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Title: Pressure-induced development of bonding in NiAs type compounds and polymorphism of NiP

A reversible, displacive, pressure-induced structural phase transition has been found to occur in nickel monophosphide NiP at approximately 3.5 GPa by means of in situ synchrotron single-crystal X-ray diffraction. The new phase, with Pearson symbol oC56, assumes an orthorhombic structure with Cmc2{sub 1} space group and unit cell parameters a=23.801(2) {angstrom}, b=5.9238(6) {angstrom}, and c=4.8479(4) {angstrom} at 5.79 GPa. The high-pressure phase is a superstructure of the ambient, oP16 phase with multiplicity of 3.5. The phosphorous sublattice gradually converts from the net of isolated P{sub 2} dimers found in the ambient NiP, towards zig-zag polymeric P{infinity} chains found in MnP-type structures. The transformation involves development of triatomic phosphorous clusters and interconnected Ni slabs with diamondoid topology. The high-pressure phase, which represents intermediate polymerization step, is a commensurately modulated superstructure of the NiAs aristotype. The phase transformation in NiP bears resemblance to the effect of successive substitution of Si or Ge in place of P found in the series of stoichiometric inhomogeneous linear structures in ternary NiP{sub 1-x}Si{sub x} and NiP{sub 1-x}Ge{sub x} systems.
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Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: J. Solid State Chem.; Journal Volume: 184; Journal Issue: (8) ; 08, 2011
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Sponsoring Org:
Country of Publication:
United States