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Kunming, China

Hu Y.-B.,Sichuan University | Hu Y.-B.,Kunming University of Science and Technology | Hu Y.-B.,Material Research Center | Qiu J.-B.,Kunming University of Science and Technology | And 3 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2010

Up-conversion luminescence properties and energy-transfer processes in Er3+, Yb3+ and Tb3+ single doped or co-doped oxyfluorogermanate glasses were studied under 980 nm laser excitation. Green and red up-conversion emissions around 524, 546 and 658 nm which can be assigned to the Tb3+:5 D4→7FJ (J=5 and 0) and Er3+:(2H11/2, 4S3/2 and 4F9/2)→4I15/2 transitions, respectively, were strongly observed at room temperature. Up-conversion luminescence intensity depended on the YbF3, TbF3 concentration and excitation power density. The energy transfer processes among Er3+, Yb3+ and Tb3+, and up-conversion mechanisms were discussed. Source


Sato T.,Kure Research Laboratory | Bergins C.,Research and Development | Imano S.,Material Research Center
Hitachi Review | Year: 2011

OVERVIEW: The development of technologies for improving the efficiency of coal-fired power generation is critical to alleviating the problem of global warming. Hitachi has supplied a large number of coal-fired power plants that have featured world-leading levels of efficiency. In recent years, it has also embarked on the development of technology for 700°C-class A-USC power generation to achieve even higher efficiency. These developments are being accelerated through a global research and development infrastructure that includes not only Japan but also active involvement by Europe. Source


Salimian S.,Kharazmi University | Azim Araghi M.E.,Kharazmi University | Golikand A.N.,Material Research Center
Journal of Physics and Chemistry of Solids | Year: 2016

So far, little is known about the experimental potential of graphene nanoribbon-carbon nanotube (GNR-CNT) heterostructure as a semiconductor nanocomposite. The present work examined the structural features, topography and electronic properties of GNR-CNT nanocomposite by using Raman spectroscopy, transmission electron microscopy, scanning tunneling microscopy and spectroscopy (STS). The homogenous semiconductor GNR-CNT nanocomposites were produced under optimized synthesis conditions. The narrow band gap was exhibited by optimization of the reduction step. The STS of the micro-scale surface of the nanocomposite shows local density of state in selected areas that represent the 0.08 eV band gap of a homogenous nanocomposite. The potential of the semiconductor nanocomposite was considered for application in stacked graphene nanoribbon-field effect transistors (SGNR-FETs). A simple method of device fabrication is proposed based on a semiconductor stacked GNR nanocomposite. The high hole mobility and rectifying effect of the p-n junction of the SGNR nanocomposite on TiO2 are demonstrated. The optimal thickness for the back gate TiO2 dielectric for the tested devices was 40 nm. This thickness decreased leakage current at the p-n junction of the SGNR/TiO2 interface, which is promising heterojunction for optoelectronics. The thickness of gate dielectric and quantum capacitance of the gate was investigated at the low 40 nm thickness by calculating the mobility. In the proposed SGNR-FET, holes dominate electrical transport with a high mobility of about 1030 cm2/V s. © 2016 Elsevier Ltd. All rights reserved. Source


Tachi T.,Infrastructure Systems Company | Tadokoro H.,Infrastructure Systems Company | Kurisu H.,Infrastructure Systems Company | Takahashi S.,Yokohama Research Laboratory | Yokoi H.,Material Research Center
Hitachi Review | Year: 2013

OVERVIEW: Fresh water suitable for drinking and other uses in daily life is unevenly distributed across the planet, estimated to make only about 0.01% of the Earth's total water. Water shortages are becoming more severe around the world as populations increase and become more urban. In Japan, meanwhile, the aging of water and sewage infrastructure and the dwindling numbers of technical personnel have become pressing issues. In response, Hitachi is promoting its intelligent water system concept that seeks to optimize water services at the city or regional level by converging information and control systems with water treatment facilities and other distribution infrastructure to overcome the challenges posed by water infrastructure in Japan and throughout the world. In doing so, it is seeking to consolidate the products it offers in each of the fields that play a role in these services, including business operations, water supply management, flood control, water treatment control, and water treatment equipment. Source


Ahmadvand H.,Isfahan University of Technology | Safdari S.R.,Isfahan University of Technology | Nozad Golikand A.,Material Research Center | Dasgupta P.,Saha Institute of Nuclear Physics | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2015

Nanostructures of Co/CoO/Co3O4 were synthesized by a chemical method at different temperatures between 300 and 600 °C. The samples were characterized by TG, XRD, TEM and SQUID magnetometry. The lower temperature sample (300 °C) is composed of Co, CoO and Co3O4, while the higher temperature sample only contains Co3O4. All the samples exhibit exchange bias effect. The exchange bias is observed below 205 K (below the CoO blocking temperature) for the sample prepared at lower temperature (300 °C), while for other samples (350-600 °C), the effect is observed below 35 K (below the Néel temperature of Co3O4, TN=40 K). The roles of CoO and Co3O4 on the magnetic properties and the mechanisms governing exchange bias effect have been discussed. © 2014 Elsevier B.V. All rights reserved. Source

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