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Advancing Mixed Anion Compounds

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Advancing Mixed Anion Compounds Impact Objectives • Establish basic theory for mixed anion compounds • Create new functionalities, discovering and developing the roots of chemical and physical functions that will meet the needs of future society • Create new materials and develop material design concepts and methodologies that will lead to practical applications for the future Advancing mixed anion compounds An ambitious collaborative effort between 40 research groups across Japan is focused on understanding the complicated properties of mixed anion compounds and applying their data to new and refined technological applications What is your Can you give us a little background on this that will meet the needs of society in the background and project and explain why we need more next 10 to 30 years. At present, we know how has that led research in this area? only a little about mixed anion systems. to your role in this There is much more to explore. Three years project? We have known about mixed anion from now, in year five of the project, I hope compounds for many years and they are that we will have established material design I have a chemistry background, but in the even found as minerals. Little attention concepts and methodologies as well as new early stages of my career, I was interested has been paid to them in the last century. functions. in the physical properties of transition However, several landmark discoveries metal oxides such as high temperature relating to them have been reported since Have you had any particularly interesting superconductivity and quantum phenomena 2000. These discoveries prompted us to or surprising findings in your investigations in frustrated magnets. After that, I came to consider that mixed anion compounds so far? believe that what I really wanted to do was should be given more attention in a wide to explore new materials and I switched variety of research areas, ranging from The introduction of H- ions in barium titanate my research focus from condensed matter chemistry to physics. Another reason is (BaTiO3), the most well-known functional physics to solid state chemistry. Using a that the guiding principles for the study oxide, induces catalytic activity in terms of variety of techniques from conventional of mixed anions in terms of synthesis, ammonia synthesis. Titanium has been solid-state reactions to topochemical analysis and function are still undiscovered regarded as a ‘dead’ element for ammonia low-temperature reactions as well as and most of our knowledge of synthesis, synthesis since titanium nitride (Ti-N) high-pressure reactions, my group in analysis and function has been developed bonding is too strong. It means that the H- Kyoto prepares various types of inorganic for oxide materials. In many cases, however, anion in oxides (oxyhydride) has the ability materials, some of which are mixed anion these cannot be applied to mixed anion to break the triple bond in the N2 molecule, compounds. Luckily for me, several of the compounds. the most difficult part of the process in NH3 mixed anion compounds exhibit exotic synthesis. In other words, the introduction chemical and physical properties such as What are the key objectives of this project? of the H- in oxides can break the so-called low-temperature hydride (H-) migration in ‘scaling rule’. Another important finding is titanium oxyhydrides and selective heavy In this new area of research, we will the discovery of H- size flexibility. Our x-ray metal capturing in titanium phosphide create new materials and establish the diffraction measurement under high pressure telluride. With these discoveries and those basic theory of mixed anion compounds, revealed that the H- anion is at least twice of other researchers, I became convinced developing material design concepts and as flexible as the oxide anion (O2-). Thus, that mixed anion compounds can be methodologies that will lead to practical the H- anion can be compared to a ‘balloon’ emerging materials with potential next- applications in the future, 10 to 30 years while the other anions are the ‘footballs’. We generation applications. from now. In addition, we will create new found that strontium vanadium oxide-hydride functionality, discovering and developing (SrVO2H) exhibits novel insulator-to-metal the roots of chemical and physical functions transition under high pressure. www.impact.pub 33 New and sustainable Since my project launched, many researchers, including organic chemists and company workers in Japan, have come to understand what a ‘mixed technologies anion compound’ is Sustainable technologies capable of changing the future of electronic devices, batteries and displays can materials that can both produce and save now be created in the laboratory, thanks to the vast variety of mixed anion compounds available ordered. In other cases, they are complexly energy. With these new developments, group disorganised.’ To address this, groups 1, 2 Project Insights 3 hopes to establish usable technologies and 3 are working to develop new methods Japan is a country rich in beauty but poor anions and much of the scientific knowledge a diverse range of anions with different that are far more diverse than single anion that can tackle this problem and deal with FUNDING in natural resources. Unlike countries such on their synthesis, analysis and function key features, such as valency, ionic radius, compounds and can sustain our future ‘correlated disorder’ within mixed anion The project was support by funding from as Venezuela, with an estimated £10.82 comes from single-oxide materials. In a five- electronegativity and polarizability. Like a society. compounds. Additionally, the synthesis of the Japan Society for the Promotion trillion worth of natural gas, petroleum and year-long study, the group aims to create, structure with different toy construction mixed anion compounds is a complicated of Science (JSPS) Grant-in-Aid for iron, Japan has virtually no natural energy observe and explore the functionalities of bricks, this variability allows for a wider DISCOVERING MIXED ANION affair. Thus, the team is focusing on using Scientific Research on Innovative Areas resources and consequently is the world’s mixed anion compounds in order to expand range of compounds with distinct structures PROPERTIES multiple tools and multistep processes programme, grant numbers JP16H6438, largest importer of coal and liquefied natural this knowledge base. With a stronger and dimensions. A recent paper by Kuriki et al., published that can provide a more diverse range of JP16H6439, JP16H6440 and JP16H6441. gas. This has a huge impact on Japan’s foundation for the make-up and properties in the Journal of the American Chemical platforms on which to manipulate these worldwide industrial competitiveness. of mixed anion compounds, the team hopes In order to properly work with mixed anion Society (volume 140, page 6648-6655, compounds. CONTACT As a result, Japanese researchers are to develop new and advanced materials that compounds, Kageyama and his team have 2018) showcases one successful example Professor Hiroshi Kageyama Project Coordinator working to develop new, high-performance can be used in practical applications in the divided their study into three subgroups: of extensive collaboration between 40 MAKING HEADWAY materials that can be applied to future future. group 1 for the creation of mixed anion research groups. This work, involving the The intriguing qualities of mixed anion T: +81 75383 2506 technologies. Professor Hiroshi Kageyama, compounds; group 2 for the observation of five PIs of this project (Associate Professor compounds can be leveraged for a wide E: [email protected] a head researcher at the Graduate School BEYOND SINGLE ANION COMPOUNDS mixed anions and group 3 for the exploration Kazuhiko Maeda, Dr Kengo Oka, Assistant variety of applications. However, there is still W: https://www.mixed-anion.jp (the of Engineering at Kyoto University, is the Until the year 2000, many researchers were of innovative functionalities. Group 1, led Professor Kenta Hongo, Dr Ryo Maezono much to discover about the principles and project website), http://www.ehcc.kyoto-u. project coordinator for a collaboration of not paying much attention to mixed anion by Dr Hiraku Ogino from the National and Kageyama), describes the discovery applications of these chemical structures. ac.jp/eh10 (the Kageyama lab in Kyoto) 40 leading Japanese research groups that compounds. This is due to the fact that the Institute of Advanced Industrial Science and of an oxyfluoride semiconductor known ‘Most of the researchers are either not BIOS seeks to investigate and develop mixed- Earth’s atmosphere is far more conducive Technology, is focused on establishing and as pyrochlore (Pb Ti O F ), that has an familiar with mixed anion materials or they 2 2 5.4 1.2 Professor Hiroshi Kageyama graduated anion compounds for new functionalities. to simpler single-anion compounds such as synthesising mixed anion compounds using unprecedented small band gap of around are not aware of mixed anion compounds,’ from Kyoto University in Japan with a BS Currently, inorganic compounds such metal oxides. For example, when elemental techniques such as high-pressure synthesis, 2.4 eV and the ability to act as a stable Kageyama states. ‘Since my project in chemistry in 1993 and followed this up as oxides and nitrides, typically binary iron is heated in the air, iron oxide – or rust topochemical reaction and solvothermal semiconductor photocatalyst, opening up launched, many researchers, including with an MS in chemistry in 1995 and PhD compounds containing oxygen or nitrides, – is quickly created. Complex oxides can also methods. Additionally, this group is new opportunities within materials research organic chemists and company workers in 1998, both also from Kyoto University. are base materials that support a wide be obtained by heating a mixture of binary also working to define the rules of anion for heterogeneous photocatalysis with visible in Japan, have come to understand what a He has been awarded a number of variety of industry appliances, including oxides to high temperatures in a process arrangement through both experimental light.
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