An in-depth investigation by Raman, TEM and Impedance Spectroscopy of Field-assisted sintered Barium Strontium Titanate ceramics
RIBEIRO C. 1, TKACH A. 1, ZORRO F. 2, FERREIRA P. 2, NOUDEM J. 3, VILARINHO R. 4, M. GOMES M. 4, MOREIRA J. 4, COSTA M. 1, VILARINHO P. 1
1 Department of Materials and Ceramic Engineering, CICECO – Aveiro Institute of Materials, University of Aveiro, Aveiro, Portugal; 2 International Iberian Nanotechnology Laboratory - INL, Braga, Portugal; 3 Normandie Univ, ENSICAEN, UNICAEN, CNRS, CRISMAT, Caen, France; 4 IFIMUP, Department of Physics and Astronomy, Faculty of Sciences, University of Porto, Porto, Portugal
(Ba0.7Sr0.3)TiO3 (BST) ceramics, a powerful dielectric material for tunable applications, is commonly produced by conventional sintering at high temperatures (1500 ºC) for long times (5 h) [1]. These sintering conditions are often associated with increased grain growth, and likely abnormal grain growth. At the same time, some new alternative sintering techniques have been used to “design” suitable materials/properties for specific applications through, for example, microstructure refinement. In this work, Spark Plasma Sintering (SPS) and its derivative, Spark Plasma Texturing (SPT) [2], were used to prepare BST ceramics with peculiar structural, microstructural, and electrical properties. Here we address an in-depth investigation of structure and microstructure by Raman spectroscopy and (Scanning) Transmission Electron Microscopy (STEM/TEM), respectively and correlated with a systematic electrical characterization by Impedance Spectroscopy. Raman spectra were recorded and analyzed to establish the link between the sintering and local structural changes. TEM/STEM was used for a complete study of grain morphology, nature of grain boundaries and their interfaces. Impedance spectroscopy complemented the former studies by identifying the electrical nature of grains and grain boundaries. A comparison with conventionally sintered ceramics is also discussed.
[1] Ostapchuk, T., Petzelt, J., Kužel, P., Veljko, S., Tkach, A., Vilarinho, P., Ponomareva, I., Bellaiche, L., Smirnova, E., Lemanov, V., Sotnikov, A., Weihnacht, M. (2008) Infrared and THz soft-mode spectroscopy of (Ba,Sr)TiO3 ceramics, Ferroelectrics, 367, 139-148
[2] Pinho, R., Tkach, A., Zlotnik, S., Costa, M. E., Noudem, J., Reaney, I. M., & Vilarinho, P. M. (2020). Spark plasma texturing: A strategy to enhance the electro-mechanical properties of lead-free potassium sodium niobate ceramics. Applied Materials Today, 19, 100566.
