Diamond anvil cell technique

The melting temperature of a-Si3N4 up to a pressure of 37 GPa was determined by diamond-anvil cell technique [122]. The melting temperature varied from 2200 75 K at 3.5 GPa to 3600 200 K at 37 GPa. The authors did not refer to a phase transition a-Si3N4/c-Si3N4. 

Weingartner, H., Klante, D., and Schneider, G.M. (1999) High-pressure liquid-liquid immis-cibility in aqueous solutions of tetra-n-butylammonium bromide studied by a diamond anvil cell technique, J. Solut. Chem., in press. 

A new technique for the identification of components of polymer laminates is the diamond anvil cell technique supplied by Perkin Elmer [29]. A laminate is separated by cutting a small portion of the sample with a razor blade. The layers are then separated by sectioning each piece with the blade. All sample preparation is performed under a stereo microscope. The separated layers are then individually placed in the diamond cell and a spectrum is obtained. This work was performed using a Perkin Elmer model 1650 instrument (a DTGS detector) at 8 cm resolution and 16 scans. Figure 3.7 shows spectra identifying the components of a three-layer polymer laminate. 

A technique for the identification of components or polymer laminates is the diamond anvil cell technique supplied by Perkin Elmer [59]. A laminate is separated by cutting... 

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. 

A. P. Jephcoat, H. K. Mao, and P. M. Bell, Operation of the megabar diamond anvil cell, in Hydrothermal Experimental Techniques, G. C. Ulmer and H. E. Barnes, eds., Wiley-lnter-science, New York, 1978, p. 469. 

For diamond anvil cells, heating comes in two distinctive forms, resistive and laser, with the former being more convenient although the upper temperature is considerably less than that obtainable with lasers. Both techniques were pioneered by W.A. Bassett and his coworkers [196, 197]. Two recent reviews [198, 199] provide an excellent introduction to HP-HT methods. 

Meanwhile, the diamond anvil cell (DAC) has become the dominant device in high-pressure research. Although optical studies build up a big part of research performed with DACs, nearly every method used to study physical properties of matter has been successfully employed also in high-pressure DACs. Examples are electrical measurements (Gonzalez et al., 1986), X-ray diffraction (Hazen and Finger, 1982 Holzapfel, 1989), X-ray absorption (Tolentino et al., 1990), Mossbauer spectroscopy (Lubbers et al., 2000), neutron scattering (Vettier, 1989), resonance techniques (Sakai and Pifer, 1985). 

The simplest technique is EDX, because no optical setup is needed. The drawback of this technique is that, due to preferential orientations and to the insufficient number of diffracting grains in the beam when working in a diamond anvil cell, the intensity of the diffracted peaks is not reliable, and cannot be used to determine the atomic positions in the unit cell. On the contrary, in ADX, even with preferential orientations and with poor grain statistics, by integrating a whole ring of diffraction corresponding to the same 0, the atomic positions may be deduced. 

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. ... 

Since the 1990s the combination of diamond anvil cell (DAC) techniques with imaging plate detectors has turned the investigation of compressibility and... 

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