Nanowerk August 1, 2023 Laser slicing is a technique of slicing materials along cracks formed by scanning a focused ultrashort-pulse laser beam inside the materials. Researchers in Japan proposed a novel slicing technique to fabricate diamond wafers and demonstrate slicing at the {100} surface. Cracks parallel to the {100} plane are needed to fabricate the wafer. However, crystal materials contain a cleavage plane at the {111} plane, which cracks easily. Typically, cracks propagate not only along the {100} plane, which was the intended slicing plane, but also along the {111} plane, which increased the kerf loss. To restrict these undesirable […]
Category Archives: Materials science
Self-healing plastic becomes biodegradable
Science Daily July 27, 2023 Mineral plastics are a promising class of bio-inspired materials that have properties, like self-heal ability, stretchability, hardness, and non-flammability, they can be reshaped easily. However, current mineral plastics are hardly biodegradable, and thus persistent in nature. Researchers in Germany have developed the next generation of mineral plastics, which are bio-based and biodegradable. Physically cross-linked (poly)glutamic-acid (PGlu)-based mineral plastics using various alcohol-water mixtures, metal ion ratios and molecular weights. The rheological properties were easily adjusted using these parameters. The general procedure involved addition of equimolar solution of CaCl2 to PGlu in equal volumes followed by addition […]
Some alloys don’t change size when heated, and we now know why
Phys.org July 31, 2023 The low thermal expansion of Fe–Ni Invar has long been associated with magnetism, but to date, the microscopic underpinnings of the Invar behaviour have eluded both theory and experiment. An international team of researchers (USA – Caltech, Boston College, Argonne National Laboratory, Israel) applied thermodynamic Maxwell relation to nuclear resonant X-ray scattering measurements of the phonon and magnetic entropies under pressure to obtain the separate phonon and magnetic contributions to thermal expansion. They found that the Invar behaviour stems from a competition between phonons and spins. In particular, the phonon contribution to thermal expansion cancelled the […]
‘Stunning’ discovery: Metals can heal themselves
Science Daily July 19, 2023 In traditional metallurgical design for fatigue resistance in metals, microstructures are developed to either arrest or slow the progression of cracks. Crack growth is assumed to be irreversible. By contrast, in other material classes, there is a compelling alternative based on latent healing mechanisms and damage. A team of researchers in the US (Sandia National Laboratory, Texas A&M University, University of Tennessee) has shown that fatigue cracks in pure metals can undergo intrinsic self-healing. They directly observed the early progression of nanoscale fatigue cracks, and as expected, the cracks advanced, deflected and arrested at local […]
Insights into designing advanced stimuli-responsive porous materials
Phys.org July 21, 2023 MOFs which possess a high degree of crystallinity and a large surface area with tunable inorganic nodes and organic linkers. The adsorption in MOFs changes the crystalline structure and elastic moduli. Thus, the coexistence of adsorbed/desorbed sites makes the host matrices elastically heterogeneous. To show the asymmetric role of elastic heterogeneity in the adsorption–desorption transition researchers in Japan constructed a minimal model incorporating adsorption-induced lattice expansion/contraction and an increase/decrease in the elastic moduli. They found that the transition was hindered by the entropic and energetic effects which become asymmetric in the adsorption process and desorption process, […]
New study reveals remarkable impact of intrinsic spin shielding in platinum-rare earth alloys on electrocatalysis
Phys.org July 24. 2023 Researchers in China introduced platinum–rare earth metal-based alloy catalyst, Pt2Gd, to reveal the role of spin configurations in the catalytic activity of materials. The catalyst exhibited a unique intrinsic spin reconfiguration because of interactions between the Gd-4f and Pt-5d orbitals. The adsorption and desorption of the oxygen species were optimized by modifying the spin symmetry and electronic structures of the material for increased oxygen reduction reaction (ORR) efficiency. The Pt2Gd alloy exhibited a half-wave potential, and a superior mass activity, and higher durability than conventional Pt/C catalysts. Theoretical calculations have proved that the spin shielding effect […]
A novel approach for balancing properties in composite materials
Phys.org July 26, 2023 Researchers at Texas A&M University introduced a programmable spray coating process for depositing multiple nanomaterials with tailorable patterns in composite. They showed that such patterns regulate the formation of interfaces, damage containment, and electrical-thermal conductivity of the composites, which is absent in conventional manufacturing that primarily rely on incorporating nanomaterials to achieve specific functionalities. Molecular dynamics simulations showed that increasing the hydrophilicity of the hybrid nanomaterials improved the interactions between the carbon surfaces and epoxy at the interfaces, manifested in enhanced interlaminar and flexural performance. Transitioning from ring to disk created a larger interconnected network leading […]
Intelligent rubber materials
Nanowerk July 18, 2023 Researchers in Germany have developed intelligent humidity-programmed hydrogel patches with high stretchability and tunable water-uptake and -release by copolymerization and crosslinking of N-isopropylacrylamide and oligo(ethylene glycol) comonomers. The intelligent elastomeric patches strongly responded to different humidities and temperatures in terms of mechanical properties which made them applicable for soft robotics and smart skin applications where autonomous adaption to environmental conditions was a key requirement. Beyond using the hydrogel in the conventional state in aqueous media, the new patches could be controlled by relative humidity. The humidity programming of the patches allowed to tune drug release kinetics, […]
New material could hold key to reducing energy consumption in computers and electronics
Nanowerk July 13, 2023 Contrary to topological insulators, topological semimetals possess a nontrivial chiral anomaly that leads to negative magnetoresistance and host to both conductive bulk states and topological surface states with intriguing transport properties for spintronics. Researchers at the University of Minnesota fabricated highly ordered metallic Pt3Sn and Pt3SnxFe1-x thin films via sputtering technology. Systematic angular dependence (both in-plane and out-of-plane) study of magnetoresistance presented surprisingly robust quadratic and linear negative longitudinal magnetoresistance features for Pt3Sn and Pt3SnxFe1-x, respectively. They attributed the anomalous negative longitudinal magnetoresistance to the type-II Dirac semimetal phase (pristine Pt3Sn) and/or the formation of tunable […]
Researchers achieve interdimensional superconductivity
Nanowerk July 19, 2023 Spatial disorder has been shown to drive two-dimensional (2D) superconductors to an insulating phase through a superconductor–insulator transition (SIT). Numerical calculations predict that with increasing disorder, emergent electronic granularity is expected in these materials—a phenomenon where superconducting (SC) domains on the scale of the material’s coherence length are embedded in an insulating matrix and coherently coupled by Josephson tunneling. An international team of researchers (USA – SLAC National Accelerator Laboratory, Colombia) has shown spatially resolved scanning tunneling spectroscopy (STS) measurements of the three-dimensional (3D) superconductor BaPb1−xBixO3 (BPBO), which surprisingly demonstrated three key signatures of emergent electronic […]