Thursday, 31 July 2014
masthead+quote+image
Advanced search

Team changes colour of gold by altering surface structure

A research team in the UK has found a way to change the colour of gold by making microscopic alterations to its surface structure.

In what is claimed to be a world first, researchers at Southampton University have demonstrated that by embossing nanoscale raised or indented patterns onto the metal’s surface they can change its colour without using coatings or chemical treatments.

This technique, which could also be applied to other metals, could be used in jewellery manufacture or in the security industry to create banknotes or other items with sophisticated optical properties that would be almost impossible to imitate.

According to the group at the university’s Centre for Photonic Metamaterials, the behaviour of the light striking the metal (and therefore the colour that is created) can be modified simply by varying the shape and height of these patterns in order to produce a wide range of colours.

Developed through the £5m EPSRC-funded ‘Nanostructured Photonic Metamaterials’ initiative, the breakthrough is one of the latest additions to the field of structural colour, in which materials are coloured not through dye or pigmentation but through the way in which light interacts with tiny structures on a material’s surface. The iridescent greens and blues of beetles are an example of this phenomenon occurring naturally.

According to the research manager on the project, Dr Kevin Macdonald, the Southampton technique has a number of advantages over existing approaches. He told The Engineer that it can be applied in a single layer on a continuous surface and that unlike other techniques the colour can be varied throughout the structure.

Macdonald explained that the nano-patterning is carried out at the research level using techniques such as ion beam milling and electron beam lithography. For larger-scale commercial applications, he envisages the use of nano-imprint processes, whereby large areas are stamped out from a master template in a manner comparable to CD or DVD production.

Although he wouldn’t be drawn on a ‘killer application’ for the technology, he confirmed that a patent application covering the work has been filed and that the group is currently talking to potential end users in both the security and aesthetic markets.


Have your say

Mandatory
Mandatory
Mandatory
Mandatory

Related images

My saved stories (Empty)

You have no saved stories

Save this article

Digital Edition

The Engineer July Digi Issue

Poll

London Mayor Boris Johnson is lobbying for a £10 additional charge for diesel cars to drive into Central London by 2020, and for road tax on diesel cars and all pre-2006 cars to be increased, to counter air pollution. What option most closely matches your opinion on this?

Previous Poll

Europe's largest tidal array in the Pentand Firth off Orkney will eventually generate up to 86MW of power. What will it take for tidal energy to make an appreciable contribution to the UK's energy needs?

Read and comment on the results here