Rapid synthesis and characterization of (Ca1−xBax)3Co4O9 thin films using combinatorial methods

We have successfully fabricated high-quality thin film of Ca3Co4O9, an oxide with superior thermoelectric properties, on a lattice matched TiO2 (1 0 0) substrate using PLD. In order to investigate the effect of elemental substitution on thermoelectric properties, we fabricated a composition-spread library of (Ca1−xBax)3Co4O9 (0≤x≤0.2), having linear compositional variation x along one direction of the substrate surface. A pin-probe type multi-channel measurement system was developed to quickly measure the thermoelectric properties (Seebeck coefficient and electric conductivity) of the library for the rapid characterization. The good correspondence of the data for Ca3Co4O9 film with those for bulk sample verifies that we can accelerate the exploration of thermoelectric oxides at least 10 times faster than the conventional one-by-one approach.