Electrical conductivity enhancement of doped-SrO/SrTiO_3 Ruddlesden Popper phase prepared by molten salt method

摘要

SrO/SrTiO_3 Ruddlesden Popper (RP) phase is a superlattice oxide compound with alternatively stacking perovskite-type SrTiO_3 layers and rock salt SrO layers. This compound is a promising candidate for thermoelectric material with a high electrical conductivity by maintaining the favorable electronic properties and low thermal conductivity. In this present work, we doped the titanium sites with niobium and Sr sites with samarium to improve its electrical properties. The XRD pattern shows the peaks of the sample prepared without addition of salt did not show the formation of a single RP phase powder, on the other hand, the XRD pattern of all doped Sr_2Ti_(1-x)Nb_xO_4 and Sr_2Ti_(1-x)Sm_xO_4 PR phase samples correspond to that of Sr_2TiO_4 polycrystalline. Microstructural studies of the particles of the doped and undoped powder were carried out by SEM and showed a similar particle shape and size distribution. The electrical conductivity measurement by LCR meter showed that the substitution in particular site of Sr_2TiO_4 with higher valence dopants forming Sr_2Ti_(1-x)Nb_xO_4 and Sr_2Ti_(1-x)Sm_xO_4 increased the number of carrier concentration, thus the electrical conductivity could be improved.