Phase transformations of silicon caused by contact loading

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364340· OSTI ID:526498

Kailer, A; Gogotsi, Y G; Nickel, K G ^[1]

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1. Eberhard-Karls-Universitaet Tuebingen, Angewandte Mineralogie, Wilhelmstrasse 56, D-72074 Tuebingen (Germany)

Combining hardness indentation tests and micro-Raman spectroscopy it is shown that metallic Si-II is produced near the interface of a diamond indenter and silicon to a depth of about 0.5 {mu}m, where the highest stresses (hydrostatic and deviatoric) exist. At fast unloading rates Si-II transforms to the amorphous state, whereas a mixture of the r8 high pressure polymorph Si-XII and the bc8 phase Si-III forms upon a slow load release. The region of Si-III+Si-XII is surrounded by the wurtzite structured Si-IV, where the stresses during the indentation had not been high enough to cause the transition to the metallic state. Thus, because of shear deformation a direct transformation to Si-IV takes place. Outside the phase-transformed regions the classical aspects of indentation-induced deformation by dislocation glide, twinning and crack formation are observed. Annealing of the high pressure phases leads to the formation of Si-IV at moderate temperatures and to the reversal to the original diamond structure (Si-I) at temperatures above 500{degree}C. Using the laser beam of the Raman spectrometer to anneal the samples the phase transitions could be monitored directly. The formation of silicon polymorphs other than amorphous or metallic structures during hardness indentation is, to the best of our knowledge, reported here for the first time. The results compare well with the polymorphism in Si that is known from diamond anvil cell experiments. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 526498
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 7 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AMORPHOUS STATE
ANNEALING
CRACKS
CRYSTAL STRUCTURE
DEFORMATION
DIAMONDS
DISLOCATIONS
HARDNESS
MECHANICAL PROPERTIES
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
PRESSURE DEPENDENCE
RAMAN SPECTRA
SILICON
SLIP
STRESSES
TWINNING
VERY HIGH PRESSURE