Tag Archives: glass

Strongest glass in the world can scratch diamonds

A piece of 1mm-wide AM-III glass left scratch marks on the surface of a natural diamond. Photo: National Science Review

Glass is associated with brittleness and fragility rather than strength. However, researchers in China were able to create a new transparent amorphous material that is so strong and hard that it can scratch diamonds. What’s more, this high-tech glass has a semiconductor bandgap, which makes it appealing for solar panels.

Strongest amorphous material in the world

Diamond, the hardest material known to date in the universe, is often used in tools for cutting glass. But the tables have turned.

“Comprehensive mechanical tests demonstrate that the synthesized AM-III carbon is the hardest and strongest amorphous material known so far, which can scratch diamond crystal and approach its strength. The produced AM carbon materials combine outstanding mechanical and electronic properties, and may potentially be used in photovoltaic applications that require ultrahigh strength and wear resistance,” the authors of the new study wrote.

The new material developed by scientists at Yanshan University in Hebei province, China, is tentatively named AM-III and was rated at 113 gigapascals (GPA) in the Vickers hardness test. Vickers hardness, a measure of the hardness of a material, is calculated from the size of an impression produced under load by a pyramid-shaped diamond indenter.

That’s more than many natural diamonds that have a Vickers score in the range of 70-100 GPa, but less than the hardest diamonds that can score up to 150 GPa.

It’s about ten times harder than mild steel and could be 20 to 100 times tougher than most bulletproof windows.

Shaped like diamonds, looks like glass

Like diamonds, AM-III is mostly made of carbon. But while carbon atoms in diamond are arranged in an orderly crystal lattice, glass has a chaotic internal structure typical of an amorphous material. This is why glass is typically weak, but AM-III has micro-structures in the material that appear orderly, just like crystals. So, AM-III is part glass, part crystal, which explains its strength.

In order to make AM-III, the Chinese researchers had to employ a process that is even more complicated than manufacturing artificial diamonds. The most common method for creating synthetic diamonds used in the industry is called high pressure, high temperature (HPHT). During HPHT, carbon is subjected to similarly high temperatures and pressure as those that led to the formation of natural diamonds deep in the Earth, around 1,300 degrees Celsius (1650 to 2370 degrees Fahrenheit) and a pressure 50,000 times greater on the surface.

Instead of graphite, the raw material of artificial diamonds, the Chinese researchers started off with fullerene, also called buckminsterfullerene. These molecules contain at least 60 atoms of carbon, commonly denoted as C60, arranged in a lattice that can either form a ball or sphere shape and are typically 1nm diameter.

These carbon “footballs” are typically soft and squishy. But after being subjected to great heat and pressure, the carbon balls are crushed and blended together.

The fullerene was subjected to about 25 GPa of pressure and 1,200 degrees Celsius (2,192 degrees Fahrenheit). However, the researchers were careful to reach these conditions very gradually, taking their time over the course of about 12 hours. Immediately subjecting the material to high pressure and heat may have turned the carbon balls into diamonds.

The resulting transparent material is not only hard but also a semiconductor, with a bandgap range almost as effective as silicon, the main semiconductor used in electronics. So besides bulletproof glass, it could prove useful in the solar panel industry where its properties can shine by allowing sunlight to reach photovoltaic cells, while also enhancing the lifespan of the product.

AM-III was described in a recent study published in the journal National Science Review

Researchers found intact, 2,000-year-old brain cells turned to glass after the eruption of Mount Vesuvius

Italian researchers report finding intact brain cells in the skull of a man who died 2,000 years ago in the shadow of Mount Vesuvius.

Fragments of glassy black material extracted from the ancient skull. Image credits Pierpaolo Petrone et al., (2020), N Engl J Med.

The eruption of Mount Vesuvius, which destroyed the Roman city of Pompeii in the year 79 AD, is perhaps one of the widest-known events of its kind in history. However, Pompeii was not the only city that was claimed by the ashes on that day — Herculaneum, Oplontis, Stabiae, and other smaller settlements suffered the same fate.

New investigations on the remains of a young man discovered during digs in Herculaneum in the 1960s found that some of his brain cells were still intact, despite being thousands of years old.

Keep your head in the game

“The brain exposed to the hot volcanic ash must first have liquefied and then immediately turned into a glassy material by the rapid cooling of the volcanic ash deposit,” explains Pier Paolo Petrone, a forensic anthropologist at the University of Naples Federico II who led the research.

“[The cells in his spinal cord were preserved] incredibly well preserved with a resolution that is impossible to find anywhere else.”

The remains were found face-down on a wooden bed and he was likely around 25 at the time of his death, according to the team. The investigations were prompted by one researcher noticing “some glassy material shining from within the skull” in 2008.

That shiny material was the result of the vitrification (the process of something turning into glass, or becoming glass-like) of the young man’s brain during the eruption. Vitrification is the process used to create ceramics or glass from raw materials, and involves high heat and rapid cooling which alters a material’s molecular structure.

Despite the fact that this process was probably quick and very intense, brain cells in the individual’s spinal cord maintained their shape and position. In effect, they became excellent, glassy fossils. Guido Giordano, a volcanologist at Roma Tre University and co-author of the study called it a “perfect” preservation and a “totally unprecedented” finding in a vitrified specimen.

“This opens up the room for studies of these ancient people that have never been possible,” he added.

Charred wood found next to the victim allowed the team to estimate that it experienced temperatures of more than 500 degrees Celsius (932 degrees Fahrenheit). The skeleton was found inside the city’s college of the Augustales, a temple dedicated to the Roman Emperor Augustus who was the first to be worshipped as a god.

