Diamond anvil cell laser heating

A short review on the development of laser heating in special applications under pressure has been published by Bassett (2001). A heating system to be used, with either ruby or YAG laser, under pressure in a diamond anvil cell has been described. Graphite to diamond and several silicate phase transformations have been studied. 

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. 

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. 

Jephcoat, A. P., Besedin, S. P. (1996) Temperature measurement and melting determination in the laser-heated diamond anvil cell. Phil. Trans. Roy. Soc. A, 354, 133-60. 

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). 

Experiments have established that there are four polymorphs in solid iron (a-, y-, S-, and s-phases). Saxena et al (1993) proposed a fifth iron phase (/3-phase) based on changes in thermal emission while laser heating the sample in a diamond-anvil cell. Boehler (1993) also observed similar changes in optical properties of iron in the same P-T range. Subsequent in situ X-ray diffraction measurements in the laser-heated diamond-anvil cell supported the occurrence of this new iron phase, although the structure of this phase is still under debate (Saxena et al, 1996 Yoo et al, 1996 Andrault et al, 1997, 2000 Saxena and Dubrovinsky, 2000). However, this phase was not observed in... 

The eutectic temperamre of the Fe-S binary system has been measured in a multi-anvil apparatus to 25 GPa (Fei et al, 1997, 2000 Li et al, 2001), and in a laser-heated diamond-anvil cell to 62 GPa (Boehler, 1996). Within the common pressure range, the diamond-anvil cell results are higher than the multi-anvil apparams results by as much as 400°. Despite the discrepancies, the existing data show that between... 

Shock-compressed carbon dioxide exhibits a strong slope change in the Hugoniot (recall Fig. 1), a clear indication of chemical reaction, at around 40 GPa and estimated temperature of 4500 K [1]. The previous theoretical calculation has confirmed that it is indeed due to chemical dissociation of carbon dioxide to elementary products such as diamond and oxygen. In recent diamond-anvil cell experiments [74], the similar dissociative products, lonstaleite diamond and oxygen have also been observed from the quenched products after laser-heating of CO2 samples at 67 GPa. The transition temperatures were estimated to be about 2500 K at 35 GPa, substantially lower than the estimated shock transition temperature 4500 K. 

Technique of C02-Laser Heating in a Diamond Anvil Cell... 

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