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Binary neodymium silicates were thoroughly investigated with respect to their crystal chemistry and physical properties. Formation and structure types of all known binary phases were confirmed. Moreover, the crystal structure determination of a phase previously reported to exist with approximate composition Nd(3)Si(4) was successfully performed from X-ray powder data on the basis of the isotypic orthorhombic Ho(3)Si(4)-type structure. The magnetic properties of these Nd silicates are characterized by the onset of ferromagnetic order below 120 K. Nd(5)Si(3) shows a canted spin structure, which might eventually also be the case for NdSi (T(c) = 45 K). Nd(5)Si(4) (T(C) = 67 K) and NdSi(1,4) (T(c) = 75 K) exhibit magnetic behavior as typically observed in narrow domain wall ferromagnets favouring easy axis anisotropy. NdSi(2-x) (I) (T(c) = 9 K) seems to adopt a more complex non-linear spin arrangement. NdSi(2-x) (II) exhibits an antiferromagnetic transition at a Neel temperature of T( N) = 10 K followed by a spin reorientation towards a parallel spin alignment at 9 K. The electrical resistivities resemble the temperature dependence of metals, with characteristic changes of slope of the p(T) curves at the Curie temperatures. The p(T) plots follow T(2) relations as predicted for isotropic ferromagnets, with the exception of NdSi(2-x) (I) (T(3.6), as usually observed for antiferromagnets).

Additional information

Authors: BOULET P, EC-JRC, Institute for Transuranium Elements, Karlsruhe (DE);WEITZER F, Institute fur Physikalische Chemie, Universitat Wien (AT);HIEBL K, Institute fur Physikalische Chemie, Universitat Wien (AT);NOEL H, Laboratoire de Chemie du Solide et Inorganique Moleculaire, Rennes (FR)
Bibliographic Reference: An article published in: Journal of Alloys and Compounds 315 (2001) pp. 75-81
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