Scientists at the Department of Energy’s Oak Ridge National Laboratory have found a simple, reliable process to capture carbon dioxide directly from ambient air, offering a new option for carbon capture and storage strategies to combat global warming.
Initially, the ORNL team was studying methods to remove environmental contaminants such as sulfate, chromate or phosphate from water. To remove those negatively charged ions, the researchers synthesized a simple compound known as guanidine designed to bind strongly to the contaminants and form insoluble crystals that are easily separated from water.
In the process, they discovered a method to capture and release carbon dioxide that requires minimal energy and chemical input. Their results are published in the journal Angewandte Chemie International Edition.
“When we left an aqueous solution of the guanidine open to air, beautiful prism-like crystals started to form,” ORNL’s Radu Custelcean said. “After analyzing their structure by X-ray diffraction, we were surprised to find the crystals contained carbonate, which forms when carbon dioxide from air reacts with water.”
Decades of research has led to the development of carbon capture and long-term storage strategies to lessen the output or remove power plants’ emissions of carbon dioxide, a heat-trapping greenhouse gas contributing to a global rise in temperatures. Carbon capture and storage strategies comprise an integrated system of technologies that collects carbon dioxide from the point of release or directly from the air, then transports and stores it at designated locations.
A less traditional method that absorbs carbon dioxide already present in the atmosphere, called direct air capture, is the focus of ORNL’s research described in this paper, although it could also be used at the point where carbon dioxide is emitted.
Once carbon dioxide is captured, it needs to be released from the compound so the gas can be transported, usually through a pipeline, and injected deep underground for storage. Traditional direct air capture materials must be heated up to 900 degrees Celsius to release the gas — a process that often emits more carbon dioxide than initially removed. The ORNL-developed guanidine material offers a less energy-intensive alternative.
“Through our process, we were able to release the bound carbon dioxide by heating the crystals at 80-120 degrees Celsius, which is relatively mild when compared with current methods,” Custelcean said. After heating, the crystals reverted to the original guanidine material. The recovered compound was recycled through three consecutive carbon capture and release cycles.
While the direct air capture method is gaining traction, according to Custelcean, the process needs to be further developed and aggressively implemented to be effective in combatting global warming. Also, they need to gain a better understanding of the guanidine material and how it could benefit existing and future carbon capture and storage applications.
The research team is now studying the material’s crystalline structure and properties with the unique neutron scattering capabilities at ORNL’s Spallation Neutron Source (SNS), a DOE Office of Science User Facility. By analyzing carbonate binding in the crystals, they hope to better understand the molecular mechanism of carbon dioxide capture and release and help design the next generation of sorbents.
The scientists also plan to evaluate the use of solar energy as a sustainable heat source to release the bound carbon dioxide from the crystals.
ORNL is the largest science and energy national laboratory in the Department of Energy system by acreage. ORNL is located in Oak Ridge, Tennessee, near Knoxville. ORNL’s scientific programs focus on materials, neutron science, energy, high-performance computing, systems biology and national security.
ORNL partners with the state of Tennessee, universities and industries to solve challenges in energy, advanced materials, manufacturing, security and physics.
The laboratory is home to several of the world’s top supercomputers including the world’s second most powerful supercomputer ranked by the TOP500, Titan, and is a leading neutron science and nuclear energy research facility that includes the Spallation Neutron Source and High Flux Isotope Reactor. ORNL hosts the Titan supercomputer; the Center for Nanophase Materials Sciences, the BioEnergy Science Center, and the Consortium for Advanced Simulation of Light-Water Reactors.
