P-V-T equation of state of boron carbide

Abstract

We report the P-V-T equation of state measurements of B 4 C to 50 GPa and approximately 2500 K in laser-heated diamond anvil cells. We obtain an ambient temperature, third-order Birch–Murnaghan fit to the P-V data that yields a bulk modulus K 0 of 221(2) GPa and derivative, (d K /d P ) 0 of 3.3(1). These were used in fits with both a Mie–Grüneisen–Debye model and a temperature-dependent, Birch–Murnaghan equation of state that includes thermal pressure estimated by thermal expansion ( α ) and a temperature-dependent bulk modulus (d K 0 /d T ). The ambient pressure thermal expansion coefficient ( α 0 + α 1 T ), Grüneisen γ ( V ) = γ 0 ( V / V 0 ) q and volume-dependent Debye temperature, were used as input parameters for these fits and found to be sufficient to describe the data in the whole P-T range of this study. This article is part of the theme issue ‘Exploring the length scales, timescales and chemistry of challenging materials (Part 1)’.

Exploring the length scales, timescales and chemistry of challenging materials (Part 1)

“…However, this intriguing material shows a number of anomalous properties, including a loss of shear strength at high pressure, that may limit its application. The study presented by Somayazulu et al [ 34 ] provides information on the elastic properties of boron carbide. Their study provides the equation of state determined by XRD measurements at HPCAT of the APS, made in situ using a laser-heated diamond anvil call, expanding the pressure and temperature range of the equation of state to 50 GPa and 2500 K.…”