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Infrared Study of the Effect of High External Pressures on Crystalline -Silicon Nitride

Volume 46, Number 8 (Aug. 1992) Page 1303-1304

Butler, Ian S.; Huang, Yining


Crystalline silicon nitride (Si3N4) is of considerable interest commercially, e.g., as a passivating layer in the microelectronics industry and in the construction of advanced heat engines. The high-temperature, nitriding processes normally used in the manufacture of this ceramic yield materials in which the ratio of the α- and β-Si3N4 polymorphic, crystalline modifications varies considerably depending on the actual synthetic conditions employed. Almost ten years ago, Luongo showed that IR spectroscopy could readily be used for the rapid, quantitative identification of crystalline α- and β-Si3N4 in the presence of each other, despite the very close structural similarities between the two polymorphic phases. The IR method was based on determining the ratio of the absorbances (I685/I578) of two characteristic marker bands which appear at 685 (α-Si3N4) and 578 cm−1 (β-Si3N4). A graph for determining the relative amounts of the two polymorphic phases in the presence of each other in an unknown sample was published as part of Luongo's paper.