The team will continue to study the remains and try to understand what conditions are needed to create such spectacular vitrification. They also hope to isolate and analyze proteins from the remains, perhaps even genetic material.

The paper “Heat-Induced Brain Vitrification from the Vesuvius Eruption in c.e. 79” has been published in the New England Journal of Medicine.

Complex glass objects 3D-printed using new take on old method

Researchers at ETH Zürich have developed the first 3D-printing method that can produce highly-complex, porous glass objects. The approach relies on a special resin that can be cured using ultraviolet (UV) light.

Several of the 3-D printed objects created by the team.
Image credits Group for Complex Materials / ETH Zurich.

Glass has been a long-standing goal of 3D-printing enthusiasts for a long time now; it’s also proven to be the most elusive. The inherent problem regarding printable glass is that the material requires very high temperatures to process. The two approaches we’ve tried so far are to either ‘print’ molten glass — which requires expensive and specialized heat-resistant equipment — or to use ceramic powders as ink to sinter into glass — an approach that sacrifices precision and thus the complexity of the finished product.

In order to solve the issue, the team from ETH Zurich went back to the roots, and worked from stereolithography, one of the first 3-D printing techniques developed during the 1980s. They developed a resin which contains a plastic material and organic molecules tied to glass precursors that can be hardened by exposure to UV light.

A light touch

When blasted with UV light — the team says commercially available Digital Light Processing technology works just fine — photosensitive components in the resin bind together. The plastic in the ink forms into a maze-like polymer that provides the structural framework. Ceramic-bearing molecules link together in the empty areas created by the framework.

This allows an object to be built layer-by-layer, and by modifying the intensity of the UV light, the team can change various parameters in each layer. Weak light intensity results in large pores, for example, while intense illumination produces small pores.

“We discovered that by accident, but we can use this to directly influence the pore size of the printed object,” says Kunal Masania, a co-author of the study.

So where does the glass fit into this? The team explains that they can modify the microstructure of their (hardened) ink by mixing silica with borate or phosphate and adding it to the resin. Silica is the main component of glass, while borate and phosphate are added to specialized, heat-resistant and optical glass respectively. The team explains that their approach allows for single or multiple types of inks to be mixed into a single object, allowing for several kinds of glass to be produced in the end.

The final step involves using heat to actually turn the hardened ink into glass. The printed ‘blanks’ are fired at 600˚C, which burns away the polymer framework, and then at 1000˚C to transform the ceramic structure into glass. During the thermal treatment, the blanks shrink significantly, the authors report, while becoming as transparent and hard as window glass.

So far, the approach can only be used for small objects — about the size of a die. Larger objects such as bottles, drinking glasses, or window panes cannot be produced this way, but that wasn’t the goal here, Masania explains. The team wanted to prove that glass is a viable material for 3D-printing, he explains.

The team has applied for a patent on their technology and are negotiating with industry representatives to take their process to market.

The paper “Three-dimensional printing of multicomponent glasses using phase-separating resins” has been published in the journal Nature Materials.

‘Smart’ glass recognizes numbers without the need for sensors or even electrical power

A new type of glass can identify numbers all by itself by bending light in specific ways. Credit: Zongfu Yu.

Many phones can now be unlocked with face ID, a technology that is the pinnacle of computer vision and artificial intelligence — but which also uses significant computing resources and battery life. Imagine a future, however, where the same function could be achieved with a single piece of glass that can recognize your face or other imagery without using any sensors or even power at all. Sounds like science fiction but a team of creative engineers at the University of Wisconsin-Madison has recently demonstrated such a “smart” glass.

In other words, researchers managed to embed artificial intelligence inside an inert object. The novel approach provides a low-tech alternative to traditional digital artificial vision.

The researchers led by Zongfu Yu, a professor of electrical and computer engineering, designed translucent glass with tiny bubbles and impurities embedded at strategic locations.

“We’re using optics to condense the normal setup of cameras, sensors and deep neural networks into a single piece of thin glass,” he said in a statement.

As a proof of concept, Yu and colleagues designed a glass that can identify handwritten numbers. Light reflected off an image of a number enters one end of the glass, and then focuses on one of nine spots on the side, each corresponding to individual digits. Even when a handwritten “3” was altered to become an “8”, this clever system was dynamic enough to recognize the new digit. How fast? As fast as the speed of light, the fastest thing there is.

“The fact that we were able to get this complex behavior with such a simple structure was really something,” says Erfan Khoram, a graduate student in Yu’s lab.

The system shines due to the fact that it is completely self-contained and all the “computational” machinery is embedded inside it. There is zero latency because there is no need to send information to the cloud for processing. There is also no need for electrical power.

“We could potentially use the glass as a biometric lock, tuned to recognize only one person’s face,” says Yu. “Once built, it would last forever without needing power or internet, meaning it could keep something safe for you even after thousands of years.”

Zongfu Yu (left), Ang Chen (center) and Efram Khoram (right). Credit: Sam Million-Weaver.

According to the researchers, this is an example of analog artificial vision. Designing the glass was similar to machine-learning training processes used by artificial neural networks — except that the training was done on an analog material rather than digital information. The tweaking was performed by embedding air bubbles of different sizes and shapes, as well as light-absorbing materials like graphene, at specific locations inside the glass.

“We’re accustomed to digital computing, but this has broadened our view,” says Yu. “The wave dynamics of light propagation provide a new way to perform analog artificial neural computing”

In the future, the researchers plan to test their approach for more complex image recognition, such as facial recognition.

