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DF: Dielektrische Festkörper

DF 10: Elektrische, elektromechanische und optische Eigenschaften

DF 10.1: Vortrag

Dienstag, 8. März 2005, 14:00–14:20, TU EMH225

In-situ small-angle x-ray scattering study of interface morphology in sintered nano-ceramics — •Rudolf Winter and Daniel A Le Messrier — Materials Physics, University of Wales Aberystwyth, Aberystwyth, Wales, UK

The bonding of granular ceramics depends in reactions at the grain interface. These reactions can be pure solid-state or solid-liquid interface reactions. The former require ionic diffusion and are usually diffusion limited once an interface of a certain thickness has been formed.

We report here on combined small and wide angle x-ray scattering experiments performed under in-situ heating conditions at beamline 6.2 at Daresbury. Sol-gel prepared ZrO₂ nanoparticles were mixed with a powdered silicate (Na₂Si₃O₇) glass, pelletised and heated up to 1 000^∘C while acquiring data at photon energies of 8.3 keV and near the absorption edge of zirconium, 18 keV. Macroscopic grain surface scattering following Porod’s law is subtracted from the raw data.

The evolution of the scattering pattern enables us to model the change of the morphology of the interface. While the original powder mixture is characterised by fractal aggregates of small primary particles, larger product particles with smoother interfaces are formed above about 550^∘C. The solid-state reaction kinetics is deceleratory in line with a diffusion-based model of interface growth.