APPLICATION OF AN INDENTER-OBJECTIVE FOR OPTICAL SPECTROSCOPY OF THE STRUCTURE AND PROPERTIES OF MATERIALS

Abstract

We considered the possibilities of using indenter-objectives for optical and spectrometric studies of local properties and structure of materials. Due to their special faceting, such indenters allow obtaining a full-fledged optical image of the investigated area of the sample surface during measurements by indentation and scratching methods. The diamond indenter has two centrally symmetric Berkovich pyramids, rotated relative to each other by 60 °, at its opposite ends. These pyramids form three plane-parallel plates, through which a quasi-parallel light beam from the microscope passes, without undergoing total internal reflection, both to the sample and to back. We obtained the presented data via an indenter in the form of a two Berkovich pyramids. We demonstrated the Raman and Mandelstam-Brillouin scattering spectra from the region under the indenter using serial spectrometers. It appears that by combining optical and mechanical research methods, it is possible to obtain detailed information on the phase state of a substance under severe plastic deformation. The proposed approach is applicable to both transparent and opaque materials, since observation occurs through a transparent diamond indenter objective. We discussed the possibility of simultaneous mapping of the optical and mechanical properties of the material under study with the spatial referencing of the obtained data with micron accuracy. We demonstrated detachment of a diamond-like film during indentation, a change in the phase composition of silicon in the region of developed plastic deformation of honey using Raman spectroscopy, the speed of sound in plastic deformed by a diamond indenter was measured by the Mandelstam-Brillouin scattering method. We expect that this approach, which combines optical and mechanical research methods, will be productive in the study of high molecular weight polymeric materials and pharmaceuticals prone to the formation of polycrystalline structures and falling into different conformational states.