Heat and free energy of formation of carbon dioxide, and of the transition between graphite and diamond

Rossini, Frederick D.; Jessup, R.S.

doi:10.6028/jres.021.028

Cited by 112 publications

(47 citation statements)

References 34 publications

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“…Equation (6) is consistent with the assumption of stress equilibrium between the two phases. 39 Because the shock-induced graphite-diamond transition occurs at stresses far from the equilibrium phase boundary 40 (defined by equality of the Gibbs free energies for the two phases), the transformation rate was determined using a stress criterion,…”

Section: B Multi-phase Modeling Frameworkmentioning

confidence: 99%

Shock-compressed graphite to diamond transformation on nanosecond time scales

Winey

Gupta

2013

Phys. Rev. B

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Numerical simulations of previous plane shock wave measurements on highly oriented pyrolytic graphite (HOPG), shocked to four peak stresses ranging from 27 -50 GPa, are presented to address a long-standing question: When is the diamond phase formed in the shock-compressed graphite to diamond transition? A multi-phase material description was developed to simulate measured wave profiles in shocked HOPG. Our results showed good agreement with the measured profiles for all four peak stresses and demonstrated the following: transformation completion in less than 10 nanoseconds; the density and stiffness of the high pressure phase match that of cubic diamond; and the mechanical response of the diamond phase is nonlinear elastic.2

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Section: B Multi-phase Modeling Frameworkmentioning

confidence: 99%

Shock-compressed graphite to diamond transformation on nanosecond time scales

Winey

Gupta

2013

Phys. Rev. B

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“…Although it has been demonstrated [7,8] that graphite can be burned successfully in an oxygen bomb to-give precise data, attempts to determine the heat of formation of carbon tetrafluoride by direct combination of the elements has not been as simple. Von Wartenburg and Schutte [77] calculated the heat of formation of CF4 to be -162 ±2 kcal mole-as a result of the direct combination of the elements.…”

Section: Okimentioning

confidence: 99%

“…Wise, Margrave, Feder and Hubbard [J4] 7etermined the heat of formation of boron trifluoride to be -269.88 ±0.+9 kcal mole -1 in a bomb calorimeter by direct combination. Recent work by Johnson, Feder and Hubbard [15], using a two-chapter combustion bomb shows AH 29 8[BF 3 (g)] = -271.65 keal mole -1 from the direct combination of the elements.…”

Section: Okimentioning

confidence: 99%

“…Kirkblide and Davidson [23] and Ion Wartenberg et al [24,25] calculated -218, -231 and -225 kcal mole-, respectively, for the heat of formation of CF 4 (g) from the following reaction: [21] and upon recalculation they found AH. 29 8[CF (g)) = -220.6 ±1.4 kcal mole -1 .…”

Section: Okimentioning

confidence: 99%

“…The heats of formation of a-ALBI2 and y-ALBj 2 have been calculated from the data in Tables 11 and 12, and our data on alami= fluoride [2) and boron trifluoride according to reactions (8) and (9) Because of the relatively large amounts of impurities in the aluminum borides studied, we have attempted to estimate limits to the uncertainties introduced into the oalmvlated heats of formation by the lack of knowledge oe the exmct nature of the imprities. This has been done by using the composition of the samples listed in Tables 16, 17 and 18 an columns (W), (2), (3) and (4), respectively.…”

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confidence: 99%

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Heats of Formation of Metallic Borides by Fluorine Bomb Calorimetry

Domalski¹,

Armstrong²

1965

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Diamond, Synthetic

Wentorf¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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In 1955, a team of research workers at General Electric developed the necessary high pressure equipment and discovered solvent–catalytic processes by which ordinary forms of carbon could be changed into diamond. In the catalyzed synthesis process, a mixture of carbon (eg, graphite) and catalyst metal is heated high enough to be melted, while the system is at a pressure high enough for diamond to be stable. Graphite is then dissolved by the metal and diamond is produced from it. Effective catalysts are Cr, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, and Ta, and their alloys and compounds. Many kinds of apparatus have been devised for simultaneously producing the high pressures and temperatures necessary for diamond synthesis. An early successful design is the belt apparatus. A belt apparatus is capable of holding pressures of 7 GPa (70 kbar) and temperatures of up to 3300 K for periods of hours. Size, shape, color, and impurities are dependent on the conditions of synthesis. Lower temperatures favor dark‐colored, less pure crystals; high temperatures promote paler, purer crystals. Low pressures (5 GPa) and temperatures produce octahedral faces. If diamond seed crystals are placed in the active diamond growing zone of a typical graphite–catalyst metal apparatus, new diamond usually forms on the seed crystals. Excellent growth can be obtained if pressure and composition are held relatively constant. In the direct graphite‐to‐diamond process, diamond forms from graphite without a catalyst. The refractory nature of carbon demands a fairly high temperature (2500–3000 K) for sufficient atomic mobility for the transformation. When graphite is strongly compressed and heated by the shock produced by an explosive charge, some (up to 10%) diamond may form. The annual production of diamond by this process is only a small fraction of total industrial diamond consumption. Diamond can form directly from graphite at pressures of about 13 GPa (130 kbar) and higher at temperatures of about 3300–4300 K. No catalyst is needed. The transformation is carried out in a static high pressure apparatus. Diamond forms in a few milliseconds. Metastable growth of diamond takes place from gases rich in carbon and hydrogen at low pressures where diamond would appear to be thermodynamically unstable. In a typical use of this method, a mixture of hydrogen and methane is fed into a reaction chamber at a pressure of about 1.33 kPa (10 torr). The substrate upon which diamond forms is at about 950°C and lies about 1 cm away from a tungsten wire at 2200°C. This method has been actively studied since 1993. As of this writing (1993) the price of synthesized diamond is competitive with that of natural diamonds. The bulk of synthetic industrial diamond production consists of the smaller crystal sizes up to 0.7‐mm particle size (25 mesh). This size range has wide utility in industry, and a significant fraction of the world's need for diamond abrasive grit is now met by synthetic production yielding thousands of kilograms per year. Semiconducting diamonds are prepared by adding small amounts of boron, beryllium, or aluminum to the growing mixture. The production of synthetic sintered diamond masses having excellent mechanical properties has only been achieved recently. About 90% of industrial diamond is synthesized at high pressures because its price is relatively low, and it can be tailor‐made for efficiency in each application.

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Heat and free energy of formation of carbon dioxide, and of the transition between graphite and diamond

Cited by 112 publications

References 34 publications

Shock-compressed graphite to diamond transformation on nanosecond time scales

Shock-compressed graphite to diamond transformation on nanosecond time scales

Heats of Formation of Metallic Borides by Fluorine Bomb Calorimetry

Diamond, Synthetic

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