Movement of Pt markers in MgO during a solid-state reaction

The effectiveness of Pt in marking the initial location of heterophase boundaries between two reactants in a thin-film solid-state reaction is discussed. The Pt markers were produced by dewetting a continuous Pt film at elevated temperatures, thus forming an array of small isolated particles. These particles can then serve as fine-scale markers for tracking the motion of interfaces. The thin-film diffusion couples with Pt markers were used, in this study, to investigate the effect of an applied electric field on a spinel-forming reaction. The reacted diffusion couples with Pt markers were analysed using both transmission and scanning electron microscopy. Analysis of the diffusion couples showed that the Pt markers could be affected by, or themselves affect, the reaction process. The interface between the Pt marker and surrounding oxide matrix plays an important role in the reliability of Pt as an effective marker. © 1999, Taylor & Francis Group, LLC. All rights reserved.