TY - JOUR
T1 - Nitridation of silicon powder studied by XRD, 29Si MAS NMR and surface analysis techniques
AU - MacKenzie, K. J.D.
AU - Sheppard, C. M.
AU - Okada, K.
AU - Kameshima, Y.
N1 - Funding Information:
K.J.D.M is indebted to the Royal Society of New Zealand for a James Cook Research Fellowship under which part of this work was carried out. We are also indebted to R. H. Meinhold for useful discussion on the Si NMR shifts.
PY - 1999/12
Y1 - 1999/12
N2 - The nitridation of elemental silicon powder at 900-1475 °C was studied by X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), XRD, thermal analysis and 29Si MAS NMR. An initial mass gain of about 12% at 1250-1300 °C corresponds to the formation of a product layer about 0·2 μm thick (assuming spherical particles). XPS and XAES show that in this temperature range, the surface atomic ratio of N/Si increases and the ratio O/Si decreases as the surface layer is converted to Si2N2O. XRD shows that above 1300 °C the Si is rapidly converted to a mixture of α- and β-Si3N4, the latter predominating >1400 °C. In this temperature range there are only slight changes in the composition of the surface material, which at the higher temperatures regains a small amount of an oxidised surface layer. By contrast, in the interval 1400-1475 °C, the 29Si MAS NMR chemical shift of the elemental Si changes progressively from about -80 ppm to -70 ppm, in tandem with the growth of the Si3N4 resonance at about -48 ppm. Possible reasons for this previously unreported change in the Si chemical shift are discussed.
AB - The nitridation of elemental silicon powder at 900-1475 °C was studied by X-ray photoelectron spectroscopy (XPS), X-ray excited Auger electron spectroscopy (XAES), XRD, thermal analysis and 29Si MAS NMR. An initial mass gain of about 12% at 1250-1300 °C corresponds to the formation of a product layer about 0·2 μm thick (assuming spherical particles). XPS and XAES show that in this temperature range, the surface atomic ratio of N/Si increases and the ratio O/Si decreases as the surface layer is converted to Si2N2O. XRD shows that above 1300 °C the Si is rapidly converted to a mixture of α- and β-Si3N4, the latter predominating >1400 °C. In this temperature range there are only slight changes in the composition of the surface material, which at the higher temperatures regains a small amount of an oxidised surface layer. By contrast, in the interval 1400-1475 °C, the 29Si MAS NMR chemical shift of the elemental Si changes progressively from about -80 ppm to -70 ppm, in tandem with the growth of the Si3N4 resonance at about -48 ppm. Possible reasons for this previously unreported change in the Si chemical shift are discussed.
KW - Nitridation
KW - SiN
KW - Silicon.
KW - X-ray methods
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U2 - 10.1016/S0955-2219(99)00057-6
DO - 10.1016/S0955-2219(99)00057-6
M3 - Article
AN - SCOPUS:0033328989
VL - 19
SP - 2731
EP - 2737
JO - Journal of the European Ceramic Society
JF - Journal of the European Ceramic Society
SN - 0955-2219
IS - 16
ER -