsch. 50a, 1—6 (1995); received October 5 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0001.pdf
	Identifier	ZNA-1995-50a-0001
	Volume	50

2	Author	Hiroyasu Nomura, Shinobu Koda, Takashi Sakurai	Requires cookie*
	Title
	Abstract	Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The Raman band of the Vj(Ax) mode of S04~ of Li2S04 dissolved in water and water-dimethyl-formamide mixtures was measured in the concentration range 0.01 to 0.2 mol • dm-3. The central frequency of the sulfate ion increases with sulfate concentration. The limiting frequency at infinite dilution depends on the DMF content. The Raman band becomes asymmetric with increasing concentration of Li2S04 in 20 wt% DMF mixtures and with addition of LiCl to the aqueous solution of Li2S04. The vibrational relaxation behavior of the v1(A1) mode was investigated by analyzing the vibrational correlation function based on Kubo's stochastic theory. D y n a m ic s o f th e S u lfa te Io n in D ilu te W a te r -D M F S o lu tio n s
	Reference	Z. Naturforsch. 50a, 7—10 (1995); received November 4 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0007.pdf
	Identifier	ZNA-1995-50a-0007
	Volume	50

3	Author	Makoto Koide, Shin-Ichi Ishiguro	Requires cookie*
	Title	T
	Abstract	h e r m o d y n a m ic s a n d S t r u c t u r e o f I s o th io c y a n a te C o m p le x e s o f M a n g a n e s e (I I) , C o b a l t(I I) a n d Z i n c (I I) Io n s in N ,N -D im e th y la c e ta m id e Dedicated to Prof. Dr. Ohtaki on his occasion of 60th birthday The complexation of manganese (II), cobalt (II) and zinc(II) with thiocyanate ions has been studied in N,N-dimethylacetamide (DMA) by calorimetry and spectrophotometry at 298 K. In these metal systems the formation of a series of four isothiocyanato complexes, [M(NCS)J<2-n)+ (n = 1-^4; M = Mn, Co, and Zn) was established, and their formation constants, enthalpies and entropies were determined. Interestingly, the complexation behavior in DMA is significantly different from that in N,N-dimethylformamide (DMF), despite of the similarity of the physicochemical properties of these solvents. The complexation is indeed enhanced significantly in DMA over DMF and is more exothermic in the former solvent. Furthermore, with cobalt(II) an octahedral to tetrahedral coordi nation geometry change was found to occur in DMA at an earlier step of complexation than in DMF. These results suggest that six-coordination of DMA molecules to a metal ion is severely sterically hindered.
	Reference	Z. Naturforsch. 50a, 11—17 (1995); received September 26 1994
	Published	1995
	Keywords	Thiocyanato complexes, Transition metal(II) ions, N, N-dimethylacetamide, Calorime try, Spectrophotometry
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0011.pdf
	Identifier	ZNA-1995-50a-0011
	Volume	50

4	Author	A. D. Trokhymchuk, M. F. Holovkob, K. Heinzinger0	Requires cookie*
	Title
	Abstract	The possibility of the existence of a pre-preak in the structure factor of water at 0.6 Ä ~1 is discussed on the basis of the combination of computer simulation and integral equation theory techniques. It indicates spatial correlations in water at distances of the order of 10 A.
	Reference	Z. Naturforsch. 50a, 18—20 (1995); received November 4 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0018.pdf
	Identifier	ZNA-1995-50a-0018
	Volume	50

