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NMR investigation of boron impurities in refined metallurgical grade silicon
Author(s) -
Grafe HansJoachim,
Löser Wolfgang,
Schmitz Steffen,
Sakaliyska Miroslava,
Wurmehl Sabine,
Eisert Stefan,
Reichenbach Birk,
Acker Jörg,
Rietig Anja,
Ducke Jana,
Müller Tim
Publication year - 2015
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201431908
Subject(s) - boron , impurity , materials science , silicon , leaching (pedology) , analytical chemistry (journal) , metallurgy , chemistry , soil water , environmental science , organic chemistry , chromatography , soil science
The nuclear magnetic resonance (NMR) method was applied for tracking boron impurities in the refining process of metallurgical grade (MG) silicon. From the NMR signal of the 11 B isotope at an operating temperature 4.2 K, the boron concentration can be estimated down to the order of 1–10 wppm B. After melting and resolidification of MG‐Si alloyed with Ca and Ti, a major fraction of B impurities remains in the Si solid solution as inferred from the characteristic NMR frequency. The alloying element Ti does not form substantial fractions of TiB 2 . Acid leaching of crushed powders of MG‐Si alloyed with Ca and Ti can diminish the initial impurity content of B suggesting its accumulation in the grain boundary phases. NMR signals of TiB 2 at 4.2 K and room temperature (RT), and of poly‐Si with different B doping at 4.2 K.