English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In this study, we have investigated the crystal structure and equation of state of tetragonal CaSiO 3 - perovskite up to 200 GPa using synchrotron X‑ray diffraction in laser-heated diamond-anvil cells. X‑ray diffraction patterns of the quenched CaSiO 3 -perovskite above 148 GPa clearly show that 200, 211, and 220 peaks of the cubic phase split into 004+220, 204+312, and 224+400 peak pairs, respectively, in the tetragonal structure, and their calculated full-width at half maximum (FWHM) exhibits a substantial increase with pressure. The distribution of diffraction peaks suggests that the tetragonal CaSiO 3 - perovskite most likely has an  I 4/ mcm  space group at 300 K between 148 and 199 GPa, although other possibilities might still exist. Using the Birch-Murnaghan equations, we have determined the equation of state of tetragonal CaSiO 3 -perovskite, yielding the bulk modulus  K  0T  = 227(21) GPa with the pressure derivative of the bulk modulus,  K ′ 0T  = 4.0(3). Modeled sound velocities at 580 K and around 50 GPa using our results and literature values show the difference in the compressional ( V  P ) and shear-wave velocity ( V  S ) between the tetragonal and cubic phases to be 5.3 and 6.7%, respectively. At ~110 GPa and 1000 K, this phase transition leads to a 4.3 and 9.1% jump in  V  P  and  V  S , respectively. Since the addition of Ti can elevate the transition temperature, the transition from the tetragonal to cubic phase may have a seismic signature compatible with the observed mid-lower mantle discontinuity around the cold subduction slabs, which needs to be explored in future studies.

High-pressure experimental study of tetragonal CaSiO 3 -perovskite to 200 GPa