It turns out that silver nanoparticles are not as solid as initially thought, making their use in electronic components and circuits a bit challenging as gadgets become increasingly smaller. Fortunately, there is a solution.
Because of its superb electrical conductivity and high melting temperature, silver is used in many aspects of electronic design. Recently, however, scientists have discovered that as the particles become microscopically smaller – in the 10 nanometer range – their outside layer mimics water droplets, wobbling and changing shape, while the inside stays stable. This can be problematic for their use in electrical contacts at the molecular level (10 nanometers is one-thousandth of the width of a human hair) as the silver could leak and cause short circuits. This could be especially challenging in devices that move around a lot or rely on movement like tiny motors or sensors in mobile applications.
A research team at MIT first noticed this phenomenon while studying silver nanoparticles but they believe it will apply to other metal nanoparticles as well.
MIT professor Ju Li notes that the use of nanoparticles in applications ranging from electronics to pharmaceuticals is a crucial area of research at the moment: “These researchers want to form shapes, and they want these shapes to be stable, in many cases over a period of years. If gold or silver nanoparticles are used in electronic circuits, these deformations could quickly cause electrical connections to fail.”
Once Li and his team began delving into this behavior, they saw that only the top layers – one or two atoms thick – actually moved. As they moved, they deposited themselves elsewhere on the surface. However, the inside atoms remained solid and in perfect shape.
Scientists had theorized that this surface movement was happening but this is the first time it has been confirmed. Now that this movement has been observed and understood, the solution to allowing nanoparticles to retain their shapes turns out to be rather simple. When a thin layer of oxide is applied, the liquid-like movement is almost completely eliminated and the nanoparticle remains stable, ensuring that silver will remain a solid choice for nanotechnology applications.
Source: The Silver Institute (subscribe to the newsletter)