Electrical conductivity of yttrium-doped SrTiO3: influence of transition metal additives

The electrical conductivity of yttrium-doped SrTiO₃ with transition metals added as acceptor dopants (V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Mg, Zr, Al, or Ga) was measured by the dc four-probe method at 600-900°C in reducing atmospheres. The replacement of 5 mol% titanium by acceptors leads to a decrease of conductivity of Sr_1−1.5xY_xTiO_3−δ. The degree of the decrease depends strongly on the type of dopant. Of the 5 mol% acceptor-doped compositions, the system Sr_0.85Y_0.10Ti_0.95Co_0.05O_3−δ had the highest conductivity of 45 S/cm at 800°C and oxygen partial pressure of 10⁻¹⁹ atm. The oxidation kinetics of yttrium-doped SrTiO₃ was significantly retarded by the addition of cobalt or manganese dopants. The ionic conductivity of SrTiO₃ doped with 5 mol% acceptors at Ti-sites was estimated from the total conductivity to lie in the vicinity of 10⁻⁴ S/cm, depending on oxygen partial pressure and temperature.