Flash sintering of potassium-niobate

The challenge in creating stable and dense KNbO₃ ceramics is suppressing the K₂O volatility that occurs at elevated temperature and avoiding the formation of unwanted phases. This challenge could be addressed by applying a field-assisted sintering technique. Flash sintering was conducted successfully on KNbO₃ powder, under applied electric field ofThe linear shrinkage of 600V/cm at 750°C. The linear shrinkage of the sample was approximately 18%, and its density was 95% of the theoretical density. Homogeneous dense samples were obtained, containing grains with similar size to that of the green powder. The stoichiometry ratio of potassium to niobium (K/Nb) remains similar to that of the green powder. Flash sintering is proven here as a process which overcomes the main challenge of sintering ceramics with highly volatile species. In addition to its known advantages, we show here that the process is also a breakthrough in the synthesis of dense stoichiometric KNbO₃.