Back to Search
Start Over
A Modified Oxidative Refinement Process for Removing Boron from Molten Silicon Under Enhanced Electromagnetic Force
- Source :
- Journal of Nanoscience and Nanotechnology. 15:8547-8552
- Publication Year :
- 2015
- Publisher :
- American Scientific Publishers, 2015.
-
Abstract
- The removal of boron is one of the main challenges in the purification of metallurgical grade silicon destined for low-cost photovoltaic applications. However, boron is very difficult to remove in its elemental form due to its large segregation coefficient in silicon and its low vapor pressure. The removal of boron by slag treatment is today regarded as a highly promising method, but its refining efficiency is relatively low. Also, the reduction of boron by plasma treatment exhibits a high refining efficiency, but the processing cost is high due to the large amount of electricity consumed by the process. In this regard, the use of an oxidizing reactive gas in the refinement process offers some advantages both in terms of low energy consumption and promising refinement rates. Boron can be extracted in various gaseous forms as B(x)O(y) and/or B(x)H(z)O(y) phases, but the vapor pressure of B(x)H(z)O(y) is much greater than that of the other specie at a temperature of 1700 K. The present study reports a modified oxidative refining method designed to enhance the vaporization of boron as B(x)H(z)O(y) by blowing gaseous water onto the silicon melt in a segmented crucible to enhance the electromagnetic force, whereby the processing cost can be dramatically reduced due to the use of a reusable quartz crucible in a graphite crucible. An initial boron content of 13 ppm in the metallurgical grade silicon was significantly decreased to 0.3 ppm by the employment of 1.7SLM Ar + 100 ml/h H2O. Also, a mechanism capable of reducing boron based on thermodynamic considerations is proposed.
- Subjects :
- Materials science
Silicon
Vapor pressure
Metallurgy
Biomedical Engineering
Crucible
Slag
chemistry.chemical_element
Bioengineering
General Chemistry
Condensed Matter Physics
Chemical engineering
chemistry
visual_art
Vaporization
Oxidizing agent
visual_art.visual_art_medium
General Materials Science
Boron
Refining (metallurgy)
Subjects
Details
- ISSN :
- 15334899 and 15334880
- Volume :
- 15
- Database :
- OpenAIRE
- Journal :
- Journal of Nanoscience and Nanotechnology
- Accession number :
- edsair.doi.dedup.....828662f320cb5b9e7d6323ee2a3d1600
- Full Text :
- https://doi.org/10.1166/jnn.2015.11471