Ultrafast laser lithography allows additive fabrication of 3D sub-micrometric size objects in various materials. Here we demonstrate significant new capabilities achievable with this approach by using hybrid organic–inorganic material as the initial medium for laser structuring, and adding a high-temperature post-fabrication treatment. Calcination at temperatures of up to 1500°C leads to decomposition of the organic component in the initial material, and sintering of the inorganic component into a stable matrix. This results in the final object composed purely of glass-ceramic material, and having volume and size significantly reduced in comparison to those of the initial object. Possibilities to control both the composition and degree of the thermal down-scaling will be demonstrated. The proposed new pathway to inorganic 3D nanoscale objects and structures is easy to implement, and allows one to significantly surpass the spatial resolution and feature size achievable using laser lithography only. We study optical properties of transparent inorganic microstructures and optimize them for specific photonic functions. In the future it may be useful in space and defense-related areas for realization of chemically and thermally resilient photonic components, such as narrow-band IR emitters and optical sensors to be used in nuclear power plants and other harsh environments.
D. Gailevicius, V. Padolskyte, L. Mikoliunaite, S. Sakirzanovas, S. Juodkazis, and M. Malinauskas, ”Additive-Manufacturing of 3D Glass-Ceramics down to Nanoscale Resolution,” Nanoscale Horiz., 10.1039/C8NH00293B (2019), online first.
Ceramics as advanced materials play an important role in science and technology as they are mechanically robust, can withstand immense heat, are chemically inert. Consequently, there is a direct end-user driven need to find ways for efficiently acquiring free-form 3D ceramic structures. Recently, stereo-lithographic 3D printing of hybrid organic-inorganic photo-polymer and subsequent heating was demonstrated to be capable of providing true 3D ceramic and glass structures. Up to now, this was limited to (sub-)millimeter scale and naturally the next step is to acquire functional glass-/ceramic-like 3D structures in micro-/nano-dimensions. In this paper, we explore a possibility to apply ultrafast 3D laser nanolithography followed by heating to acquire ceramic 3D structures down to micro-/nano-dimension. Laser fabrication is employed for the production of initial 3D structures with varying (ranging within hundreds of nm) feature sizes out of hybrid organic-inorganic material SZ2080. Then, a post-fabrication heating at different temperatures up to 1500 °C in an air atmosphere facilitates metal-organic framework decomposition, which results in the glass-ceramic hybrid material. Additionally, annealing procedure densifies the obtained objects providing an extra route for size control. As we show, this can be applied to bulk and free-form objects. We uncover that the geometric downscaling can reach up to 40%, while the aspect ratio of single features, as well as filling ratio of the whole object, remains the same regardless of volume/surface-area ratio. The structures proved to be qualitatively resistant to dry etching, hinting at significantly increased resiliency. Finally, Raman spectrum and X-ray diffraction (XRD) analysis were performed in order to uncover undergoing chemical processes during heat-treatment in order to determine the composition of material obtained. Revealed physical and chemical properties prove the proposed approach paving a route towards 3D opto-structuring of ceramics at the nanoscale for diverse photonic, microfluidic and biomedical applications.
Glass-ceramics play an important role in todays science and industry as it can withstand immense heat, mechanical and other hazards. Consequently, there is a need to find ever-new ways to acquire more sophisticated free-form 3D ceramic and glass structures. Recently, stereo-lithographic 3D printing of hybrid organic-inorganic photopolymer and subsequent pyrolysis was demonstrated to be capable of providing true 3D ceramic and glass structures. However, such approach was limited to (sub-)millimeter scale, while one of the aims in the field is to acquire functional 3D glass-like structures in micro- or even nano-dimensions. In this paper, we explore a possibility to apply ultrafast 3D laser nanolithography in conjunction with pyrolysis to acquire glass-ceramic 3D structures in micro- and nano-scale. Laser fabrication allows production of initial 3D structures with relatively small (hundreds of nm) feature sizes out of hybrid organic-inorganic material SZ2080. Then, a post-fabrication heating at different temperatures up to 1000°C in Ar , air or O2 atmospheres decomposes organic part of the material leaving only the glass-ceramic component of the hybrid. As we show, this can be done to 3D woodpiles and bulk objects. We uncover that the shrinkage during sintering can reach up to 40%, while the aspect ratio of single features as well as filling ratio of the whole object remains the same. This hints at homogeneous reduction in size that can be easily accounted for and pre-compensated before manufacturing. Additionally, the structures prove to be relatively resilient to focused ion beam (FIB) milling, hinting at increased rigidity. Finally, thermal gravimetric analysis (TGA) and Fourier transform infrared micro-spectroscopy measurements are performed in order to uncover undergoing chemical and physical phenomena during pyrolysis and composition of the remnant material. The proposed post-processing approach offers a straightforward way to downscale true 3D micro-/nanostructures for applications in nanophotonics, microoptics and mechanic devices with improved performance while being highly resilient to harsh surrounding conditions.