Transport and defect mechanisms in cuprous delafossites.: 2.: CuScO2and CuYO2

The delafossite structure (ABO(2)) accommodates a wide range of transition and rare-earth cations on the B-site in combination with a short list of A-site cations. This paper reports the effects on defect chemistry and transport as a function of the B-Site cation in copper-based delafossite materials, with CuScO2 and CuYO2) as examples. Large B-site cation delafossites exhibit small polaron conduction, a diffusion-limited conduct-ion mechanism, ;ith an activation energy approximately twice that of GuAlO(2), (0.22 eV vs 0.14 eV, respectively). The mobility for these materials is found to be <1 cm(2) V-1 s(-1) further evidence of small polaron conduction. The majority defect species is highly dependent, on the B-Site cation, such that CuScO2 and CuYO2 are dominated by extrinsic defects (acceptor doping) and free oxygen interstitials, whereas off-stoichiometry dominates CuAlO2. Dopant solubility is shown to be 1% for bulk CuScO2 samples and lower in CuYO2.