Eur. Phys. J. B (2013) 86: 311
https://doi.org/10.1140/epjb/e2013-40086-3

Regular Article

Probing nonequivalent sites in iron phosphide Fe₂P and its mechanism of phase transition

¹ Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, Peking University & School of Earth and Space Sciences, Peking University, Beijing 100871, P.R. China
² Bayerisches Geoinstitut, Bayreuth University, 95440 Bayreuth, Germany

^a e-mail: gtt.pku@gmail.com
^b e-mail: xiang.wu@pku.edu.cn

Received: 1 February 2013
Received in final form: 16 May 2013
Published online: 8 July 2013

Abstract

Comparative studies of two polymorphs ( and Pnma structures) of Fe₂P up to 16.8 GPa and 1800 ± 200 K were performed using Mössbauer spectroscopy combined with diamond anvil cell and laser heating facilities. Mössbauer spectra were collected before and after its phase transition from to Pnma structures. Mössbauer hyperfine parameters in two non-equivalent sites Fe I and Fe II in Fe₂P were evaluated and compared. An evident drop of quadrupole splitting for the ⁵⁷Fe in Fe II site was observed in its high temperature polymorph, indicating that a more sensitive pyramidal Fe II site to pressure change could serve as a trigger to this phase transition.