Stress dependence of infrared-active mode of the β-Si₃N₄ ceramic appearing at 1020 cm^-1 measured by micro-FT-IR spectroscopy

The stress dependence of the β-Si₃N₄ infrared-active band appearing at ∼1020 cm^-1 was evaluated by using micro-FT-IR. A four-point-bending jig was built to apply stress to the sample. Two β-Si₃N₄ ceramics, prepared by pressureless sintering and hot-pressed sintering, were examined. The hot-pressed sample showed a linear relation to applied stress, whereas the pressureless sintered sample showed relatively scattered stress dependence due to the inferior signal-to-noise ratio of the spectra. The stress dependence parameter of the 1020 cm^-1 band was evaluated as ∼2 cm^-1/GPa.