(a) Photo of the polishing tool used to prepare CZ anvils: (i) protruding brilliant-cut gem anvil, (ii) clamping plate, (iii) height adjustment screw, and (iv) buffer-polishing plate. (b) Schematic of the tool in cross-section. Clamping and buffer-polishing plates are each fixed in place by three cirumferential screws. Diameter and height of the polishing tool are 30 and 15 mm, respectively.
Polishing sequence to obtain final polished CZ gem anvil. (a) and (b) are the removal of sharp tip by polishing on a SiC abrading mat (P4000 grade); (c) and (d) are results of polishing on a soft mat impregnated with diamond powder spray to attain rounded culet edges. Darker shaded areas (in reflected light) at the perimeters are indicative of the curvature. Results of polishing on diamond grit impregnated polymer mat shown in (e) to obtain flattest possible truncated tip; (f) is further flattening and then viewed with an inverted microscope. Panel (g) is final quality-control test of anvil in (f)—the appearance of a symmetric pattern of Newton’s rings as viewed through the table of the anvil in contact with a glass slide. Panel (h) shows typical picture of Newton’s ring pattern indicative of two well aligned anvils in a pressure cell with a thin glass slide sandwiched between them. Culet dimension in panels (e)–(h) is diameter.
Raman spectra taken in the gem anvil cell from the strong scatterer anatase , which completely dominates any background signal from the CZ anvil. Arrows and dashed lines serve to indicate regimes in which there are structural transitions. Inset shows example of ruby fluorescence spectra taken at some of the highest pressures attained in one of the runs.
Raman spectra of a weak scatterer, monoclinic ceramic, taken at in situ pressures in the GAC. The spectrum at ambient conditions is recorded outside of the GAC. Contaminating background contributions from the CZ anvils obscure some of the signatures of the sample, but various Raman bands from the sample are readily discerned. Inset shows the Raman spectrum of a CZ anvil.
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