5	Author	Ingmar Persson, Magnus Sandström, Haruhiko Yokoyama, Monika Chaudhry, Japan	Requires cookie*
	Title	S
	Abstract	tr u c tu r e o f th e S o lv a te d S tr o n tiu m a n d B a riu m I o n s in A q u e o u s, D im e th y l S u lfo x id e a n d P y r id in e S o lu tio n , a n d C r y s ta l S tr u c tu r e o f S tr o n tiu m a n d B a r iu m H y d r o x id e O c t a h y d r a te Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Single crystal X-ray data, collected at 298 K, are used to redetermine the crystal structure of the non-isomorphic compounds [Sr(H20)8](0H)2 and [Ba(H20)8](0H)2. The eight water oxygen atoms form distorted Archimedean antiprisms around the octahydrated metal ions with mean metal ion-oxygen distances 2.62 and 2.79 Ä for strontium and barium, respectively. A second coordination shell of 24 hydrogen-bonded oxygen atoms with mean metal ion-oxygen distances M • • • O" 4.76 and 4.80 A, respectively, is observed. The hydroxide ions in both structures have an unusual hydrogen bond arrangement with 5 bonds accepted and one donated. The structure of the solvated strontium and barium ions in aqueous, dimethyl sulfoxide and pyridine solutions has been studied by means of large angle X-ray scattering and extended X-ray absorption fine structure spectroscopy techniques. In aqueous solution independent determinations of the first-sphere metal-oxygen coordination by the two techniques resulted in the bond lengths Sr-O 2.63 (2) and Ba-O 2.81 (3) A, and for both metal ions a hydration number of 8.1 (3). The second coordination spheres are very diffuse with only about 13 water molecules at similar M • • • O" distances as in the crystal structures and 2-3 water molecules closer to the metal ions. In dimethyl sulfoxide solution both ions were found to coordinate 6.0 (5) solvent molecules with the distances Sr-O 2.54(1), Sr -S 3.77(1) A, and Ba-O 2.76(1), Ba -S 3.99(1) A. For the solvated ions in pyridine solution EXAFS measurements yielded the distances Sr-N 2.57 (2) and Ba-N 2.78 (3) A, with a probable solvation number of 6. Correlations of hydration enthalpies and partial molar volumes with experimental M-O bond distances in aqueous solution are used to discuss hydration numbers and bond character for all of the alkaline earth metal ions.
	Reference	Z. Naturforsch. 50a, 21—37 (1995); received November 8 1994
	Published	1995
	Keywords	Barium, Strontium, Hydration, Solvation, Structure
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0021.pdf
	Identifier	ZNA-1995-50a-0021
	Volume	50

6	Author	PiaC. Schoester3, ManfredD. Zeidlera, Tamäs Radnaib, PhilippeA. Boppc	Requires cookie*
	Title	C
	Abstract	o m p a ris o n o f th e S t r u c t u r e o f L iq u id A m id e s a s D e te rm in e d b y D if fr a c tio n E x p e r im e n ts a n d M o le c u la r D y n a m ic s S im u la tio n s Dedicated to Professor Hitoshi Ohtaki on the occasion of his 60th birthday The intermodular structures of liquid formamide, N-methylformamide and N,N-dimethylfor-mamide at room temperature are studied by means of NVE molecular dynamics computer simula tions. Newly developed flexible models are used. X-ray and neutron weighted structure and total radial pair distribution functions are computed from the simulated site-site pair distribution func tions. They are compared with experimental results. The agreement is usually satisfactory as far as heavy atom pairs are concerned while the lengths of the hydrogen bonds are found to be systemat ically too long in the simulations.
	Reference	Z. Naturforsch. 50a, 38—50 (1995); received October 8 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0038.pdf
	Identifier	ZNA-1995-50a-0038
	Volume	50

7	Author	Y. Marcus	Requires cookie*
	Title	T r a n
	Abstract	s f e r G ib b s F r e e E n e r g ie s o f D iv a le n t A n io n s fro m W a te r to O r g a n ic a n d M ix e d A q u e o u s -O r g a n ic S o lv e n ts Dedicated to Professor Hitoshi Ohtaki on the occasion of his 60th birthday The standard molar Gibbs free energies of transfer of divalent anions, in particular sulfate, from water into methanol, ethanol, ethylene glycol, dioxane, tetrahydrofuran, acetone, N-methylform amide, N,N-dimethylformamide, pyridine, acetonitrile, and dimethylsulfoxide and mixtures of some of them with water or some other solvent have been obtained from the literature. The tetraphenyl-arsonium tetraphenylborate extrathermodynamic assumption has been used as far as possible in order to obtain the single ion values. The generally unfavorable transfers from water (or protic solvents) into polar aprotic ones are interpreted in terms of the properties of the anions and of the solvents, dominated by the hydrogen-bonding acidity of water.
	Reference	Z. Naturforsch. 50a, 51—58 (1995); received October 6 1994
	Published	1995
	Keywords	Divalent anions, Ion properties, Sulfate, Solvent properties, Transfer Gibbs energy
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0051.pdf
	Identifier	ZNA-1995-50a-0051
	Volume	50

