Entity

Time filter

Source Type


Yasuda K.,University of Tokyo | Yasuda K.,Osaka Titanium Technologies Co. | Saegusa K.,Sumitomo Chemical | Okabe T.H.,University of Tokyo
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2011

To develop a new production process for solar-grade Si, a fundamental study on halidothermic reduction based on the subhalide reduction of SiCl4 by Al subchloride reductant was carried out at 1273 K (1000 °C). Aluminum subchloride reductant was produced by reacting AlCl3 vapor with metallic Al. Silicon tetrachloride was reduced to Si in a gas-phase reaction by vapors of Al subchloride reductant. Silicon deposits produced in the halidothermic reduction were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray fluorescence (XRF). The Al content in the Si deposits was no more than 0.5 at pct. The Si deposits have a fibrous or hexagonal columnar morphology with diameters ranging from 100 nm to several tens of microns. The reaction was discussed by comparison with the results of the conventional aluminothermic reduction of SiCl4. Moreover, the halidothermic reduction reactions were analyzed from thermodynamical viewpoints. This study demonstrates the feasibility of a halidothermic reduction for producing solar-grade Si with high productivity. © 2010 The minerals, metals & materials society and ASM international. Source


Yasuda K.,University of Tokyo | Yasuda K.,Osaka Titanium Technologies Co. | Okabe T.H.,University of Tokyo
Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals | Year: 2010

High purity silicon used for photovoltaic application, namely solar grade silicon (SOG-Si), has been commercially supplied mainly from the off-grade high purity silicon manufactured by the Siemens process. However, recent and rapid growth in solar cell production induces a serious shortage of SOG-Si. With an aim of resolving low productivity of the Siemens process, various types of SOG-Si production/purification processes have been invented as a post-Siemens process. Some processes are currently under development aiming at establishment of commercial process. These processes can be classified into the following three technologies: (1) decomposition and/or hydrogen reduction of silane gases by improving the current commercial Siemens-based processes, (2) metallothermic reduction of silicon halide compounds by zinc or aluminum, and (3) upgrading metallurgical-grade silicon by employing metallurgical purification methods. This paper reviews the features of the SOG-Si production processes, particularly the processes based on the metallothermic reduction. These metallothermic reduction processes are classified from the viewpoint of the reductant types and silicon com-pounds. The future prospect for the development of new high purity silicon production process is presented. © 2010 The Japan Institute of Metals. Source


Yasuda K.,University of Tokyo | Yasuda K.,Osaka Titanium Technologies Co. | Okabe T.H.,University of Tokyo
JOM | Year: 2010

Various types of processes for solargrade silicon (SOG-Si) production/purification have been developed with the aim of overcoming the low productivity of the Siemens process. These processes can be divided into three groups: decomposition and/or hydrogen reduction of silane gases by improving the currently used commercial processes; purification of metallurgical-grade silicon using metallurgical purification methods; and metallothermic reduction of silicon halides by metal reductants such as zinc and aluminum. This paper reviews the features of various SOG-Si production processes, particularly the processes based on metallothermic reduction, by classifying them according to the types of reductants and the silicon compounds used. Prospects for development of new processes for producing high-purity silicon are presented. © 2010 TMS. Source


Patent
Osaka Titanium Technologies Co. | Date: 2010-06-17

A silicon oxide in the form of powder is represented by SiO


A negative electrode material powder for a lithium ion secondary battery having a conductive carbon film on the surface of a lower-silicon-oxide powder; wherein a specific surface area in BET measurement ranges from more than 0.3 m Accordingly, said powder can be used in the secondary battery with a large discharge capacity and a preferable cycle characteristics for practical use.

Discover hidden collaborations