Oak Ridge National Laboratory research articles from Innovation Toronto
- ORNL technique could set new course for extracting uranium from seawater – December 19, 2015
- White graphene could usher in a new era in electronics and quantum devices – December 2, 2015
- New ORNL device combines power of mass spectrometry, microscopy – November 9, 2015
- Better fluorescent lighting using far less rare-earth elements – October 18, 2015
- Integrated energy demo connects 3D-printed building and 3D-printed vehicle – October 15, 2015
- New ORNL device combines power of mass spectrometry, microscopy – November 9, 2015
- Old tires can become supercapacitors – September 26, 2015
- SHAPE-SHIFTING PLASTIC – May 25, 2015
- ORNL demonstrates first large-scale graphene composite fabrication – May 18, 2015
- ORNL superhydrophobic glass coating offers clear benefits – May 13, 2015
- ORNL-led team demonstrates desalination with nanoporous graphene membrane – March 26, 2015
- Innovative, Lower Cost Sensors and Controls Yield Better Energy Efficiency – March 8, 2015
- Your Own Energy “Island?” ORNL Microgrid Could Standardize Small, Self-Sustaining Electric Grids – November 6, 2014
- New ORNL electric vehicle technology packs more punch in smaller package – October 18, 2014
- A cheaper plant-based battery is possible – Septembewr 23, 2014
- UT, ORNL Scientists’ Discoveries Could Help Neutralize Chemical Weapons – June 24, 2014
- Novel ORNL technique enables air-stable water droplet networks – May 17, 2014
- Self-cleaning solar panel coating optimizes energy collection, reduces costs
- Chaotic physics in ferroelectrics hints at brain-like computing
- ORNL-grown oxygen ‘sponge’ presents path to better catalysts, energy materials
- Beyond Silicon: Transistors without Semiconductors
- China’s Tianhe-2 is the new world champ of supercomputing
- New all-solid sulfur-based battery outperforms lithium-ion technology
- Awake Imaging device moves diagnostics field forward
- Breakthrough in hydrogen fuel production by Virginia Tech researchers could revolutionize alternative energy market
- Mystery Surrounding the Harnessing of Fusion Energy Unlocked
- Oak Ridge unveils Titan, the world’s most powerful supercomputer
- Water-wise biofuel crop study to alter plants metabolic, photosynthesis process
- Uranium supply extracted from Seawater could last for Centuries
- Boundary Between Electronics and Biology Is Blurring
- Technology Breakthrough for Geothermal
- Standoff Sensing Enters New Realm With Dual-Laser Technique
- ORNL discovers amazing electrical properties in polymers
- ORNL invention unravels mystery of protein folding
- Culturomics research uses quarter-century of media coverage to forecast human behavior
- Energy Harvesters Transform Waste Into Electricity
- New solar cell technology boosts efficiency of photovoltaics by 80%
- New Lignin ‘Lite’ Switchgrass Boosts Biofuel Yield by More Than One-Third
- Bacteria produce potential gasoline replacement directly from cellulose
- Could 135,000 Laptops Help Solve the Energy Challenge?
- Bionic sense of touch through carbon nanotube research?
- Scientists Work To Plug Microorganisms Into The Energy Grid
‘Beautiful accident’ leads to advances in high pressure materials synthesis
Unexpected results from a neutron scattering experiment at the Department of Energy’s Oak Ridge National Laboratory could open a new pathway for the synthesis of novel materials and also help explain the formation of complex organic structures observed in interstellar space.
In a paper published in the journal Angewandte Chemie International Edition, the multi-institutional team of researchers, led by Haiyan Zheng from the Center for High Pressure Science and Technology Advanced Research in Beijing, formerly of the Carnegie Institution of Washington, discuss their discovery of using high pressures—rather than high temperatures—to initiate chemical reactions.
Their research will significantly improve scientists’ understanding of complex carbon structures and may offer clues to the formation of amino acids from nonbiological processes.
“This discovery was somewhat of a beautiful accident,” said Ilia Ivanov, a research scientist at the ORNL’s Center for Nanophase Materials Sciences, a Department of Energy Office of Science User Facility.
Ivanov explains that it all began during a neutron diffraction experiment at ORNL’s Spallation Neutron Source—also a DOE Office of Science User Facility. While performing a high-pressure polymerization experiment on the chemical compound acetonitrile (CH3CN) using the SNAP instrument, researchers detected the unexpected presence of ammonia. Ammonia is a colorless gas but has a very distinct odor that can be detected in even minute quantities.
“If you put acetonitrile under high pressures, you’ll bring molecules together and see it reacting with itself, and eventually, it forms either a solid yellowish polymer or, as we found out, a black, carbon-rich material,” Ivanov said.
