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Introduction of our research method

A) Reaction and materials science by ultra-high shock pressure

Explosives are known to be one of the highest energy density materials except for nuclear energy. Physicochemical experiments that studies how explosives act directly on a substance is a rare field in the world. This phenomena is also known as high-strain-rate phenomena.
Sojo University is one of the only few universities and institution in Japan that have the facilities to conduct research in this field. Here at Sojo University, Tomoshige Laboratory is responsible for the management of this rare research facility which is the Research Center for Advances in Impact engineering (*1).
Utilizing extremely high energy in hundreds of thousands to one million atm in the material for a very short time by utilizing the extremely large energy of the explosive, phenomena and materials which can not be obtained under normal temperature and normal pressure It must be obtained. For example, the collision phenomenon of Debris in outer space, the behavior when the material is placed under pressure similar to the Earth's mantle, the synthesis of materials that can only exist at high pressure, the high speed deformation of crystals It is a research field full of unknown phenomena.

There are opportunities for you to understand the science and utilize the chemistry technology of the mysterious state that is full of charm as mentioned above in this laboratory.

Why don't you try to challenge yourself in this once in a lifetime opportunity in this fascinating "research facility that the world envies"

* 1 In 2001, it was selected as a privately funded high-tech research center development project from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and was set up at Sojo University. The research theme proposed to the MEXT was "Development of ultra-high pressure by explosive impact and its use for development of new materials".

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Examples of ultra-high pressure research that can be conducted in our laboratory

(1) Hot Explosive Welding of Different Kind of Materials; Ceramics / Metals

It is the first in the world that different materials are joined together at ultrahigh pressure and it is being developled in our laboratory

So far, we hve succeeded in obtaining "bonding material of relatively large area" of "ceramic material and metal material" with different chemical bonding modes.

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(2) Impact compression of powder

In our laboratory, efficient thermal shock processing using chemical reaction heat when synthesizing compounds without external heating is possible.
This revealed a method that can synthesize and densify functional materials called various ceramics materials and intermetallic compounds on the spot. Many ceramic materials and intermetallic compounds have melting points up to several thousand degrees, and it takes a long time to densify them in the method of synthesis or densification using an electric furnace or any similar heating apparatus. In addition to this, most of this heat source are not energy efficient. It certainly does not comply with the current situation where energy conservation is highly desired.
This method can synthesize the compound of interest in a few minutes and complete up to densification.

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(3) Explosion welding of dissimilar metal plate

Combining dissimilar metal materials produces a functional material called a composite material having both properties of the material. Generally, the method of rolling is done in to obtain it. However, if the crystal system of the target metal material is different, the characteristics of the material will be altered. In addition to this, if both metal's melting point is different, joining the metals by rolling will be difficult.

On the other hand, it is possible to join dissimilar metals by impact processing with explosives. Its characteristic is that the junction interface becomes wavy (in some combinations it becomes a smooth interface). Because of this, each material is driven by a wedge to each other, so that a strong bonding material can be obtained together with the strength of bonding at the time of explosion.

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(4) Super high pressure generation of 1 TPa order and synthesis of new substances

Explained that a wave-shaped interface appears when a metal plate is joined by explosive pressure welding. This is related to the phenomenon of droplet-shaped metal called metal jet (Jet Jet) blowing when the metal plate collides. Since this jet to be jetted is a speed of several km / sec, the relative speed becomes ten-odd km / sec if it makes a head-on collision. The pressure at the time of the crash is estimated to be close to 1 TPa (1 Tera Pascal ≈ 10 Million atm). This pressure can be realized with the model as shown in Figure A using the explosive power. The metal jets flying when using this model and how they collide are shown in Fig. As a result of the frontal collision, the metal at the center of the V shape shown in Fig. (A) seems to be greatly gouged (Fig. This means that high pressure acted. It looks like a shape like a meteorite hits the Earth. It is an experimental method that can clarify the mystery of the universe and have the potential to be used for synthesizing new substances by creating conditions that can not be obtained in normal condition.

