Icosahedra clustering and short range order in Ni-Nb-Zr amorphous membranes

S Sarker; D Isheim; G King; Q An; D Chandra; S I Morozov; K Page; J N Wermer; D N Seidman; M Dolan

doi:10.1038/s41598-018-24433-9

Icosahedra clustering and short range order in Ni-Nb-Zr amorphous membranes

Sci Rep. 2018 Apr 17;8(1):6084. doi: 10.1038/s41598-018-24433-9.

Authors

S Sarker¹, D Isheim², G King³, Q An⁴, D Chandra⁵, S I Morozov⁶, K Page⁷, J N Wermer³, D N Seidman², M Dolan⁸

Affiliations

¹ Departments of Chemical and Materials Engineering, University of Nevada, Reno, Nevada, 89557, USA. suchismita13994@gmail.com.
² Department of Materials Science and Engineering, Center for Atom Probe Tomography, Northwestern University, 2220 Campus Dr., Evanston, IL, 60028, USA.
³ Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87545, USA.
⁴ Departments of Chemical and Materials Engineering, University of Nevada, Reno, Nevada, 89557, USA. qia@unr.edu.
⁵ Departments of Chemical and Materials Engineering, University of Nevada, Reno, Nevada, 89557, USA. dchandra@unr.edu.
⁶ Department of Computer Simulation and Nanotechnology, South Ural State University, Chelyabinsk, 454080, Russia.
⁷ Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁸ CSIRO, Division of Energy Technology, Kenmore, QLD 4069, Australia.

Abstract

Crystalline Pd/Pd-Ag membranes are widely used for hydrogen separation from CO₂ and other gases in power generation applications. To substitute these high cost noble metal alloy membranes, the Ni-Nb-Zr amorphous alloys are being developed that exhibit relatively high permeability of hydrogen between 200-400 °C. Atom probe tomography (APT) experiments performed on these ribbons revealed nm-scale Nb-rich and Zr-rich regions (clusters) embedded in a ternary matrix, indicating phase separation within the Ni-Nb-Zr amorphous alloy. Density functional theory (DFT) simulations have predicted that these clusters are composed of icosahedral coordination polyhedra. The interatomic distances and correlation lengths of the short range order of these alloys were determined by neutron total scattering which match well with our DFT based molecular dynamics (DFT-MD) simulations.