Spark plasma sintering of microwave processed nanocrystalline barium titanate and their characterisations

Nanocrystalline barium titanate (BT) was synthesized by the high-energy planetary mill assisted novel hybrid processing methodology. As-milled precursors were microwave calcined and subsequently sintered by spark plasma sintering (SPS). Powders were characterised by XRD, laser Raman spectroscopy, BET and TEM techniques. Microstructure, purity, thermal stability and dielectric characteristics of the sintered BT were analyzed using FE-SEM, EDX, TGA and LCZ meter. Nanocrystalline nature of BT was evident from the enhanced peak broadening noticed in the XRD pattern and from the TEM image. Raman spectra corroborated well with the XRD results. FE-SEM image revealed a fairly dense and uniform microstructure, which was attributed to the high reactivity and needle shaped morphology of the mechanically activated microwave calcined powders, which showed a surface area of about 20 m2 g−1. Microwave calcined SPS processed BT showed a thermal stability of 99.5% as evident from the thermo-gravimetric analysis. Superior dielectric response was shown by the hybrid processed BT which is highly suitable for capacitor applications.

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► Nanostructured barium titanate synthesized by a novel 3-step hybrid method.
► The powders were densified by spark plasma sintering.
► Average grain size was found to be 150 nm.
► Agglomerated, needle shaped grains were noticed in the microwave calcined as-milled precursors.
► Plasma sintered barium titanate showed a thermal stability of 99.5% and superior dielectric response.