“The true power of this technology lies in its ability to handle much more complex classification tasks instantly without any energy consumption,” says Ming Yuan, a collaborator on the research and professor of statistics at Columbia University. “These tasks are the key to create artificial intelligence: to teach driverless cars to recognize a traffic signal, to enable voice control in consumer devices, among numerous other examples.”

“We’re always thinking about how we provide vision for machines in the future, and imagining application specific, mission-driven technologies.” says Yu. “This changes almost everything about how we design machine vision.”

A piece of Libyan desert glass that weighs 22 grams and is about 55 mm wide. Credit: Wikimedia Commons.

Scientists solve 100-year-old mystery of yellow desert glass prized by Egyptian pharaohs

A piece of Libyan desert glass that weighs 22 grams and is about 55 mm wide. Credit: Wikimedia Commons.

A piece of Libyan desert glass that weighs 22 grams and is about 55 mm wide. Credit: Wikimedia Commons.

An exotic and beautiful type of glass found in the Sahara desert has a cosmic origin, according to a new study. After analyzing the chemical makeup of Libyan desert glass — a naturally occurring glass whose striking yellow color made it a much-sought-after decorative material — researchers found that it was produced by ancient meteorite impacts.

Cosmic glass fit for kings

Breastplate found in King Tutankhamun’s tomb. The scarab is made out of Libyan desert glass. Credit: Wikimedia Commons.

Breastplate found in King Tutankhamun’s tomb. The scarab is made out of Libyan desert glass. Credit: Wikimedia Commons.

The rare Libyan desert glass has been prized for its beauty for thousands of years. The glass — the purest natural silica glass ever found on Earth — is generally yellow in color and can be very clear, although most pieces are milky and may even contain tiny bubbles, white wisps, and inky black swirls.

By one estimate, over a thousand tons of Libyan desert glass are strewn across the deserts of eastern Libya and western Egypt. Most are the size of pebbles, although some chunks can have a considerable size and weight — the biggest piece ever found weighs around 26 kg.

Local inhabitants in the Neolithic period made tools out of the glass, and later the Egyptians used it to fashion jewelry. In fact, the carved stone on the breastplate of the famous Egyptian pharaoh Tutankhamun was made of Libyan desert glass. But these piece of glass were created long before King Tut was born — about 29 million years by one estimate.

Silica glass at the Great Sand Sea. Credit: Mohamed El-Hebeishy.

Silica glass at the Great Sand Sea. Credit: Mohamed El-Hebeishy.

 

For more than a hundred years, scientists have debated what forces could have created the enchanting glasses. There are two major hypotheses that explain their formation: either a meteor impact or an airburst (an atmospheric explosion which happens when meteoroids explode in the lower atmosphere) was responsible. A recently published study supports the former theory.

In a new study, Aaron Cavosie from Curtin University in Australia and colleagues performed chemical analyses of Libyan desert glass samples that unequivocally supports the meteorite formation theory.

While they were examining zircon minerals embedded in the glasses, the researchers found traces of another mineral called reidite. This mineral only forms in high pressure and heat — so far, it hasn’t been found anywhere other than meteorite impact craters.

“Both meteorite impacts and airbursts can cause melting, however, only meteorite impacts create shock waves that form high-pressure minerals,” says Cavosie.

“So finding evidence of former reidite confirms it was created as the result of a meteorite impact.”

Whatever meteorite impacted the desert all those millions of years ago, it must have caused a gigantic explosion. It vitrified (glassified) a huge area, resulting in a broad range of glasses ranging from cloudy dark to stunningly luminous lemon yellow — all depending on the kind of contaminants that dissolved into the liquid silica created by the powerful impact.

A variety of Libyan Desert Glasses. Credit: Corning Museum of Glasses.

A variety of Libyan Desert Glasses. Credit: Corning Museum of Glasses.

The findings published in the journal Geology are useful for establishing how often near-Earth objects come in contact with our planet’s surface. The study seems to suggest that the kind of impacts that are powerful enough to create Libyan desert glass are, thankfully, quite rare.

“Meteorite impacts are catastrophic events, but they are not common,” says Cavosie.

“Airbursts happen more frequently, but we now know not to expect a Libyan desert glass-forming event in the near future, which is cause for some comfort.”

3d printed pretzel

Novel technique can 3-D print intricate glass objects like a pretzel

German researchers have 3D-printed glass objects with very intricate shapes. What makes their novel technique interesting is that they started from common, commercially available 3-D printers. Complex lenses, filters, or even aesthetically pleasing ornaments are some of the applications.

3-D printing glass: now possible

3d printed pretzel

Credit: Karlsruhe Institute of Technology.

“Glass is one of the oldest materials known to mankind,” says study co-author Bastian Rapp of the Karlsruhe Institute of Technology, “and it has been pretty much ignored in the 3D printing revolution of the 21st century.”

Rapp and colleagues set out to show just how trivial 3D printing glass can really be. Some of the objects that the researchers at  Karlsruhe Institute of Technology 3-D printed include a honeycomb structure, a castle or an adorably-looking pretzel, all of which are fairly complicated to make out of glass.

3d printed castle

Credit: Karlsruhe Institute of Technology.

The technique relies on using a “liquid glass” extruder material instead of the various kinds of polymers employed by commercial 3-D printers hobbyists know and love. The material is a nanocomposite of glass nanoparticles suspended in a prepolymer. When light is shone on the glass particle-containing resin, it hardens. The final step involves moving the printed object into an oven where the prepolymer is burned off and glass nanoparticles melt, ultimately fusing into a familiar glass structure.

