Due to the high operating temperatures (900-1000 °C) the material demands upon Solid Oxide Fuel Cell (SOFC) components are quite stringent. Preferably lower operating temperatures (700-800 °C) are desired so that gas feed lines, heat exchangers, and structure components can be fabricated from relatively cheap stainless steel components.
Typically, the materials used in a SOFC are yttria stabilized zirconia (YSZ) as the solid electrolyte, nickel-zirconia cermet as the anode, strontium doped lanthanum manganite as the cathode, and magnesium doped lanthanum chromite as the interconnection material. The electrolyte and interconnect are difficult to fabricate, because they need to be gas tight, yet thin (30-50 microns) and mechanically stable. Due to the high volatility of CrO3 the densification of LaCrO3 into thin layers is a more demanding challenge than the fabrication of the electrolyte.
Electr°Chemical Vapor Deposition is the key technology for making thin layers of the solid electrolyte as well as the interconnection material LaCrO3. In the simplest case the oxide growth can be modeled with the Wagner oxidation theory for metals. In this paper theory and experiment of the growth of ionically conducting YSZ and electronically conducting LaCrO3 will be discussed.