Density of NaAlSi2O6 Melt at High Pressure and Temperature Measured by In-Situ X-ray Microtomography

In this study, the volumetric compression of jadeite (NaAlSi2O6) melt at high pressures was determined by three-dimensional volume imaging using the synchrotron-based X-ray microtomography technique in a rotation-anvil device. Combined with the sample mass, measured using a high-precision analytical balance prior to the high-pressure experiment, the density of jadeite melt was obtained at high pressures and high temperatures up to 4.8 GPa and 1955 K. The density data were fitted to a third-order Birch-Murnaghan equation of state, resulting in a best-fit isothermal bulk modulus K T 0 of 10.8 − 5.3 + 1.9 GPa and its pressure derivative K T 0 ′ of 3.4 − 0.4 + 6.6 . Comparison with data for silicate melts of various compositions from the literature shows that alkali-rich, polymerized melts are generally more compressible than alkali-poor, depolymerized ones. The high compressibility of jadeite melt at high pressures implies that polymerized sodium aluminosilicate melts, if generated by low-degree partial melting of mantle peridotite at ~250–400 km depth in the deep upper mantle, are likely denser than surrounding mantle materials, and thus gravitationally stable.

The High-pressure Thallium Triborate HP-TlB3O5

The thallium triborate HP-TlB3O5 (HP=high-pressure) was synthesized in a Walker-type multianvil apparatus under high-pressure=high-temperature conditions of 6 GPa and 1400°C. A mixture of thallium carbonate Tl2CO3 and boric acid H3BO3 initially heated at 850°C under ambient-pressure conditions was used as a precursor for the high-pressure experiment. Single-crystal X-ray diffraction data revealed that HP-TlB3O5 is isotypic to HP-M′B3O5 (M′ =K, Rb). Furthermore the B-O network is identical to the substitutional variants HP-M″B3O5 [M″ =Cs1-x(H3O)x (x=0.5 - 0.7), NH4]. HP-TlB3O5 crystallizes with eight formula units (Z =8) in the monoclinic space group C2=c (no. 15). The lattice parameters are a=996.3(2), b=884.0(2), c=913.1(2) pm, β =103:3(1)°, and V =782.5(3) Å3. Trigonal-planar BO3 groups, corner-sharing BO4 tetrahedra, and B2O6 groups consisting of two edge-sharing BO4 tetrahedra are present in the structure, forming a three-dimensional network. The thallium ions are located in channels of the boron-oxygen network being tenfold coordinated by oxygen atoms and do not show any lone pair effect at all. IR and Raman spectroscopic investigations were performed on single crystals of the compound.

Experimental Research on Rheological Properties of Slick Water Mixed with CO2 System

Rheological properties of slick water mixed with CO2 system are studied,through the large foam fracturing fluid of high temperature and high pressure experiment system,in detail in this paper, based on the principle of tube type rheometer. The influence laws temperature, foam quality, shear rate and pressure have on the rheological characteristics are studied. The fracturing fluid rheological parameters calculation correlations are also obtained, and the foam quality influence on rheological index and rheological coefficient of the slick water mixed with CO2 system are analyzed.