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Phosphorus-doping limits nickel nanoparticles

NSF Award:

Chemical Transformations of Nanoparticles for Isolation of Metastable Phases  (Cornell University)

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Nanoparticles have many potential applications including those in medicine, life sciences and electronics. Nickel nanoparticles are often used to efficiently jumpstart chemical reactions because of their large size. During research on nickel nanoparticle synthesis, Cornell University researchers discovered that these nanoparticles can be unintentionally doped with phosphorus using conventional synthesis recipes.

The doping is substitutional and can occur within the nickel nanoparticles to surprisingly high (5 percent) concentrations and result in significant and unfavorable changes on the magnetic properties. Phosphorus content also greatly affects properties in copper and iron, nickel's transition metal sisters.

This previously undetected phosphorus doping is of critical importance because the doping results in a significant and unfavorable impact on the magnetic and catalytic properties of nanoparticles. These results apply to other nanoparticle syntheses that employ similarly strong-binding phosphorus ligands (molecules that bind to a central atom). 

To fine-tune nanoparticle properties for use in applications, the researchers suggest others consider the possibility of such dopants and alternate phases when using reactive synthetic agents. This work proposes a method to estimate the phosphorus atomic percentage based on the X-ray diffraction peak position.

Images (1 of )

  • schematic depicts unintentional doping of nickel nanoparticles with phosphorus
  • microscopy image of nickel nanoparticles
Phosphorus doping can alter the magnetic properties of nickel nanoparticles.
R.D. Robinson, Cornell University
Nickel nanoparticles viewed with transmission electron microscopy.
R.D. Robinson, Cornell University

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