Stronger or tougher? For designers of advanced materials, this tradeoff may complicate efforts to devise efficient methods for assembling nanometer-scale building blocks into exotic ceramics, glasses and other types of customized materials.
“Not all properties may benefit from microstructural refinement, so due caution needs to be exercised in materials design,” writes the National Institute of Standards and Technology’s (NIST) Brian Lawn in the January issue of Journal of Materials Research.* An expert on brittle materials, Lawn advises that past experience is not always a useful guide for predicting material properties and performance when film thicknesses, grain sizes and other characteristic dimensions shrink toward molecular proportions. At this level, materials designers must reckon with interatomic force laws that are obscured at larger scales, from micrometers (millionths of a meter) on up.
“Generally in brittle materials, strength (resistance to crack initiation) increases and toughness (resistance to crack propagation) decreases as characteristic scaling dimensions diminish,” Lawn concludes from his work to refine ceramics used in biomechanical applications such as dental crowns and orthopedic implants. At the nanoscale, tiny cracks require more load to spread them, but have little resistance to extension once they start and are, therefore, more likely to spread catastrophically. Depending on the application in mind, the decrease in fracture toughness may more than offset initial gains in strength, or the ability to withstand stresses that squeeze, stretch or twist the material.
Mark Bello | NIST
New material could lead to erasable and rewriteable optical chips
07.12.2016 | University of Texas at Austin
Porous crystalline materials: TU Graz researcher shows method for controlled growth
07.12.2016 | Technische Universität Graz
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Health and Medicine
07.12.2016 | Life Sciences
07.12.2016 | Health and Medicine