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'Lithium Nickel Oxides' in keywords
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1998 (1)
1995 (1)
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    V. Massarotti, D. Capsoni, M. Bini, C. B. Azzoni, M. C. Mozzati, A. PaleariRequires cookie*
 Title    Structural and Magnetic Characterization of Mixed Oxides: A Study of Li-Ni-O and Li-Mn-O Systems  
 Abstract    The present paper details the way to determine the cation distribution in mixed oxides with transition ions from the diffraction and magnetic susceptibility data. This approach allows one to determine phase abundances and phase compositions by two combined procedures. By X-ray diffraction Rietveld pro-file refinement and magnetic susceptibility data analysis it is possible to estimate the ratio and the oc-cupancy factor of paramagnetic ions in different oxidation states. A brief discussion of practical cases is reported. In the Li-Ni-0 system the lithium cationic fraction of the ordered phase Li 2r Ni2_2 X 0 2 in-creases monotonically with the total lithium fraction x, for 0.31 < x, < 0.46. In the Li-Mn-0 system for 0.36 < JC, < 0.53 the Li 2 Mn0 3 fraction has been determined, and for the coexistent Li [Li-y Mn 2 _ > ,] 0 4 spi-nel phase the dependence of y on x t has been evaluated. 
  Reference    Z. Naturforsch. 53a, 150—156 (1998); received January 30 1998 
  Published    1998 
  Keywords    X-ray Powder Diffraction, Magnetic Susceptibility, Lithium Nickel Oxides, Lithium Man-ganese Oxides, Lithium Manganese Spinel 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0150.pdf 
 Identifier    ZNA-1998-53a-0150 
 Volume    53