Tracer diffusion and chemical diffusion of oxygen in acceptor doped SrTiO3

✍ Scribed by J. Claus; M. Leonhardt; J. Maier

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 263 KB
• Volume: 61
• Category: Article
• ISSN: 0022-3697
• DOI: 10.1016/s0022-3697(99)00421-7

✦ Synopsis

Oxygen tracer and oxygen chemical diffusion coefficients have been determined for single crystalline SrTiO 3 under defined temperature (f ), oxygen partial pressure (p(O 2 )), and acceptor (Fe) dopant concentration (m Fe ) conditions. Oxygen tracer diffusion results were obtained 873 K Յ T Յ 1173 K; pO 2 10 5 Pa by means of 18 O isotope exchange with subsequent analysis of the 18 O in-diffusion profiles by secondary ion mass spectrometry (SIMS). In the case of chemical diffusion an in situ and spatially resolved, optical relaxation technique was applied 673 K Յ T Յ 973 K; 10 Pa Յ pO 2 Յ 10 5 Pa: The dopant concentration in both experiments was varied between 4:3 × 10 18 cm Ϫ3 Յ m Fe Յ 4:9 × 10 19 cm Ϫ3 : The evaluation of (ex situ) tracer and (in situ) concentration profiles are shown to be in excellent agreement with defect chemical calculations. In contrast to the tracer diffusion coefficients (D ‫ء‬ ) the chemical diffusion coefficients (D d ) are sensitive to ionic-electronic (short-range) defect interactions (internal buffer effects influence the thermodynamic factor) caused by valence changes of the redox-active Fe-doping.