ZfN: Search Results

1	Author	C. B. Azzoni, M. C. Mozzati, A. Paleari, V. Massarotti, D. Capsoni, M. Bini	Requires cookie*
	Title	Magnetic Order in Li-Mn Spinels
	Abstract	Magnetic measurements were carried out on different samples of Lithium-Manganese spinel LiMn 2 0 4 , great care having been taken to avoid the presence of spurious magnetic phases, such as Mn 3 0 4 . Sus-ceptibility data, showing deviations from paramagnetic behaviour at about 40 K, were analyzed in terms of local magnetic interactions, taking into account the structural and transport properties of these com-pounds. The magnetic response of pure and stoichiometric samples suggests that the onset of a long-range magnetic ordering is hindered by the topological frustration of the antiferromagnetic octahedral sublattice of the spinel.
	Reference	Z. Naturforsch. 53a, 693—698 (1998); received April 25 1998
	Published	1998
	Keywords	Magnetic Susceptibility, Electron Paramagnetic Resonance, Lithium Manganese Oxides, Lithium Manganese Spinel
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	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0693.pdf
	Identifier	ZNA-1998-53a-0693
	Volume	53

2	Author	C. B. Azzoni, M. C. Mozzati, A. Paleari, V. Massarotti, M. Bini, D. Capsoni	Requires cookie*
	Title	Evidence of a Cationic Substitution Domain in Lithium-Manganese Spinels
	Abstract	Magnetic susceptibility measurements and electron paramagnetic resonance spectra of samples prepared from the reactive system Mn0/Li 2 C0 3 with different starting Li cationic fraction x are analyzed, taking into account the structural and compositional information provided by x-ray diffrac-tion. Parent phases, as Mn 2 0 3 , Mn 3 0 4 and Li 2 Mn0 3 , arise together with the lithium-manganese spinel as a result of Li-deficiency or Li-excess with respect to the x = 0.33 composition pertinent to the stoichiometric LiMn 2 0 4 spinel. The data show that the spinel phase can sustain a partial Li-Mn substitution in the cation sites, according to compositional models described, for x > 0.33, by Lii +y Mnit 3y Mnf+ 2y 0 4 (Li-rich spinel) and, for x < 0.33, by Lii_\| J/ \|Mn^\|Mn^\| y \|Mnfi\| I/ \|0 4 (Li-poor spinel). Paramagnetic resonance data of the Li-poor spinel phase are analyzed to discuss the possible oxidation state of Mn in the tetrahedral site.
	Reference	Z. Naturforsch. 53a, 771—778 (1998); received June 22 1998
	Published	1998
	Keywords	Stoichiometric LiMn 2 0 4 Spinel Phase, Magnetic Susceptibility, Electron Paramagnetic Resonance
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	TEI-XML for	default:Reihe_A/53/ZNA-1998-53a-0771.pdf
	Identifier	ZNA-1998-53a-0771
	Volume	53

3	Author	V. Massarotti, D. Capsoni, M. Bini, C. B. Azzoni, M. C. Mozzati, A. Paleari	Requires 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

4	Author	Rainer Niewa3, GrigoriV. Vajenine3, FrancisJ. Disalvo, Haihua Luob, WilliamB. Yelonb	Requires cookie*
	Title	Unusual Bonding in Ternary Nitrides: Preparation, Structure and Properties of Ce2MnN3
	Abstract	CeiMnNj was prepared by reaction of cerium nitride and manganese with nitrogen gas at 900 °C. It crystallizes isotypic to AC2MN3 (Ac = U, Th; M = Cr, Mn) and Ce^CrN^, space group Immm (No. 71), a = 3.74994(6) A, b = 3.44450(6) A and c = 12.4601(2) A. The manganese atoms are coordinated in a nearly square planar fashion by four nitrogen atoms. These corner-connected MnN* units form infinite J. [MnN2N2/ 2 ] chains, which run parallel to each other along the crystallographic a-axis, forming the motif of hexagonal rod packing. Cerium atoms connect the chains into a three-dimensional network. The results of measurements of the magnetic susceptibility, as well as of the electrical resistivity suggest metallic behavior. Electronic effects leading to shorter bonds between manganese and bridging nitrogen atoms than between manganese and terminal nitrogen atoms in the J. [MnN2N2/ 2 ] chains were investigated through extended Hiickel and LMTO band structure calculations. Issues pertaining to stability of this and some other nitridometallate structures are discussed.
	Reference	(Z. Naturforsch. 53b, 63—74 [1998]; received September 17 1997)
	Published	1998
	Keywords	Ternary Nitride, Crystal Structure, Magnetic Susceptibility, Electrical Resistivity, Extended Hiickel Method
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	TEI-XML for	default:Reihe_B/53/ZNB-1998-53b-0063.pdf
	Identifier	ZNB-1998-53b-0063
	Volume	53