Effects of Composition and Annealing on the Electrical Properties of CoSb₃

A series of CoSb 3 samples was synthesized at low temperature (∼150 °C) using modulated elemental reactants, with composition varying between Co-rich and Sb-rich, resulting in lattice parameters ranging from 9.023 to 9.090 Å. The samples were annealed in 100 °C increments from 200 to 600 °C, with lattice parameter, electrical resistivity, and Seebeck coefficient measured after each annealing. The spread of lattice parameters decreased with annealing (9.045 to 9.062 Å). The electrical resistivity of the samples changed from being nominally temperature independent, characteristic of a heavily doped semiconductor, to an exponential temperature dependence expected for a semiconductor, with band gaps of ∼0.1 eV. Seebeck measurements confirm the reduction in electrically active defect concentration with increasing annealing temperature. The nonequilibrium defect concentration trapped by low-temperature crystallization and varying composition, combined with the annealing studies, allowed a wide range of structural and electrical properties to manifest within a limited sample set.