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1Author    V. Massarotti, D. Capsoni, M. BiniRequires cookie*
 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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 TEI-XML for    default:Reihe_A/50/ZNA-1995-50a-0155.pdf 
 Identifier    ZNA-1995-50a-0155 
 Volume    50 
2Author    Mohamed Yalpani, WernerE. KlotzbücherRequires cookie*
 Title    Transformations in Thin Solid Layers: The Reversible Polymerization-Depolymerization of 2,6-Di-n-propyl- l,3>5,7-tetraoxa-2,6-dibora-4,8-octalindiones at Low Temperatures  
 Abstract    The course of Aggregation of molecules of the title compound (lb) through different, spectro-scopically discernible and chemically identifiable forms of associations could be followed by matrix isolation and thin film infrared and UV-visible spectroscopy. It was found that molecules of lb in thin films form clusters which at low temperatures interact weakly, probably through the carbonyl oxygens of one and the boron atoms of the neighbouring molecules. On warming to 260 K this association gradually takes the form of more defined chelate bonds, probably with ordered three-dimensional intermolecular structures. Above this temperature spontaneous for-mation of crystallites of the previously reported 'hot' and 'cold' modifications was observed. Studies with films of varying thickness indicate an interdependence of crystallite size and lattice energies. 
  Reference    Z. Naturforsch. 40b, 222—228 (1985); received September 24 1984 
  Published    1985 
  Keywords    Solid State Reaction, Matrix Isolation, Aggregation, Phase Transformation, Microcrystals 
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 TEI-XML for    default:Reihe_B/40/ZNB-1985-40b-0222.pdf 
 Identifier    ZNB-1985-40b-0222 
 Volume    40 
3Author    V. Massarotti, M. Bini, D. CapsoniRequires cookie*
 Title    Structural and Defect Study of LiMn 2 0 4 Formation  
 Abstract    The LiMn 2 0 4 formation from MnO and Li 2 C0 3 mixtures with lithium cationic fraction 0.31 < x < 0.40 was studied by structural profile refinement from X-ray data, thermal (TGA and DSC) measurements and scanning electron microscopy (SEM) observations. Quantitative phase analysis, structural and microstructural parameters and composition of the coexisting phases were obtained. Different behaviours were observed in the composition ranges 0.33 < x < 0.35 and x > 0.37. In the former range only the stoichiometric spinel phase was obtained, in the latter, in addition to the Li 2 Mn0 3 compound, two spinel phases could be considered: I) LiMn 2 0 4 stoichiometric spinel; II) Li i +> Mn2-> .04 (0.11 < y < 0.23), a non-stoichiometric phase whose small particle size resulted practically independent of the initial composition and annealing temperature. Such a conclusion was supported also by SEM observations. The relative abundance of phase II increased with increasing lithium content and with decreasing temperature. 
  Reference    Z. Naturforsch. 51a, 267—276 (1996); received March 3 1996 
  Published    1996 
  Keywords    Solid state reaction, Lithium Manganese Spinel, Structural and microstructural parameters, Non-stoichiometry, Substitutional defects 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0267.pdf 
 Identifier    ZNA-1996-51a-0267 
 Volume    51 
4Author    V. Berbenni, A. Marini, D. CapsoniRequires cookie*
 Title    Solid State Reaction Study of the System Li 2 C03/Fe 2 03  
 Abstract    A thermoanalytical (TGA/DSC) and diffractometric (XRD) study has been performed on the solid state reaction system Li 2 C0 3 -Fe 2 0 3 in the x Li range 0.10-^0.50. A detailed analysis of the results shows that the data are in agreement with a reaction model where the carbonate decomposition is regulated by the formation of both LiFe0 2 and LiFe 5 0 8 , and the relative amount of the two phases depends on the initial composition. The DSC evidence offers the possibility to directly quantify the LiFe 5 O x phase. Fur-thermore it allows one to obtain the enthalpies of formation of both LiFe0 2 and LiFe 5 0 8 . 
  Reference    Z. Naturforsch. 53a, 997—1003 (1998) 
  Published    1998 
  Keywords    Lithium Ferrites, Solid State Reaction, Iron (III) Oxide, Lithium Carbonate, TGA, DSC 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0997.pdf 
 Identifier    ZNA-1998-53a-0997 
 Volume    53