National Institute of Advanced Industrial Science and Technology

About: National Institute of Advanced Industrial Science and Technology is a government organization based out in Tsukuba, Ibaraki, Japan. It is known for research contribution in the topics: Catalysis & Thin film. The organization has 22114 authors who have published 65856 publications receiving 1669827 citations. The organization is also known as: Sangyō Gijutsu Sōgō Kenkyū-sho.

Giant tunnel magnetoresistance in magnetic tunnel junctions with a crystalline MgO(0 0 1) barrier

Abstract: A magnetic tunnel junction (MTJ), which consists of a thin insulating layer (a tunnel barrier) sandwiched between two ferromagnetic electrode layers, exhibits tunnel magnetoresistance (TMR) due to spin-dependent electron tunnelling. Since the 1995 discovery of room-temperature TMR, MTJs with an amorphous aluminium oxide (Al–O) tunnel barrier have been studied extensively. Al–O-based MTJs exhibit magnetoresistance (MR) ratios up to about 70% at room temperature (RT) and are currently used in magnetoresistive random access memory (MRAM) and the read heads of hard disk drives. MTJs with MR ratios significantly higher than 70% at RT, however, are needed for next-generation spintronic devices. In 2001 first-principle theories predicted that the MR ratios of epitaxial Fe/MgO/Fe MTJs with a crystalline MgO(0 0 1) barrier would be over 1000% because of the coherent tunnelling of fully spin-polarized Δ1 electrons. In 2004 MR ratios of about 200% were obtained in MTJs with a single-crystal MgO(0 0 1) barrier or a textured MgO(0 0 1) barrier. CoFeB/MgO/CoFeB MTJs for practical applications were also developed and found to have MR ratios up to 500% at RT. MgO-based MTJs are of great importance not only for device applications but also for clarifying the physics of spin-dependent tunnelling. In this article we introduce recent studies on physics and applications of the giant TMR in MgO-based MTJs.

Efficiencies of Electron Injection from Excited N3 Dye into Nanocrystalline Semiconductor (ZrO2, TiO2, ZnO, Nb2O5, SnO2, In2O3) Films

Abstract: The efficiency of electron injection from excited N3 dye (cis-bis-(4,4‘-dicarboxy-2,2‘-bipyridine) dithiocyanato ruthenium(II), Ru(dcbpy)2 (NCS)2), into various nanocrystalline semiconductor (ZrO2, TiO2, ZnO, Nb2O5, SnO2, In2O3) films was studied by transient absorption spectroscopy. For TiO2, ZnO, Nb2O5, SnO2, or In2O3 films, injection efficiencies were found to be very high; for ZrO2 film, the efficiency was very low. These findings indicate that electron injection occurs efficiently if the LUMO level of N3 dye is located sufficiently far above the bottom of the conduction band of the semiconductor film. On the basis of the results, we discuss the reason TiO2 exhibits higher solar cell performance than other materials.

Metal–organic frameworks as a platform for clean energy applications

Abstract: Metal–organic frameworks (MOFs), an emerging class of porous materials, have shown intriguing and promising properties in a wide range of applications due to their versatile structures, large surface areas, tunable porosity and tailorable chemistry. In recent years one of the most active research fields is to explore energy applications of MOF-based materials. In this review, we present a critical overview on the recent progress of the use of MOF-based materials for gaseous fuel storage, chemical hydrogen storage, solar and electrochemical energy storage and conversion. The challenges and opportunities towards advanced energy technologies with the MOF-based materials are discussed.

Ultraviolet Emission From a Diamond Pn Junction

Abstract: We report the realization of an ultraviolet light–emitting diode with the use of a diamond pn junction. The pn junction was formed from a boron-doped p-type diamond layer and phosphorus-doped n-type diamond layer grown epitaxially on the {111} surface of single crystalline diamond. The pn junction exhibited good diode characteristics, and at forward bias of about 20 volts strong ultraviolet light emission at 235 nanometers was observed and was attributed to free exciton recombination.

Efficient Decomposition of Environmentally Persistent Perfluorocarboxylic Acids by Use of Persulfate as a Photochemical Oxidant

Abstract: Photochemical decomposition of persistent perfluorocarboxylic acids (PFCAs) in water by use of persulfate ion (S2O82-) was examined to develop a technique to neutralize stationary sources of PFCAs. Photolysis of S2O82- produced highly oxidative sulfate radical anions (SO4•-), which efficiently decomposed perfluorooctanoic acid (PFOA) and other PFCAs bearing C4−C8 perfluoroalkyl groups. The major products were F- and CO2; also, small amounts of PFCAs with shorter than initial chain lengths were detected in the reaction solution. PFOA at a concentration of 1.35 mM (typical of that in untreated wastewater after an emulsifying process in fluoropolymer manufacture) was completely decomposed by a photochemical system with 50 mM S2O82- and 4 h of irradiation from a 200-W xenon−mercury lamp. The initial PFOA decomposition rate was 11 times higher than with photolysis alone. All sulfur-containing species in the reaction solution were eventually transformed to sulfate ions by this method. This method was successful...