Thermal equation of state of cubic boron nitride: Implications for a high-temperature pressure scale

Abstract

The equation of state of cubic boron nitride ͑cBN͒ has been determined to a maximum temperature of 3300 K at a simultaneous static pressure of up to more than 70 GPa. Ab initio calculations to 80 GPa and 2000 K have also been performed. Our experimental data can be reconciled with theoretical results and with the known thermal expansion at 1 bar if we assume a small increase in pressure during heating relative to that measured at ambient temperature. The present data combined with the Raman measurements we presented earlier form the basis of a high-temperature pressure scale that is good to at least 3300 K.

A flash heating method for measuring thermal conductivity at high pressure and temperature: Application to Pt

“…359 fitting. This is assumed to be 30% of the isochoric thermal pressure (Dewaele et al, 361 1998;Goncharov et al, 2007) taken from equation-of-state data on Pt (Dorogokupets 362 and Dewaele, 2007;Jin et al, 2011), and equals ~2 GPa/1000 K. 363…”

“…This value was found to be consistent with that 193 determined from the equation of state and initial thickness. Foil expansion upon 194 heating is small (<2%) compared to the thickness uncertainty (5-10%, table I) in part 195 due to sample confinement which limits free expansion and instead produces thermal 196 pressure (Dewaele et al, 1998;Goncharov et al, 2007). 197…”

Computational prediction of body-centered cubic carbon in an all-sp3six-member ring configuration

“…22 By fitting the calculated total energy as a function of volume to Murnaghan's equation of state, 33 we obtain the bulk modulus (B 0 ) of BC12 as 428 GPa, which is lower than the value for diamond (452 GPa), but larger than the value for BC8 (409 GPa) and c-BN (396 GPa). 34 The calculated equilibrium structural parameters and bulk modulus for diamond, BC8, BC12, and SC24 carbon at zero pressure are summarized in Table I, compared to available experimental data. 20,35 As listed in Table I, our calculated lattice parameter is 5.116 Å from LDA and 5.172 Å from GGA.…”

Experimental method for in situ determination of material textures at simultaneous high pressure and high temperature by means of radial diffraction in the diamond anvil cell

“…Spectroscopic methods have been used to determine the accurate pressure using fluorescence shifts in ruby, SrB 4 O 7 :Sm 2+ or yttrium aluminum garnet crystals. [18][19][20] More recently shifts in the first order Raman peaks of diamond 34 and cubic boron nitride 20 at high temperature have also been used. Alternatively, one may determine pressure using a P-V-T thermal equation of state ͑EoS͒ of an internal standard such as Au or Pt.…”

“…In addition, accurate measurement of pressure at high temperature has been an ongoing problem in resistive heated DACs but is now actively being addressed by the community. [18][19][20][21][22] In contrast to the other two techniques mentioned above, the externally heated DAC experiment offers good temperature and pressure control and can reach much higher pressures then the LVP. Furthermore, the development of sintered nanodiamond anvils could significantly expand the accessible pressure temperature range because the high temperature strength of the anvils can be significantly improved.…”