Structures and Physical Properties of Ternary Antimonides RE 3 M Sb 5 ( M = Zr, Hf), U 3 M Sb 5 ( M = Zr, Hf, Nb), and Y
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Structures and Physical Properties of Ternary Antimonides RE3MSb5 (M = Zr, Hf), U3MSb5 (M = Zr, Hf, Nb), and YbCrSb3 Andriy V. Tkachuk, Shane J. Crerar, Xing Wu, Craig P. T. Muirhead, Laura Deakin, and Arthur Mar Department of Chemistry University of Alberta Edmonton, AB Canada T6G 2G2 ABSTRACT Ternary rare-earth transition-metal antimonides RExMySbz have provided fertile ground for discovering materials with varied electrical and magnetic properties such as superconductivity and ferromagnetism. The properties of two important classes of these compounds, RE3TiSb5 and RECrSb3, have been previously investigated. These studies have now been extended to RE3MSb5 (M = Zr, Hf), which show anomalies in their resistivity curves suggestive of electronic transitions, and YbCrSb3, which undergoes long-range magnetic ordering at 285 K, the highest Tc observed so far of all RECrSb3 members . Strong magnetic exchange interactions develop through coupling of f and d electrons in these compounds. The substitution of uranium for rare earth in RE3MSb5 results in the compounds U3MSb5 (M = Zr, Hf, Nb), which also display prominent transitions in their electrical resistivity and magnetic susceptibility curves. INTRODUCTION The structures of many ternary rare-earth antimonides RExMySbz with a high proportion of antimony can often be rationalized by an extension of the Zintl concept to the anionic substructures that are present [1]. These Sb substructures are frequently manifested as chains, ribbons, or sheets, extended in one or two dimensions, giving rise to partially filled wide bands in the electronic band structure that are associated with highly anisotropic electrical conduction. Necessarily, an inherent anisotropy is also imparted to the rest of the structure, so that the rareearth atoms are in low-dimensional arrangements. We have previously investigated ternary antimonides where M is another main-group element such as Ga, Ge, In, or Sn [1]. The magnetic properties of these compounds, which arise from the rare-earth atoms, are generally characterized by ordering at relatively low temperatures (< 10 K) [2, 3]. When M is a transition metal, higher magnetic ordering temperatures can be attained because of coupling of f and d electrons. Much of the impetus for studying these ternary rare-earth transition-metal antimonides stems from their varied physical properties. Until recently, these studies have largely been limited to compounds where M is a late transition metal. We have examined the properties of two extensive classes of compounds where M is an early transition metal, RE3TiSb5 [4] and RECrSb3 [5–7] In this work, we present extensions of these studies to RE3MSb5 (M = Zr, Hf), U3MSb5 (M = Zr, Hf, Nb), and YbCrSb3. EXPERIMENTAL DETAILS Starting materials were powders of the elements, generally of 99.9% or greater purity, obtained from Cerac, Alfa-Aesar, or Aldrich, or binary antimonides. Reactions were conducted
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on a 0.25-g scale, by combining stoichiometric mixtures of the elements. Powder samples were prepared
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