Discover Top Posts Tagged with #supercrystals

Ordered 'supercrystal' could make lasers faster, smaller and more efficient

An advance from Monash University could pave the way for faster, smaller, and more energy-efficient lasers and other light-based technologies. Engineers have developed a new type of perovskite material arranged into an ordered "supercrystal." In this structure, tiny packets of energy called excitons work together rather than individually, allowing the material to amplify light far more efficiently. The findings, published in Laser & Photonics Reviews, could have applications in communications, sensors, and computing, improving the performance of devices that rely on light, such as sensors in autonomous vehicles, medical imaging, or electronics. Corresponding author Professor Jacek Jasieniak at Monash Materials Science and Engineering highlighted the potential for faster, more energy-efficient optical devices. "What's exciting here is that we're not changing the material itself, but how it's organized. By assembling nanocrystals into an ordered supercrystal, the excitations created by light can cooperate rather than compete, which allows light to be amplified much more efficiently," Professor Jasieniak said.

Metastable marvel: X-rays illuminate an exotic material transformation

A dry material makes a great fire starter, and a soft material lends itself to a sweater. Batteries require materials that can store lots of energy, and microchips need components that can turn the flow of electricity on and off. Each material's properties are a result of what's happening internally. The structure of a material's atomic scaffolding can take many forms and is often a complex combination of competing patterns. This atomic and electronic landscape determines how a material will interact with the rest of the world, including other materials, electric and magnetic fields, and light. Scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory, as part of a multi-institutional team of universities and national laboratories, are investigating a material with a highly unusual structure—one that changes dramatically when exposed to an ultrafast pulse of light from a laser.

Spontaneous supercrystal discovered in switching metal-insulator

A supercrystal formation previously unobserved in a metal-insulating material was discovered by a Cornell-led research team, potentially unlocking new ways to engineer materials and devices with tunable electronic properties. The researchers showed that the atomic structure in the thin-film Mott insulator Ca2RuO4—part of a unique family of materials that can switch between being a metal and an insulator due to quantum effects—forms an anisotropic, organized pattern with multiple spatial periods below temperatures of 200 to 250-degrees Kelvin. The spontaneous supercrystal formation was detailed June 17 in the journal Advanced Materials. "This is a great example of complexity arising from simplicity," said Oleg Gorobtsov, postdoctoral fellow and lead author of the study.

Super-strong magnetic supercrystals can assemble themselves

Verner Håkonsen works with cubes so tiny that nearly 5 billion of them could fit on a pinhead.

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He cooks up the cubes in the Norwegian University of Science and Technology's (NTNU) NanoLab, in a weird-looking glass flask with three necks on the top using a mixture of chemicals and special soap.

And when he exposes these invisible cubes to a magnetic field, they perform a magical feat: they assemble themselves into whatever shape he wants.

"It's like building a house, except you don't have to build it," he says. The magnetic force along with other forces cause "the house to build itself -- all the building blocks assemble themselves perfectly under the right conditions."

Supercrystal: A hidden phase of matter created by a burst of light

"Frustration" plus a pulse of laser light resulted in a stable "supercrystal" created by a team of researchers led by Penn State and Argonne National Laboratory, together with University of California, Berkeley, and two other national laboratories.

This is one of the first examples of a new state of matter with long-term stability transfigured by the energy from a sub-pico-second laser pulse. The team's goal, supported by the Department of Energy, is to discover interesting states of matter with unusual properties that do not exist in equilibrium in nature.

"We are looking for hidden states of matter by taking the matter out of its comfortable state, which we call the ground state," says the Penn State team leader Venkatraman Gopalan, professor of materials science. "We do this by exciting the electrons into a higher state using a photon, and then watching as the material falls back to its normal state. The idea is that in the excited state, or in a state it passes through for the blink of an eye on the way to the ground state, we will find properties that we would desire to have, such as new forms of polar, magnetic and electronic states."

Nanoparticles form supercrystals under pressure

Self-assembly and crystallisation of nanoparticles (NPs) is generally a complex process, based on the evaporation or precipitation of NP-building blocks. Obtaining high-quality supercrystals is slow, dependent on forming and maintaining homogenous crystallisation conditions. Recent studies have used applied pressure as a homogenous method to induce various structural transformations and phase transitions in pre-ordered nanoparticle assemblies. Now, in work recently published in the Journal of Physical Chemistry Letters, a team of German researchers studying solutions of gold nanoparticles coated with poly(ethylene glycol)- (PEG-) based ligands has discovered that supercrystals can be induced to form rapidly within the whole suspension.

Over the last few decades, there has been considerable interest in the formation of nanoparticle (NP) supercrystals, which can exhibit tunable and collective properties that are different from that of their component parts, and which have potential applications in areas such as optics, electronics, and sensor platforms. Whilst the formation of high-quality supercrystals is normally a slow and complex process, recent research has shown that applying pressure can induce gold nanoparticles to form supercrystals. Building on this and the established effect of salts on the solubility of gold nanoparticles (AuNP) coated with PEG-based ligands, Dr. Martin Schroer and his team carried out a series of experiments investigating the effect of varying pressure on gold nanoparticles in aqueous solutions. They made an unexpected observation – when a salt is added to the solution, the nanoparticles crystallise at a certain pressure. The phase diagram is very sensitive, and the crystallisation can be tuned by varying the type of salt added, and its concentration.

'Incomprehensible' birth of supercrystal explained

Two years ago, a research team led by Utrecht University published an article in Science explaining how they had created a material with unique and extremely interesting electronic characteristics. In this 'supercrystal', the electrons move almost with the speed of photons, and the electric current can be switched on and off. This makes it ideal for ultra-fast electronics. But at the time, the researchers were at a loss to explain how this 'supercrystal' obtained its unique structure. Now they have unravelled the mystery, and it appears to involve a completely different mechanism for crystal formation. This is an important insight for research into new materials with unique electronic characteristics. The results of their research were published online in Nature Materials.

The 'supercrystal' develops when tiny nanocrystals form a perfectly ordered surface one layer thick. In this super-matrix, the structure of the atoms -- A, B, A, B -- precisely follows that of the nanocrystals itself. "But how such a neatly ordered super-matrix could be born from all of those nanocrystals was incomprehensible to us," says Prof. Daniël Vanmaekelbergh from Utrecht University. "Now that we have insight into how the matrix is formed, we can conduct much more focused research into how we can make the structures that we would like to have."

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