Diamond anvil cell characteristics

The cubic SrSi2 structure shows no characteristic axial ratio from which a change in the pyramidal group of Si atoms can be deduced. For BaSi2-III in diamond anvil cell experiments up to 420 kbar, only the decreases in both the cubic lattice parameters and the specific volumes VIVo are apparent (Table... 

Shen Y, Kumar RS, Pravica M, Nicol ME (2004) Characteristics of silicone fluid as a pressure transmitting medium in diamond anvil cells. Rev Sci Instr 75 4450... 

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]. 

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