Arrays of well‐aligned, ca. 4.7 mm long carbon nanotubes (CNTs) are grown in a simple, safe, and cost‐effective manner using an efficient Al2O3/Fe catalyst prepared by an ion‐beam assisted deposition technique (see figure). Importantly, the as‐synthesized CNT arrays with lengths ranging from 500 μm to 1.5 mm are conducive to spinning, and CNT fibers spun from such long CNT arrays show remarkably improved tensile strength.

Broadband perfect absorber based on one ultrathin layer of the refractory metal chromium without structure patterning is proposed and demonstrated. The ideal permittivity of the metal layer for achieving broadband perfect absorption is derived based on the impedance transformation method. Since the permittivity of the refractory metal chromium matches this ideal permittivity well in the visible and near-infrared range, a silica-chromium-silica three-layer absorber is fabricated to demonstrate the broadband perfect absorption. The experimental results under normal incidence show that the absorption is above 90% over the wavelength range of 0.4-1.4 μm, and the measurements under angled incidence within 400-800 nm prove that the absorber is angle-insensitive and polarization-independent.

We report a structural color printing platform based on aluminum plasmonic metamaterials supporting near perfect light absorption and narrow-band spectral response tunable across the visible spectrum to realize high-resolution, angle-insensitive color printing with high color purity and saturation. Additionally, the fabricated metamaterials can be protected by a transparent polymer thin layer for ambient use with further improved color performance. The demonstrated structural color printing with aluminum plasmonic metamaterials offers great potential for relevant applications such as security marking and information storage.

Surface texture and interior residual stress variation induced by thickness of YBa2Cu3O7-δ thin films J. Appl. Phys. 112, 053903 (2012) New application of temperature-dependent modelling of high temperature superconductors: Quench propagation and pulse magnetization J. Appl. Phys. 112, 043912 (2012) Flux-pinning-induced interfacial shearing and transverse normal stress in a superconducting coated conductor long strip J. Appl. Phys. 112, 043908 (2012) High, magnetic field independent critical currents in (Ba,K)Fe2As2 crystals Appl. Phys. Lett. 101, 012601 (2012) Fabrication of binary FeSe superconducting wires by diffusion process

Two additional structural forms, free-standing nanomembranes and microtubes, are reported and added to the vanadium dioxide (VO) material family. Free-standing VO nanomembranes were fabricated by precisely thinning as-grown VO thin films and etching away the sacrificial layer underneath. VO microtubes with a range of controllable diameters were rolled-up from the VO nanomembranes. When a VO nanomembrane is rolled-up into a microtubular structure, a significant compressive strain is generated and accommodated therein, which decreases the phase transition temperature of the VO material. The magnitude of the compressive strain is determined by the curvature of the VO microtube, which can be rationally and accurately designed by controlling the tube diameter during the rolling-up fabrication process. The VO microtube rolling-up process presents a novel way to controllably tune the phase transition temperature of VO materials over a wide range toward practical applications. Furthermore, the rolling-up process is reversible. A VO microtube can be transformed back into a nanomembrane by introducing an external strain. Because of its tunable phase transition temperature and reversible shape transformation, the VO nanomembrane-microtube structure is promising for device applications. As an example application, a tubular microactuator device with low driving energy but large displacement is demonstrated at various triggering temperatures.

Data‐driven materials discovery has become increasingly important in identifying materials that exhibit specific, desirable properties from a vast chemical search space. Synergic prediction and experimental validation are needed to accelerate scientific advances related to critical societal applications. A design‐to‐device study that uses high‐throughput screens with algorithmic encodings of structure–property relationships is reported to identify new materials with panchromatic optical absorption, whose photovoltaic device applications are then experimentally verified. The data‐mining methods source 9431 dye candidates, which are auto‐generated from the literature using a custom text‐mining tool. These candidates are sifted via a data‐mining workflow that is tailored to identify optimal combinations of organic dyes that have complementary optical absorption properties such that they can harvest all available sunlight when acting as co‐sensitizers for dye‐sensitized solar cells (DSSCs). Six promising dye combinations are shortlisted for device testing, whereupon one dye combination yields co‐sensitized DSSCs with power conversion efficiencies comparable to those of the high‐performance, organometallic dye, N719. These results demonstrate how data‐driven molecular engineering can accelerate materials discovery for panchromatic photovoltaic or other applications.

Directly spinning carbon nanotube (CNT) fibers from vertically aligned CNT arrays is a promising way for the application of CNTs in the field of high-performance materials. However, most of the reported CNT arrays are not spinnable. In this work, by controlling catalyst pretreatment conditions, we demonstrate that the degree of spinnability of CNTs is closely related to the morphology of CNT arrays. Shortest catalyst pretreatment time led to CNT arrays with the best spinnability, while prolonged pretreatment resulted in coarsening of catalyst particles and nonspinnable CNTs. By controlling the coalescence of catalyst particles, we further demonstrate the growth of undulating CNT arrays with uniform and tunable waviness. The CNT arrays can be tuned from well-aligned, spinnable forests to uniformly wavy, foam-like films. To the best of our knowledge, this is the first systematical study on the correlation between catalyst pretreatment, CNT morphology, and CNT spinnability.

The field of oxide electronics has benefited from the wide spectrum of functionalities available to the ABO3 perovskites, and researchers are now employing defect engineering in single crystalline heterostructures to tailor properties. However, bulk oxide single crystals are not conducive to many types of applications, particularly those requiring mechanical flexibility. Here, we demonstrate the realization of an all-oxide, single-crystalline nanomembrane heterostructure. With a surface-to-volume ratio of 2 × 10(7), the nanomembranes are fully flexible and can be readily transferred to other materials for handling purposes or for new materials integration schemes. Using in situ synchrotron X-ray scattering, we find that the nanomembranes can bond to other host substrates near room temperature and demonstrate coupling between surface reactivity and electromechanical properties in ferroelectric nanomembrane systems. The synthesis technique described here represents a significant advancement in materials integration and provides a new platform for the development of flexible oxide electronics.