Equation of State of a Natural Chromian Spinel at Ambient Temperature

Abstract

A natural chromian spinel with the composition (Mg0.48(3)Fe0.52(3))(Fe0.06(1)Al0.28(1)Cr0.66(2))2O4 was investigated up to 15 GPa via synchrotron X-ray diffraction with a diamond-anvil cell at room temperature. No phase transition was clearly observed up to the maximum experimental pressure. The pressure–volume data fitted to the third-order Birch–Murnaghan equation of state yielded an isothermal bulk modulus ( K T 0 ) of 207(5) GPa and its first pressure derivative ( K T 0 ′ ) of 3.2(7), or K T 0 = 202(2) GPa with K T 0 ′ fixed as 4. With this new experimental result and the results on some natural chromian spinels in the literature, a simple algorithm describing the relation between the K T 0 and the compositions of the natural chromian spinels was proposed. To examine this algorithm further, more compression experiments should be performed on natural chromian spinels with different chemical compositions.

Influence of High Conductive Magnetite Impurity on the Electrical Conductivity of Dry Olivine Aggregates at High Temperature and High Pressure

“…% magnetite was required to achieve interconnection of magnetite in serpentinite at 1.0 GPa and 750 K. Clearly, this value cannot correspond to the conditions of a really regional geotectonic environment, which is impossible to contain such high volume factions of magnetite at that depth range of the slab-mantle wedge interface of the subduction zone. In consideration of the crystal structure and its phase stability in the solid solution of spinel (or spinelloid)-structured minerals and the high-pressure polymorphs of olivine (such as wadsleyite and ringwoodite) [50][51][52][53], further research is required under higher temperature and pressure conditions to explore the influence of the magnetite fraction on the electrical conductivity of the minerals and rocks of the mantle transition zone in the future. In summary, the presence of an interconnected high conductivity impurity phase in olivine aggregates with the 5% volume fraction of magnetite is unlikely to account for the high conductivity anomaly in the deep Earth's interior.…”

Quantum Stirling engine based on dinuclear metal complexes

“…When a high pressure is applied to a metal complex, it is possible for changes to occur in the electron density, bonding, and crystal structure of the system [60]. As presented in reference [42], the third-order Birch-Murnaghan equation [61][62][63] relates the magneto-structural change in metal complexes with the pressure to which the substance is subjected. Thus, a hydrostatic pressure allows one to control the magnetic coupling, which then controls the degree of quantum correlations in low dimensional metal complexes [42].…”