The scale and finesse of the printed objects depend only on the printer itself, the German researchers claim in their paper published in Nature. This means the same technique could be used to make anything from tiny lenses for cameras or microscopes to large facades on skyscrapers. Previously, in 2015, MIT researchers printed transparent glass objects by heating the precursor extruder material up to about 1,037 degrees Celsius (1,900 degrees Fahrenheit), but the approach required a custom-built 3-D printer.

The 3-D printed glass objects can withstand temperatures as high as 1,472 degrees Fahrenheit. Credit: Karlsruhe Institute of Technology.

The 3-D printed glass objects can withstand temperatures as high as 1,472 degrees Fahrenheit. Credit: Karlsruhe Institute of Technology.

3D-printers are far more versatile than they were only a decade ago. Besides various plastics, you can now 3-D print objects out of metal, ceramics or even biological cells. Is there anything that we can’t print nowadays?

“This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia,” the researchers conclude.

 

 

Cooking nuclear waste into glass and ceramic materials could provide safe, efficient containment

Containing radioactive waste in glass and other ceramic materials might be the key to protect people — and the environment — from their harmful effects.

Image via Pexels / Public Domain.

Nuclear power is awesome. Splitting the atom can yield huge amounts of energy for no greenhouse gas emissions. The downside, however, is that you’re left with piles of radioactive by-product (waste) that is really, really harmful for people, animals, plants, pretty much everything. The good news is that radioactivity naturally decays over time — usually a few million years.

The bad news is that the waste is chemically mobile in water (it gets carried around by rain or rivers) and in air — so you have to keep it well isolated and locked up until that time passes. Which is quite a hassle. The way we go about it now is geological disposal — a fancy way of saying “we bury it really deep” — in disused mines, ocean floor disposal, or (planned) specialized deep-storage.

Rutgers University researcher and assistant professor in the Department of Materials Science and Engineering Ashutosh Goel thinks he’s found a better way to go about it, by immobilizing radioactive waste in glass and ceramic materials. Goel is the principal investigator (PI) or co-PI for six glass or glass-related waste containment projects. His work may help to one-day safely dispose of highly radioactive waste, now stored at commercial nuclear power plants.

“Glass is a perfect material for immobilizing the radioactive wastes with excellent chemical durability,” said Goel.

One of his projects involves mass-producing apatite glasses to immobilize iodine-129 atoms in a chemically-stable form. This isotope of iodine has a half-life of 15.7 million years and is highly mobile in water and air according to the EPA. Exposure to iodine-129 affects the thyroid gland and increases the risk of cancer. Another one of his projects developed a way to synthesize apatite minerals from silver iodide particles. Goel is also studying how to capture sodium and aluminum atoms from highly radioactive wastes in borosilicate glasses which resist crystallization.

Containing waste in glass might provide us with a safe way to dispose of them in the future. And it will look like this.
Image credits Albert Kruger / U.S. Department of Energy.

Among Goel’s major founders is the U.S. Department of Energy (DOE), which currently oversees one of the most wide-scale nuclear cleanup programs in the world, following the U.S.’s 45 year-long nuclear weapon development and production program. This project once included 16 major facilities throughout Idaho, Nevada, South Carolina, Tennessee and Washington state, according to the DOE. The site in Washington state, Hanford, is one of the biggest clean-up challenges the department faces. This complex manufactured more than 20 million pieces of uranium metal fuel, processing around 110,000 tons of fuel from nine reactors on the Columbia River.

Around 56 million gallons of radioactive waste from the Hanford plants went to underground storage in 177 tanks. It’s estimated that 67 of these tanks — more than a third — have leaked part of the waste, the DOE says. In 1989, clean-up efforts started at the site. The liquids have been pumped out of the tanks, leaving behind mostly-dry waste. Work began on a radioactive liquid waste treatment plant in 1999, which is nearing completion.

“What we’re talking about here is highly complex, multicomponent radioactive waste which contains almost everything in the periodic table,” Goel said. “What we’re focusing on is underground and has to be immobilized.”

The DOE hopes to start churning out radioactive-waste-glass by 2022 or 2023 at Hanford, Goel said.

“The implications of our research will be much more visible by that time.”

“[The process] depends on its [the waste material’s] composition, how complex it is and what it contains,” Goel added. “If we know the chemical composition of the nuclear waste coming out from those plants, we can definitely work on it.”

The full paper “Can radioactive waste be immobilized in glass for millions of years?” is still awaiting publication. Materials provided by Rutgers University can be found here.

Israeli archaeologists uncover roman-period glass factory underpinning trade throughout the empire

Israel Antiques Authority (IAA) archaeologists have uncovered the ruins of a 1,600 year-old complex of glass kilns in the Jezreel Valley. Their size indicates that Israel was one of the most important glass manufacturing center in the ancient world, says Dr. Yael Gorin-Rosen, IAA’s Glass Department head curator.

Small fragments of raw glass found at the site. Now that’s pretty.
Image credits Assaf Peretz / Israel Antiquities Authority.

The structures are built in two compartments — a firebox where fuel was burned to create the huge temperatures required for the process and a melting chamber. Here, clean beach sand and salt were mixed and melted at temperatures in excess of 1,200 degrees Celsius (2190 Fahrenheit.) The raw glass would take a week or two to form into huge chunks, some of which weighed in excess of 10 tons. When the kilns cooled, the blocks were broken into smaller pieces that were sold to workshops where it was melted again to produce glassware.

