Raman Spectroscopy of -Si3N4 and -Ge3
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- 作者：Emmanuel Soignard and Paul F. McMillan
- 刊名：Chemistry of Materials
- 出版年：2004
- 出版时间：September 7, 2004
- 年：2004
- 卷：16
- 期：18
- 页码：3533 - 3542
- 全文大小：198K
- 年卷期：v.16,no.18(September 7, 2004)
- ISSN：1520-5002
文摘
The discovery of dense spinel nitride phases, 
-Si3N4 and -Ge3N4, synthesized under high-pressure-high-temperature conditions has resulted in renewed interest in solid-state nitridematerials chemistry. The new materials are high hardness ceramics, and they represent anew family of wide band gap semiconductors and optoelectronic materials. The compoundshave been characterized by X-ray and electron diffraction and by Raman scattering carriedout both on quenched samples and in situ at high pressure in the diamond anvil cell. Here,we assign the Raman-active modes of -Si3N4 and -Ge3N4 spinels, taking account of impurityphases that can be present within the samples. Laser-heating diamond anvil cell studiescarried out at high pressures and at various temperatures lead to the identification ofadditional Raman features that we assign to the presence of defects, most likely N3-vacancies, within the nitride spinels. The intensity of the "defect" peaks varies systematicallywith the temperature and pressure of synthesis, corresponding to changes in the N2 activityin equilibrium between the solid nitrides and the surrounding N2 fluid. The results pointthe way toward future measurement and control of the defect chemistry achieved withinspinel nitrides prepared under high-pressure-high-temperature conditions.
-Si3N4 and -Ge3N4, synthesized under high-pressure-high-temperature conditions has resulted in renewed interest in solid-state nitridematerials chemistry. The new materials are high hardness ceramics, and they represent anew family of wide band gap semiconductors and optoelectronic materials. The compoundshave been characterized by X-ray and electron diffraction and by Raman scattering carriedout both on quenched samples and in situ at high pressure in the diamond anvil cell. Here,we assign the Raman-active modes of -Si3N4 and -Ge3N4 spinels, taking account of impurityphases that can be present within the samples. Laser-heating diamond anvil cell studiescarried out at high pressures and at various temperatures lead to the identification ofadditional Raman features that we assign to the presence of defects, most likely N3-vacancies, within the nitride spinels. The intensity of the "defect" peaks varies systematicallywith the temperature and pressure of synthesis, corresponding to changes in the N2 activityin equilibrium between the solid nitrides and the surrounding N2 fluid. The results pointthe way toward future measurement and control of the defect chemistry achieved withinspinel nitrides prepared under high-pressure-high-temperature conditions.