Oxygen Tracer Diffusion in Lanthanum‐Doped Single‐Crystal Strontium Titanate

Strontium titanate (SrTiO 3 ) is known as a good high‐temperature resistive oxygen sensor material; its response time depends on oxygen bulk diffusion and surface exchange processes. In the present work, 18 O diffusion has been investigated in lanthanum‐doped SrTiO 3 , single crystals in the temperature range 700° to 900°C by secondary ion mass spectrometry (SIMS). Oxygen tracer diffusivities between 2 × 10 −15 and 1 × 10 −13 cm 2 /s have been calculated from the SIMS results. Low surface enrichment of 18 O compared to the 18 O concentration in the gas atmosphere gives clear evidence for a surface exchange reaction.