Temperature Promotes Photoluminescence in Lanthanide‐Doped 3D Ceramic Microarchitectures

Two‐photon lithography (TPL) is a powerful technique for creating 3D microarchitectures. Applied to high‐refractive‐index materials like ZrO 2 , it promises advanced optics. This is the case of ZrO 2 host matrixes in combination with luminescent dopants. However, due to the nonideal crystallinity attained to the TPL pre‐ceramic replica from a custom‐made photoresin, the emission of lanthanide (Ln) dopants in ZrO 2 microarchitectures can be suboptimal. However, crystallinity exacerbated by annealing can promote Ln‐emission, thereby enabling the integration of ceramic micro‐optic into a low‐temperature process. This work presents a photoresin containing a metal‐organic monomer tailored for TPL, enabling the fabrication of Ln‐doped tetragonal ZrO 2 ( t ‐ZrO 2 ) microarchitectures. The emission properties of Ln‐doped microarchitectures with trivalent Ln ions (Ln 3+ ), i.e., Yb 3+ (2.5 mol%), Er 3+ (0.35 mol%), and Tm 3+ (0.35 mol%) are studied. The results demonstrate that Ln emission is absent when annealing the microarchitectures at 600 °C. Annealing at 750 °C activates Ln 3+ emissions, including 2 F 5/2 – 2 F 7/2 (infrared), 4 S 3/2 – 4 I 15/2 (green), and 3 H 4 – 3 F 6 (near‐infrared) transitions corresponding to Yb, Er, and Tm species. Transmission electron microscopy (TEM) confirms that t ‐ZrO 2 crystallinity becomes more prominent at 750 °C, demonstrating the promotion of Ln emissions upon thermal treatment and underscoring the role of crystalline in TPL micro‐optical ceramics.