World’s Lightest Material: DIAMOND AEROGEL

World’s Lightest Material

Aerogels are a class of materials that exhibit the lowest density, thermal conductivity, refractive index and sound velocity of any bulk solid. Aerogels are among the most versatile materials available for technical applications due to their many exceptional properties.

The new form of diamond, the diamond aerogel, has a very low density similar to that of the precursor of around 40 milligrams per cubic centimeter, which is only about 40 times denser than air.

When it comes to light weight materials, the first thing that comes to our mind is Thermocol. Since its discovery in the year 1941, it has been used in many applications that are suitable for the common man like small life raft, disposable coffee cups, cushioning material in packaging, and so on. Since then, the weights of most light weight materials are compared to Thermocol, and have been given a special category called Ultra-light materials. A team of researchers from HRL Laboratories (Hughes Research Laboratories), in collaboration with Caltech and the University of California, developed a new material that weighs only 1/100^th of the weight of Thermocol. The material is also known o be lighter than a diamond aerogel, one of the best ultra-light materials in the world. Before going into detail about the lightest material, let us make a brief study about diamond aerogels.

Diamond aerogel was discovered by researchers at the Lawrence Rivermore National Laboratory by combining high density diamond substances and least dense materials called aerogels. Aerogel is known to be a porous, diffuse rigid material that looks similar to a solid block of smoke and with the texture of a chunk of thermocol. They are industrially manufactured by constructing a conventional gel and then removing the liquid though supercritical drying. The material finds various applications in the making of insulate space suits, pick up cosmic particles, and even home insulation.

The combination of both the materials gave birth to a spongy, translucent version of a diamond. This material when tested was found out to be the least dense diamond ever, and thus the most expensive aerogel ever. They called it a diamond aerogel, definitely the least dense diamond ever and perhaps one of the most valuable aerogels ever. The material was found to be a little denser than air and has all the physical capabilities of a non-liquid gel component. This material also found many applications in the field of structural engineering, optical engineering, and quantum computing and so on.

By combining high pressure with high temperature, Livermore researchers have created a nanocyrstalline diamond aerogel that could improve the optics for something as big as a telescope or as small as the lenses in eyeglasses.

Aerogels are a class of materials that exhibit the lowest density, thermal conductivity, refractive index and sound velocity of any bulk solid. Aerogels are among the most versatile materials available for technical applications due to their many exceptional properties. This material has chemists, physicists, astronomers, and materials scientists utilizing its properties in myriad applications, from a water purifier for desalinizing seawater to installation on a NASA satellite as a meteorite particle collector.

In new research appearing in the May 9-13 online edition of the Proceedings of the National Academy of Sciences, a Livermore team created a diamond aerogel from a standard carbon-based aerogel precursor using a laser-heated diamond anvil cell.

A diamond anvil cell consists of two opposing diamonds with the sample compressed between them. It can compress a small piece of material (tens of micrometers or smaller) to extreme pressures, which can exceed 3 million atmospheres. The device has been used to recreate the pressure existing deep inside planets, creating materials and phases not observed under normal conditions. Since diamonds are transparent, intense laser light also can be focused onto the sample to simultaneously heat it to thousands of degrees.

The new form of diamond has a very low density similar to that of the precursor of around 40 milligrams per cubic centimeter, which is only about 40 times denser than air.

The diamond aerogel could have applications in antireflection coatings, a type of optical coating applied to the surface of lenses and other optical devices to reduce reflection. Less light is lost, improving the efficiency of the system. It can be applied to telescopes, binoculars, eyeglasses or any other device that may require reflection reduction. It also has potential applications in enhanced or modified biocompatibility, chemical doping, thermal conduction and electrical field emission.

In creating diamond aergoels, lead researcher Peter Pauzauskie, a former Lawrence fellow now at the University of Washington, infused the pores of a standard, carbon-based aerogel with neon, preventing the entire aerogel from collapsing on itself.

At that point, the team subjected the aerogel sample to tremendous pressures and temperatures (above 200,000 atmospheres and in excess of 2,240 degrees Fahrenheit), forcing the carbon atoms within to shift their arrangement and create crystalline diamonds.

The success of this work also leads the team to speculate that additional novel forms of diamond may be obtained by exposing appropriate precursors to the right combination of high pressure and temperature.

The aerogel is only 40 times as dense as air. Someday, it may coat the windows, the TV, and the inside of a person's body.

There are plenty of things out there that are shiny, but diamonds have occupied an enduring place in cultural history. At first this was because they were hard. Although it's easy to destroy other gemstones, diamonds are tougher to demolish, don't tarnish, and so can be worn with greater regularity than other jewelry. The particular hardness of diamonds also had industrial uses. Artificial diamonds helped drill bits and saw blades move through materials faster. Upon more study, scientists discovered new characteristics of diamonds - including the fact that they, like water, grow less dense when they freeze. This means that diamond oceans (such as those that might exist on Neptune) could have diamond icebergs floating in them.

To make a diamond aerogel, a carbon aerogel is constructed, and any spaces in the gel are pumped full of neon gas. The gas supports the structure and keeps it from collapsing when the scientists hit the carbon structure with everything they've got. The aerogel is compressed in a diamond-lined cell while being heated with high-intensity lasers. The combination of the heat and pressure change the pliable carbon to diamond, while keeping the structure.

This gel can be molded like plastic, is completely transparent, and is made up of diamonds smaller than a quarter of the wavelength of violet light. Because it doesn't react with many elements, it's biocompatible. This diamond matrix can be used to coat structures in the human body. Because it's transparent, it can be overlaid onto glass or clear plastic, creating tough but well-insulated windows and instruments for spacecraft. Because diamonds give off electrons, it can be used in ultra-light, ultra-tough quantum computers.