Acetonitrile is one of a number of organic compounds that have been discovered in outer space and is thought to be implicated in the origins of simple amino acids, one of the basic molecules of life. In a cosmic event such as an asteroid collision, the pressures and temperatures generated can be very large, and in the presence of acetonitrile, could mimic the experiment the researchers conducted at SNAP.
The formation of the yellowish polymer was the expected result of the SNAP experiment, said SNAP instrument scientist Chris Tulk, but a surprise was just ahead.
“When the sample was depressurized and the pressure cell opened, ammonia was detected. It has a very distinct scent,” Tulk said. “We thought, ‘there shouldn’t be ammonia in this sample right now.’ So we started looking for what could have happened to first form, and then release, ammonia.”
The experimental researchers then collaborated with experts in advanced electron microscopy, materials science and computing to understand the mysterious results. Based on a combination of computer simulations and microscopy, they concluded that nitrogen had left the acetonitrile sample, resulting in an enriched carbon-based material.
“The carbon material that was left was imaged using our best electron microscopes,” Ivanov said. “It had onion-like layers—one shell of carbon sheet after another. So nitrogen went somewhere, but where did it go? It escaped in the form of ammonia gas.”
Because a temperature-based catalyst is usually required to convert a polymer into another material, this ability to cause a chemical reaction through pressure alone is unusual.
“I wanted to continue doing these experiments to determine how much we could control the structure of a carbon material through pressure, not temperature,” said Ivanov, comparing the experimental conditions with those found in household pressure cookers.
“In most cases, pressure cookers still use high temperatures to help foods cook thoroughly. But with our experiments, we’ve been able to use a sort of pressure cooking at room temperature, albeit at much higher pressures.”
While a pressure cooker operates at 0.1 megapascals, these experiments used much higher pressures—up to 23,000 megapascals, which corresponds to the pressure found 650 kilometers below the Earth’s surface at the boundary between its upper and lower mantle.
“This paper is truly exciting for us,” Tulk said. “Using this process with the addition of oxygen, possibly by the addition of carbon dioxide or water into the reactants, complex carbon structures similar to the kind we suspect throughout early formation of amino acids on Earth may be realized.”
The researchers note that cross-disciplinary expertise in neutron sciences and nanoscience, together with Energy Frontier Research in Extreme Environments (EFree) Center, made the research possible. EFree is a DOE Energy Frontier Research Center.
“One without the other seemed like a one-sided mission. Two aspects of research, structure and functionality, were brought together through the synergetic work. Through joint efforts like this, we continue to help users drive the discovery of new materials and new functionalities,” Ivanov said.
Researchers at the Department of Energy’s Oak Ridge National Laboratory have demonstrated that permanent magnets produced by additive manufacturing can outperform bonded magnets made using traditional techniques while conserving critical materials.
Scientists fabricated isotropic, near-net-shape, neodymium-iron-boron (NdFeB) bonded magnets at DOE’s Manufacturing Demonstration Facility at ORNL using the Big Area Additive Manufacturing (BAAM) machine. The result, published in Scientific Reports, was a product with comparable or better magnetic, mechanical, and microstructural properties than bonded magnets made using traditional injection molding with the same composition.
The additive manufacturing process began with composite pellets consisting of 65 volume percent isotropic NdFeB powder and 35 percent polyamide (Nylon-12) manufactured by Magnet Applications, Inc. The pellets were melted, compounded, and extruded layer-by-layer by BAAM into desired forms.
While conventional sintered magnet manufacturing may result in material waste of as much as 30 to 50 percent, additive manufacturing will simply capture and reuse those materials with nearly zero waste, said Parans Paranthaman, principal investigator and a group leader in ORNL’s Chemical Sciences Division. The project was funded by DOE’s Critical Materials Institute (CMI).
Using a process that conserves material is especially important in the manufacture of permanent magnets made with neodymium, dysprosium—rare earth elements that are mined and separated outside the United States. NdFeB magnets are the most powerful on earth, and used in everything from computer hard drives and head phones to clean energy technologies such as electric vehicles and wind turbines.
