Abstract

Mn3Ge5 was obtained by high-pressure, high temperature synthesis. The compound adopts a Nowotny-Chimney-Ladder type crystal structure [tetragonal, space group P4n2, a = 5.7449(1) angstrom, c = 13.9096(4) angstrom, Z = 4]. Magnetic measurements reveal a ferromagnetic transition around 40 K and metallic conductivity in the temperature range from 3 K to 350 K. Despite a low thermal conductivity, the metallic character of the sample and the low Seebeck coefficient result in low values for the thermoelectric Figure of merit, ZT. Band-structure calculations show that the Fermi level is located slightly below a pseudo-gap in the electronic density of states. Chemical bonding analysis in position space discloses moderate charge transfer and two- as well as three-atomic directed, heteroatomic bonding involving both the manganese and the germanium atoms.