Tag Archives: Kristin Persson

Largest database of elemental crystal surfaces and shapes in the world

A Sept. 13, 2016 news item on Nanowerk describes the database,

Nanoengineers at the University of California San Diego [UCSD], in collaboration with the Materials Project at Lawrence Berkeley National Laboratory (Berkeley Lab), have created the world’s largest database of elemental crystal surfaces and shapes to date. Dubbed Crystalium, this new open-source database can help researchers design new materials for technologies in which surfaces and interfaces play an important role, such as fuel cells, catalytic converters in cars, computer microchips, nanomaterials and solid-state batteries.

rystalium is a new open-source database with the largest collection of elemental crystal surfaces and shapes to date. Image courtesy of the Materials Virtual Lab at UC San Diego

Crystalium is a new open-source database with the largest collection of elemental crystal surfaces and shapes to date. Image courtesy of the Materials Virtual Lab at UC San Diego

A Sept. 13, 2016 UCSD news release reveals more about the goals for the database and the database itself (Note: Links have been removed),

“This work is an important starting point for studying the material surfaces and interfaces, where many novel properties can be found. We’ve developed a new resource that can be used to better understand surface science and find better materials for surface-driven technologies,” said Shyue Ping Ong, a nanoengineering professor at UC San Diego and senior author of the study.

For example, fuel cell performance is partly influenced by the reaction of molecules such as hydrogen and oxygen on the surfaces of metal catalysts. Also, interfaces between the electrodes and electrolyte in a rechargeable lithium-ion battery host a variety of chemical reactions that can limit the battery’s performance. The work in this study is useful for these applications, said Ong, who is also part of a larger effort by the UC San Diego Sustainable Power and Energy Center to design better battery materials.

“Researchers can use this database to figure out which elements or materials are more likely to be viable catalysts for processes like ammonia production or making hydrogen gas from water,” said Richard Tran, a nanoengineering PhD student in Ong’s Materials Virtual Lab and the study’s first author. Tran did this work while he was an undergraduate at UC San Diego.

The work, published Sept. 13 [2016] in the journal Scientific Data, provides the surface energies and equilibrium crystal shapes of more than 100 polymorphs of 72 elements in the periodic table. Surface energy describes the stability of a surface; it is a measure of the excess energy of atoms on the surface relative to those in the bulk material. Knowing surface energies is useful for designing materials that perform their functions primarily on their surfaces, like catalysts and nanoparticles.

The surface energies of some elements in their crystal form have been measured experimentally, but this is not a trivial task. It involves melting the crystal, measuring the resulting liquid’s surface tension at the melting temperature, then extrapolating that value back to room temperature. This process also requires that the sample have a clean surface, which is challenging because other atoms and molecules (like oxygen and water) can easily adsorb to the surface and modify the surface energy.

Surface energies obtained by this method are averaged values that lack the facet-specific resolution that is necessary for design, Ong said. “This is one of the areas where the ’virtual laboratory’ can create the most value—by allowing us to precisely control the models and conditions in a way that is extremely difficult to do in experiments.”

Also, the surface energy is not just a single number for each crystal because it depends on the crystal’s orientation. “A crystal is a regular arrangement of atoms. When you cut a crystal in different places and at different angles, you expose different facets with unique arrangements of atoms,” explained Ong, who teaches the course NANO106 – Crystallography of Materials at UC San Diego.

To carry out this ambitious project, Ong and his team developed highly sophisticated automated workflows to calculate surface energies from first principles. These workflows are built on the popular open-source Python Materials Genomics library and FireWorks workflow codes of the Materials Project, which were co-authored by Ong.

“The techniques for calculating surface energies have been known for decades. The major accomplishment is the codification of how to generate surface models and run these complex calculations in a robust and efficient manner,” Tran said. The surface model generation software code developed by the team has already been extended by others to study substrates and interfaces. Powerful supercomputers at the San Diego Supercomputer Center and the National Energy Research Scientific Computing Center at the Lawrence Berkeley National Lab were used for the calculations.

