Defect-controlled electronic properties in AZn₂Sb₂ Zintl phases

Experimentally, AZn₂Sb₂ samples (A=Ca, Sr, Eu, Yb) are found to have large charge carrier concentrations that increase with increasing electronegativity of A. Using density functional theory (DFT) calculations, we show that this trend can be explained by stable cation vacancies and the corresponding finite phase width in A_1-xZn ₂Sb₂ compounds. Experimentally, AZn₂Sb ₂ samples (A=Ca, Sr, Eu, Yb) are found to have large charge carrier concentrations that increase with increasing electronegativity of A. DFT calculations now confirm that the defect energies of A-site vacancies follow the same trend, suggesting that cation vacancies are the primary mechanism responsible for varying the carrier concentration in nominally valence-precise AZn₂Sb₂ compounds.