Carbon soot (CS) has the advantages of cost-effectiveness and production scalability over other carbons (i.e., graphene, CNTs) in their synthesis. However, little research has been conducted to explore the potential applications of CS. In this study, we demonstrated that a common daily waste-CS-can be used for developing a cost-effective absorbent (CS-sponge) to remove oil contaminants from water. The CS was synthesized by an ethylene-oxygen combustion flame. The CS-sponge was prepared via a dip-coating method. Without further surface modification and pretreatments, the CS-sponge demonstrates high absorption capacities (up to 80 times its own weight) for a broad spectrum of oils and organic solvents with a recyclability of more than 10 times. These research results show evidence that the CS-sponge is promising in environmental remediation for large-scale, low-cost removal of oils from water.

We report a giant, ∼22%, electroresistance modulation for a metallic alloy above room temperature. It is achieved by a small electric field of 2 kV/cm via piezoelectric strain-mediated magnetoelectric coupling and the resulting magnetic phase transition in epitaxial FeRh/BaTiO3 heterostructures. This work presents a detailed experimental evidence for an isothermal magnetic phase transition driven by tetragonality modulation in FeRh thin films, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh. Moreover, all the experimental results in this work illustrate FeRh as a mixed-phase model system well similar to phase-separated colossal magnetoresistance systems with phase instability therein.

Emergent phenomena at polar-nonpolar oxide interfaces have been studied intensely in pursuit of next-generation oxide electronics and spintronics. Here we report the disentanglement of critical thicknesses for electron reconstruction and the emergence of ferromagnetism in polar-mismatched LaMnO3/SrTiO3 (001) heterostructures. Using a combination of element-specific X-ray absorption spectroscopy and dichroism, and first-principles calculations, interfacial electron accumulation and ferromagnetism have been observed within the polar, antiferromagnetic insulator LaMnO3.Our results show that the critical thickness for the onset of electron accumulation is as thin as 2 unit cells (UC), significantly thinner than the observed critical thickness for ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely induced by electron over-accumulation.In turn, by controlling the doping of the LaMnO3, we are able to neutralize the excessive electrons from the polar mismatch in ultrathin LaMnO3 films and thus enable ferromagnetism in films as thin as 3 UC, extending the limits of our ability to synthesize and tailor emergent phenomena at interfaces and demonstrating manipulation of the electronic and magnetic structures of materials at the shortest length scales.

The ability to design complex copper (Cu) parts into the most efficient thermal structures is an old dream, but difficult to realize with conventional manufacturing techniques.The recent development of laser 3D printing techniques makes it possible to fully explore intricate designs and maximize the thermal performance of Cu-based thermal management components but present significant challenges due to its high optical reflectivity. In this study, we demonstrated the laser 3D printing of pure Cu with a moderate laser power (400 W). Dense Cu parts (95 %) with smooth surface finishing (Ra ~18 μm) were obtained at a scan speed of 400 mm/s, a hatch distance of 0.12 mm, and a layer thickness of 0.03 mm. The hardness, electrical, and thermal conductivity of the printed Cu parts are 108 MPa, 5.71×10 7 S/m, and 368 W/m•K, respectively, which are close to those of bulk Cu. Additionally, complex heat sink structures were printed with large surface areas (600 mm 2 /g), and their cooling performances were compared to a commercial heat sink with a smaller surface area (286 mm 2 /g) on an electronic chip. The complex heat sinks printed cools the electronic chip 45% more efficiently than the commercial one. The introduction of selective laser melting to additively manufacturing Cu heat sinks offers the promise to enhance the performance beyond the scope of exciting thermal management components.

