The roles of interstitial oxygen and phase compositions on the thermoelectric properties CuCr0.85Mg0.15O2 delafossite material

In this work, role of phase composition and interstitial oxygen on the thermoelectric properties of CuCr0.85Mg0.15O2 materials prepared at different sintering temperatures (1273–1673 K) for short time (3 h) are reported. Interestingly, the samples sintered at 1273 K and 1673 K had the same Seebeck coefficient, despite the 1273 K sample having significantly lower conductivity, which are discussed via phase composition and interstitial oxygen induced during the CuCrO2 phase formation and its related defect (VCu, VCr, …). Besides, high conductivity of the 1673 K sample originated from the low percentage of CuO phase and the appearance of Cu2O phase. Since the 1273 K and 1673 K sintered samples have almost the same percentage of delafossite and spinel phases so the 1673 K sample still remain its high Seebeck coefficient. We suggest some reaction chemical equations for elucidating the roles of interstitial oxygen on the phase composition and thermoelectric properties CuCr0.85Mg0.15O2 delafossite material. [Display omitted] •Phase composition and interstitial oxygen control thermoelectric properties of CuCr0.85Mg0.15O2.•Native interstitial oxygen is induced during the CuCrO2 phase formation.•Samples sintered at 1273 and 1673 K have the same Seebeck coefficient but different conductivity.•High conductivity of the 1673 K sample originated from the low percentage of CuO phase and the appearance of Cu2O phase.•Seebeck coefficient of samples depends on component phases but its behavior follow Heikes or Pysarenko law by defect-type.