Crystal growth of diamond in the system of carbon and water under very high pressure and temperature

Synthesis of cubic diamond in the graphite-magnesium carbonate and graphite-K2Mg(CO3)2 systems at high pressure of 9–10 GPa region

“…In order to consider further possible mechanism of c-diamond formation in this system, the effect of a volatile component in the reaction system might be taken into account, as in the system graphite-water in which growth of diamond took place. 5 Comparing MgCO 3 with MgO and CaCO 3 , the decomposition temperature at ambient atmosphere of the former is seen to be lower than that of the latter. 23 At high pressure, however, previous research did not show the evidence of free-CO 2 in liquid MgCO 3 above 8 GPa.…”

“…This process seems to be similar to that of reported studies of other graphiteinorganic compound systems. [1][2][3][4][5][6] While each carbonate component in the system of K 2 CO 3 and MgCO 3 exhibited the catalytic effect to form c-diamond above 2000 ± C at the 7.7 GPa region, 1 the binary carbonate system of K 2 Mg(CO 3 ) 2 synthesizes c-diamond above 1650 ± C at the 9 GPa region. Such a reduction of temperature to form c-diamond may be attributed to the reduction of melting temperature due to the peritectic relationship with this binary carbonate system.…”

“…[1][2][3] Following the first discovery, several experimental investigations for the growth and nucleation of synthetic diamond with the inorganic compounds have been reported. [4][5][6] Among the several inorganic compounds identified in these pilot studies, the graphite-carbonate system is particularly interesting, because carbonate minerals are common in the earth. The reported studies for the carbonate-graphite system have been carried out in the pressure range up to 8 GPa at HT near 2150 ± C. 1,3 As mentioned in these papers, the synthesis temperature for diamond in this system is much higher than that for the formation of natural diamond.…”

Carbonate reduction by Fe-S-O melts at high pressure and high temperature

“…The fi rst group has been the most extensively explored, with solvents or catalysts (other than transition metal melts) such as kimberlitic melts (Arima et al 1993), solid or liquid carbonate (Akaishi et al 1990;Taniguchi et al 1996;Pal'yanov et al 1999aPal'yanov et al , 1999bPal'yanov et al , 2002aSato et al 1999;Sokol et al 2000Sokol et al , 2001aSpivak and Litvin 2004;Tomlinson et al 2004), sulfi de melts (Pal'yanov et al 2001;Sato and Katsura 2001), and both oxidized (CO 2 -H 2 O) and reduced (CH 4 -H 2 O) fl uids (Yamaoka et al 1992(Yamaoka et al , 2002a(Yamaoka et al , 2002bKumar et al 2000Kumar et al , 2001Sun et al 2000;Akaishi et al , 2001Sokol et al 2001b;Okada et al 2002;Dobrzhinetskaya et al 2004). To the authors' knowledge, no study has reported oxidation of a reduced, carbon-bearing (e.g., CH 4 -rich) fl uid to produce diamond in the absence of graphite or another source of carbon.…”

Crystal Growth of Diamond

“…Some of them are components in natural rocks, suggesting that natural diamond has grown from these compounds in the deep earth interior. It has been confirmed that diamond forms from H 2 O as well [23]. The growth mechanism of diamond from these nonmetallic compounds may be interpreted in the carbon-oxygen system with the following chemical reaction:…”