Trivalent-intermediate valent cerium ordering in Ce2RuZn 4

Abstract

The new intermetallic cerium compound Ce2RuZn4 was synthesized from the elements in a sealed tantalum tube in a water-cooled sample chamber of an induction furnace. Ce2RuZn4 crystallizes with a new structure type: P4/nmm, Z = 2, a = 719.6(1), c = 520.2(1) pm, wR2 = 0.0816, 273 F2 values and 15 variables. The structure contains two crystallographically independent cerium atoms: Ce1 with CN 16 (12 Zn + 4 Ce) and Ce2 with CN 14 (2 Ru + 8 Zn + 4 Ce). Based on the interatomic distances the two sites can be assigned to trivalent Ce1 and intermediate valent Ce2. The trivalent-intermediate valent cerium ordering is underlined by magnetic susceptibility measurements. Ce2RuZn4 shows modified Curie-Weiss behaviour in the temperature range 10-290 K with an experimental magnetic moment of 2.57(1) μB per formula unit. Thus only half of the cerium atoms are trivalent in Ce2RuZn4. A remarkable feature of the Ce2RuZn4 structure are short Ce2-Ru distances of 260 pm. The crystal chemistry of Ce2RuZn4 is discussed. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.