Structural chemistry, magnetism and electrical properties of binary Pr-silicides

Binary praseodymium silicides have been thoroughly investigated with respect to their crystal chemistry and physical properties. Formation and structure types of all known binary phases have been confirmed. Moreover, the crystal structure determination of a phase, previously reported to exist with the approximate composition Pr3Si4, was successfully performed from X-ray powder data on the basis of the isotypic orthorhombic Ho3Si4 type of structure. The magnetic properties of these Pr-silicides are characterized by the onset of ferromagnetic order below 110 K. Pr5Si3 (T-C=44 K) shows a canted spin structure. Pr5Si4 (T-C=40 K) and PrSi (T-C=51 K) reveal a weak aniosotropy. Whereas Pr3Si4 (T-C=105 K) exhibits a magnetic behavior as typically observed in narrow domain wall ferromagnets favoring easy axis anisotropy, the reduced saturation moment suggests a ferrimagnetic spin structure. PrSi2-x (x=0.12, GdSi2 type) exhibits an antiferromagnetic transition at a Neel temperature T-N = 11 K followed by a spin reorientation towards a parallel spin alignment at 9 K. The electrical resistivities resemble a temperature dependence of metals, with characteristic changes of slope of the p(T) curves at the Curie temperatures. The rho(T) plots follow similar toT(2) relations as predicted for isotropic ferromagnets in the ordered state for the compound PrSi1.33, only, whilst for the other compounds a similar toT(2.8-3.7) dependency was observed. (C) 2002 Elsevier Science B.V. All rights reserved.