We have critically reviewed and discussed currently available information regarding the spin valence states of iron in lower mantle minerals associated effects transitions on physical, chemical, transport properties deep Earth. A high‐spin to low‐spin crossover Fe 2+ ferropericlase has been observed occur at pressure‐temperature conditions corresponding middle part mantle. In contrast, recent studies consistently show that predominantly exhibits extremely high quadrupole splitting values...

Compressional wave velocity-density (V(P)--ρ) relations of candidate Fe alloys at relevant pressure-temperature conditions the Earth's core are critically needed to evaluate composition, seismic signatures, and geodynamics planet's remotest region. Specifically, comparison between V(P)--ρ profiles provides first-order information on amount type potential light elements--including H, C, O, Si, and/or S-needed compensate density deficit core. To address this issue, here we have surveyed...

In this work, we examine the high-pressure behavior of superhard material candidate WB${}_{4}$ using synchrotron x-ray diffraction in a diamond anvil cell up to 58.4 GPa. The zero-pressure bulk modulus, ${K}_{0}$, obtained from fitting pressure-volume data second-order Birch-Murnaghan equation state is 326 $\ifmmode\pm\else\textpm\fi{}$ 3 A reversible, discontinuous change slope $c/a$ ratio further observed at \ensuremath{\sim}42 GPa, suggesting that lattice softening occurs $c$ direction...

[1] The thermal equation of state ferropericlase [(Mg0.75Fe0.25)O] has been investigated by synchrotron X-ray diffraction up to 140 GPa and 2000 K in a laser-heated diamond anvil cell. Based on results at high pressure-temperature conditions, the derived phase diagram shows that spin crossover widens elevated temperatures. Along lower-mantle geotherm, occurs between 1700 km 2700 depth. Compared high-spin state, thermoelastic modeling data ∼1.2% increase density, factor two expansion...

The report of the 20th National Congress Communist Party China has proposed to promote green development, which is an important concern in realizing agricultural development (AGD). Based on connotations AGD, mechanism impact digital inclusive finance AGD explored from perspective technology innovation, production socialization services and rural industry integration. Using spatial Durbin model 2011 2021, regional differences are analyzed. results as follows. (1) level eastern region...

Water, dissolved as hydroxyl (OH) − into the solid silicate minerals of upper mantle can reduce adiabatic wave speeds through associated defects. Here we report Brillouin spectroscopy measurements sound velocities and single‐crystal elastic constants hydrous forsterite (hy‐Fo 100 ) olivine 97 containing 0.8–0.9 wt% H 2 O. The samples, synthesized at 12 GPa 1250°C, represent nearly maximum storage capacity water in conditions 350–400 km depth. bulk ( K S0 shear G 0 moduli hy‐Fo are...

Knowledge of the pressure effect on elasticity hydrous olivine polymorphs is necessary to model seismic wave speeds for potential regions mantle. Here we report single‐crystal elastic properties wadsleyite, β ‐Mg 2 SiO 4 , with 0.84 wt.% H O measured 12 GPa by Brillouin scattering. Pressure derivatives aggregate bulk modulus, K ′ S 0 and shear G wadsleyite are 4.1(1) 1.4(1) respectively. These values indistinguishable within uncertainty from those anhydrous wadsleyite. We estimate that ∼1 in...

The electronic spin and valence states of iron in lower-mantle silicate perovskite have been previously investigated at high pressures using various experimental theoretical techniques. However, results their interpretation remain highly debated. Here we studied a wellcharacterized starting sample [(Mg0.9,Fe0.1)SiO3] chemically inert Ne pressure medium up to 120 GPa synchrotron Mössbauer spectra. Analyses the spectra explicitly show high-spin low-spin transition octahedral-site Fe3+...

In situ synchrotron X-ray diffraction experiments on natural magnesiosiderite [(Mg0.35Fe0.65)CO3] were conducted using resistive and laser-heated diamond-anvil cells (DACs) up to 78 GPa 1200 K. Based thermal elastic modeling of the measured pressure-volume curves at given temperatures, we have derived equation state (EoS) parameters spin-crossover diagram across spin transition. These results show crossover broadened shifted toward higher pressures elevated temperatures. Low-spin is 6%...

Abstract Andesitic magmatism and rocks are widespread at convergent plate boundaries. Electrically conductive bodies beneath subduction zone arc volcanoes, such as the Uturuncu Volcano, Bolivia, may correspond to active reservoirs of H 2 O‐bearing andesitic magma. Laboratory measurements electrical conductivity hydrous melts required constrain physicochemical conditions these magma in combination with magnetotelluric data. This experimental study investigates 0.01–5.9 wt % O 1164–1573 K...

Seismological observation has revealed the ubiquitous presence of small-scale seismic scatterers with significant shear velocity reduction in mid-lower mantle. In particular, more than 70% scatters were observed at depths 700-1300 km, while 20% them are distributed 1300-1900 km depth. Only less 10% detected exceeding 1900 km. The phase transition from stishovite rutile-type structure to post-stishovite CaCl2-type SiO2 subducted oceanic crusts was regarded as main reason for these scatterers....

SiO2 is a crucial oxide in Earth and other terrestrial planets such as super-Earth, making the study of its high-pressure structural phase transitions physical properties vital. Due to extremely high pressures required for SiO2, significant uncertainty exist boundaries from experiments theoretical calculations. Given similarities structures between AF2 difluorides, latter serve excellent analogs studying SiO2. The transition difluorides strongly depends on cationic radius, pressure,...

Phase transitions and equations of state the alkaline earth fluorides ${\text{CaF}}_{2}$, ${\text{SrF}}_{2}$, ${\text{BaF}}_{2}$ were examined by static compression to pressures as high 146 GPa. Angle-dispersive x-ray diffraction experiments performed on polycrystalline samples in laser-heated diamond-anvil cell. We confirmed that at less than 10 GPa all three materials undergo a phase transition from cubic $(Fm\overline{3}m)$ fluorite structure orthorhombic $(Pnam)$ cotunnite-type...

[1] Dolomite is a major constituent of subducted carbonates; therefore evaluation its phase stability and equation state at high pressures temperatures important for understanding the deep Earth carbon cycle. X-ray diffraction experiments in diamond anvil cell show that Ca0.988Mg0.918Fe0.078Mn0.016(CO3)2 dolomite transforms to dolomite-II ∼17 GPa 300 K then upon laser-heating new monoclinic (dolomite-III), observed between 36 83 GPa. Both high-pressure polymorphs are stable up 1500 K,...

The single-crystal elastic properties of Fe-bearing wadsleyite with 1.93 wt% H2O (Mg1.634Fe0.202H0.305SiO4) have been determined by Brillouin scattering. At ambient conditions, the aggregate bulk and shear moduli (KS0, G0) this are 156.2(5) 98.0(3) GPa, respectively. Compared to corresponding anhydrous wadsleyite, lowers KS0 G0 8.1% 9.3%, High-pressure measurements up 12 GPa show that pressure derivative modulus, K′S0 = 4.8(1), is similar Fe-wadsleyite reported values 4.6-4.74, but addition...