Raman imaging of stress‐induced phase transformation in transparent ZnSe ceramic and sapphire single crystals

Abstract

It is known that the polishing of a material can cause pressure-induced phase transformation and modify its surface properties. Indentation was used to apply controlled perturbation on optically clear ZnSe ceramics and on a-alumina single-crystal wafers. New Raman bands are observed at the periphery and/or the centre of the indented area. Confocal Raman and Rayleigh imaging of the peak intensity, bandwidth and wavenumber shift show complex transformations of the indented area. Peak intensity can be used to map the surface geometry with approximately micrometre resolution. For ZnSe, the new bands (ca 235 and 248 cm −1 / are assigned to the phases obtained above 5 and 34 GPa under hydrostatic pressure. Comparison is made with zirconia and corundum crystals. Stress-induced modifications are observed on the a-alumina wafer. They seem to be due to an unknown disordered phase rather than to a high remnant stress. The relationship between the Raman parameters and the applied stress is discussed.

Flexural strength, fatigue life, and stress‐induced phase transformation study of Y‐TZP dental ceramic

“…The stresses not only cause crack formation by dislocation gliding, but a complete change of the crystal structure and formation of amorphous phases 19. Raman spectroscopy combined with hardness indentation testing has been used in some studies19–22 in order to examine pressure‐induced phase transformations. One study by Behrens22 examined the t→m transformation of Y‐TZP around and within the indent, which was annealed with different temperatures and loaded with 500 N of Vickers indentation.…”

Response to “Comment on ‘Nanoindentation hardness anisotropy of alumina crystal: a molecular-dynamics study’” [Appl. Phys. Lett. 94, 146101 (2009)]

“…15,16 In summary, our MD simulation of nanoindentation anisotropy of alumina crystal has been validated by firstprinciples DFT calculations where possible, and its findings are likely valid at nanometer indentation depths. However, their generalization to larger indentation depths and different indenter shapes is nontrivial and would require further study.…”

Structural insights of hierarchically engineered feldspars by confocal Raman microscopy

“…Additionally, Raman measurements with temperature allow investigating phenomena such as Al, Si‐O tetrahedral distortions due to Al, Si disorder, phase transitions or alkali/alkaline earth site ordering, and local distortion of Si‐Al‐O network . Using the elastic scattering of light, areas with slight differences in refractive index or density might be discriminated in a sample, as a source of optical contrast, which allows to obtain more information about the chemical composition …”