Thermoelectric Properties of Lanthanum-Doped Europium Titanate

Abstract

The thermoelectric properties of lanthanum-doped polycrystalline perovskite-type europium titanate were measured from room temperature to 900 K and compared to those of MTiO₃ (M=Ca, Sr, Ba). The differences in the titanates were calculated in terms of the differences of A-site ion and Ti–O distance that determined the covalent bonding strength. The A-site ion appeared to have little influence on the electrical properties. The small Ti–O(Ti) distance results in strong bonding and it causes high thermal conductivity together with high electrical conductivity. Europium titanate showed power factor similar to and thermal conductivity lower than those of the strontium titanate. Eu_0.9La_0.1TiO₃ showed the highest dimensionless figure of merit of 0.25 at 900 K.