Thermodynamics of phosphorus in molten Si and Si based alloys

Takahiro Miki, Shigeru Ueda, Kazuki Morita, Nobuo Sano

Research output: Contribution to conferencePaperpeer-review


In order to use metallurgical grade silicon (MG-Si) as a starting material for solar cell, phosphorus has to be removed from silicon because phosphorus is a n-type dopant. On the other hand, silicon, ferrosilicon, and silicomanganese are widely used as deoxidizers in steel refining processes. Since most of the phosphorus introduced during the deoxidation process is brought into final products, it is important to lower the phosphorus content of these alloys. Hence, thermodynamics of phosphorus in such metals is important for the evaluation of dephosphorization processes. In the present study, thermodynamic properties of phosphorus in molten Si-P alloys at 1723-1848 K and those of Si-Fe-P and Si-Mn-P alloys at 1723 K have been determined by equilibrating respective metals in a controlled phosphorus partial pressure. The results are expressed as follows. 1/2 P2(g) = P(X, in SI) ΔG° = -139,000+82.5T(J/mol) εPFe = 7.43, ρPFe = -16.4 (XFe<0.65) εPMn = 12.0, ρPMn = -22.2 (XMn<0.5). Further discussion has revealed that the Si-Fe-P and Si-Mn-P systems approximately conform to a regular solution within the composition range investigated in the present work.

Original languageEnglish
Number of pages10
Publication statusPublished - 1998 Jan 1
Externally publishedYes
EventProceedings of the 1998 TMS Annual Meeting - San Antonio, TX, USA
Duration: 1998 Feb 161998 Feb 19


OtherProceedings of the 1998 TMS Annual Meeting
CitySan Antonio, TX, USA

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys


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