The lately found ultra-light material has a density of 0.9 mg/cc, and is known to have its own unique kind of “micro-lattice” cellular architecture. The researchers were successful in making a material that consists of 99.99% open volume by designing the 0.01% solid at the nanometer, micron and millimetre scales.

The material was developed for DARPA so that it could be used for applications in battery electrodes, catalyst supports, vibration or shock energy damping applications and so on. The material has shown excellent mechanical behaviour for a metal, including complete recovery from compression exceeding 50% strain and extraordinarily high energy absorption, when compared to its compact architecture.

This discovery has led the researchers to bring in more ideas to revolutionalize lightweight materials by using this concept to the materials level and designing their architectures at the nano scale.

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NEXT GENERATION ELECTRONICS:ATOMTRONICS

Atomtronics refers to the process of creatinganalogues to electronic devices and circuits using atoms.

When super-cooled toform Bose-Einstein condensates, atoms placed in an optical lattice may formstates analogous to electrons in solid-state crystalline media such as semiconductors.Impurity doping allows the creation of n and p-type semiconductor analoguestates, and an atomtronic battery can be created by maintaining two contacts atdifferent chemical potentials. Analogues to diodes and transistors have alsobeen theoretically demonstrated.

Although atomtronic devices have yetto be realized experimentally, the properties of condensed atoms offers a widerange of possible applications. The use of ultra-cold atoms allows for circuitelements that allow for the coherent flow of information and may be useful inconnecting classical electronic devices and quantum computers. The use ofatomtronics may allow for quantum computers that work on macroscopic scales anddo not require the technological precision of laser controlled few ioncomputing methods. Since the atoms are Bose condensed, they have the propertyof superfluidity and, therefore, have resistance-less current in which noenergy is lost or heat dissipated, similar to superconducting electronicdevices. The vast knowledge of electronics may be leveraged to easily adapt toultracold atomic atomtronic circuits.

TAKING ASPINThis doughnut of ultracold gas spins without friction, creating a currentof atoms that could be used to develop the first “atomtronic” sensors.JointQuantum Institute

Forgetabout wires, silicon and electricity. Physicists have developed a new type ofcircuit that is little more than a puff of gas dancing in laser beams. Bychoreographing the atoms of this ultracold gas to flow as a current that can becontrolled and switched on and off, the scientists have taken a step towardbuilding the world’s first “atomtronic” device.

Atomtronicsis a young, small and mostly theoretical field based on the idea that atoms inunusual quantum states of matter may provide an alternative to thetried-and-true electron for making useful devices. The field’s proponents havedrawn up blueprints for atomic versions of many traditional electroniccomponents — from wires and batteries to transistors and diodes.

At theJoint Quantum Institute in Gaithersburg, Md., graduate student Anand Ramanathanand his colleagues hope to use an ultracold gas called a Bose-Einsteincondensate to make atomtronic sensors. In an upcoming paper in PhysicalReview Letters, the team reports creating this gas by cooling sodium atomssuspended in magnetic fields. The researchers then trapped the atoms in a pairof crossed laser beams and further chilled the atoms to less than 10 billionthsof a degree above absolute zero. The two beams also shaped the condensate thatformed at these low temperatures into a flattened doughnut with a radius ofabout 20 micrometers.

“A lot ofcare was required in how we created the trap,” said Ramanathan. “We had to makeit as smooth as possible to make sure that imperfections played a minimalrole.”

A secondpair of lasers transferred energy to the doughnut to start it rotating. Becauseatoms in the condensate behave as a single, coherent quantum particle, such aring of the substance doesn’t speed up or slow down gradually — it jumpsbetween different speeds, much like a blender would if it could change settingsinstantaneously. The scientists chose the lowest setting for their ring, aboutone revolution every second.

Becausethe condensate also happens to be frictionless, this ring should, in theory,rotate forever. Limited by technical difficulties, the research team kept itgoing for about 40 seconds, the lifetime of their condensate.

“This isthe first time that someone has actually made a ring-shaped condensate,” saidteam member and physicist Gretchen Campbell. “We’re hoping to use thiscondensate in much the way that superconductors have been used to make improveddevices and sensors.”

Her first idea for a useful device was inspired bysuperconducting quantum interference devices, commonly known as SQUIDs. Thesedevices reveal the presence of very weak magnetic fields by detecting suddenchanges of current in semiconductor loops.

Using asimilar principle, Campbell’s team believes that Bose-Einstein condensate couldprovide an extremely sensitive rotation sensor. They added a “weak link” totheir condensate ring — a barrier created by a blue laser that could speed upor shut down the flow. Theoretically, if the condensate were kept still and thebarrier attached to a rotating sensor, the barrier would cause a sudden jump incurrent at certain rotation speeds.

Theteam’s approach to creating an atomtronic device is only one of half a dozenbeing pursued in laboratories around the world. “They’ve added another toolthat we can start to use to build up the atomtronics toolbox,” said DanaAnderson, a physicist at the University of Colorado at Boulder.

All ofthese pioneers hope that, for certain applications, atoms will prove to be moreinteresting than electrons.

BIRTH OF THE ULTRACOOL CLOUD

PhysicistsSatyendra Nath Bose and Albert Einstein proposed in 1924 that large numbers ofatoms could be chilled to the point that they joined together in a singlequantum state, bringing subatomic effects to a scale accessible by laboratoryexperiments. But it

wasn’t until 1995 that scientists made a Bose-Einsteincondensate, using lasers to carefully cool rubidium-87 atoms down totemperatures less than a millionth of a degree above absolute zero. The 2001Nobel Prize in Physics celebrated this accomplishment, which was also achievedusing sodium atoms. This image shows the distribution of atomic velocities in arubidium gas just before (left) and after (center and right) the formation of acondensate.

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