The printing process not only conserves materials but also produces complex shapes, requires no tooling and is faster than traditional injection methods, potentially resulting in a much more economic manufacturing process, Paranthaman said.
“Manufacturing is changing rapidly, and a customer may need 50 different designs for the magnets they want to use,” said ORNL researcher and co-author Ling Li. Traditional injection molding would require the expense of creating a new mold and tooling for each, but with additive manufacturing the forms can be crafted simply and quickly using computer-assisted design, she explained.
Future work will explore the printing of anisotropic, or directional, bonded magnets, which are stronger than isotropic magnets that have no preferred magnetization direction. Researchers will also examine the effect of binder type, the loading fraction of magnetic powder, and processing temperature on the magnetic and mechanical properties of printed magnets.
Alex King, Director of the Critical Materials Institute, thinks that this research has tremendous potential. “The ability to print high-strength magnets in complex shapes is a game changer for the design of efficient electric motors and generators,” he said. “It removes many of the restrictions imposed by today’s manufacturing methods.”
“This work has demonstrated the potential of additive manufacturing to be applied to the fabrication of a wide range of magnetic materials and assemblies,” said co-author John Ormerod. “Magnet Applications and many of our customers are excited to explore the commercial impact of this technology in the near future,” he stated.
In a new twist to waste-to-fuel technology, scientists at the Department of Energy’s Oak Ridge National Laboratory have developed an electrochemical process that uses tiny spikes of carbon and copper to turn carbon dioxide, a greenhouse gas, into ethanol. Their finding, which involves nanofabrication and catalysis science, was serendipitous.
“We discovered somewhat by accident that this material worked,” said ORNL’s Adam Rondinone, lead author of the team’s study published in ChemistrySelect. “We were trying to study the first step of a proposed reaction when we realized that the catalyst was doing the entire reaction on its own.”
The team used a catalyst made of carbon, copper and nitrogen and applied voltage to trigger a complicated chemical reaction that essentially reverses the combustion process. With the help of the nanotechnology-based catalyst which contains multiple reaction sites, the solution of carbon dioxide dissolved in water turned into ethanol with a yield of 63 percent. Typically, this type of electrochemical reaction results in a mix of several different products in small amounts.
“We’re taking carbon dioxide, a waste product of combustion, and we’re pushing that combustion reaction backwards with very high selectivity to a useful fuel,” Rondinone said. “Ethanol was a surprise — it’s extremely difficult to go straight from carbon dioxide to ethanol with a single catalyst.”
The catalyst’s novelty lies in its nanoscale structure, consisting of copper nanoparticles embedded in carbon spikes. This nano-texturing approach avoids the use of expensive or rare metals such as platinum that limit the economic viability of many catalysts.
“By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want,” Rondinone said.
The researchers’ initial analysis suggests that the spiky textured surface of the catalysts provides ample reactive sites to facilitate the carbon dioxide-to-ethanol conversion.
“They are like 50-nanometer lightning rods that concentrate electrochemical reactivity at the tip of the spike,” Rondinone said.
Given the technique’s reliance on low-cost materials and an ability to operate at room temperature in water, the researchers believe the approach could be scaled up for industrially relevant applications. For instance, the process could be used to store excess electricity generated from variable power sources such as wind and solar.
“A process like this would allow you to consume extra electricity when it’s available to make and store as ethanol,” Rondinone said. “This could help to balance a grid supplied by intermittent renewable sources.”
The researchers plan to refine their approach to improve the overall production rate and further study the catalyst’s properties and behavior.
Scientists at the Department of Energy’s Oak Ridge National Laboratory are the first to harness a scanning transmission electron microscope (STEM) to directly write tiny patterns in metallic “ink,” forming features in liquid that are finer than half the width of a human hair.
The automated process is controlled by weaving a STEM instrument’s electron beam through a liquid-filled cell to spur deposition of metal onto a silicon microchip. The patterns created are “nanoscale,” or on the size scale of atoms or molecules.
Usually fabrication of nanoscale patterns requires lithography, which employs masks to prevent material from accumulating on protected areas. ORNL’s new direct-write technology is like lithography without the mask.
