Crystal Structure and Thermoelectric Properties of the Incommensurate Chimney–Ladder Compound VGeγ (γ ~1.82)

摘要: A single-phase sample of a Nowotny chimney–ladder phase known as V17Ge31 has been prepared and its modulated crystal structure determined by means (3+1)-dimensional superspace approach. As in the case higher manganese silicides (HMSs) MnSiγ, compound consists two tetragonal subsystems [V] [Ge] with an irrational c-axis ratio $$\gamma $$ = $$c_{\rm{V}}$$ / $$c_{\rm{Ge}} \sim 1.82, hence formula is represented VGe γ . expected from valence electron count estimated refined γ, present germanide exhibits metallic behavior electrical conductivity σ 6.25 × 103 S/cm Seebeck coefficient S 10.2 μV/K at 900 K. The resulting thermoelectric power factor $$S^2\sigma 6.56 × 10-5 W/mK2 dimensionless figure-of-merit, ZT, 3.7 × 10-3 K demonstrate that not promising material. However, lattice thermal comparable to HMSs, properties can be maximized through partial substitution V group 6–8 elements decrease hole carrier concentration.