Strontium Vanadate would be a great name for a heavy metal band … or more appropriately, a ‘transparent’ metal band. Strontium vanadate is a new transparent metal that may soon reduce the costs of smart phones, save energy in smart windows and allow people to see what you’re doing while driving your car.
OK, that last one may not be a good application of transparent metal, but replacing the current displays on smart phones is. Their screens and those on most tablets are generally made with a transparent conducting oxide called indium tin oxide which makes up a whopping 40 percent of the cost of these devices. The price of indium tin oxide has ranged from $200/kg to $1000/kg over the past ten years and shows no signs of going down.
That’s where researchers from Pennsylvania State University may have saved the day. To match the transparency and conductivity of a film of indium tin oxide, they developed something unique called correlated metal. While the electrons in most metals (copper, gold, aluminum, etc.) bounce around randomly, those in correlated metal flow like a liquid.
According to their report in Nature Materials, strontium vanadate and calcium vanadate are two correlated metals. Strontium, vanadium and calcium are abundant materials, with vanadium selling for $25/kg and strontium even less.
That takes care of the cost, but what about the performance? Roman Engel-Herbert, assistant professor of materials science and engineering and team leader, says correlated metals perform the same function as indium tin oxide.
This electron liquid is still highly conductive, but when you shine light on it, it becomes less reflective, thus much more transparent.
The next step is to ramp up the manufacturing of strontium vanadate and calcium vanadate on the large scale that Silicon Valley demands. A part of that may be applying the technology to smart windows that change from transparent to translucent depending on light and heat conditions. Once that’s done, Engel-Herbert and his team will move to a new type of solar cell based on organic perovskites (materials with the same type of crystal structure as calcium titanium oxide) that need an inexpensive transparent conductor to make them affordable.
It’s time to scratch “transparent metal” from your list of oxymorons.