Ong’s team worked with researchers from the Berkeley Lab’s Materials Project to develop and construct Crystalium’s website. Co-founded and directed by Berkeley Lab scientist Kristin Persson, the Materials Project is a Google-like database of material properties calculated by supercomputers.

“The Materials Project was designed to be an open and accessible tool for scientists and engineers to accelerate materials innovation,” Persson said. “In five years, it has attracted more than 20,000 users working on everything from batteries to photovoltaics to thermoelectrics, and it’s extremely gratifying to see scientists like Ong providing lots of high quality computed data of high interest and making it freely available and easily accessible to the public.”

The researchers pointed out that their database is the most extensive collection of calculated surface energies for elemental crystalline solids to date. Compared to previous compilations, Crystalium contains surface energies for far more elements, including both metals and non-metals, and for more facets in each crystal. The elements that have been excluded from their calculations are gases and radioactive elements. Notably, Ong and his team have validated their calculated surface energies with those from experiments, and the values are in excellent agreement.

Moving forward, the team will work on expanding the scope of the database beyond single elements to multi-element compounds like alloys, which are made of two or more different metals, and binary oxides, which are made of oxygen and one other element. Efforts are also underway to study the effect of common adsorbates, such as hydrogen, on surface energies, which is key to understanding the stability of surfaces in aqueous media.

“As we continue to build this database, we hope that the research community will see it as a useful resource for the rational design of target surface or interfacial properties,” said Ong,

Here’s a link to and a citation for the paper,

Surface energies of elemental crystals by Richard Tran, Zihan Xu, Balachandran Radhakrishnan, Donald Winston, Wenhao Sun, Kristin A. Persson, & Shyue Ping Ong.  Scientific Data 3, Article number: 160080 (2016)  doi:10.1038/sdata.2016.80 Published online: 13 September 2016

This paper is open access.

Here, too, is a link to Crystalium.

A treasure trove of molecule and battery data released to the public

Scientists working on The Materials Project have taken the notion of open science to their hearts and opened up access to their data according to a June 9, 2016 news item on Nanowerk,

The Materials Project, a Google-like database of material properties aimed at accelerating innovation, has released an enormous trove of data to the public, giving scientists working on fuel cells, photovoltaics, thermoelectrics, and a host of other advanced materials a powerful tool to explore new research avenues. But it has become a particularly important resource for researchers working on batteries. Co-founded and directed by Lawrence Berkeley National Laboratory (Berkeley Lab) scientist Kristin Persson, the Materials Project uses supercomputers to calculate the properties of materials based on first-principles quantum-mechanical frameworks. It was launched in 2011 by the U.S. Department of Energy’s (DOE) Office of Science.

A June 8, 2016 Berkeley Lab news release, which originated the news item, provides more explanation about The Materials Project,

The idea behind the Materials Project is that it can save researchers time by predicting material properties without needing to synthesize the materials first in the lab. It can also suggest new candidate materials that experimentalists had not previously dreamed up. With a user-friendly web interface, users can look up the calculated properties, such as voltage, capacity, band gap, and density, for tens of thousands of materials.

Two sets of data were released last month: nearly 1,500 compounds investigated for multivalent intercalation electrodes and more than 21,000 organic molecules relevant for liquid electrolytes as well as a host of other research applications. Batteries with multivalent cathodes (which have multiple electrons per mobile ion available for charge transfer) are promising candidates for reducing cost and achieving higher energy density than that available with current lithium-ion technology.

The sheer volume and scope of the data is unprecedented, said Persson, who is also a professor in UC Berkeley’s Department of Materials Science and Engineering. “As far as the multivalent cathodes, there’s nothing similar in the world that exists,” she said. “To give you an idea, experimentalists are usually able to focus on one of these materials at a time. Using calculations, we’ve added data on 1,500 different compositions.”

While other research groups have made their data publicly available, what makes the Materials Project so useful are the online tools to search all that data. The recent release includes two new web apps—the Molecules Explorer and the Redox Flow Battery Dashboard—plus an add-on to the Battery Explorer web app enabling researchers to work with other ions in addition to lithium.

