Ultra-high residual compressive stress (>2 GPa) in a very small volume (<1  m3) of indented quartz

Abstract

Indentation testing of natural single-crystal α-quartz parallel to the crystallographic c axis, using a triangular pyramidal diamond indenter at a maximum load of 500 mN, produced a very small residual volume of less than 1 µm 3 in which α-quartz is highly stressed. Laser Raman microspectroscopy across the indentation at room temperature and pressure revealed a shift in the Raman bands, interpreted to reflect the residual stress field generated within the α-quartz. Based on the observed Raman shift, we identified a steep gradient in the residual non-hydrostatic stress field after complete unloading in quartz near the impression formed by indentation. At the center of the indentation, the maximum compressive stress and tensile stress were inferred to be higher than 2.2 and 0.1 GPa, respectively.

Amorphization of quartz by friction: Implication to silica‐gel lubrication of fault surfaces

“…[12] Blue shifts of the Raman bands and appearance of new peaks on the higher wavenumber side have been reported for solid-state amorphization of quartz in ultra-high pressure experiments using diamond anvil cells [Schmidt and Ziemann, 2000], and indentation hardness tests [Masuda et al, 2011]. In the present experiments, the apparent stresses s h and s r at the pin-and-disk contacts are around 10 MPa (Table 1); however, if we assume that the real contact areas were restricted within the colored areas in Figure 4, the real contact stress under a normal load of 1 N is estimated to be 5 GPa, which well exceeds the quartz-coesite transition pressure of 1.8 GPa at room temperature.…”

Correlation between Structure and Mechanical Properties in Α-Quartz Single Crystal by Nanoindentation, Afm and Confocal Raman Microscopy

“…Therefore, the phenomena occurred in quartz at high pressures are not well understood and there is very little work in the literature that correlates structural changes produced by high-pressure stress with the mechanical properties. Masuda et al measured the Raman shift produced in quartz after a nanoindentation, however, they do not correlate this Raman measurements with the mechanical properties obtained by the nanoindentation technique [6]. Williams et al studied the structural changes of quartz at high pressures by FTIR and Raman, but they do not performance nanoindentation, so they do not correlate the structural changes with the mechanical properties [12].…”