(※ Collaborative research with the laboratory of Professor Akio Kira Department of Mechanical Engineering, Faculty of Engineering)

B) High speed reaction science under ultra high temperature

Among numerous chemical reactions, it can be said that self-propagating high temperature synthesis method (aka, combustion synthesis method) is extremely distinctive. As shown in the above picture, this synthesis method, when ignited at the upper end of compacted mixed powder (for example, a mixture of metallic titanium powder and graphite at an atomic ratio of 1: 1) ignite, The chemical reaction proceeds spontaneously and the stick burns up. This method was discovered in Russia and later spread to the United States and Eastern European countries. Its advantage is that it is low cost and high rate of reaction. Even in Japan, related research have been conducted. Our laboratory is one of the few laboratories working on synthesizing compounds by combustion synthesis. We have been using this method to make various non-oxide materials and evaluate their characteristics. The MAX phase material that as shown below one of them.

C) Material science at the nano level

Our laboratory synthesize various inorganic materials and conduct the material characterization continuously. The Professors and students are putting many effort into producing new and innovative materials that will make our life convenient, as well as materials that will ensure personal safety as well as contributing to better health standards .
We understand that the structure of materials, especially the state of crystals in which the atoms and ions are regularly arranged, is very important information. For this reason, our laboratory observes detailed information on the arrangement of atoms that can not be discriminated by human eyes using advanced equipment such as electron microscope and X-ray diffractometer. Transmission type analytical electron microscope TEM in our university is the state-of-the-art aircraft of FEI Inc. of America (currently · Thermo Fisher Scientific), and it was introduced to Japan for the first time.
In our laboratory, we take good care in maintaining and managing the electron microscope which is Japan's first machine, so we are in an environment where we can frequently observe and care for the equipment.

D) Structure-derived science

The structure of the inorganic material varies. A wide variety of crystal structures can be observed from the typical cubic / hexagonal structure that metals have to complex structures that makes up the ceramics material . Utilizing this structure and developing a functional materials has been done so far. A well-known example is the graphite seen in the above diagram. The nano-level space that emerges from the way the atoms are tied together gives it electrochemical characteristics and mechanical properties.
There is a material that has recently drawn much attention in the form of metal carbide or metal nitride with a structure similar to graphite called the MAX phase. This is a substance in which an element from transition metal (M group element) and from group A element on the periodic table such as aluminum or sulfur are combined with carbon or nitrogen (X element). These abbreviations of element groups given individually are called MAX phases. This name was given in the year 2000 by the American researcher, however its existence has long been known prior to that. Our laboratory has already done its synthesis in 1996 and has revealed its characteristic. Studies of this MAX phase material is not only limited to its intermediate property between ceramics and metal but also its catalytic function, electrochemical function, and partly biocompatibility. It is drawing attention in the United States, Europe and China as to whether it shows excellent characteristics. In Japan, we are not paying much attention to the material, but we are conducting research to derive the characteristics of the MAX phase material that has been successfully synthesized before.

E) Catalytic chemistry

Under construction

F) Science to save humanity from illness

The utilization of inorganic materials is very wide covering many range of knowledge disciplines. Medical field is one example. Metals and ceramics are such example of organic material that is indispensable in the medical field. One example is titanium dioxide TiO2. It is well known for its photocatalytic activity and by applying it to the wall surface in the operating room, bacteria adhering to the wall are killed by photocatalytic oxidation. This ensures that any medical procedure performed in the room are safer. Laser scalpels used in laparoscopic surgery use laser light that passes through glass fibers which is made from inorganic materials. This is another example on how we can support medical care as surgical tools and powerful supporters

In addition to this our laboratory offers various inorganic materials that can directly contribute to medical care. For example, the material hydroxyapatite HAp is an important material that makes up our bones and teeth, but it can also be synthesized in the laboratory. We have been collaborating with the laboratory of Prof. Taku Matsushita from the Department of Applied Life Sciences, Faculty of Biological and Life Science, College of Techology for many years. We have found that when the above-mentioned HAp material when given a special form and cultured in the human, the proliferation properties of the cells depending on the surface shape appear (see electron microscope picture above).

This technology would benefit patients suffering from diseases that are in need for organ transplant as it reduces the body’s natural rejection reactions of artificial organ obtained from cell culturing. This engineering method would ensure a higher success rate and safety in organ transplant

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