Glass: The Quintessential Nanotech Material
Glass: The Quintessential Nanotech Material
Long before physicist Richard Feynman launched the nanotechnology era with his 1959 assertion, “There’s plenty of room at the bottom,” people were manipulating glass at the nano level – often without realizing it.
For thousands of years, artists have worked with glass because of how it forms, feels, and handles light, while craftsmen have used glass for practical applications because of its stability, impermeability, and transparency. In the last century, scientists have made extraordinary advances in the characterization and fabrication of glass, leading to innovative applications in diverse fields such as architecture, transportation, electronics, communications, and medicine.
How can one material do so much?
At its core, glass is quite simple. The primary building block of glass is silica in the form of sand. But silica is an extremely gracious collaborator with its friends on the Periodic Table. In fact, an overview of glass research reveals that scientists have added more than 50 different elements to silica to create glass compositions with unique attributes.
But composition is just the beginning. Scientists also use a broad range of techniques such as irradiation, surface modification, and precise temperature control to develop specialized glasses with different colors, form factors, strengths, degrees of flexibility, and light-handling abilities.
By fine-tuning the formulation and fabrication of glass, scientists can unleash a nearly limitless stream of new capabilities. This tremendous versatility has prompted scientist David Pye of Alfred University to describe glass as “the quintessential nanotech material.”
Lycurgus Cup
Nanotechnology, albeit unknowingly, has played a central role in crafting beautiful colored artistic works such as the Lycurgus Cup, created in Italy in the 4th Century. The glass chalice appears jade green when lit from the front but blood-red when lit from behind. The phenomenon, which puzzled scientists for centuries, results from particles of silver and gold that Roman artisans ground down until they were as small as 50 nanometers in diameter-- less than one-thousandth the size of a grain of table salt.
©The Trustees British Museum
Optical Technology
Controlling optical properties is classic glass science at the nano-scale level. Small differences in spacing and bonding between elements result in varying degrees of light absorption, transmission, reflection and scattering. The ability to fine-tune these attributes has made glass vital to technologies such as optical filters, fluorescent solids, and lasing systems.
Photochromic Glasses
Ever wonder what makes some eye glasses turn dark in sunlight and clear indoors? The answer lies on the nano-scale. Photochromic lenses contain nano-sized silver halide crystals, whose electrical properties have been modified by the addition of copper. When exposed to light, tiny specks of metallic silver within the crystals absorb the rays, turning the glass dark. However, once the light source is removed, the glass will return to its original colorless state.
Lycurgus Cup
Lycurgus Cup
Nanotechnology, albeit unknowingly, has played a central role in crafting beautiful colored artistic works such as the Lycurgus Cup, created in Italy in the 4th Century. The glass chalice appears jade green when lit from the front but blood-red when lit from behind. The phenomenon, which puzzled scientists for centuries, results from particles of silver and gold that Roman artisans ground down until they were as small as 50 nanometers in diameter-- less than one-thousandth the size of a grain of table salt.
©The Trustees British Museum
Nanotechnology, albeit unknowingly, has played a central role in crafting beautiful colored artistic works such as the Lycurgus Cup, created in Italy in the 4th Century. The glass chalice appears jade green when lit from the front but blood-red when lit from behind. The phenomenon, which puzzled scientists for centuries, results from particles of silver and gold that Roman artisans ground down until they were as small as 50 nanometers in diameter-- less than one-thousandth the size of a grain of table salt.
©The trustees British Museum
Optical Technology
Optical Technology
Controlling optical properties is classic glass science at the nano-scale level. Small differences in spacing and bonding between elements result in varying degrees of light absorption, transmission, reflection and scattering. The ability to fine-tune these attributes has made glass vital to technologies such as optical filters, fluorescent solids, and lasing systems.
Controlling optical properties is classic glass science at the nano-scale level. Small differences in spacing and bonding between elements result in varying degrees of light absorption, transmission, reflection and scattering. The ability to fine-tune these attributes has made glass vital to technologies such as optical filters, fluorescent solids, and lasing systems.
Photochromic Glasses
Photochromic Glasses
Ever wonder what makes some eye glasses turn dark in sunlight and clear indoors? The answer lies on the nano-scale. Photochromic lenses contain nano-sized silver halide crystals, whose electrical properties have been modified by the addition of copper. When exposed to light, tiny specks of metallic silver within the crystals absorb the rays, turning the glass dark. However, once the light source is removed, the glass will return to its original colorless state.