Details of this unique capability are published online in Nanoscale, a journal of the Royal Society of Chemistry, and researchers are applying for a patent. The technique may provide a new way to tailor devices for electronics and other applications.
“We can now deposit high-purity metals at specific sites to build structures, with tailored material properties for a specific application,” said lead author Raymond Unocic of the Center for Nanophase Materials Sciences (CNMS), a DOE Office of Science User Facility at ORNL. “We can customize architectures and chemistries. We’re only limited by systems that are dissolvable in the liquid and can undergo chemical reactions.”
The experimenters used grayscale images to create nanoscale templates. Then they beamed electrons into a cell filled with a solution containing palladium chloride. Pure palladium separated out and deposited wherever the electron beam passed.
Liquid environments are a must for chemistry. Researchers first needed a way to encapsulate the liquid so the extreme dryness of the vacuum inside the microscope would not evaporate the liquid. The researchers started with a cell made of microchips with a silicon nitride membrane to serve as a window through which the electron beam could pass.
Then they needed to elicit a new capability from a STEM instrument. “It’s one thing to utilize a microscope for imaging and spectroscopy. It’s another to take control of that microscope to perform controlled and site-specific nanoscale chemical reactions,” Unocic said. “With other techniques for electron-beam lithography, there are ways to interface that microscope where you can control the beam. But this isn’t the way that aberration-corrected scanning transmission electron microscopes are set up.”
Enter Stephen Jesse, leader of CNMS’s Directed Nanoscale Transformations theme. This group looks at tools that scientists use to see and understand matter and its nanoscale properties in a new light, and explores whether those tools can also transform matter one atom at a time and build structures with specified functions. “Think of what we are doing as working in nanoscale laboratories,” Jesse said. “This means being able to induce and stop reactions at will, as well as monitor them while they are happening.”
Jesse had recently developed a system that serves as an interface between a nanolithography pattern and a STEM’s scan coils, and ORNL researchers had already used it to selectively transform solids. The microscope focuses the electron beam to a fine point, which microscopists could move just by taking control of the scan coils. Unocic with Andrew Lupini, Albina Borisevich and Sergei Kalinin integrated Jesse’s scan control/nanolithography system within the microscope so that they could control the beam entering the liquid cell. David Cullen performed subsequent chemical analysis.
“This beam-induced nanolithography relies critically on controlling chemical reactions in nanoscale volumes with a beam of energetic electrons,” said Jesse. The system controls electron-beam position, speed and dose. The dose—how many electrons are being pumped into the system—governs how fast chemicals are transformed.
This nanoscale technology is similar to larger-scale activities, such as using electron beams to transform materials for 3D printing at ORNL’s Manufacturing Demonstration Facility. In that case, an electron beam melts powder so that it solidifies, layer by layer, to create an object.
“We’re essentially doing the same thing, but within a liquid,” Unocic said. “Now we can create structures from a liquid-phase precursor solution in the shape that we want and the chemistry that we want, tuning the physiochemical properties for a given application.”
Precise control of the beam position and the electron dose produces tailored architectures. Encapsulating different liquids and sequentially flowing them during patterning customizes the chemistry too.
The current resolution of metallic “pixels” the liquid ink can direct-write is 40 nanometers, or twice the width of an influenza virus. In future work, Unocic and colleagues would like to push the resolution down to approach the state of the art of conventional nanolithography, 10 nanometers. They would also like to fabricate multi-component structures.
Researchers studying the behavior of nanoscale materials at the Department of Energy’s Oak Ridge National Laboratory have uncovered remarkable behavior that could advance microprocessors beyond today’s silicon-based chips.
The study, featured on the cover of Advanced Electronic Materials, shows that a single crystal complex oxide material, when confined to micro- and nanoscales, can act like a multi-component electrical circuit. This behavior stems from an unusual feature of certain complex oxides called phase separation, in which tiny regions in the material exhibit vastly different electronic and magnetic properties.
It means individual nanoscale regions in complex oxide materials can behave as self-organized circuit elements, which could support new multifunctional types of computing architectures.
