EU4BI3 - CRYSTAL-STRUCTURE, MAGNETIC AND ELECTRONIC-PROPERTIES

The Eu-Bi system contains the phases Eu5Bi3, Eu4Bi3 and Eu11Bi10. The structure types of these phases have been determined by powder X-ray d iffraction. Crystals of Eu4Bi3 (cubic, space group <I(4)over bar 3d>; a = 9.920 Angstrom, Z = 4, T = 130 K, R1/wR2 = 4.86/10.84%) were obtai ned in low yield by reaction of Eu, Mn, and Ei in the ratio 14:1:11 in a closed niobium tube (heating rate 30 degrees C/h; reaction at 1050 degrees C for 300 h, cooling rate 100 degrees C/h). The crystal struct ure consists of distorted octahedra made up of six Bi coordinated to a central Eu atom. Eu is also coordinated to three other Eu atoms and f orms a three-dimensional network composed of interconnected rings. The Bi atoms are coordinated to eight Eu atoms. High yields of Eu4Bi3 can be prepared by reacting stoichiometric amount of the elements in a se aled tantalum tube at 1100 degrees C for 24 h. Temperature dependent m agnetic susceptibility is consistent with antiferromagnetic behavior w ith an ordering temperature of 18 K. The data could be fit with the Cu rie-Weiss law and a moment of 7.38 mu(B)/Eu is obtained, consistent wi th all Eu atoms being Eu-II. Temperature dependent resistivity indicat es that Eu4Bi3 is a metal with a room temperature resistance of 1.3 Om ega cm.