metamaterials (4)

Super Strength...


A sample of the new titanium lattice structure 3D printed in cube form. Credit: RMIT. New titanium lattice structure 3D printed in cube form. Credit: RMIT

Topics: 3D Printing, Additive Manufacturing, Materials Science, Metamaterials

A 3D printed ‘metamaterial’ boasting levels of strength for weight not normally seen in nature or manufacturing could change how we make everything from medical implants to aircraft or rocket parts.

RMIT University researchers created the new metamaterial – a term used to describe an artificial material with unique properties not observed in nature – from common titanium alloy.

But it’s the material’s unique lattice structure design, recently revealed in the journal Advanced Materials, that makes it anything but common: tests show it’s 50% stronger than the next strongest alloy of similar density used in aerospace applications.

Nature-Inspired Designs and Innovations

Lattice structures made of hollow struts were originally inspired by nature: strong hollow-stemmed plants like the Victoria water lily or the hardy organ pipe coral (Tubipora musica) showed us the way to combine lightness and strength.

Supernatural Strength: 3D Printed Titanium Structure Is 50% Stronger Than Aerospace Alloy, SciTech Daily, RMIT University

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Strange Metals II...


Credit: CC0 Public Domain

Topics: Applied Physics, Chemistry, Materials Science, Metamaterials, Quantum Mechanics

The behavior of so-called "strange metals" has long puzzled scientists—but a group of researchers at the University of Toronto may be one step closer to understanding these materials.

Electrons are discrete, subatomic particles that flow through wires like molecules of water flowing through a pipe. The flow is known as electricity, and it is harnessed to power and control everything from lightbulbs to the Large Hadron Collider.

In quantum matter, by contrast, electrons don't behave as they do in normal materials. They are much stronger, and the four fundamental properties of electrons—charge, spin, orbit, and lattice—become intertwined, resulting in complex states of matter.

"In quantum matter, electrons shed their particle-like character and exhibit strange collective behavior," says condensed matter physicist Arun Paramekanti, a professor in the U of T's Department of Physics in the Faculty of Arts & Science. "These materials are known as non-Fermi liquids, in which the simple rules break down."

Now, three researchers from the university's Department of Physics and Centre for Quantum Information & Quantum Control (CQIQC) have developed a theoretical model describing the interactions between subatomic particles in non-Fermi liquids. The framework expands on existing models and will help researchers understand the behavior of these "strange metals."

Their research was published in the journal Proceedings of the National Academy of Sciences (PNAS). The lead author is physics Ph.D. student Andrew Hardy, with co-authors Paramekanti and post-doctoral researcher Arijit Haldar.

"We know that the flow of a complex fluid like blood through arteries is much harder to understand than water through pipes," says Paramekanti. "Similarly, the flow of electrons in non-Fermi liquids is much harder to study than that in simple metals."

Hardy adds, "What we've done is construct a model, a tool, to study non-Fermi liquid behavior. And specifically, to deal with what happens when there is symmetry breaking, when there is a phase transition into a new type of system."

"Symmetry breaking" is the term used to describe a fundamental process found in all of nature. Symmetry breaks when a system—whether a droplet of water or the entire universe—loses its symmetry and homogeneity and becomes more complex.

Researchers develop new insight into the enigmatic realm of 'strange metals', Chris Sasaki, University of Toronto,

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Magnetic Plasmons in Nanostructures...


FIG. 1. (a) Sketches of the excitations of surface plasmons polaritons - SPP (top), localized surface plasmons - LSP (middle), and magnetic plasmons - MP (bottom). All these excitations are associated with a collective motion of surface charges under light illumination. (b) Diagram of MP-based plasmonic nanostructures used for fundamental studies and their applications in various research fields.

Topics: Electromagnetism, Magnetism, Metamaterials, Nanoclusters, Nanomaterials, Plasmonic Nanostructures


The magnetic response of most natural materials, characterized by magnetic permeability, is generally weak. Particularly in the optical range, the weakness of magnetic effects is directly related to the asymmetry between electric and magnetic charges. Harnessing artificial magnetism started with a pursuit of metamaterial design exhibiting magnetic properties. A plasmonic nanostructure called split-ring resonators gave the first demonstration of artificial magnetism. Engineered circulating currents form magnetic plasmons, acting as the source of artificial magnetism in response to external electromagnetic excitation. In the past two decades, magnetic plasmons supported by plasmonic nanostructures have become an active topic of study. This Perspective reviews the latest studies on magnetic plasmons in plasmonic nanostructures. A comprehensive summary of various plasmonic nanostructures supporting magnetic plasmons, including split-ring resonators, metal–insulator–metal structures, metallic deep groove arrays, and plasmonic nanoclusters, is presented. Fundamental studies and applications based on magnetic plasmons are discussed. The formidable challenges and the prospects of the future study directions on developing magnetic plasmonic nanostructures are proposed.

Magnetic plasmons in plasmonic nanostructures: An overview

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2D MXenes...

Helper two-dimensional metal-carbide layers could improve perovskite solar cell stability and help make these complex solar cells a viable green energy option. Credit: iStock Milos-Muller


Topics: Condensed Matter Physics, Green Tech, Materials Science, Metamaterials, Nanotechnology, Solar Power

With the reality of climate change looming, the importance of realistic green energy sources is higher than ever. Solar cells are one promising avenue, as they can convert readily available visible and ultraviolet energy into usable electricity. In particular, perovskite materials sandwiched between other support layers have demonstrated impressive power conversion efficiencies. Current challenges reside in optimizing perovskite/support layer interfaces, which can directly impact power conversion and cell degradation. Researchers Antonio Agresti et al. under the direction of Aldo Di Carlo at the University of Rome Tor Vergata in Italy have investigated how cells containing two-dimensional titanium-carbide MXene support layers could improve perovskite solar cell performance.

To obtain good power conversion within a perovskite solar cell, all layers and layer interfaces within the cell must have good compatibility. Typical cells contain the active perovskite material sandwiched between two charge transport layers, which are then adjacent to their corresponding electrodes. Support layers may also be added. Charge mobility, energy barriers, interface energy alignment, and interfacial vacancies all impact compatibility and subsequent cell performance and stability. Thus, engineering well-suited interfaces with the cell is paramount to cell success and long-term stability, an important criterion for potential commercialization.

Two-dimensional buffer materials could help to modify and promote useful interface interactions. MXenes, a growing class of two-dimensional transitional metal carbides, nitrides, and carbonitrides, have shown impressive electronic properties that are easily tuned via surface modification. For example, the band gap of an MXene can be modified by changing the surface termination group from an oxygen atom to a hydroxide molecule. Additionally, MXene composition impacts the overall material performance. This type of fine-tuning allows impressive control over MXene properties and makes them ideal for interface adjustments.


Two-dimensional MXenes improve perovskite solar cell efficiency
Amanda Carr, Physics World

#P4TC: MXenes...August 24, 2015

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