Phys.org June 8, 2923 A team of researchers in the US (University of Minnesota, University of Utah, Argonne National Laboratory) demonstrated the ability to continuously tune the thermal conductivity of nanoscale films of La0.5Sr0.5CoO3-δ (LSCO) by a factor of over 5, via a room-temperature electrolyte-gate-induced non-volatile topotactic phase transformation from perovskite to an oxygen-vacancy-ordered brownmillerite phase accompanied by a metal-insulator transition. Combining time-domain thermoreflectance and electronic transport measurements, model analyses based on molecular dynamics and Boltzmann transport equation, and structural characterization by X-ray diffraction, they uncovered and deconvolved the effects of these transitions on heat carriers, including electrons and lattice […]
Category Archives: Materials science
Unveiling the invisible: A breakthrough in spectroscopy to allow discoveries in materials physics
Phys.org June 12, 2023 Slow motion movies allow us to see intricate details of the mechanical dynamics of complex phenomena. If the images in each frame are replaced by terahertz (THz) waves, such movies can monitor low-energy resonances and reveal fast structural or chemical transitions. An international team of researchers (Canada, Germany) combined THz spectroscopy as a non-invasive optical probe with a real-time monitoring technique to demonstrate the ability to resolve non-reproducible phenomena at 50k frames per second, extracting each of the generated THz waveforms every 20 μs. Based on a photonic time-stretch technique to achieve unprecedented data acquisition speeds, […]
Buckle up! A new class of materials is here
Science Daily June 2, 2023 Many passive damping methods rely on using low stiffness, complex mechanical structures, or electrical systems, which render them unfeasible in many of applications. Researchers in the Netherlands have developed a new method for passive vibration damping by allowing buckling of the primary load path in mechanical metamaterials and lattice structures, which sets an upper limit for vibration transmission: the transmitted acceleration saturates at a maximum value in both tension and compression, no matter what the input acceleration is. This nonlinear mechanism leads to an extreme damping coefficient —orders of magnitude larger than the linear damping […]
Carbon-based stimuli-responsive nanomaterials: Their classification and application
Phys.org June 5, 2023 With the development of material synthesis technology, carbon-based nanomaterials can be functionalized and used in various fields such as energy, environment, and biomedicine. Researchers in China applied carbon-based nanomaterials to different disease treatments based on their stimulus-response properties. They categorized them into carbon nanotubes, carbon nanospheres, and carbon nanofibers according to their morphology. They discussed the materials’’ applications in probes, bioimaging, tumor therapy, and other fields. They addressed the advantages and disadvantages of carbon-based stimuli-responsive nanomaterials and discussed their future perspective… read more. Open Access TECHNICAL ARTICLE
Researchers demonstrate novel way to convert heat to electricity
Nanowerk May 19, 2023 To compete with conventional energy-conversion technologies, a thermoelectric material must possess the mutually exclusive properties of both an electrical conductor and a thermal insulator. Recent theoretical investigations on sub-device scales have revealed that nanopillars attached to a membrane exhibit a multitude of local phonon resonances, spanning the full spectrum, that couple with the heat-carrying phonons in the membrane and cause a reduction in the in-plane thermal conductivity, with no expected change in the electrical properties because the nanopillars are outside the pathway of voltage generation and charge transport. A team of researchers in the US (NIST, […]
Smart material prototype challenges Newton’s laws of motion
Nanowerk May 18, 2023 The conventional mechanical metamaterials with inner resonators are characterized as homogenized solids with symmetric effective mass density tensors to interpret subwavelength wave attenuation mechanism. A team of researchers at the University of Missouri has presented a class of active metamaterials described by an odd mass density tensor which is no longer symmetric and whose nonzero asymmetric part arises from active and nonconservative forces. The unconventional wave phenomena caused by the odd mass density were demonstrated experimentally and numerically. The directional wave amplification was also illustrated by controllable feed-forward electric circuits. According to the researchers their findings […]
Team uses 3D printing to strengthen a key material in aerospace, energy-generation applications
MIT News May 19, 2022 An international team of researchers (USA – MIT, Turkey) used additive manufacturing (AM) of a nickel superalloy metallic matrix composite (Ni-MMC) using laser powder bed fusion (LPBF). They prepared nanoceramic-containing composite powders by high-speed blender decluttering and ball milling of as-received SiC nanowires (2 vol%) and Inconel 718 alloy powders which produced a homogeneous decoration of SiC on the surfaces of Inconel particles. Analysing the as-printed specimens revealed the dissolution of SiC nanowires during laser melting, leading to the in-situ formation of Nb- and Ti-based silicide and carbide nanoparticles. The in-situ formed nanoparticles resulted in […]
The exciting possibilities of tiny, twisted superconductors
Phys.org May 5, 2023 A team of researchers in the USA (Rutgers University, Harvard University, University of Connecticut, Louisiana State University, Flatiron Institute, Princeton University) proposed how to experimentally manipulate the quasiparticles, in very thin layers of ordinary superconductors to create topological superconductors by slightly twisting the stacked layers. They theorized that the application of a current makes the quasiparticles in the superconductor behave as if they were in a topological superconductor. They theorized that the twist at any angle essentially determines the properties. Even deviations by .1 degree in twist is strongly detrimental. The interactions between quasiparticles are shown […]
Leaky-wave metasurfaces: A perfect interface between free-space and integrated optical systems
Phys.org May 8, 2023 Metasurfaces have been rapidly advancing our command over the many degrees of freedom of light; however, so far, they have been mostly limited to manipulating light in free space. Metasurfaces integrated on top of guided-wave photonic systems have been explored to control the scattering of light off-chip with enhanced functionalities. However, these efforts have so far been limited to controlling one or two optical degrees of freedom at best. A team of researchers in the US (Columbia University, City University of New York) has developed leaky-wave metasurfaces, which are based on symmetry-broken photonic crystal slabs that […]
Better understanding soft material behavior
Science Daily May 1, 2023 The direct connections between the macroscopic flow/deformation and microscopic structure or dynamics has not been determined. An international team of researchers (USA – University of Illinois, Argonne National Laboratory, South Korea, Canada) They probed the microstructural yielding dynamics of a concentrated colloidal system by performing creep/recovery tests with simultaneous collection of coherent scattering data via X-ray Photon Correlation Spectroscopy (XPCS). This combination of rheology and scattering allowed for time-resolved observations of the microstructural dynamics as yielding occurred, which could be linked back to the applied rheological deformation to form structure–property relations. Under sufficiently small, applied […]