8	Author	Heinz Gamsjäger1, Harald Marhold1, Erich Königsberger1, YiJung Tsai1, Hans Kolmer2	Requires cookie*
	Title	S o lid - 3) 4 * **H20
	Abstract	S o lu te P h a s e E q u ilib ria in A q u e o u s S o lu tio n s IX . T h e rm o d y n a m ic A n a ly s is o f S o lu b ility M e a s u r e m e n ts : L a (0 H) M(C 0 Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The aqueous solubilities of La(OH)p^(COaJjA 0.1 H20, basic lanthanum carbonate of ancylite type, have been investigated as a function of ionic strength at 25.0 °C. The stoichiometric solubility constants defined by log* K1 0 = log [La3 + ] + 1.1 log pco — 3 log [H+1 have the values 11.10, 11.32, 11.42, 11.63, and 11.70 for / = 0.1, 0.25, 1.0, 2.0, and 4.0 mol kg (Na)C104 respectively. The extrapolation to infinite dilution using the Pitzer equations resulted in a "thermodynamic" solubility constant, log* K° 0 = 10.48 ± 0.08. This in turn led to the Gibbs energy of ancylite formation: Af G f98 {La(OH)08(CO3)11 0.1 H20} = -1.531.5 kJ mol-1.
	Reference	Z. Naturforsch. 50a, 59—64 (1995); received October 1 1994
	Published	1995
	Keywords	Solubility, Carbonates, Lanthanum, Thermodynamics, Pitzer model
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0059.pdf
	Identifier	ZNA-1995-50a-0059
	Volume	50

9	Author	J. Barthel, K. Bachhuber, R. Büchner	Requires cookie*
	Title	D
	Abstract	ie le c tr ic R e la x a tio n o f N a C 1 0 4 S o lu tio n s in F o r m a m id e , N -M e th y lf o r m a m id e , a n d N ,N -D im e th y lf o rm a m id e Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday Complex permittivity spectra in the frequency range 0.95 < v/[GHz] < 89 for N,N-dimethylform-amide (DMF), N-methylformamide (NMF), formamide (FA) and their solutions of NaC104 are investigated to study the change of liquid structure and dynamics arising from the availability of one hydrogen-bond acceptor site together with no (DMF), one (NMF), or two (FA) donor sites on the same molecule. Three solvent relaxation processes are observed for NMF and two for FA and DMF. The relaxation parameters are used to determine solvation numbers. They show that ion-solvent interactions lead to a reduction of the average length of the H-bonded NMF chains but have only moderate influence on the FA structure. An additional solute relaxation process in DMF solutions is due to the diffusion-controlled formation and decomposition of solvent-shared ion pairs.
	Reference	Z. Naturforsch. 50a, 65—74 (1995); received October 22 1994
	Published	1995
	Keywords	Dielectric relaxation, Formamides, Solvation, Solvent dynamics, Ion association
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0065.pdf
	Identifier	ZNA-1995-50a-0065
	Volume	50

10	Author	Moshe Belinskii, Ivano Bertini2, Oleg Galas2, Claudio Luchinat3	Requires cookie*
	Title	T
	Abstract	h e E le c tro n ic S tr u c t u r e o f th e F e 4S4 + C lu s te r in P r o te in s : T h e I m p o r ta n c e o f D o u b le E x c h a n g e P a r a m e te r Dedicated to Prof. Hitoshi Ohtaki on the occasion of his 60th birthday The recently obtained Mössbauer and EPR parameters of the Fe4S4+ polymetallic center in the High Potential Iron-Sulfur Protein (HiPIP) II from E. halophila have been reproduced with models based on pure Heisenberg exchange. The role of double exchange versus ./-inequivalence is dis cussed. An evaluation of the upper limit of the double exchange parameter in the Fe4S \|+ bimetallic center is also presented. The present calculations shed further light on the electronic structure of the Fe4S4+ center.
	Reference	Z. Naturforsch. 50a, 75—80 (1995); received September 21 1994
	Published	1995
	Keywords	Heisenberg exchange, Double exchange, Iron-sulfur proteins
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0075.pdf
	Identifier	ZNA-1995-50a-0075
	Volume	50