“Within a single piece of material, there are coexisting pockets of different magnetic and/or electronic behaviors,” said ORNL’s Zac Ward, the study’s corresponding author. “What was interesting in this study was that we found we can use those phases to act like circuit elements. The fact that it is possible to also move these elements around offers the intriguing opportunity of creating rewritable circuitry in the material.”
Because the phases respond to both magnetic and electrical fields, the material can be controlled in multiple ways, which creates the possibility for new types of computer chips.
“It’s a new way of thinking about electronics, where you don’t just have electrical fields switching off and on for your bits,” Ward said. “This is not going for raw power. It’s looking to explore completely different approaches towards multifunctional architectures where integration of multiple outside stimuli can be done in a single material.”
As the computing industry looks to move past the limits of silicon-based chips, the ORNL proof-of-principle experiment shows that phase separated materials could be a way beyond the “one-chip-fits-all” approach. Unlike a chip that performs only one role, a multifunctional chip could handle several inputs and outputs that are tailored to the needs of a specific application.
“Typically you would need to link several different components together on a computer board if you wanted access to multiple outside senses,” Ward said. “One big difference in our work is that we show certain complex materials already have these components built in, which may cut down on size and power requirements.”
The researchers demonstrated their approach on a material called LPCMO, but Ward notes that other phase-separated materials have different properties that engineers could tap into.
“The new approach aims to increase performance by developing hardware around intended applications,” he said. “This means that materials and architectures driving supercomputers, desktops, and smart phones, which each have very different needs, would no longer be forced to follow a one-chip-fits-all approach.”
A team of scientists from the Department of Energy’s Oak Ridge National Laboratory and the University of Florida has developed a novel method that could yield lower-cost, higher-efficiency systems for water heating in residential buildings.
The theory behind the newly termed “semi-open” natural gas-fired design, explained in an ORNL-led paper published in Renewable Energy: An International Journal, reduces the cost and complexity of traditional closed gas-fired systems by streamlining, and even eliminating, certain components.
“When applied, the new concept could result in better than 100 percent energy efficiency, because the system draws energy from the surrounding air as well as from the natural gas,” said ORNL’s Kyle Gluesenkamp, lead author of “Efficiency analysis of semi-open sorption heat pump systems.”
The versatile design combines water heating and dehumidification functions, which are typically found in separate architectures. In the semi-open scenario, the novel absorber device acts in place of the traditional evaporator component, pulling water vapor directly from the air through a membrane into a liquid solution. As the vapor is absorbed, much of the heat is transferred to domestic hot water.
The simpler semi-open system would operate at the surrounding atmospheric pressure, using an inexpensive, non-sealed solution pump. This approach eliminates the need for vacuum pumps found in closed systems that purge gas build up. It also allows manufacturers to consider lower-cost, lightweight polymers instead of costly, bulkier metals to build equipment, making it less susceptible to corrosion.
“The semi-open architecture introduces a new class of ultra-efficient heat pump water heaters that could become commercially available in a few years to homeowners seeking to replace their existing gas water heater,” Gluesenkamp said.
UF researchers are leading the development of a semi-open gas-fired heat pump prototype and are using both ORNL’s Building Technologies Research and Integration Center, a DOE user facility, and UF facilities to evaluate the potential of commercial applications.
Implanted helium ions “tuned” complex behaviors—enabling design of new materials for efficient electricity storage and testing theories.
With just a bit of helium, the lighter-than-air element that makes balloons float, scientists have done what was once thought impossible—they stretched a crystal lattice in just one dimension, allowing them to tune the structure’s electronic and magnetic properties. To achieve this elongation, scientists devised a new method called “strain doping.” Scientists implant helium ions into a crystal. The helium gently pushes up against the structure, like a balloon under a sheet. The process does not cause structural damage.
“Strain doping” could let scientists tune the electronic and magnetic properties of complex materials creating what’s needed to advance transmitting, storing, and otherwise working with electricity. These new types of materials could transmit electricity without loss. Also, this technique brings complex oxide materials closer to commercialization because it can be scaled up for wafer-scale processing and uses existing infrastructure in the semiconductor industry—leveraging this multi-billion industry with existing fabrication facilities including clean rooms to eliminate dust and specialized machines. Commercializing complex oxides is important because they exhibit exciting phenomena that can address limitations in solar cells, thermoelectrics (conversion of waste heat to electricity), and energy conversion, transmission, and storage. In addition, this technique lets scientists controllably vary one parameter in a material, allowing them to experimentally investigate theoretical predictions of promising properties in different materials.