“This is evidence that Israel constituted a production center on an international scale; hence its glassware was widely distributed throughout the Mediterranean and Europe,” said Dr. Gorin-Rosen.

The kilns, undisturbed for 1,600 years.
Image credits Assaf Peretz / Israel Antiquities Authority.

“We know from historical sources dating to the Roman period that the Valley of Akko was renowned for the excellent quality sand located there, which was highly suitable for the manufacture of glass,” Dr. Gorin-Rosen said. “Chemical analyses conducted on glass vessels from this period which were discovered until now at sites in Europe and in shipwrecks in the Mediterranean basin have shown that the source of the glass is from our region.”

“Now, for the first time, the kilns have been found where the raw material was manufactured that was used to produce this glassware,” he added. “This is a very important discovery with implications regarding the history of the glass industry both in Israel and in the entire ancient world.”

Demand for glassware soared during the Early Roman period. It was highly appreciated for its transparency, beauty, the feeling of delicacy these items exuded. As glass blowing was adapted throughout the empire (an inexpensive production technique that dramatically sped up production and lowered costs,) the demand grew even higher.

Glass thus became a common sight from the Roman period onward, being used in almost every household and adorning public buildings as windows, mosaics and lighting fixtures. Large quantities of raw glass were required to fill this demand, production being taken over by specialized centers who could manufacture it on an industrial scale.

A price edict issue by Emperor Diocletian early in the 4th century CE differentiated between two kinds of glass. The first one, known as Judean glass (from the Land of Israel) was a light green color and less expensive than the second – Alexandrian glass (from Alexandria, Egypt).

“This is a sensational discovery and it is of great significance for understanding the entire system of the glass trade in antiquity,” added Prof. Ian Freestone, a researcher with the University College London, UK.

Japan casts steel-like glass using levitation

Using a newly-developed production method, the Institute of Industrial Science at Tokyo University succeeded in producing a type of glass that rivals steel in hardness. The new material opens huge developmental lanes for any glass and glass-related product, from tableware to bulletproof glass.

Steel-strong glass? That’s so metal!
Image via gizmodo

“We will establish a way to mass-produce the new material shortly,” said Atsunobu Masuno, assistant professor for the University. “We are looking to commercialize the technique within five years.”

Typical glass is usually made of silicon dioxide, with an added sprinkle of alumina (an aluminium oxide) thrown in to boost it’s hardness. However, there’s a limit to how strong it can be made traditionally — if you add too much alumina, it causes crystallization at the glass-container contact when the glass is prepared. Tokyo’s scientists devised an elegant solution to the problem — take out everything but the glass.

The mixing process is underpinned by a dash of tantalum powder and a containerless processing technique: they push the chemical components together at high pressure and temperature, then raise them into the air using pressurized oxygen gas and blast them with carbon dioxide lasers until they mix into glass — they named this the aerodynamic levitation furnace. The resulting material is transparent, colorless and very very tough, thanks to its 50 percent alumina content.

The glass underwent several tests for hardness, strength and elasticity. These showed the Young modulus was twice as high than that of typical types of glass — almost as high as that of steel and iron, the team reports. The study also notes that alumina glass made via this process can yield a product that’s thin and light or thick and heavy, and has excellent optical properties.

However, it’s not a wonder material: what those tests measure is the ability of a material, in this case the glass, to resist indentation by another object. The team reports that, in toying around with samples of the material and applying every force they could think of on them, they discovered they could generate radial cracks that propagate from a central point throughout the material — while being very very tough, in some respects it performs and behaves just as regular heavy duty industrial glass.

Still, glass that won’t shatter when i drop it? Glass that won’t scratch? Virtually unsearchable smartphone screens and bouncy beer bottles?

Japan will have the drunk student market all to themselves!

 

1000 ft Long, 600 ft High Suspension Bridge Opens in China – and it’s Transparent

A 300 meter long (984 ft) glass suspension bridge, 180 meters (591 ft) above the ground has recently opened in Hunan, part of China’s Shiniuzhai National Geological Park. As if that wasn’t scary enough, the entire thing is made of glass-like material, and it’s transparent.

Eloquently named Haohan Qiao or ‘Brave Men’s Bridge’, the bridge is an adventure in itself, as the first visitors found out. The bridge was initially meant to be made from wood, but authorities it wouldn’t have been strong enough, so they used a type of reinforced glass.

 

Another glass bridge is set to open in the same area soon, in the Zhangjiajie Grand Canyon area. When complete, it will measure be the world’s highest and longest glass bridge at 430 meters (1411 ft) long and 300 meters (984 ft) high. Would you dare to cross it?

 

Electron scan microscope images of metallic glass.

Scientists make recipes for metal glass, the wonder material you’ve never heard of

Electron scan microscope images of metallic glass.

Electron scan microscope images of metallic glass.

What happens when you mix the physical properties of glass (brittle and flowing) and metal (stiff and tough)? You get metal glass, of course. Since the 1960s, scientists showed you can make certain alloys into metal glass by rapidly cooling them. Really, really fast. Hundreds of degrees in a fraction of a second. Eventually you end up with an alloy that both behaves like a metal and glass. Some are three times stronger than titanium and have the elastic modulus of bone, all while being extremely lightweight. They’re also a lot more easy to machine than metals. All in all, metal glass is amazing and has the possibility to transform the world, just like another wonder material: graphene. So, why aren’t we seeing more of it? Part of the problem is that research is moving painfully slow, but this may set to change after a team of researchers in Sydney reported a model for the atomic structure of metal glass. If until now scientists were testing various alloys and technique in the dark, by trial and error, now they have a cook book for metal glass.

