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Research Results

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1998
2006
Dec. 2006
  Scientists at the Institute for Material Research found a new method to substantially improve the properties of superconducting wire. The High Field Laboratory for Superconducting Materials research group lead by Associate Professor Satoshi Awaji and Professor Kazoo Watanabe repeatedly bent (prebent) the practical Nb3Sn superconducting wire, used in many superconducting magnets, to demonstrate a world-first, interesting result. The phenomenon was verified on coil shapes, indicating that the method can be used for practical superconducting application. Generally, the superconducting properties of the brittle Nb3Sn wire are known to deteriorate dramatically with the slight deformation. For this reason, these properties are reduced by thermal strain, which is produced when the wire is cooled as low as -269 °C. However, researchers discovered that the superconducting properties can actually be improved sharply by prebending the Nb3Sn wire. The interesting finding suggests that prebending is equivalent to training the Nb3Sn wire, which is essentially weak against distortion, to improve superconducting properties, thus challenging the accepted notion. The new finding will be likely to increase the performance and reduce the cost of superconducting application using Nb3Sn superconducting wires.
Dec. 2006
  We grew high quality single crystals of NpO2, and clarified the new ordered state due to the magnetic octupolar by the nuclear magnetic resonance (NMR) measurements. The magnetic octupole order is related with the anisotropic distribution of the magnetic moment, which is induced by the quantum behavior of spin and orbital. This is "spontaneous symmetry breaking", which is universally observed as a physical phenomenon. High quality single crystals and microscopic experiments put an end to the half century mystery. This result was published in Phys. Rev. Lett., and was reported in "Kahoku Shimpo" and "Nikkan Kogyo Shimbun" on Dec. 20, 2006, as well. The work has been done in collaboration with Japan Atomic Energy Agency.
Prof. Shiokawa’s group (Radiochemistry of Metals),
International Research Center for Nuclear Materials Science
Oct. 2006
  The joint research group of Prof Takafumi Yao and Associate Professor Meoungwhan Cho has succeeded in the development of novel processing technology for vertical light-emitting diodes of nitrides based on chemical lift-off technique. The key technology which has lead to the success is chemical lift-off technique in which GaN-based materials and devices are grown on sapphire substrates using metal buffer so that the metal buffer can be removed by chemical etching after the growth of GaN-based materials. The chemical lift-off technology was developed by the same group last year for the first time and has attracted considerable attention from industries. Consequently a research consortium was established last December, which intends to apply the chemical lift-off technique to various fields of nitride semiconductors including the fabrication of GaN wafers. It is expected that this novel process technology will contribute to the production of high brightness and high efficient LEDs at low cost. This result was introduced in Kahoku Shimpo on Oct. 26, 2006.
Prof. Yao’s group (Physics of Electronic Materials)
Sept. 2006
  Magnetic Materials group (Prof. K. Takanashi’s group) discovered in collaboration with Dr. S. Sakai et al., Advanced Science Research Center, Japan Atomic Energy Agency, that a nanostructured hybrid system consisting of Co nanoparticles embedded in a fullerene-Co compound matrix showed giant magnetoresistance (GMR), suggesting that the materials including fullerene might be useful in the field of spin electronics. This result was published in Applied Physic Letters, and also introduced in Nikkan-Kogyo Shinbun on September 25, 2006.
Sept. 2006
  Dr. Konashi has proposed a new hydride neutron absorber of nuclearreactor based on the results of irradiation experiments in JMTR of JAEA. A metal-hydride has very high hydrogen atom density, which is equivalent to that of liquid water. Fast neutrons in nuclear reactors are efficiently moderated and are absorbed in the metal-hydride. The Hafnium hydride and Gd hydride are considered as neutron absorber in FBR (Fast Breeder Reactor). The development program of hydride neutron absorber has been started, which is accepted as an innovative nuclear research and development program of Ministry of Education, Culture, Sports, Science and Technology of Japan. The program will be accomplished in 2009, with the budget of about 400 million yen. This is published as an article of The Nikkan Kogyou Shimbun on Sep. 6, being expected to be useful for reduction of cost and nuclear wastes.
Aug. 2006
  We succeeded in development of a new technique to grow a high-quality polycrystalline Si ingot for solar cells named as “Dendritic casting method”, which utilizes the dendrite growth along the bottom of the crucible wall at the initial stage of directional growth. This method permits to obtain a textured polycrystalline Si ingot with large-size grains. Furthermore, its crystal quality was revealed to be highly maintained from the bottom to top in the ingot, which is a great advantage from a view of a material yield. Solar cells based on this polycrystalline Si show high energy conversion efficiencies closing to that of Si single crystal solar cells. Importantly, this growth technique is applicable to the industrial casting method, and our technique has attracted much attention both from the industrial and the scientific fields because it is promising to contribute to the global spreading of low-energy-cost solar cells in the near future. Results of the research have been published in Acta Materialia and Journal of Crystal Growth and reported in a newspaper of “Kagaku Kogyo Nippo” on July 31.
