Nevertheless, the carrier concentrationincreases and the resistivity decreases for the sample f(aSiO2)/BST with f ¼ 0.55 vol. %, while its Seebeck coefficientincreases, leading to enhancement of PF, which could beascribed to energy filtering effect arising from enhanced carrier scattering by the interface potentials due to the embeddeda-SiO2 nanoparticles.