11	Author	GlennH. Penner3, Baiyi Zhaoa, KennethR. Jeffrey0	Requires cookie*
	Title
	Abstract	The molecular dynamics of solid (CH3)3NBH3 is investigated by deuterium NMR spectroscopy. Variable temperature lineshape analyses yield activation energies of 27 + 3, 19 + 2, and 12.5 ± 2 kJ/mol for -CH3, -N(CH3)3 and -BH3 rotation, respectively. Analysis of the temperature depen dence of the spin-lattice relaxation times, Tt , gives activation energies of 33 + 3, 15 + 1.5, and 14 + 1.5 kJ/mol, respectively. Direct comparison of rotational exchange rates (from lineshape simu lations) an of rotational correlation times (from Tx analyses) for -N(CH3)3 and -BH3 rotation indicate that the two motions are correlated in solid (CH3)3NBH3 and together constitute a whole molecule reorientation about the N-B bond. This is supported by an internal rotational barrier of 18.0 kJ/mol for-BH3 rotation, obtained from ab initio molecular orbital calculations at the MP2/6-31G* level.
	Reference	Z. Naturforsch. 50a, 81—89 (1995); received September 22 1994
	Published	1995
	Keywords	NMR spectroscopy, Molecular dynamics, NMR relaxation
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0081.pdf
	Identifier	ZNA-1995-50a-0081
	Volume	50

12	Author	P. Hartmann, G. Scheler	Requires cookie*
	Title
	Abstract	Herrn Prof. W . Müller-Warmuth zum 65. Geburtstag gewidmet Is solid state 91 Zr NMR feasible? 91Zr solid state NMR spectra have been observed for samples possessing different zirconium local-site environments (e.g. phosphates, fluorides). Depending on the quadrupole coupling, different NMR experiments have been utilized. In case of weak quadrupole coupling, magic angle spinning (MAS) is suitable. Otherwise, spin echo techniques are necessary to overcome "acoustic ringing" and receiver dead-time limitations. Using the step echo method, the detection of the very broad 91Zr signals is not limited by non-uniform spectral excitation. The obtained 91Zr chemical shifts range from —246 ppm to 208 ppm, the quadrupole coupling frequencies from 50 kHz to 2.7 MHz.. I s t 91Z r -F e s tk ö r p e r -K e r n r e s o n a n z s p e k tr o s k o p ie p r a k tik a b e l?
	Reference	Z. Naturforsch. 50a, 90—94 (1995); received September 26 1994
	Published	1995
	Keywords	Solid state NMR, Zirconium-91, MAS, Spin echo, Acoustic ringing
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0090.pdf
	Identifier	ZNA-1995-50a-0090
	Volume	50

13	Author	A. Detken, P. Focke, H. Zimmermann, U. Haeberlen, Z. Olejniczak, Z. T. Lalowicz	Requires cookie*
	Title	D
	Abstract	e u te r o n N M R o f M e th y l G r o u p s in t h e T u n n e lin g R e g im e . A S in g le C r y s ta l S tu d y o f A s p ir in -C D 3 We dedicate this paper to Prof. Dr. Werner Müller-Warmuth on the occasion of his 65th birthday. Z. T. L. and U. H. owe much to his advice. We report the first single crystal deuteron NMR spectra of CD3 groups which display the so-called ±ß, ± (\|a\| ± ß) and ±(2\|a\| ± ß) lines characteristic of rotational tunneling in a sufficiently clear manner to allow a quantitative comparison with the respective theory developed in 1988 by the group of W. Müller-Warmuth. The molecular system we study is aspirin-CD3. We recorded spectra for differently oriented single crystals and measured spin-lattice relaxation times T\ in a wide temperature range. At 12.5 K we exploit the dependence of the ±(\|a\| ± ß) and ±(2\|a\| ± ß) lines on the orientation of the applied field Bo for determining the equilibrium orientation of the CD3 group in the crystal lattice. The spectra display features which allow, by comparison with simulated spectra, a measurement of the tunnel frequency ut. Its low temperature limit is (2.7 ± 0.1) MHz. It allows to infer the height V3 of the potential V(</?) in which the CD3 group moves, provided that this potential is purely threefold. We get V3 = (47.2 ± 0.5) meV. The transition from the tunneling to the classical, fast reorienting regime occurs in the 15 K ~ T ~ 35 K temperature range. In this range we observe a broadening, merging and eventually narrowing of the ± \|a \| and ±2\|a\| lines in very much the way predicted by Heuer. His theory, however, must be extended by taking into account all librational levels. The behaviour of the ± ß lines in the transition temperature range signalizes a reduction of the observable tunnel frequency with increasing temperature. This reduction allows an independent measurement of the potential height and represents a test of the assumption of a purely threefold potential. From the T\ -data we derive the temperature dependence of the correlation time t c of the reorientational jumps. The plot of log rc vs. 1 /T follows a straight line for more than five decades. From its slope we get yet another independent number for the potential height. It agrees well with the other ones, which confirms the assumption of the essentially threefold potential V(<p) in aspirin-CD 3.
	Reference	Z. Naturforsch. 50a, 95—116 (1995); received October 41994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0095.pdf
	Identifier	ZNA-1995-50a-0095
	Volume	50

