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Valence states and magnetic properties of LaNi1-xMnxO3 (for 0≤x≤0.2 and x=0.5)

Vasanthacharya, NY and Ganguly, P and Goodenough, JB and Rao, CNR (1984) Valence states and magnetic properties of LaNi1-xMnxO3 (for 0≤x≤0.2 and x=0.5). In: Journal of physics C: Solide state physics, 17 . 2745-2760.

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Single-phase LaNi1-xMnxO3 samples in the compositional range 0<or=x<or=0.2 were prepared by the decomposition of precursor hydroxide solid solutions, and La2NiMnO6 was prepared from a mixture of carbonates. All the samples contained a disordered array of nickel and manganese ions. X-ray absorption and XPS measurements indicate the presence of Mn(III) and Ni(III) valence states at room temperature for x=0.1, 0.2 and 0.5. Magnetic susceptibility data suggest Mn4+ solute ions and Stoner-enhanced Pauli paramagnetism of the metallic solvent for x=0.01 with a smooth transition to Mn3+ solute ions and a spontaneously magnetised solvent conduction band at x=0.05. Below 200K, the x=0.05 sample forms superparamagnetic clusters, and below 40K there is evidence for an antiferromagnet spin-density wave. Comparisons with LaCo0.95Mn0.05O3 and La0.98Sr0.02CoO3 confirm that the long-range magnetic coupling occurs via solvent electrons in a narrow conduction band. The conductivity changes from that of a narrow-band metal for x<0.01 to that more characteristic of diffusive motion for x>0.05, but any motional enthalpy appears to remain small ( Delta Hm approximately=0). The x=0.1 sample exhibits ferrimagnetic spin glass behaviour below 40K, and the ferromagnetic interactions increase with manganese concentration. The oxide with x=0.50 is ferromagnetic with a well defined Curie temperature.

Item Type: Journal Article
Publication: Journal of physics C: Solide state physics
Publisher: Institute of Physics
Additional Information: Copyright for this article belongs to Institute of Physics.
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited: 27 Jan 2010 12:09
Last Modified: 19 Sep 2010 05:44
URI: http://eprints.iisc.ac.in/id/eprint/22971

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