Glass seems to be a solid, but in reality it’s not exactly so. It’s both solid and liquid at the same time. It’s actually viscous, but it flows sooo slow that you’d think it’s perfectly solid. The scientific name for glass is amorphous solid, while metals are non-amorphous solids. The difference between the two lies in the atomic structure. Glass, an amorphous solid, has its constituting atoms arranged in a chaotic, random pattern, while in metals there are arranged in an orderly lattice.

amorphous vs non-amorphous

Reinforced glass isn’t exactly new. Corning’s Gorilla Glass coats cell phones, TVs and other consumer electronics so it doesn’t instantly shatter when you drop it. Pyrex, used in telescope mirrors and baking dishes since 1915, is treated with heat to resist breakage. But these sort of glasses are only less brittle, not tough. Ideally, you want a type of glass you can use to build airplanes, cars, buildings and even spaceships with. These sort of applications require a material that is both tough and strong, which is why steel is so popular. But metal glass has a better combination of toughness and strength than any steel.

Photograph of a thin, flexible metallic glass fiber (left) and an electron microscopy image of a metallic glass rope weaved from such fibers (right). Image: Nature

Photograph of a thin, flexible metallic glass fiber (left) and an electron microscopy image of a metallic glass rope weaved from such fibers (right). Image: Nature

These amorphous glassy structures are metal alloys, composed of three or more metals such as magnesium, copper, and yttrium (Mg-Cu-Y). The mechanical and physical properties of BMGs depend strongly on the concentrations of the chemical elements that make up the alloy. And when the correct combination of elements are heated or cooled at specific temperatures at specific rates the resulting materials can be extremely impressive. Some claim metal glass might revolutionize the world, second only to plastic in impact.

Identifying those alloys that can form metal glass is a tedious process, though. It has been estimated that only a minute fraction of the potential bulk metallic glass formers have been explored so far. Researchers at the School of Materials Science and Engineering, New South Wales propose an alternate solution: fishing with a net instead of hooks. Specifically, they  came up with a novel model of the atomic structure of metallic glass which allows them to predict which combination of metals will render the best metallic glasses. No fewer than 200 new metallic glass alloys just based on titanium, magnesium, silver, copper, and zinc were showcased in the study published in Nature. Now, it’s only a matter of shifting through each of these, systematically. The future looks good.

Scientists Turn Pure Metal into Glass

A team of researchers has managed to create metallic glasses from pure, monoatomic metals. These metals are amorphous like glass, but they retain some of the properties of metals – like ultrafast cooling and solid state reaction.

False color, high-resolution image of the vanadium metallic glass, showing typical amorphous characteristics. Image credit: Li Zhong et al.

Metallic glasses (also called glassy metals or amorphous metals) are solid metallic materials with a highly disordered arrangement of atoms. Amorphous metals are non-crystalline, and have a glass-like structure. But unlike common glasses, such as window glass, which are typically insulators, amorphous metals have good electrical conductivity. Glassy metals are highly regarded on the market, due to their special properties which include extremely rapid cooling, physical vapor deposition, solid-state reaction, ion irradiation, and mechanical alloying.

In this study, scientists developed metallic glasses using an innovative technique – a cooling nano-device under in-situ transmission electron microscope.

“Combining in situ transmission electron microscopy observation and atoms-to-continuum modelling, we investigated the formation condition and thermal stability of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses”, the study reads.

[Also Read: Modern ‘alchemy’ turns cement into semiconducting metal]

This technique was not only successful in developing the material, but achieved unprecedentedly high cooling rate that allowed for the transformation of liquefied elemental metals tantalum (Ta) and vanadium (V) into glass.

“This is a fundamental issue explored by people in this field for a long time, but nobody could solve the problem,” said Prof Mao, who is the senior author of a paper describing the new technique in the journal Nature.

This is not the first time someone has been able to get a pure metal into a glassy state though, but this is a new method, with remarkable properties. Traditionally, metallic glasses were formed by heating metal to extreme temperatures, then pouring the molten metal onto a very high speed rotor. The rotor then sprays metal droplets into liquid helium.

Journal Reference: Li Zhong, Jiangwei Wang, Hongwei Sheng, Ze Zhang & Scott X. Mao. Formation of monatomic metallic glasses through ultrafast liquid quenching. Nature 512,177–180doi:10.1038/nature13617

Glasses form when their molecules get jammed into fractal "wells," as shown on the right, rather than smooth or slightly rough wells (left). Photo credit: Patrick Charbonneau:

Glass molecules jam to form fractal wells

Water is liquid, air is gaseous, but glass? For years at end, glass has perplexed scholars intending on fixing it under a state of matter. Neither liquid, nor solid, explaining glass is a lot harder than some might think. Researchers at Duke University have contributed to solving the puzzle after they performed numerical solutions and found the energy landscapes of glasses are far rougher than previously believed, as their constituting molecules jam to form wells.

Glass: forever in between

matter_arrangement-

On the left, quartz a solid which display an orderly, period arrangement of its molecules. On the right, glass with molecules aligned in a disorderly fashion. Photo: cmog.org

In glass, molecules still flow, but their rate flow is so low that it’s barely perceptible. As such, it’s not enough to class glasses as liquid, but neither as solids. Chemists seem to be contend on calling them  amorphous solids— a state somewhere between those two states of matter.

