Demands for efficient energy and time densification processes have conditioned the advancement of the thermal treatment of polycrystalline ceramics, specifically sintering. Recently developed, blacklight sintering is a technique that embodies a highly energy-efficient thermal process.¹ Namely, thermal energy is only transferred to the sample, and a furnace containing the thermal energy is not required. This novel rapid densification technique provides extreme heating and cooling rates of 100-200 °C/s, thus, the entire sintering cycle lasts for a minute or two. Furthermore, it is simple to operate as it doesn’t require complex sample holders, sintering dies, or specific protective atmospheres. Hence, it is suitable for rapid prototyping of new materials and large-scale, on-demand, and on-the-spot production.

Our previous work demonstrated the feasibility of blacklight sintering for barium titanate ceramics,² achieving a relative density of about 90 %. Furthermore, established electrical properties were reached, e.g., room temperature permittivity of 5000 and Curie point at 130 °C. The current study focuses on the microstructural evolution of barium titanate using blacklight sintering. Powder compacts were thermally treated to obtain a relative density of 65 to 90 %. Temperature-dependent density curves were compared to reference furnace-sintered samples. Additionally, the microstructure was analysed in the entire cross-section of the disk-shaped pellet with SEM, and for each sintering stage. In the case of blacklight, samples exhibited profound microstructural gradients, particularly in the second stage of sintering. However, a homogeneous microstructure with uniform average grain size was attained at relative densities higher than 85 %. Furthermore, the characteristic strong grain growth of barium titanate was enhanced compared to a furnace-sintered reference. Overall, blacklight-sintered samples demonstrated comparable densities and sintering temperatures to their furnace-sintered counterparts despite extreme heating rates and short exposure time.

1.    Porz, L. et al. Blacklight sintering of ceramics. Mater. Horizons 9, 1717–1726 (2022).
2.    Scherer, M. et al. Blacklight sintering of BaTiO3 ceramics. J. Eur. Ceram. Soc. 43, 5406–5411 (2023).