Phonon-glass electron-crystal behaviour by A site disorder in n-type thermoelectric oxides

Phonon-glass electron-crystal (PGEC) behaviour is realised in La 0.5 Na 0.5 Ti 1−x Nb x O 3 thermoelectric oxides. The vibrational disorder imposed by the presence of both La 3+ and Na + cations on the A site of the ABO 3 perovskite oxide La 0.5 Na 0.5 TiO 3 produces a phonon-glass with a thermal conductivity, κ , 80% lower than that of SrTiO 3 at room temperature. Unlike other state-of-the-art thermoelectric oxides, where there is strong coupling of κ to the electronic power factor, the electronic transport of these materials can be optimised independently of the thermal transport through cation substitution at the octahedral B site. The low κ of the phonon-glass parent is retained across the La 0.5 Na 0.5 Ti 1−x Nb x O 3 series without disrupting the electronic conductivity, affording PGEC behaviour in oxides.