Structure and Behavior of the Ni End-Member Schreibersite Ni3P under Compression to 50 GPa

Abstract

To better understand the potential presence of light element alloys of Fe and Ni in the Earth’s interior, the crystal structure and compressional behavior of the Ni-P binary compound, schreibersite (Ni3P), have been investigated using synchrotron X-ray diffraction experiments. Both powder and two single-crystal samples of synthetic Ni3P (in different orientations with respect to the loading axis of the diamond anvil cell) were compressed up to approximately 50 GPa at ambient temperature. The compressional data obtained for Ni3P were fitted with a 3rd order Birch–Murnaghan equation of state. All data indicated that the c/a ratio of unit cell parameters remained approximately constant up to about 30 GPa but then increased progressively with pressure, exhibiting a second slight discontinuity at approximately 40 GPa. The changes in unit cell parameters at ~30 GPa and ~40 GPa suggested discontinuous changes in magnetic ordering. Moreover, the threshold of these subtle discontinuities is sensitive to the stress state and orientation of the crystal in the diamond anvil cell. This study is the first report on the compressional behavior of both powder and single-crystal schreibersite at high-pressure (up to 50 GPa). It offers insights into the effects of Ni3P components on the compressional behavior of the Earth’s core.

Synthesis, Crystal Structure, Electronic Structure, and Electrocatalytic Hydrogen Evolution Reaction of Synthetic Perryite Mineral

“…On the basis of the elemental analysis, these minerals all contain Ni and Fe transition metals, which implies that they formed under a reduced environment. The crystal structures and chemical compositions for schreibersite and kamacite mineral are relatively well-established compared with those the perryite mineral . Schreibersite adopts the Ni 3 P structure type, and it can be an either Ni-rich or Fe-rich compound (e.g., Ni 2 FeP or NiFe 2 P), whereas kamacite is an α-Fe/Ni alloy with an Fe-to-Ni ratio of roughly 9:1. , …”

“…The crystal structures and chemical compositions for schreibersite and kamacite mineral are relatively well-established compared with those the perryite mineral. 4 Schreibersite adopts the Ni 3 P structure type, and it can be an either Ni-rich or Fe-rich compound (e.g., Ni 2 FeP or NiFe 2 P), whereas kamacite is an α-Fe/Ni alloy with an Fe-to-Ni ratio of roughly 9:1. 5,6 The crystal structure of the synthetic perryite mineral was first investigated by Okada et al, and it adopts the noncentrosymmetric space group R3c; 7 However, because of the twinning problem of the analyzed crystal, the centrosymmetric space group R3̅ c may be a more suitable choice to describe this phase.…”

Crystal chemistry of schreibersite, (Fe,Ni)3P

“…The mineral may constitute for up to 14 % of metal matrix in iron and stony-iron meteorites (Buchwald 1975;Wasson and Choe 2009). Being a dominant phosphide phase in the metal-rich part of the Fe-Ni-P(S) system, schreibersite is a regular subject of studies devoted to evolution of planetary interiors (e.g., Clarke and Goldstein 1978;Scott et al 2007;Goldstein et al 2009;Gu et al 2014Gu et al , 2016He et al 2019; Khisina et al 2019;Chabot et al 2020;Chornkrathok et al 2020). The mineral is a typical constituent of enstatite chondrites and achondrites (Wasson and Wai 1970); it was encountered in carbonaceous chondrites (Zolensky et al 2002), acapulcoites, lodranites and winonaites (Li et al 2011; Keil and McCoy 2018) and in Lunar rocks (Smith and Steele 1976;Gleißner and Becker 2017).…”