Solids are highly organized structures. They include crystals, like sugar and salt, with their millions of atoms lined up in a row, explains Mark Ediger, a chemistry professor at the University of Wisconsin, Madison. “Liquids and glasses don’t have that order,” he notes. Glasses, though more organized than liquids, do not attain the rigid order of crystals. “Amorphous means it doesn’t have that long-range order,” Ediger says. With a “solid—if you grab it, it holds its shape,” he adds.

Previously, researchers used mathematical models to describe how the energy landscapes of glasses look like. As stated earlier, glasses distinguish themselves from other matter due to their constituting molecules lack of order. These molecules steadily and sluggishly cool until molecules are trapped by their neighbors, but in an unpredictable fashion. This is why the older the glass, the more it looks like a solid. One way for researchers to visualize this is with an energy landscape, a map of all the possible configurations of the molecules in a system.

“There have been beautiful mathematical models, but with sometimes tenuous connection to real, structural glasses. Now we have a model that’s much closer to real glasses,” said Patrick Charbonneau, one of the co-authors and assistant professor of chemistry and physics at Duke University.

The wells of glass

Glasses form when their molecules get jammed into fractal "wells," as shown on the right, rather than smooth or slightly rough wells (left). Photo credit: Patrick Charbonneau:

Glasses form when their molecules get jammed into fractal “wells,” as shown on the right, rather than smooth or slightly rough wells (left). Photo credit: Patrick Charbonneau:

Charbonneau and colleagues performed  numerical simulations, combined with what they know from the theory of glasses, to render energy landscapes . Their analysis suggests molecules in glassy materials settle into a fractal hierarchy of states, which can be imagined as a series of ponds or wells.

When the water is high (the temperature is warmer), the particles within float around as they please, crossing from pond to pond without problem. But as you begin to lower the water level (by lowering the temperature or increasing the density), the particles become trapped in one of the small ponds. Eventually, as the pond empties, the molecules become jammed into disordered and rigid configurations.

“Jamming is what happens when you take sand and squeeze it,” Charbonneau said. “First it’s easy to squeeze, and then after a while it gets very hard, and eventually it becomes impossible.”

“At the bottom of these lakes or wells, what you find is variation in which particles have a force contact or bond,” Charbonneau said. “So even though you start from a single configuration, as you go to the bottom or compress them, you get different realizations of which pairs of particles are actually in contact.”

These findings make sense of empirical observations, which were difficult to explain previously, like  the property known as avalanching, which describes a random rearrangement of molecules that leads to crystallization.

“There are a lot of properties of glasses that are not understood, and this finding has the potential to bring together a wide range of those problems into one coherent picture,” said Charbonneau.

Findings were reported in the journal Nature Communications.

The atomic patterns in quasicrystals like this model of an aluminium-palladium-manganese surface exhibit order, but never repeat. (Photo: J.W. Evans, Ames Laboratory, U.S. Department of Energy)

State of matter difference between liquids and solids redefined

What’s the difference between a solid and liquid? You might find this question trivial – naturally, liquids flow and solids… well, they don’t. From a physical point of view, however, things aren’t that simple. Intrigued by some ever so often encountered exceptions in the current accepted theory that describes the differences between the states of matter, scientists have tried to provide a new explanation. American researchers now argue that  the main difference between liquids and solids is the way they respond to shear, or twisting forces and not the way atoms are arranged.

The atomic patterns in quasicrystals like this model of an aluminium-palladium-manganese surface exhibit order, but never repeat. (Photo: J.W. Evans, Ames Laboratory, U.S. Department of Energy)

The atomic patterns in quasicrystals like this model of an aluminium-palladium-manganese surface exhibit order, but never repeat. (Photo: J.W. Evans, Ames Laboratory, U.S. Department of Energy)

The water in the ocean, in liquid state, and a glacier, in solid state, are made out of the same H2O molecules. It’s how the atoms are arranged that governs what state of matter water will hold, or so classic textbooks have it. In liquids, atoms slosh around freely, while in solids the atoms are locked together in a crystal lattice. Because this crystal lattice is so stable, it needs a considerable amount of energy for the atoms to break rank.

This theory of rigidity fails to account for a number of exceptions – too many to remain unnoticed. For instance, it  fails to account for quasicrystals — bizarre solids first discovered in the lab in 1982 and found in nature in 2009, which are arranged in patterns that never repeat, but the material is nonetheless rigid. Glass, one of the most familiar materials, is classed as amorphous – noncrystalline solid in which the atoms and molecules are not organized in a definite lattice pattern – and behaves like a solid, but if one looks closely enough it looks more like a liquid frozen in time.

“Glasses have been around for thousands of years,” said Daniel Stein, a professor of physics and mathematics at New York University. “Chemists understand them. Engineers understand them. From the point of view of physics, we don’t understand them. Why are they rigid?”

Even glaciers can’t be rigidly classified, since their atoms still flow, albeit very slowly. Even liquid water seems rigid if it collides with an object dropped from a large distance or if it’s crossed at high speeds. All these problems have prompted scientists to look for new ways to define the physical differences between liquids and solids, and a team of researchers from France and America believe they have pinpointed a more precise factor to mark the transition between the two states of matter – the way they respond to shear.

Response to shear delimits solids from liquids

Liquids pose minimal resistance to shear and can be twisted in any manner, while solids, even glass or quasi-crystals, pose resistance to shear in an attempt to maintain their shape. The liquid-solid phase transition should thus be marked, the researchers say, by the “shear response” of a material jumping from zero to a positive value.

