Additive Manufacturing of 3D‐Architected Multifunctional Metal Oxides

Abstract

Additive manufacturing (AM) of complex three‐dimensional (3D) metal oxides at the micro‐ and nanoscales has attracted considerable attention in recent years. State‐of‐the‐art techniques that use slurry‐based or organic–inorganic photoresins are often hampered by challenges in resin preparation and synthesis, and/or by the limited resolution of patterned features. A facile process for fabricating 3D‐architected metal oxides via the use of an aqueous metal‐ion‐containing photoresin is presented. The efficacy of this process, which is termed photopolymer complex synthesis, is demonstrated by creating nanoarchitected zinc oxide (ZnO) architectures with feature sizes of 250 nm, by first patterning a zinc‐ion‐containing aqueous photoresin using two‐photon lithography and subsequently calcining them at 500 ºC. Transmission electron microscopy (TEM) analysis reveals their microstructure to be nanocrystalline ZnO with grain sizes of 5.1 ± 1.6 nm. In situ compression experiments conducted in a scanning electron microscope show an emergent electromechanical response: a 200 nm mechanical compression of an architected ZnO structure results in a voltage drop of 0.52 mV. This photopolymer complex synthesis provides a pathway to easily create arbitrarily shaped 3D metal oxides that could enable previously impossible devices and smart materials.

3D nonlinear photolithography of Tin oxide ceramics via femtosecond laser

“…By using photosensitive TiO 2 resist, the complex 3D nanostructures were patterned by femtosecond laser direct writing, which provided a novel way to structure 3D ceramic materials [23]. Followed by calcination, 3D-architected zinc oxide ceramics were fabricated by femtosecond laser direct writing [24]. Furthermore, by controlling the shrinkage, sub-100 nm of structural feature size was achieved while keeping the 3D geometry [25,26].…”

Additive Manufacturing of High-Refractive-Index, Nanoarchitected Titanium Dioxide for 3D Dielectric Photonic Crystals

“…Facilitating these technologies requires a fabrication process to create a variety of functional materials in 3D, however the material choice for AM at the nano-and micro-scale is limited. This limitation is especially pronounced when particular material properties, including piezoelectric, magnetic, or optical, are required for the final application [8][9][10] .…”

“…Direct Laser Writing (DLW) of As 2 S 3 chalcogenide glasses with n between 2.45 and 2.53 in the infrared has been demonstrated by taking advantage of their photo-induced metastability 9 , but the high index mismatch between the lens and the printed material complicated the feature size control. Metal oxides with refractive indices n~1.9 have been nano-architected using DLW of aqueous metal-containing photopolymers followed by calcination, but the low metal ion loading in these resins led to linear shrinkage of up to 87%, which made it challenging to preserve complex 3D geometry 8,17 . TPL of organic-inorganic resists combined with post-lithography thermal treatment has shown promise to create 3D nanolattices of metals and ceramics, but the residual porosity of up to 20% within the beams reduces the effective refractive index 18,19 .…”

Great chiral fluorescence from the optical duality of silver nanostructures enabled by 3D laser printing

“…43,44 During the past few decades, the printing strategy that achieves ultrahigh spatial resolution 21 has been used to additively create a myriad of functionalized structures for advanced nanoscale photonic and optoelectronic applications. 22,23,43 The flexibilities and fidelities rooted in the technique add vast advantages to arbitrarily and precisely producing stereo architectures for spatially manipulating electromagnetic field. 24 Nevertheless, most of these achievements feature with producing structures based on materials with monocharacteristic supremely well.…”