Heriot-Watt scientists working on new type of matter

By Ken Macdonald
BBC Scotland Science Correspondent

Published
image captionProf Martin McCoustra and his colleagues are building on work which began in Denmark

Scientists at Heriot-Watt University are working with an entirely new type of solid matter.

Spontelectric materials carry a massive electric charge and could explain why life has been able to exist on Earth.

It's been cold recently, but not as cold as in this laboratory on the edge of Edinburgh. Helium gas has to be very cold before it turns to liquid, but using liquid helium is only the start of the process.

Prof Martin McCoustra shows me his ultra-high vacuum chamber. Because to create spontelectrics you need not only low temperatures but what he describes as "very, very, very low pressures".

How low?

"If you think about your household vacuum cleaner," he says, "the pressure is about one-hundredth of atmospheric.

"We go to at least a hundred-billionth of atmospheric pressure.

"We can also cool a little bit of the inside of that down to just a few degrees above absolute zero."

To these extremes, add a gas like nitrous oxide or carbon monoxide. Something made up of fairly simple molecules.

image captionProf McCoustra demonstrates how he creates spontelectrics

The unexpected happens: the gas becomes a solid. And no ordinary solid at that.

Until now it's been possible to divide solid matter into two types. If the molecules are arranged regularly it's a crystal. Less regularly arranged, it's an amorphous material like glass.

Spontelectric materials break that binary. They're a new type of solid matter, the first to be discovered for decades.

They were first created by the astrophysicist Prof David Field and his colleagues at Aarhus University in Denmark. Martin McCoustra's team at Heriot-Watt is further exploring their properties.

The most remarkable of these is that they are spontaneously electric - hence the name spontelectric.

The solid has a massive electric field of more than 100 million volts per metre. Although you don't measure spontelectrics in metres - they're a film just a few tens or hundreds of molecules thick.

Why might this matter? Because of stardust.

The lab environment in which spontelectrics are created - high vacuum, extreme cold, a silica substrate and simple gas molecules - mimic the conditions in the clouds of dust and gas that dot interstellar space. The nurseries in which stars are born.

image copyrightEyeWire
image captionThe spontelectric effect could be used to make new kinds of organic light emitting diodes.

Prof McCoustra says: "If these observations of these electric fields are translated into that interstellar environment, then there is potential for impacting on the charge balance in these dense clouds from which we make stars and planets."

He says the presence in the dust clouds of molecules like carbon monoxide could have had huge implications for life on Earth.

"It's strange that actually we need molecules to help us form small stars.

"If you take molecules out of the picture and you assume that all your gas is atomic hydrogen, the only things you can make are massive stars. If you want to make smaller stars like our Sun you need to have molecules."

And small - some might say insignificant - stars like our own matter, at least to us.

He adds: "If you don't get small stars you don't necessarily get stars that live very long.

"You won't get evolution on planets."

There is just one catch. So far, spontelectric solids are too small for us to see.

image captionThe lab at Heriot-Watt University creates the particular conditions needed to create spontelectric materials

"The human hair is about one micron across," the professor says.

"We're working with films that are typically between ten and 50 nanometres, which is a hundred times smaller."

That means spontelectrics can only be looked at indirectly for now, with an infra-red spectrometer.

As well as laughing gas and carbon monoxide the Heriot-Watt team is now working with a more complex molecule, ethyl formate. The temperature required to transform that into a spontelectric solid is not quite so low.

In years to come there could be spinoffs for our everyday world. One possibility could be better and longer lasting video displays if the spontelectric effect can be used to make new kinds of organic light emitting diodes.

Until then it's giving us an tantalising glimpse of a possible answer to one of the biggest questions of the lot: why we're here at all.

image captionPrecision instruments such as this sample holder are used in the work

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