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One of the challenges in the field of multi-photon 3D laser printing lies in further increasing the print speed in terms of voxels/s. Here, we present a setup based on a 7 × 7 focus array (rather than 3 × 3 in our previous work) and using a focus velocity of about 1 m/s (rather than 0.5 m/s in our previous work) at the diffraction limit (40×/NA1.4 microscope objective lens). Combined, this advance leads to a ten times increased print speed of about 108 voxels/s. We demonstrate polymer printing of a chiral metamaterial containing more than 1.7 × 1012 voxels as well as millions of printed microparticles for potential pharmaceutical applications. The critical high-quality micro-optical components of the setup, namely a diffractive optical element generating the 7 × 7 beamlets and a 7 × 7 lens array, are manufactured by using a commercial two-photon grayscale 3D laser printer.

Abstract During light‐driven 3D additive manufacturing, an object represented in digital form is initially translated into a spatial distribution of light intensity (sequentially or in parallel), which then results in a spatial material distribution. To date, this process typically proceeds by photoexcitation of small functional molecules, leading to photochemically induced crosslinking of soft materials. Alternatively, thermal triggers can be employed, yet thermal processes are often slow and provide only low spatial localization. Nevertheless, sub‐micrometer ZnO structures for functional microelectronic devices have recently been laser‐printed. Herein, the photothermal laser‐printing of ZnO is advanced by i) introducing single‐crystalline rather than amorphous sub‐micrometer ZnO shapes that crystallize in the hexagonal ZnO wurtzite structure, ii) employing dimethyl sulfoxide (DMSO) instead of water, enabling higher local process temperatures without micro‐bubble formation, and iii) using substrates tailored for light absorption and heat management, resolving the challenge of light to heat conversion. Finally, the herein‐demonstrated ZnO printing requires no post‐processing and is a cleanroom‐free technique for the fabrication of crystalline semiconductors.

Phase separation into an A2+B2 two-phase microstructure in refractory compositionally complex alloys (RCCA) has been speculated as being spinodal in nature with continuous chemical distribution during the separation. However, these reactions might instead occur as precipitation by nucleation and growth. In order to unequivocally elucidate the distinct nature of phase separation sequence in RCCA from the system Ta-Mo-Ti-Cr-Al, atom probe tomography and electron microscopy techniques were utilized on samples that were annealed over multiple orders of magnitude in time. The composition 82(TaMoTi)-8Cr-10Al (at.%) was chosen, as it exhibits a two-phase microstructure, with a desired A2 matrix and embedded B2 phase. Quenching the samples from 1200°C resulted in a microstructure consisting of ordered clusters (2 nm) of distinct chemical composition. Subsequent annealing at 800°C to 1000°C leads to an increase in the volume fraction of the precipitating phase, which saturates after 10 h. Further annealing leads to the ripening of the microstructure; however, the absolute size of the precipitates stays

Abstract This work establishes carbon nanofibre-mediated patterning of metal oxide nanostructures, through the combination of electrospinning and vapor-phase transport growth. Electrospinning of a suitable precursor with subsequent carbonization results in the patterning of catalyst gold nanoparticles embedded within carbon nanofibres. During vapor-phase transport growth, these nanofibres allow preferential growth of one-dimensional metal oxide nanostructures, which grow radially outward from the nanofibril axis, yielding a hairy caterpillar-like morphology. The synthesis of metal oxide caterpillars is demonstrated using zinc oxide, indium oxide, and tin oxide. Source and substrate temperatures play the most crucial role in determining the morphology of the metal oxide caterpillars, whereas the distribution of the nanofibres also has a significant impact on the overall morphology. Introducing the current methodology with near-field electrospinning further facilitates user-defined custom patterning of metal oxide caterpillar-like structures.

Abstract The thermoelectric generator (TEG) shows great promise for energy harvesting and waste heat recovery applications. Cost barriers for this technology could be overcome by using printing technologies. However, the development of thermoelectric (TE) materials that combine printability, high‐efficiency, and mechanical flexibility is a serious challenge. Here, flexible (SbBi)2(TeSe)3‐based screen‐printed TE films exhibiting record‐high figure of merits (ZT) and power factors are reported. A high power factor of 24 µW cm−1 K−2 (ZTmax ≈ 1.45) for a p‐type film and a power factor of 10.5 µW cm−1 K−2 (ZTmax ≈ 0.75) for an n‐type film are achieved. The TE inks, comprised of p‐Bi0.5Sb1.5Te3 (BST)/n‐Bi2Te2.7Se0.3 (BT) and a Cu‐Se‐based inorganic binder (IB), are prepared by a one‐pot synthesis process. The TE inks are printed on different substrates and sintered using photonic‐curing leading to the formation of a highly conducting β‐Cu2−δSe phase that connects “microsolders,” the grains resulting in high‐performance. Folded TEGs (f‐TEGs) are fabricated using the materials. A half‐millimeter thick f‐TEG exhibits an open‐circuit voltage (VOC) of 203 mV with a maximum power density (pmax) of 5.1 W m−2 at ∆T = 68 K. This result signifies that a few millimeters thick f‐TEG could power Internet‐of‐Things (IoTs) devices converting low‐grade heat to electricity.