Dense and single-phase KTaO3 ceramics obtained by spark plasma sintering
Résumé
Potassium tantalate (KTaO3) is a promising material for dielectric applications at low temperature. However, dense and single-phase ceramics cannot be obtained by conventional sintering because of the evaporation of potassium that leads to secondary phases. Here, we demonstrate that spark plasma sintering is a suitable method to obtain dense and single-phase KTaO3 ceramics, by optimizing three parameters: initial composition, temperature, and pressure. A 2 mol% K-excess in the precursors leads to a large grain growth and dense single-phase ceramics. Without K-excess, a small amount of secondary phase (K6Ta10.8O30) is observed at the surface but can be removed by polishing. At ~10 K, the dielectric permittivity is 4 times higher in the ceramic from the 2 mol% K-excess powder, because of the larger grain size. The thermal conductivity decreases with decreasing grain size and stays above the thermal conductivity of KNbO3 ceramics.
Domaines
Matériaux
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Dense and single phase KTaO3 ceramics obtained by SPS_final.pdf (1.18 Mo)
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