No abstract

No abstract

KNi(4)(PO(4))(3) has been synthesised following a method previously reported by some of us and studied on the basis of magnetization and neutron powder diffraction (NPD) data. Magnetization measurements suggest the coexistence of ferromagnetic (FM) and antiferromagnetic (AFM) interactions: magnetization versus magnetic field curves present a remanent magnetization of around 2.15 micro(B) at T=2 K. The magnetic structure of the KNi(4)(PO(4))(3) has been determined at low temperature from the NPD data. These measurements show that there are three magnetic sub-lattices of Ni(2+) ions, which interact through common oxygen or phosphate groups, giving rise to FM and AFM couplings. The resulting interactions are FM in nature. Such a complex behaviour could provide an interesting model to analyse magnetic interactions in more condensed systems, such in mixed metal oxides.

structure structure (solids and liquids) D 2000 -007Structural and Electrical Study of the Alluaudites (Ag 1−x Nax) 2 FeMn 2 (PO 4 ) 3 (x = 0, 0.5 and 1).-The title compounds are prepared by solid state reactions from stoichiometric amounts of AgNO 3 , Fe(NO 3 ) 3 ·9H 2 O, C 10 H 14 MnO 4 , (NH 4 ) 2 HPO 4 , and NaNO 3 at 1073 K. The isotypic compounds crystallize in the monoclinic space group C2/c with Z = 4 (powder XRD). The structure is formed by layers of edge-sharing FeO 6 and MnO 6 octahedra linked via common corners of PO 4 tetrahedra, yielding channels in which the monovalent cations are located. Complex impedance measurements show that the electrical conductivity in these compounds is predominantly of ionic character. The Ag derivatives are better conductors than the Ag-free one. -(DAIDOUH, A.; DURIO, C.; PICO, C.; VEIGA, M. L.; CHOUAIBI, N.; OUASSINI, A.; Solid State Sci. 4 (2002) 4, 541-548; Dep. Quim. Inorg., Fac. Cienc. Quim., Univ. Complutense, E-28040 Madrid, Spain; EN)