14	Author	D. P. Cooper, E. Schöll	Requires cookie*
	Title
	Abstract	It is demonstrated numerically that by using Pyragas' method of chaos self-control a stable semiconductor oscillator can be designed based on driven real-space transfer oscillations in a modulation-doped heterostructure. By application of a small time-continuous delayed feedback voltage control signal, different unstable periodic orbits embedded in the chaotic attractor can be stabilized. Thus different modes of self-generated periodic voltage oscillations can be selected by choosing an appropriate delay time. This provides tunability to different discrete frequencies. PACS numbers: 05.45.+ b, 72.20 Ht.
	Reference	Z. Naturforsch. 50a, 117—124 (1995); received November 5 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0117.pdf
	Identifier	ZNA-1995-50a-0117
	Volume	50

15	Author	GurpreetK. Gill, S. K. Trehan	Requires cookie*
	Title	E
	Abstract	x p lo s iv e I n s ta b ility in S u p e rp o s e d F lu id s in H y d r o m a g n e tic s We study the resonance interaction between two marginally unstable modes of small but finite amplitude waves in the Kelvin-Helmholtz flow model using the method of multiple scales. We find that, as magnetic field increases, the amplitudes of the disturbance diverge at a very high rate while for a fluid of higher density ratio e, the amplitudes diverge very slowly.
	Reference	Z. Naturforsch. 50a, 125—130 (1995); received
	Published	1995
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	Identifier	ZNA-1995-50a-0125
	Volume	50

16	Author	H. Hartwig, U. Kretschmer, H. Dreizler	Requires cookie*
	Title	T
	Abstract	h e 33S N u c le a r Q u a d r u p o le H y p e r f ln e S tr u c tu r e in th e R o ta tio n a l S p e c tr u m o f 32S , 33S D im e th y l D is u lfid e We investigated the rotational spectrum of 32S, 33S dimethyl disulfide in natural abundance by molecular beam Fourier transform microwave spectroscopy. We were able to determine the com plete 33S quadrupole coupling tensor, the rotational and centrifugal distortion constants and the internal rotation parameters of the two methyl tops. The rotational constants were found to be A = 8113.8847(23) MHz, B = 2800.6203(30) MHz and C = 2557.2245 (32) MHz. The results are compared with former publications.
	Reference	Z. Naturforsch. 50a, 131—136 (1995)
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0131.pdf
	Identifier	ZNA-1995-50a-0131
	Volume	50

17	Author	Laaksonen, RoderickE. Wasylishen	Requires cookie*
	Title	Aatto
	Abstract	Nitrogen (14N) and deuterium (2H) nuclear quadrupolar coupling constants, x(14N) and *(2H), have been calculated for liquid ammonia at 197 K, 232 K, and 271 K, using a combination of molecular dynamics simulations and ab initio molecular orbital calculations. The basis set and cluster size dependence of the calculated results has been examined. The calculated value of x(14N) for liquid ammonia at 197 K, —3.45 MHz, is found to be close to the accepted solid-state value. At 232 K and 271 K, the magnitudes of the calculated values are about 5 — 10% greater: —3.56 MHz and —3.67 MHz, respectively, but still well below the accepted gas-phase value, —4.09 MHz. The calculated values of X (2H) for liquid ammonia are by about 20% smaller than the corresponding values calculated for the gas-phase monomer. On the basis of the calculations presented here and those of previous workers it is clear that the accepted experimental value of x(2H) for solid ammonia-d3 is too small. C a lc u la tio n s o f 14N a n d 2H N u c le a r Q u a d r u p o la r C o u p lin g C o n s ta n ts f o r L iq u id A m m o n ia
	Reference	Z. Naturforsch. 50a, 137—144 (1995); received October 5 1994
	Published	1995
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0137.pdf
	Identifier	ZNA-1995-50a-0137
	Volume	50

