The Heusler phases LiRh2Si and LiRh2Ge: Synthesis, structure and properties

The isostructural Heusler phases LiRh2Si and LiRh2Ge have been synthesized from the elements and an excess of lithium at 1000 °C. Both materials adopt the CuMn2Al crystal structure, space group Fm−3m (No. 225) with the room temperature lattice parameter a=5.747(1) Å [Vol=189.866(1) Å3] and a=5.847(1) Å [Vol=199.88(6) Å3] for LiRh2Si and LiRh2Ge, respectively. X-ray analyses suggest mixed site occupancy of the form Li1−xRh2Si1+x (x<0.4), but not for LiRh2Ge. Both materials are diamagnetic, χmol(LiRh2Si)=−6×10−5 cm3(mole)−1 and χmol(LiRh2Ge)=−10×10−5 cm3(mole)−1 and metallic with room temperature resistivities of approximately 19 and 32 μΩ cm, respectively. These properties are consistent with the calculated electronic structure.