Prof. Nakajima Group (Crystal Physics)
Aug. 2006
  On Aug. 10, 2006, nature published an article on Sendai city in its "regions" section. There followed an article in its "spotlight" section describing the premier presence of Tohoku University. In chaper 3 of this article, IMR is introduced as the No. 1 COE in materials research and the policy of "industrial relevance" initiated by Dr. Kotaro Honda is highlighted. They also interviewed Director Akihisa Inoue and Prof. Masashi Kawasaki.
Jul. 2006
 Laboratory of Low Temperature Materials Science (Center for Low Temperature Science) has found that pure single crystalline silicon become ‘soft’ at very low temperatures in collaboration with Niigata University, Fujitsu Ltd and Kyushu University. This softening is measured by an ultrasonic method and can be explained in terms of the interaction between atomic vacancies and ultrasound. Ultrasonic measurement has found to be a hopeful probe for evaluating the vacancy concentration in defect-controlled-wafers in large diameter. Results of the research have been published in the meetings of the Phy. Soc. Jpn. (Matsuyama), Jpn., Soc. Appl. Phy. (Setagaya) and E-MRS 2006 (Nice). JPSJ has published a part of the results as an article (vol.75, 044602, ‘06). Comments and information in English are found in JPSJ On-line (COMMENTS AND NEWS, Apr. 10, ’06) and EE-Times On-line (Mar. 27, ’06, ID=183701148).
Jun. 2006
  Mass production prospects are clarified both for the high output torque and long life durable microgeared motors with a diameter of 2.4 mm and the miniaturized pressure sensors with high sensitivity. For the development of microgeared motors, IMR collaborated with YKK corporation and Namiki Precision Jewel Co. Ltd. IMR collaborated with YKK corporation and Naganokeiki Co. Ltd., for the pressure sensors. These achievements were reported in several newspapers and were broadcasted in TV news(June 6, 2006). By these outstanding contribution, Prof. Inoue (director of IMR,), Mr. Wakana (Namiki Precision Jewel) and Mr. Nagasaka (Naganokeiki) win the prime minister prize at the“5th Industry-Academia-Government collaboration summit”.
Prof. Inoue group(Non-equilibrium materials)
May. 2006
  The prototype of a medical wire made of newly developed biomedical titanium alloy, Ti-29Nb-13Ta-4.6Zr, was made toward practical use. Since this alloy consisting of only allergic- and toxic-free elements has low elastic modulus and good mechanical properties, it has been expected to be utilized for medical applications. This result was obtained as one of the activities of Titanomix Workshop, which was established in order to encourage the industry in Higashi Mikawa, Aichi pref., and was reported in a newspaper, Higashi Aichi Shinbun on May 8, 2006.
Apr. 2006
  An anomalous softening of a special phonon mode in high-Tc superconductors is discovered by using both neutron and X-ray scattering techniques. Particularly, the recent neutron scattering experiment clearly observed a giant phonon softening. This discovery will clarify the role of electron-phonon coupling for the mechanism of high-Tc superconductivity. The result is published in Nature April 27 in 2006. (The results of X-ray scattering was already published in Physical Review B in 2005).
Mar. 2006
  Two allergy- and toxic-free products, a mouthpiece for trumpet and a wire for medical applications, were developed. These products are made of pure titanium or a new titanium-based alloy consisting of only allergy- and toxic-free elements. For the development of the mouthpiece, IMR collaborated with Yamaha Corp. and Suzuhiro Metal Industry Co., Ltd. This result was reported in some newspapers, Chunichi shimbun on Mar. 18, Mikawa shimpo on Mar. 21 and Aisan jihou on Mar. 21. Also, IMR collaborated with Showa Ika Kohgyo Co., Ltd., for the wire development, and this result was reported in a newspaper, Tonich News on Mar. 30.
Mar. 2006
  Hund found his empirical rule in 1925 as “Minimum energy state in atoms and molecules with the same electron configuration defined by total orbital and spin angular momentum exhibits the maximum spin multiplicity”. Immediately after that quantum theoretical studies have been conducted and Slater explained this rule in 1929 by a perturbative approach based on the electron exchange energy. In most of the popular textbooks today still use this traditional explanation. However, Slater’s explanation has been doubted theoretically by Davidson, Boyd, and other researchers by using Hartree-Fock level and better approximations.   We have solved the many-body Shroedinger equation exactly with diffusion quantum Monte Carlo method (DQMC) and finally confirmed that the traditional Slater’s explanation is invalid. The exact reason of the Hund’s multiplicity rule is that the energy gain for maximum spin state is realized mainly by the electron-nucleus attractive interaction. Based on the virial theorem (2T+V=0), kinetic energy and repulsive interactions between electrons are increased for the state.   The first paper published in 2004 in Journal of Chemical Physics on the ground state in carbon atom by Hongo and Yasuhara has attracted strong attention. Recent results on the first and second period by Oyamada et al. published in the same journal proved that our conclusion is correct for all the atom species in these rows.