Structural distortions in 5–10 nm silver nanoparticles under high pressure

Abstract

We present experimental evidence that silver nanoparticles in the size range of 5 -10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa. We have used xray diffraction with a synchrotron light source to investigate pressure-dependent and size-dependent trends in the crystal structure of silver nanoparticles in a hydrostatic medium compressed in a diamond-anvil cell. Results suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. We propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. To further support this hypothesis, we also show that similar measurements of single-crystal platinum nanoparticles reveal no such distortions.

Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires

“…Mechanical property. As discussed here and in previous work [12][13][14][15][16]18 , high-pressure stress can effectively induce Ag microstructure phase transformations and potentially manipulate the mechanical stability of Ag nanoparticles. Gu et al 12 found an unexpected high stiffness of Ag and gold (Au) nanoparticles under high pressure.…”

“…Many chemical methods use such defect structures (also the most reactive sites) to achieve oriented growth of Ag nanostructures; for example, oriented attachment was used to grow chain-like Ag nanostructures 11 . It has been shown elsewhere that an external stress induced by high-pressure compression can alter the mechanism of defect motion in atomic lattices through induced phase transformations [12][13][14] . Depending on the pressure condition, different Ag phase and structural transformations were observed: under hydrostatic pressure up to 10 GPa, Ag nanoparticles with sizes of 5-10 nm underwent a reversible, linear, pressure-dependent structural transformation 14 .…”

“…It has been shown elsewhere that an external stress induced by high-pressure compression can alter the mechanism of defect motion in atomic lattices through induced phase transformations [12][13][14] . Depending on the pressure condition, different Ag phase and structural transformations were observed: under hydrostatic pressure up to 10 GPa, Ag nanoparticles with sizes of 5-10 nm underwent a reversible, linear, pressure-dependent structural transformation 14 . At higher uniaxial compressions, disordered Ag microstructure was rearranged through phase transformations to form Ag nanoparticles with much higher stiffness 12,13,15 .…”

Size-dependent structure of silver nanoparticles under high pressure

“…We are unable to propose a mechanism similar to that proposed in Ref. 99. This also doesn't necessarily mean that the variation of γ is how the crystal is distorting because of the uniqueness problem wherein there are several solutions for possible distortion here but this is an appropriate way of quantifying this distortion from an fcc to orthorhombic structure.…”

“…99 The particular problem of the distortion of icosahedral structure is both non-linear and constrained.…”