“Not only do we give the data freely, we also give algorithms and software to interpret or search over the data,” Persson said.

The Redox Flow Battery app gives scientific parameters as well as techno-economic ones, so battery designers can quickly rule out a molecule that might work well but be prohibitively expensive. The Molecules Explorer app will be useful to researchers far beyond the battery community.

“For multivalent batteries it’s so hard to get good experimental data,” Persson said. “The calculations provide rich and robust benchmarks to assess whether the experiments are actually measuring a valid intercalation process or a side reaction, which is particularly difficult for multivalent energy technology because there are so many problems with testing these batteries.”

Here’s a screen capture from the Battery Explorer app,

The Materials Project’s Battery Explorer app now allows researchers to work with other ions in addition to lithium.

The Materials Project’s Battery Explorer app now allows researchers to work with other ions in addition to lithium. Courtesy: The Materials Project

The news release goes on to describe a new discovery made possible by The Materials Project (Note: A link has been removed),

Together with Persson, Berkeley Lab scientist Gerbrand Ceder, postdoctoral associate Miao Liu, and MIT graduate student Ziqin Rong, the Materials Project team investigated some of the more promising materials in detail for high multivalent ion mobility, which is the most difficult property to achieve in these cathodes. This led the team to materials known as thiospinels. One of these thiospinels has double the capacity of the currently known multivalent cathodes and was recently synthesized and tested in the lab by JCESR researcher Linda Nazar of the University of Waterloo, Canada.

“These materials may not work well the first time you make them,” Persson said. “You have to be persistent; for example you may have to make the material very phase pure or smaller than a particular particle size and you have to test them under very controlled conditions. There are people who have actually tried this material before and discarded it because they thought it didn’t work particularly well. The power of the computations and the design metrics we have uncovered with their help is that it gives us the confidence to keep trying.”

The researchers were able to double the energy capacity of what had previously been achieved for this kind of multivalent battery. The study has been published in the journal Energy & Environmental Science in an article titled, “A High Capacity Thiospinel Cathode for Mg Batteries.”

“The new multivalent battery works really well,” Persson said. “It’s a significant advance and an excellent proof-of-concept for computational predictions as a valuable new tool for battery research.”

Here’s a link to and a citation for the paper,

A high capacity thiospinel cathode for Mg batteries by Xiaoqi Sun, Patrick Bonnick, Victor Duffort, Miao Liu, Ziqin Rong, Kristin A. Persson, Gerbrand Ceder and  Linda F. Nazar. Energy Environ. Sci., 2016, Advance Article DOI: 10.1039/C6EE00724D First published online 24 May 2016

This paper seems to be behind a paywall.

Getting back to the news release, there’s more about The Materials Project in relationship to its membership,

The Materials Project has attracted more than 20,000 users since launching five years ago. Every day about 20 new users register and 300 to 400 people log in to do research.

One of those users is Dane Morgan, a professor of engineering at the University of Wisconsin-Madison who develops new materials for a wide range of applications, including highly active catalysts for fuel cells, stable low-work function electron emitter cathodes for high-powered microwave devices, and efficient, inexpensive, and environmentally safe solar materials.

“The Materials Project has enabled some of the most exciting research in my group,” said Morgan, who also serves on the Materials Project’s advisory board. “By providing easy access to a huge database, as well as tools to process that data for thermodynamic predictions, the Materials Project has enabled my group to rapidly take on materials design projects that would have been prohibitive just a few years ago.”

More materials are being calculated and added to the database every day. In two years, Persson expects another trove of data to be released to the public.

“This is the way to reach a significant part of the research community, to reach students while they’re still learning material science,” she said. “It’s a teaching tool. It’s a science tool. It’s unprecedented.”

Supercomputing clusters at the National Energy Research Scientific Computing Center (NERSC), a DOE Office of Science User Facility hosted at Berkeley Lab, provide the infrastructure for the Materials Project.

Funding for the Materials Project is provided by the Office of Science (US Department of Energy], including support through JCESR [Joint Center for Energy Storage Research].

Happy researching!