Scientists believed that changing only one dimension of the crystal lattice structure was impossible. Now researchers led by scientists from Oak Ridge National Laboratory have controllably elongated one direction of a crystalline lattice, using a technique called “strain doping.” In this technique, scientists implant a helium ion to achieve a level of structural control previously only available to theory. The team implanted a few helium ions into a crystalline thin film and stretched the structure of the crystal film in one direction, while the other two directions were fixed by an underlying substrate. The crystalline film was a complex oxide with electronic properties that are very sensitive to stretching and pulling. The research shows that implanting the helium atoms into the crystalline lattice lets scientists control the strain in the film, thereby tuning the magnetic and electronic properties of the oxide film, and is reversible by removing the helium. Scientists could use this strain doping technique to tune electronic and magnetic properties of other materials. Because this technique uses existing ion implantation infrastructure currently found in the semiconductor industry, it could accelerate the commercial use of complex oxides with finely controlled properties. The research also shows that the elusive goal of experimentally probing theoretical models of materials’ properties by varying one parameter at a time may now be a reality.
Stronger, lighter, smarter materials are projected payoff
Additive manufacturing techniques featuring atomic precision could one day create materials with Legos flexibility and Terminator toughness, according to researchers at the Department of Energy’s Oak Ridge National Laboratory.
In a review paper published in ACS Nano, Olga Ovchinnikova and colleagues provide an overview of existing paths to 3-D materials, but the ultimate goal is to create and customize material at the atomic scale. Material would be assembled atom by atom, much like children can use Legos to build a car or castle brick by brick. This concept, known as directed matter, could lead to virtually perfect materials and products because many limitations of conventional manufacturing techniques would be eliminated.
“Being able to assemble matter atom by atom in 3-D will enable us to design materials that are stronger and lighter, more robust in extreme environments and provide economical solutions for energy, chemistry and informatics,” Ovchinnikova said.
Fundamentally, directed matter eliminates the need to remove unwanted material by lithography, etching or other traditional methods. These processes have served society well, researchers noted, but the next generation of materials and products require a new approach.
“For the vast majority of recorded history, material transformation was limited to objects visible to the naked eye and patterned using hand-held tools,” the researchers wrote. “We can admire the prowess of the rice grain writing, or fine engraving on a prized sword blade, but only two to three orders of magnitude separate these masterpieces from Stone Age technology.”
Now, with the ability to direct matter with atomic precision, the payoff could be quantum computers, cell phones with more data storage and longer intervals between charging, higher efficiency solar cells, and stronger and less expensive lightweight materials.
In a rechargeable battery, the electrolyte transports lithium ions from the negative to the positive electrode during discharging. The path of ionic flow reverses during recharging. The organic liquid electrolytes in commercial lithium-ion batteries are flammable and subject to leakage, making their large-scale application potentially problematic. Solid electrolytes, in contrast, overcome these challenges, but their ionic conductivity is typically low.
Now, a team led by the Department of Energy’s Oak Ridge National Laboratory has used state-of-the-art microscopy to identify a previously undetected feature, about 5 billionths of a meter (nanometers) wide, in a solid electrolyte. The work experimentally verifies the importance of that feature to fast ion transport, and corroborates the observations with theory. The new mechanism the researchers report in Advanced Energy Materials points out a new strategy for the design of highly conductive solid electrolytes.
“The solid electrolyte is one of the most important factors in enabling safe, high-power, high-energy, solid-state batteries,” said first author Cheng Ma of ORNL, who conducted most of the study’s experiments. “But currently the low conductivity has limited its applications.”
ORNL’s Miaofang Chi, the senior author, said, “Our work is basic science focused on how we can facilitate ion transport in solids. It is important to the design of fast ion conductors, not only for batteries, but also for other energy devices.” These include supercapacitors and fuel cells.