Abstract
An orthorhombic modification of (Fe,Ni)2P, allabogdanite, found in iron meteorites was considered to be thermodynamically stable at pressures above 8 GPa and temperatures of 1673 K according to the results of recent static high-pressure and high-temperature experiments. A hexagonal polymorphic modification of (Fe,Ni)2P, barringerite, was considered to be stable at ambient conditions. Experimental investigation through the solid-state synthesis supported by ab initio calculations was carried out to clarify the stability fields of (Fe,Ni)2P polymorphs. Both experimental and theoretical studies show that Fe2P-allabogdanite is a low-temperature phase stable at ambient conditions up to a temperature of at least 773 K and, therefore, is not necessarily associated with high pressures. This is consistent with the textural relationships of allabogdanite in iron meteorites.
Highlights
An orthorhombic modification of (Fe,Ni)2P, allabogdanite, found in iron meteorites was considered to be thermodynamically stable at pressures above 8 GPa and temperatures of 1673 K according to the results of recent static high-pressure and high-temperature experiments
We report the results of ab initio calculations and experimental investigation of the stability fields of polymorphic modifications of (Fe,Ni)2P, which show that allabogdanite is thermodynamically stable at ambient PT-conditions
The determined parameters of the phase transition and relationship between the unit cell volumes are in agreement with the results of our ab initio calculations (Fig. 3)
Summary
An orthorhombic modification of (Fe,Ni)2P, allabogdanite, found in iron meteorites was considered to be thermodynamically stable at pressures above 8 GPa and temperatures of 1673 K according to the results of recent static high-pressure and high-temperature experiments. Experimental investigation through the solid-state synthesis supported by ab initio calculations was carried out to clarify the stability fields of (Fe,Ni)2P polymorphs Both experimental and theoretical studies show that Fe2P-allabogdanite is a low-temperature phase stable at ambient conditions up to a temperature of at least 773 K and, is not necessarily associated with high pressures. The orthorhombic modification of Fe2P−Ni2P solid-solution, allabogdanite was first detected in anomalous Onello high-Ni ataxite found in 1997 in the alluvium of the Onello River, Yakutia, Russia[3] Earlier this mineral in the Onello ataxite was considered barringerite[7,8,9]. A comprehensive investigation of mineralogy and trace element composition of the Onello meteorite has been carried out by Litasov et al.[10] They argue that the morphology of the allabogdanite crystals and surrounding phases indicates equilibrium relationships (Fig. 1), though the Fe-Ni-P phase diagram has an intermediate Fe3P compound.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
