Technical ceramics such as zirconia are employed in a range of advanced technological applications due to their functional and mechanical properties [1]. It is classified as a high-performance ceramic due to its remarkable mechanical properties. The toughness of zirconia is intrinsically improved when doped with 3 mol% yttrium. This improvement is credited to its phase transformation toughening abilities (tetragonal to monoclinic phase transformation) at the site of mechanical fracture. The increase in volume due to phase transformation induces compressive stress that slow down crack propagation [2]. The mechanical properties can also be enhanced extrinsically by designing textured material with an organized microstructure. Multiple examples exist in nature. Nacre, for example, is an organic-inorganic hybrid material arranged in a “brick-and-mortar” architecture. This microstructure displays a remarkable damage resistance by inducing several processes such as crack bridging and deflection at the origin of fracture [3]. Inspired by such designs, this work focuses on the development of zirconia-based ceramics with high strength and toughness by fabricating yttrium doped zirconia anisotropic particles and organizing them to have microstructure with highly oriented texture. The chemical composition, shape and uniformity of the particles were investigated to assess their impact on the materials microstructure and properties.
Thus, this project describes the enhancement in functional properties achieved by exploiting the synergy of materials composition and micro-structural arrangement via (i) the synthesis of anisotropic zirconia-based particles using a bottom-up approach technique, and (ii) the alignment of these particles to create novel textured materials. Here, zirconia needles were produced using a sol-gel technique, and the methodology was optimized to produce monodisperse needles with controlled aspect ratio devoid of using surfactants. The needles were then organized using ice templating technique, a process that involves in freezing particle suspensions to induce self-organisation via the growth of ice crystals. The freezing conditions were optimized by studying the dynamics of particle interaction with ice growth to achieve the desired microstructure using in situ cryo-confocal microscopy. Finally, the properties of the materials were studied and correlated to the needle orientation.

References :
1- Zang X et al (2020). J Mater Res Technol. 9(4) :9029–9048
2- Vagkopoulou T et al (2009). Eur J Esthet Dent. 4(2) :130-51
3- N. Abando et al (2021). Journal of the European Ceramic Society. 41:2753–2762
4- R. Henry et al (2022). Journal of the European Ceramic Society. 42:2319–2330