18	Author	A. Heinrich-Schramm, W. E. Price, H.-D Lüdemann	Requires cookie*
	Title	T
	Abstract	h e In flu e n c e o f D ip o le -D ip o le I n te r a c tio n a n d H y d r o g e n B o n d in g U p o n T r a n s la tio n a l D iffu s iv ity in S im p le F lu id s Self-diffusion coefficients of dimethylether have been measured as a function of temperature (185-458 K) and pressure (up to 200 MPa) by pulse-gradient field spin-echo NMR. Calculated activation volumes (AV*) fall from 15 (10-6 m3/mole) at the highest temperature to 7 (10~6 m3/mole) at the lowest. This trend is in keeping with values for other non-associating liquids. Comparison with self diffusion data for propane and ethanol reveals that the translational diffusivity in dimethylether is influenced by the substance's modest dipole moment (1.3 Debye). The effect is small but measur able and becomes more pronounced at lower temperatures. S e lf-D iffu s io n in C o m p re s s e d D im e th y le th e r :
	Reference	Z. Naturforsch. 50a, 145—148 (1995); received October 5 1994
	Published	1995
	Keywords	Dimethylether, Diffusion, High Pressure
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0145.pdf
	Identifier	ZNA-1995-50a-0145
	Volume	50

19	Author	Heinrich-Schramm, W. E. Price, H.-D Lüdemann	Requires cookie*
	Title	A
	Abstract	Self-diffusion in ethanol/hexane and dimethylether/hexane mixtures of various compositions has been measured at 215-350 K and up to 200 MPa. Qualitative analysis of the results indicates that, as expected, hydrogen bonding retards the self-diffusion of ethanol in the mixture, especially at the low temperatures. Dimethylether shows a slight effect of dipole-dipole interactions on the self-diffu sion, as seen by a higher AE* value than for the alkane. However there is no significant difference in the pressure dependence for both mixtures. This is shown by considering the ratio of the two diffusion coefficients, which suggests that, contrary to what is observed for pure alcohols, pressure has little effect upon the hydrogen bonding of ethanol in the mixture. In additon, there is surprisingly little concentration dependence on the ratios for either mixture.
	Reference	Z. Naturforsch. 50a, 149—154 (1995); received October 5 1994
	Published	1995
	Keywords	Binary mixtures, Self diffusion, High pressure
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	TEI-XML for	default:Reihe_A/50/ZNA-1995-50a-0149.pdf
	Identifier	ZNA-1995-50a-0149
	Volume	50

20	Author	V. Massarotti, D. Capsoni, M. Bini	Requires cookie*
	Title	S
	Abstract	ta b ility o f (N i 1_ xL i x) (L i 1_ J,N iJ?) 0 2 O r d e r e d S o lid S o lu tio n The stability of ordered solid solutions (OSS) with LiNi02 structure has been studied in a wide range of the lithium cationic fraction (0.22 < xt < 0.42). The OSS is obtained from the reactive system Ni0/Li2C 03 at 800 °C starting with high nominal lithium content (xt = 0.5). By analysis of the decrease of x, observed after annealing, during which evaporation and a contact reaction occurs, structure-composition relationships can be obtained. The transformation of the ordered phase, due to a cation exchange process, is observed for xt < 0.31 by accurate X-Ray powder pattern analysis (Rietveld method). By increasing the annealing time (decreasing lithium content), the data can be explained on the basis of progressive formation of the simple solid solution (SSS) with only one cation site and halved c axis value. The variations of structural parameters during the transformation are compared with those reported in the litera ture. The coherence domains of the OSS become smaller and the phase percentage decreases, while the SSS percentage increases. The rate of such a process can be well described on the basis of a two dimensional diffusion mechanism.
	Reference	Z. Naturforsch. 50a, 155—168 (1995); received November 21 1994
	Published	1995
	Keywords	Lithium Nickel Oxides, Solid state reaction, Solid solution, Order-Disorder Transfor mation
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	Identifier	ZNA-1995-50a-0155
	Volume	50

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