As we mentioned at the beginning of the year in “7 materials of the future: Special 100 posts“, one of the most interesting materials for 2020 is undoubtedly transparent metals. These metals look like a product out of science fiction like Star Trek, but thanks to the latest advances in science, they are now possible!

What are transparent metals?

There are different types of transparent metals, as the definition of transparent itself is somewhat ambiguous. First, it should be known that being transparent does not mean that it cannot be seen with the naked eye, but that, at certain wavelengths, an object cannot be detected. The most common way of talking about transparency is referred to the wavelength of light belonging to the visible range. For this reason, what we do not see with our eyes, we say that it is transparent, but still there are many other wavelengths such as infrared, microwave or X-rays. As an example, some remote controls transmit the signal by infrared, and the transmitter and receiver housings are transparent at the infrared wavelength, even if the material is not transparent at the visible wavelength

Transparency in visible wavelength

Transparency at infrared wavelength

How are transparent materials?

Once this first explanation is given, we can tell you that the transparency that we are referring to for metals this time, is that of the visible range, which encompasses them within the intelligent materials of great interest.

We must say that almost any material, including metals, in very small quantities, can be transparent. This happens, for example, when making metallic coatings a few nanometers thick using techniques such as PVD (Physical Vapor Deposition). On these occasions, thin layers of metals such as gold can be deposited in different materials, being able to observe the initial color of the material, and not a golden finish as would be expected.

PVD coatings of the same material on the same substrate with different thickness

This phenomenon of transparency in thin layers has been known for a long time, and although it is very useful for making coatings that provide new properties to materials, it has its limited applications, since the amount of material that can be deposited without losing transparency is low.

However, a method has now been discovered by which, using metal nanoparticles and nanowires, a sheet-shaped metamaterial can be created. For the time being, researchers have conducted gold foil tests of such high thickness that all incident light should be reflected, and have managed to pass light through them. Furthermore, this nanostructuring technique seems to be able to contribute these transparency properties to any type of metal, not just gold.

Applications and other properties of transparent metals

The applications of the transparent metals obtained are diverse and varied, since they could replace conventional glasses in many of them. For example, they could be used in mobile screens, where they would provide the necessary transparency, and also the resistance of a metal, so that the breakage of the screens by blows or impacts could be a thing of the past. Another application of great interest would be, for example, in the construction sector, where buildings could be constructed with transparent structural elements, but with great resistance that currently do not exist in the conventional market.

Another of the interesting properties of metals compared to glass and transparent plastics, is for example its high thermal and electrical conductivity. This makes it possible for example to create electrical circuits including transparent parts and many other applications yet to be discovered.

The closest applications that the creators of these transparent metals are thinking of include optical components for analysis and communications, or solar cells, where transparent electrodes are very important because of their high performance.

Others development of transparent metals

Although it is true that the technique that we have discussed to make metals invisible seems to us the most interesting and that it can be transferred a priori to any type of metal, it is true that in recent years other types of techniques have been developed to create metals transparent.

One of them is for example that of the creation of correlated metals. These types of metals are characterized by their unique molecular structure, which allows electrons to move inside the metal as a liquid and not as a gas cloud as usual. This causes the effective mass of the electrons to change, for which metals are needed in which the electrostatic interaction between the negatively charged electrons is very large compared to their kinetic energy, which limits the number of metals suitable for this process .

We have shown you that transparent metals are no longer magic or science fiction, but rather a reality, and although they are still being developed through various techniques, we are sure that their uses will soon expand to many applications.

What do you think? Did you find the transparent metals interesting? Tell us on our networks, write to us at or contact us through our web form.

Related Projects:
Development of golden colors through physical vapor deposition
Modifying transparency using IMM
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