Ce–Cu–Sb system at 670/870 K

Phase equilibria in the Ce–Cu–Sb system were investigated by X-ray powder diffraction, electron probe X-ray analysis and the isothermal section at 870 K was obtained. The following compounds were confirmed: the ZrCuSi2-type CeCuSb2 (a = 0.43449(8) nm, c = 1.0239(3) nm, space group P4/nmm, No. 129-2), CaBe2Ge2-type CeCu2Sb2 (a = 0.4354(1) nm, c = 1.0221(4) nm, space group P4/nmm, No. 129-2) and Y3Au3Sb4-type Ce3Cu3Sb4 compound (a = 0.9759(1) nm, space group I4b3d, No. 220). The NaCl-type Ce50Cu8Sb42 compound (a = 0.6447(1) nm, space group Fm3m, No. 225) and La2Sb-type Ce2Cu0.2Sb0.8 (a = 0.45308(4) nm, c = 1.7903(3) nm, space group I4/mmm, No. 139) belong to the extended solid solution region of the NaCl-type CeSb and La2Sb-type Ce2Sb compounds, respectively.CeSb has the Seebeck coefficient S = 1.1(9) μV/K, ρ = 1.3(4) μΩ m.Substitution Cu for Sb leads to increasing the Seebeck coefficient up to S = 8.0(9)–18.3(9) μV/K (240–380 K), ρ = 0.98(9)–1.2(2) μΩ m (240–380 K) in the Ce50Cu8Sb42 compound. The NaCl-type Ce50Cu8Sb42 compound has ZT = 1.2 × 10−3–4.9 × 10−3 (240–380 K).