Bias Sputter Deposition of Dense Yttria‐Stabilized Zirconia Films on Porous Substrates

We demonstrate that completely dense yttria‐stabilized zirconia (YSZ) electrolyte films <5 μm thick can be reactively sputter deposited onto porous (∼0.5 μ pore size) La 0.8 Sr 0.2 MnO 3 substrate/electrodes. The two key factors in achieving the fully dense films were porous substrate preparation and the use of substrate bias during YSZ film deposition. Increasing the negative dc substrate bias V s from 0 to 300 V produced increasingly dense and flat‐surfaced films: V s = 75 V was chosen to yield high density without excessive film compressive stresses. Solid oxide fuel cells consisting of sputtered YSZ films ( V s = 75 V ) and a Ni‐YSZ fuel electrode on LSM exhibited open‐circuit voltage values within 5% of the theoretical values for thicknesses down to 2 μm. Cells deposited with V s = 0 V short‐circuited at thicknesses of 12 μm or less.