Crystal structure and magnetic properties of the new ternary compound Ce3MnBi5

The crystal structure of the newly discovered compound Ce3MnBi5 was determi ned from X-ray single crystal diffraction data. The space group is P6(3)/mc m with the lattice parameters a = 9.627(3), c = 6.456(1) Angstrom. The comp ound crystallizes in the Ga4Ti5 structure type. There are no isostructural compounds in ternary systems with Sb and Pb substituted for Bi. The Ce3MnBi 5 remains paramagnetic down to similar to 4.2 K, even though the paramagnet ic Curie temperature (theta(p) = -53 K) suggests an antiferromagnetic groun d state. The value of effective magnetic moment (rho(eff) = 5.85 mu(B)) per formula unit could be accounted for by two different electronic configurat ions of Ce and Mn atoms: 3Ce(3+) and 1Mn(4+) or 3Ce(4+) and 1Mn(2+). Bond d istances arguments favor the first possibility. Magnetization measurements at 5 K indicate two metamagnetic (field-induced) transitions at similar to 1.3 and similar to 5 T, which we believe are due to impurities in the sampl e. (C) 1999 Elsevier Science S.A. All rights reserved.