Structural and micromechanical analysis of ceramics and glass by Raman microprobe and cathodoluminescence spectroscopy.

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Recent achievements in high spatial resolution characterization of residual stress fields stored near the surface of ceramic and glass materials/devices have been reviewed in this project. Measurements are based on the piezo-spectroscopic effect (i.e., the light wavelength shift occurring due to the presence of a superimposed stress field) observed for selected photoluminescence(PL) and cathodoluminescence(CL) bands of ceramic and glass materials. Nano-scale stress assessments can be performed, independent of the particular mechanism behind the PL/CL emission, by exploiting the superior in-depth resolution of the Raman microprobe device and the high lateral resolution of a field-emission-gun scanning electron microscopes(FEG-SEM) specially designed for low-voltage measurements. Automatic scanning routines have been developed and expanded in order to collect and to process in nearly real time a large number of acquisition data (up to 10^6 data point per □ m^2). This capability is well suited for the nano-scale assessment of residual stresses on the surface of ceramic and glass devices. The micromechanical information achieved by this technique (referred here to as cathodoluminescence piezo-spectroscopy) lies on a significantly smaller scale than that probed by photo-stimulated luminescence and can be regarded as the natural counterpart of chemical elemental mapping routinely operated into conventional SEM devices according to electron-stimulated X-ray emission. Experimental nano-scale mechanical assessments in the FEG-SEM may provide an additional degree of freedom in the microstructural design of novel materials and also the accessibility that is essential for developing new ceramic and glass devices with high efficiency and reliability.