Application

The Gem Anvil Cell: high-pressure behaviour of diamond and related materials (Ji-An Xu, Ho-Kwang Mao and Russel J. Hemley, J. Phys.: Condens. Matter 14, 11549 (2002))

The moissanite anvil cell has been used to study the high-pressure behaviour of diamond. The first-order Raman shift of diamond shows a strong dependence on hydrostaticity, with very different pressure dependences observed under hydrostatic and non-hydrostatic conditions. The shift of the second-order Raman band under hydrostatic pressures was determined for the first time. Sapphire has almost no peaks above 1000 cm−1 in the Raman spectrum and no absorption in the ultraviolet range; it is therefore especially useful for studies in those spectral regions. A sapphire anvil cell was used in a study of graphite up to 24 GPa. A phase transition was found near 18 GPa, consistent with previous reports, and no peaks characteristic of diamond in the 1330 cm−1 range were found, indicating that the phase is not diamond.

FTIR Spectra of faceted diamonds and diamond simulants (Pimthing Thongnopkun, Sanong Ekgasit, Diamond and Related Materials 14, 1592 (2005))

FTIR spectra of faceted diamonds and diamond simulants collected by diffuse reflectance, transflectance, and specular reflection techniques were compared. The transflectance technique exploited total internal reflection phenomenon within the faceted diamond for the spectral acquisition. The transflectance spectra were similar to the well-accepted diffuse reflectance spectra with equal or better spectral qualities. Based on the observed spectral features of the faceted diamond, classification of the diamond, determination of defects, impurities, and treatment process (i.e., irradiation and high pressure and high temperature) can be performed.