With all the publications touting new materials or the creation of new properties of materials, it is often difficult to identify disparate findings into something that could combine into very useful devices. We will consider two findings.
A team of scientists from the University of Vermont. Lawrence Livermore National Labs and other Labs developed a form of silver with enhanced strength. [Ref. 1] They found a new nanoscale mechanism that enable improving metal strength without reducing electrical conductivity. Currently, in order to improve strength related properties like reducing brittleness or softening, various alloys are employed to make the materials stronger. This improvement has led to a decrease in electrical conductivity.
Starting with the fact that as grains of material get smaller, they get stronger. When the size becomes less than tens of nanometers wide, the boundaries between grains become unstable and can move. One approach to improving the strength in metals like silver is to create a special type of grain boundaries known as coherent twin boundaries. These boundaries are very strong but deteriorates when the size is less than a few nanometers due to imperfections in the lattice.
The researchers have developed an approach to create a “nanocrystalline-nanotwinned metal. Employing a small amount of copper atoms, which are slighter smaller than silver atoms, to move into defects in both grain and twin boundaries. This has created a super strong form on sliver with the conductivity of silver retained. It appears that the copper atoms move into the interface and not into the main part of the silver structure.
This effort overcomes softening previous observed as the grains get to small, which is called the Hall-Petch breakdown. The researchers a confident that their findings can be applied to other materials.
Researchers at the University of Porto (Portugal) found a negative thermal expansion (NTE) effect in Gd5Si1.3Ge2.7 magnetic nano granules. [Ref. 2] Most material expand (Positive Thermal Expansion – PTE) when heated and contract when cooled. This material is part of a family of materials that has important implications in the development of future devices.
Work in materials like glass has been developing glass that has Low Expansion Coefficients for more than 50 years. This type of precision in glass is required to manufacture the very high-resolution optical telescopes.
The ability to create materials that combine both positive expansion and negative expansion to electronics would enable the development of more robust material inter-connections (contacts) that can withstand the rigors of wide temperature extremes.
Why are these findings important? Currently, efforts are being made to create longer lasting electronics. Material fatigue and power consumption are two major concerns. What electronics are available that will be functioning 100 years from today? Excluding the obsolescence factor, there is nothing that will be working as designed. The current exploration conversations are about considering project to both the Moon and Mars. There are space probes that have been functioning for tens of years. Other probes stop functioning “mysteriously”. Multiple redundancy provides a partial work-around. But, how much redundancy is allowable when the “mission” is weight limited. There are no manufacturing facilities on places that are being considered for human exploration. The ability to manufacture devices are better able to withstand temperature extremes, use power more efficiently, and remain operations for longer periods of time are needed. The research mentioned above is not the answer, but may be the first steps to a solution.