a metallic barrier and a method for separating fuel and oxidant gases are disclosed for use in high temperature systems such as solid oxide fuel cells or cell stacks . the metallic barrier can be formed as a metallic bipolar separator plate or a seal , without requiring the use of chromium alloys or noble metals . controlled diffusion of fuel gas through the metallic barrier limits the thickness of an adherent electronically insulating oxide layer on an opposing surface in contact with oxidant gas . this stabilized oxide layer may be penetrated by refractory conductive particles such as doped lanthanum chromite to provide multiple electronically conductive paths through the oxide layer and the metallic barrier .