Physicists typically make their phase boundary calculations for a material through an oversimplified model which assumes the material is boundless – otherwise, in their defense, things would take forever to complete. Unfortunately, this simplification ignores the shape of the material, making it difficult to determine whether the shape will change in response to shear.

Charles Radin, a mathematical physicist at the University of Texas at Austin, and his former student, David Aristoff, now a mathematician at the University of Minnesota built a 2-D model material in which atoms are represented by disks: At low densities corresponding to the material’s liquid phase, it showed no response to shear, but when the disks were densely packed, like the atoms in a solid, shear caused the material to expand. “The crossover where it shows this effect is exactly the density where the system becomes crystalline,” Radin said. “We propose this as a different way of understanding what a solid is.”

Meanwhile, in France, took an alternative route to describe the phase boundary and reasoned that the difference between solids and liquids is the rate at which they flow. Glass, though by all means a solid, still flows, very slowly that is. Even diamonds flow- their atoms that is, as some hop between defects or empty spots in the crystal lattice. To see a diamond flowing under the pull of Earth’s gravity, “one would have probably to wait more than the age of the universe,” said Giulio Biroli of the Institute of Theoretical Physics at CEA in Paris.

The researchers hypothesized that glass would fall somewhere in between a crystalline solid and a liquid by exhibiting a large but finite viscosity under small shear.

“Our ways are complementary,” said Biroli, of the American and French approaches. “If we take both of them, I think we start to understand the difference between a solid and a liquid.”

A type of glass created by researchers at the University of Wisconsin-Madison using a new vapor-deposition method is extremely stable. The rainbow of colors in this super-stable glass comes from variations in its thickness. Credit: Mark Ediger/University of Wisconsin-Madison

Ordinary glass has extraordinary properties – molecules self align in ultrastable tetris-like structures

Fast-acting molecules organize themselves more randomly (left) under certain temperature conditions than slower-acting, more systematically organized molecules. The more systematically organized molecules (right) lend greater stability and technological value to glassy materials. Credit: Created for the Institute of Molecular Engineering by Peter Allen

Fast-acting molecules organize themselves more randomly (left) under certain temperature conditions than slower-acting, more systematically organized molecules. The more systematically organized molecules (right) lend greater stability and technological value to glassy materials. Credit: Created for the Institute of Molecular Engineering by Peter Allen

Aged glasses are materials that interest scientists very much due to their appealing properties. During thousands and even millions of years glass steadily evolves towards an ever stable molecular configuration. In manufacturing where the process needs to be cut short to weeks or days, similar properties are extremely difficult if not at times impossible to reproduce. Researchers at Chicago and Wisconsin-Madison have shown that using the vapor-deposition process they can produce a new class of materials similar to how glass ages and evolves in nature.

“In attempts to work with aged glasses, for example, people have examined amber,” said Juan de Pablo, UChicago’s Liew Family Professor in Molecular Theory and Simulations. “Amber is a glass that has been aged millions of years, but you cannot engineer that material. You get what you get.” de Pablo and Wisconsin co-authors Sadanand Singh and Mark Ediger report their findings in the latest issue of Nature Materials.

Ediger and colleagues has created glass for years now via vapor deposition in a vacuum chamber, a technique in which a metal sample is heated until vaporization, leading to glass formation on top of the containing surface through condensation. Several years ago, he discovered that glasses grown this way on a specially prepared surface that is kept within a certain temperature range exhibit far more stability than ordinary glasses.

Ultrastable glass analogous to tetris

Ediger claims that these conditions allows the molecules more room to arrange themselves in a more stable structure in a manner analogous to the most efficiently packed, multishaped objects in Tetris, each consisting of four squares in various configurations that rain from the top of the screen. To confirm his suppositions, Ediger enlisted Pablo and Singh to produce a computer simulation.

“There’s interest in making these materials on the computer because you have direct access to the structure, and you can therefore determine the relationship between the arrangement of the molecules and the physical properties that you measure,” said de Pablo, a former UW-Madison

“It had been believed until now that there is no correlation between the mechanical properties of a glass and the molecular structure; that somehow the properties of a glass are ‘hidden’ somewhere and that there are no obvious structural signatures,” de Pablo said.

A type of glass created by researchers at the University of Wisconsin-Madison using a new vapor-deposition method is extremely stable. The rainbow of colors in this super-stable glass comes from variations in its thickness. Credit: Mark Ediger/University of Wisconsin-Madison

A type of glass created by researchers at the University of Wisconsin-Madison using a new vapor-deposition method is extremely stable. The rainbow of colors in this super-stable glass comes from variations in its thickness. Credit: Mark Ediger/University of Wisconsin-Madison

The key to a more stable structure is to have the molecules arrange themselves as tightly and as neatly as possible, with a minimum amount of void between them – the key difference in the tetris analogy being that instead of actively arranging the various shapes to fit together, nature does all the work for us. Again, analogous to tetris, if your tetris pieces descend too quickly, you’ll be left with a chaotic structure and lose – or in our case end up with a less stable structure.

“In the experiment, if you either rain the molecules too fast or choose a low temperature at which there’s no mobility at the surface, then this trick doesn’t work,” Ediger said. “Then it would be like taking a bucket of odd-shaped pieces and just dumping them on the floor. There are all sorts of voids and gaps because the molecules didn’t have any opportunity to find a good way of packing.”

Ultrastable glass is sought after for applications like stronger metals and in faster-acting pharmaceuticals. The results have been described in a recently published paper in the journal Nature Materials.

source: U Chicago