| Abstract Scope |
Sintering ceramics under an electric field can enhance densification at lower temperatures, sparking interest in this technique. However, densification is typically accompanied by grain growth, which strongly affects material properties.
This study investigates the effect of a static electric field on grain growth in pre-densified undoped and Ca-doped alumina, where no further densification occurs. Samples were annealed at 0, 200, or 300 V/cm using alumina electrodes with platinum paste.
Electron microscopy revealed enhanced grain growth near the negative electrode. Wavelength-dispersive spectroscopy showed higher Ca concentrations near the positive electrode, where smaller grains suggest solute drag by Ca. Since Ca substitution creates positively charged oxygen vacancies, these are likely drawn toward the negative electrode, increasing grain boundary mobility and promoting growth.
The results highlight the interplay between electric fields, dopants, and defect chemistry in controlling ceramic microstructures. Mechanisms for field-enhanced grain boundary mobility are discussed. |