SYNTHESIS AND CHARACTERIZATION OF A FAMILY OF NEW INTERMETALLIC MATERIALS M5(INTE4)2 (M = CR, MN, FE, CO, NI)

A family of new amorphous intermetallic materials, M5(InTe4)2, where M = Cr, Mn, Fe, Co, Ni, has been prepared by solution reaction of the Zintl polyanion InTe45- with transition-metal cations M2+. The magnetic and conducting properties for these materials have been examined as a function of temperature. Mn5(InTe4)2 and Cr5(InTe4)2 exhibit strong antiferromagnetic coupling between localized magnetic moments and highly temperature dependent semiconductivity. The variable range hopping mechanism is found to dominate the conductivity in Cr5(InTe4)2 over a wide temperature range. Fe5(InTe4)2 undergoes double magnetic transitions, the para- to weak ferromagnetic transition at approximately 32 K and the second transition to a spin glass state at approximately 13 K. The magnetic properties of Co5(InTe4)2 are dependent on the preparation conditions. Both Fe5(InTe4)2 and Co5(InTe4)2 display conductivity consistent with a narrow energy gap semiconductor. Ni5(InTe4)2 shows a non-Curie-Weiss paramagnetism and conductivity in the boundary of metals. It appears that the magnetic and conducting properties of these materials are roughly correlated with the ability of the precursor transition metal cations to be reduced by the Zintl polyanion.