Diamond anvil cell high temperature

Problems occur with diamond anvils at high temperatures. Diamond oxidizes in air at temperatures above 900 K. At temperatures above 1200 K, diamond tends to weld to the gaskets. In practice, such cells are used to 20-30 GPa and 900-1100 K under a vacuum or in a nonoxidizing atmosphere. ... 

Chronister E L and Crowell R A 1991 Time-resolved coherent Raman spectroscopy of low-temperature molecular solids in a high-pressure diamond anvil cell Chem. Phys. Lett. 182 27... 

Several methods are also available for determination of the isothermal compressibility of materials. High pressures and temperatures can for example be obtained through the use of diamond anvil cells in combination with X-ray diffraction techniques [10]. kt is obtained by fitting the unit cell volumes measured as a function of pressure to an equation of state. Very high pressures in excess of 100 GPa can be obtained, but the disadvantage is that the compressed sample volume is small and that both temperature and pressure gradients may be present across the sample. 

Very recently, Solozhenko [540] reported the high-pressure-high-temperature synthesis of cubic BC2N with in situ control of the reaction by x-ray diffraction measurement. The first high-density product has been obtained in a laser-heated diamond anvil cell (DAC). The starting material was g-BC N, prepared... 

W. A. Bassett and M. S. Weathers, Temperature measurement in a laser heated diamond anvil cell, in High-Pressure Research in Mineral Physics, M. H. Manghnani and Y. Syono, eds., American Geophysical Union, Washington, DC, 1987, pp. 129-134. 

R. Boehler, Advances in high temperature research in a diamond anvil cell, in Recent Trends in High Pressure Research. A. K. Singh, ed., Oxford IBH Publishing Co., New Dehli, 1992, pp. 591-600. 

Technology exists to measure spectra at pressures higher than 10 bar using diamond anvil cells. Raman and IR techniques see Vibrational Spectroscopy) are most often brought into play in pressure-dependent spectroscopies. Temperature-dependent spectroscopy at high pressures is also possible. ... 

In a rather complete study Russell et al. (1993) used a specially designed high-temperature/high-pressure diamond anvil cell to determine the phase diagram and stability fields between —125 and 340 °C and atmospheric pressure to 14.0 GPa. They characterized the C phase which exists at room temperature above 0.7 GPa pressure, and obtained FTIR spectra for all five polymorphs in various regions of... 

Ammonium dinitramide and dinitro azetidinium dinitramide For both of these materials the pressure/temperature and reaction phase diagram have been determined using a high-temperature-high-pressure diamond anvil cell with FTIR spectroscopy, Raman spectroscopy and optical microscopy. For ammoninm dinitramide energy dispersive X-ray diffraction was also employed (Russell et al. 1996, 1997). 

The e - y transition boundary was determined by measuring the resistance changes during the transition in a high-compression belt apparatus (Bundy, 1965) and in an internally heated diamond-anvil cell (Boehler, 1986 Mao et al, 1987). The boundary was also determined by in situ X-ray diffraction measurements in an internally heated diamond-anvil cell (Boehler, 1986 Dubrovinsky et al, 1998), in a laser-heated diamond-anvil cell (Shen et al, 1998), and in a multi-anvil apparatus (Funamori et al, 1996 Lfchida et al, 2001). The boundaries determined by Mao et al. (1987), Shen et al (1998), and Lfchida et al (2001) are in good agreement, but are all at —75 K higher temperature (or —2 GPa lower pressure) than the boundary determined by Funamori et al. (1996), Boehler (1986), and Bundy (1965). 

Dubrovinsky L. S., Saxena S. K., and Lazor P. (1998) High-pressure and high-temperature in situ X-ray diffraction study of iron and corundum to 68 GPa using an internally heated diamond anvil cell. Phys. Chem. Mineral. 25, 434—441. 

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