Structure Evolution in CaCu1−xAgxSb (x = 0 − 1) Zintl-Phase Thermoelectric Materials

CaM(M = Cu, Ag)Sb Zintl-phase compounds have ignited tremendous research activities due to their promising thermoelectric properties. In this work, a series of CaCu 1− x Ag x Sb (x = 0, 0.2, 0.4, 0.6, 0.7, 0.8, 0.9, 1) samples have been synthesized and investigated. The continuous structure transition from the hexagonal CaCuSb to the orthorhombic CaAgSb is characterized as the composition regulation on Cu/Ag ratios. Lattice bonding hardens and the electrical band structure changes as a result of this transition. The lattice thermal conductivity of CaCu 0.2 Ag 0.8 Sb, which benefitted from the structure transition, showed a minimum value of 1.05 W m −1  K −1 at 323 K. At the same time, the Seebeck coefficient was improved as a result of the rise in effective mass. The findings show that the CaMSb compounds have flexible structural tunability for thermoelectric applications if the hole concentration can be further optimized. Graphical