International audienceAdvanced micro/nanofabrication of functional materials and structures with various dimensions represents a key research topic in modern nanoscience and technology and becomes critically important for numerous emerging technologies such as nanoelectronics, nanophotonics and micro/nanoelectromechanical systems. This review systematically explores the non-conventional material processing approaches in fabricating nanomaterials and micro/nanostructures of various dimensions which are challenging to be fabricated via conventional approaches. Research efforts are focused on laser-based techniques for the growth and fabrication of one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) nanomaterials and micro/nanostructures. The following research topics are covered, including: 1) laser-assisted chemical vapor deposition (CVD) for highly efficient growth and integration of 1D nanomaterial of carbon nanotubes (CNTs), 2) laser direct writing (LDW) of graphene ribbons under ambient conditions, and 3) LDW of 3D micro/nanostructures via additive and subtractive processes. Comparing with the conventional fabrication methods, the laser-based methods exhibit several unique advantages in the micro/nanofabrication of advanced functional materials and structures. For the 1D CNT growth, the laser-assisted CVD process can realize both rapid material synthesis and tight control of growth location and orientation of CNTs due to the highly intense energy delivery and laser-induced optical near-field effects. For the 2D graphene synthesis and patterning, room-temperature and open-air fabrication of large-scale graphene patterns on dielectric surface has been successfully realized by a LDW process. For the 3D micro/nanofabrication, the combination of additive two-photon polymerization (TPP) and subtractive multi-photon ablation (MPA) processes enables the fabrication of arbitrary complex 3D micro/nanostructures which are challenging for conventional fabrication methods. Considering the numerous unique advantages of laser-based techniques, the laser-based micro/nanofabrication is expected to play a more and more important role in the fabrication of advanced functional micro/nano-devices

Oxygen vacancies in complex oxides are indispensable for information and energy technologies. There are several means to create oxygen vacancies in bulk materials. However, the use of ionic interfaces to create oxygen vacancies has not been fully explored. Herein, we report an oxide nanobrush architecture designed to create high-density interfacial oxygen vacancies. An atomically well-defined (111) heterointerface between the fluorite CeO 2 and the bixbyite Y 2 O 3 is found to induce a charge modulation between Y 3+ and Ce 4+ ions enabled by the chemical valence mismatch between the two elements. Local structure and chemical analyses, along with theoretical calculations, suggest that more than 10% of oxygen atoms are spontaneously removed without deteriorating the lattice structure. Our fluorite-bixbyite nanobrush provides an excellent platform for the rational design of interfacial oxide architectures to precisely create, control, and transport oxygen vacancies critical for developing ionotronic and memristive devices for advanced energy and neuromorphic computing technologies.

Copper (Cu)/diamond (D) composites have been extensively studied as the nextgeneration thermal management materials due to its excellent thermal property. However, the presence of D particles makes processing these composites difficult. Additive manufacturing (AM) provides an intriguing method to overcome this issue because of its high degree of freedom to fabricate complex shapes. In this letter, we demonstrated the feasibility to additively manufacture 2 structures using Cu/D composite materials. D particles were coated with a graded TiO2-TiC interphase using a molten salt process to enhance its wettability with molten Cu. A dense Cu/coated-D composite was printed (96%) at an optimized energy density of 1200 J/mm 3. Strong bonding between the matrix and reinforcement was observed, leading to a highly thermally conductive composite (330 W/m.K). Furthermore, the quality of the coated-D remained unchanged after being exposed to the high laser power, thus making AM a suitable approach to manufacturing Cu/D composites.

Nitrogen-doped diamond was synthesized in open air using laser-assisted combustion flame method. A wavelength-tunable CO2 laser was used to resonantly excite the vibration modes of ammonia molecules, which were added into the diamond forming combustion flame. The wavelength of the CO2 laser was tuned to match frequencies of the NH wagging mode of the ammonia molecules. High efficiency energy coupling was achieved at laser wavelengths of 9.219, 10.35, and 10.719 μm, which are related to a rotational–vibrational transition (1084.63 cm−1), and splitting of the NH wagging mode (υ2+, 932.51 cm−1 and υ2−, 968.32 cm−1). Vibrational excitations of the ammonia molecules under these wavelengths actively intervenes the reaction courses, which steers the chemical reaction in the combustion flame and eventually promotes nitrogen concentration in the deposited diamond films. Concentration of the doped nitrogen atoms reaches up to 1.5 × 1020 atoms/cm3 in the diamond films deposited with a laser wavelength of 9.219 μm. Optical emission spectroscopy and mass spectrometry were used to study the evolution of chemical reactions with and without laser excitations.