Ultrahigh pressure anvils

Ultrahigh pressure anvils Photovoltaic devices Windows for spacecraft... 

Okamoto K. and Maruyama S. (1998) Multi-anvil reequilibration experiments of a Dabie Shan ultrahigh pressure eclogite within the diamond-stabihty fields. The Island Arc 7, 52-69. 

The anvil seats transmit a force to the anvil tables of the order of 10 kN. Thus the seats are subjected to a normal stress of some 2 GPa, for a 3 mm diameter table. This value may well be exceeded for ultrahigh-pressure work. Thus seats are most often made of tungsten carbide with an optical finish. In some X-ray measurements, beryllium seats have to be used, for their transparency. The mechanical performance is then drastically decreased, and the beryllium must be machined in specialized workshops. Single-crystal sapphire has been used, to provide an increased optical aperture. ... 

A most serious problem in the ultrahigh-pressure range is that of pressure homogeneity. Figure 1.36 shows the pressure gradient in a solid medium between the anvils it is representative of the pressure gradients in an actual DAC experiment—the pressure variation in the central part of a 100 GPa cell may be as large as 1 GPa j,m ... 

T. Mitsui, et al., Development of an energy-domain Fe Mossbauer spectrometer using synchrotron radiation and its application to ultrahigh-pressure studies with a diamond anvil cell.J. Synchrotron Radiat 2009, 16(6), 723-729. 

A study of RDX behaviour under static ultrahigh pressure (up to 65 GPa), generated by using diamond anvil cells (DACs) using FT-IR spectroscopy and UV-VIS absorption spectroscopy, is a topic of paper [61]. RDX changed its colour into dark red when compressed up to 20 GPa with caesium iodide (Csl), filled as a pressure medium. In this case the intensities of characteristics of IR absorption peaks of RDX decreased as the pressure increased, and did not return to the intensities measured at ambient pressure, after the pressure was unloaded. However, when RDX was compressed alone, its colour changed into yellow at a pressure above 60 GPa. In its UV-VIS absorption spectra the peak shifted from 243.5 nm at ambient pressure to 410 nm at 65.5 GPa. The authors assume that the HOMO-LUMO band gap of this nitramine decreases with increasing pressure [61] which is in line with the opinion of Kuklja and Kunz [59]. 

Piermarini, G. J. Block, S. (1975), "Ultrahigh pressure diamond-anvil cell and several semiconductor phase transition pressures in relation to the fixed point pressure scale". Rev. Sci. Instrum. 46, 973-979. 

---