Ever wonder what makes some eye glasses turn dark in sunlight and clear indoors? The answer lies on the nano-scale. Photochromic lenses contain nano-sized silver halide crystals, whose electrical properties have been modified by the addition of copper. When exposed to light, tiny specks of metallic silver within the crystals absorb the rays, turning the glass dark. However, once the light source is removed, the glass will return to its original colorless state.
Glass-Ceramics
Glass-Ceramics
The invention of glass-ceramics by Corning scientist Donald Stookey is one of the seminal discoveries in the history of nanotechnology. Glass-ceramics are distinguished by their extreme temperature tolerance and resistance to fractures. A glass-ceramic begins as a homogenous piece of glass (aluminosilicate, fluorosilicate, or iron silicate), which is then subjected to one or more heat treatments, causing the glass to grow crystals. Depending on the size of the crystals in relation to the wavelength of light, the glass can be either transparent or opaque. When a crack begins to form in the glass-ceramic material, it quickly encounters a crystal, forcing it to change direction or initiate a new crack. This torturous path makes it extremely difficult for a crack to cause a fracture.
The invention of glass-ceramics by Corning scientist Donald Stookey is one of the seminal discoveries in the history of nanotechnology. Glass-ceramics are distinguished by their extreme temperature tolerance and resistance to fractures. A glass-ceramic begins as a homogenous piece of glass (aluminosilicate, fluorosilicate, or iron silicate), which is then subjected to one or more heat treatments, causing the glass to grow crystals. Depending on the size of the crystals in relation to the wavelength of light, the glass can be either transparent or opaque. When a crack begins to form in the glass-ceramic material, it quickly encounters a crystal, forcing it to change direction or initiate a new crack. This torturous path makes it extremely difficult for a crack to cause a fracture.
Corning® Gorilla® Glass
Corning® Gorilla® Glass
Corning makes Gorilla Glass from a proprietary recipe of silicon dioxide, sodium oxide, and aluminum oxide. But the ion-exchange process is the real key to its remarkable damage resistance. The glass is placed in a hot bath of molten salt at a temperature of approximately 400° C. The sodium ions leave the glass, while larger potassium ions from the bath replace them. These potassium ions take up more room and are pressed together as the glass cools. The result: A deep layer of compressive stress that makes the surface much stronger than conventional glass. Gorilla Glass’s exceptional damage resistance has made it the cover glass of choice for nearly three billion mobile devices.
Corning makes Gorilla Glass from a proprietary recipe of silicon dioxide, sodium oxide, and aluminum oxide. But the ion-exchange process is the real key to its remarkable damage resistance. The glass is placed in a hot bath of molten salt at a temperature of approximately 400° C. The sodium ions leave the glass, while larger potassium ions from the bath replace them. These potassium ions take up more room and are pressed together as the glass cools. The result: A deep layer of compressive stress that makes the surface much stronger than conventional glass. Gorilla Glass’s exceptional damage resistance has made it the cover glass of choice for nearly three billion mobile devices.
Bio-Glasses
Bio-Glasses
New glass compositions and nano- and micro-structural designs are enabling exciting new medical applications. Glass microspheres for radiotherapy have proven remarkably successful at fighting liver and kidney cancers. Meanwhile, scientists at the Missouri University of Science & Technology have developed borate glass nanofibers that have displayed an astonishing ability to heal flesh wounds. The fibers slow bleeding, fight bacteria, and stimulate the body’s natural healing mechanisms. Because the fibers are quickly absorbed into the surrounding tissue, they can also reduce scarring and eliminate the need for removal.
Mo-Sci Corp., used with permission of The American Ceramic Society
New glass compositions and nano- and micro-structural designs are enabling exciting new medical applications. Glass microspheres for radiotherapy have proven remarkably successful at fighting liver and kidney cancers. Meanwhile, scientists at the Missouri University of Science & Technology have developed borate glass nanofibers that have displayed an astonishing ability to heal flesh wounds. The fibers slow bleeding, fight bacteria, and stimulate the body’s natural healing mechanisms. Because the fibers are quickly absorbed into the surrounding tissue, they can also reduce scarring and eliminate the need for removal.
Mo-Sci Corp., used with permission of The American Ceramic Society