How a TV catchphrase inspired a synthetic chemical compound

Chemistry World

BaZnGa was originally published in Chemistry World as part of the Chemistry in its elements: compounds series.

If you’re familiar with the TV show The big bang theory, you’ll know the catchphrase of one of the leading characters, physicist Dr Sheldon Cooper, ‘Bazinga!’ sometimes written out as the chemical element symbols Ba Zn Ga, for barium, zinc and gallium. But you’d have to be a hardcore chemistry fan to sit in front of your TV and wonder if you could actually make that compound in real life. Yet that’s exactly what Iowa State University graduate student Na Hyun Jo did.

Talking to the head of her lab, materials scientist Paul Canfield, Na Hyun realised that nobody had tried to make BaZnGa before (or to give it its formal name, barium zinc gallide), and that it might have some interesting properties. So they gave it a go.

To make BaZnGa, they heated barium and zinc to 800°C over five hours, kept it there for 12 hours, then cooled it back down to 400°C over a further 12 hours. Then they mixed the resulting material with gallium, stuck it in a sealed silica tube and heated it back up to 800°C for five hours. Finally, they cooled it back down over five days. At the end, Na Hyun was rewarded with plate-shaped crystals of BaZnGa. ‘Bazinga!’ as Sheldon would say.

Looking more closely at the compound, the team discovered that BaZnGa has a crystalline structure unique for any combination of these elements. It features identical double layers of octahedrons, each made of layers of zinc and gallium atoms separated by sheets of barium. The crystals are also very sensitive to oxygen, so they need to be carefully handled in an atmosphere of argon or nitrogen.

Bazinga molecule (BaZnGa)

Source: © 2017 Taylor & Francis

The structure of BaZnGa. Barium is shown in red. The other sites in green, cyan and blue can be occupied by zinc and gallium

Before Na Hyun and Paul made BaZnGa, nobody knew what it would be like. And it would have been amazing if a TV catchphrase had inadvertently predicted a major new material. After all, another material containing barium, zinc, gallium and oxygen – known as a barium zinc gallate – is conductive. But, alas, it was not to be.

Despite carrying out multiple tests, BaZnGa turned out to have no interesting properties at all. It doesn’t become a superconductor at low temperatures. It isn’t particularly conductive or magnetic, and it doesn’t change structure as the temperature changes either. So it’s unlikely to be useful for anything except selling mugs, T-shirts and other merchandise with the chemical formula on it.

Although Na Hyun and Paul didn’t inadvertently find a new chemical blockbuster, they’re glad they tried. In an Chemistry World interview with Tabitha Watson, Paul explained that his team are trying to invent and study brand new materials, so they have to get their inspiration from somewhere. ‘You interview the material by doing measurements and see what it has to offer. This is the nature of basic research – sometimes you explore at the edges of knowledge.’ That’s a nice lesson for every scientist to take to heart, especially when you’ve spent a long time making an exploratory compound based on a joke in a comedy show.

I’ve now spent far too long trying to spell out words using the periodic table. I’ve spotted CoPErNiCuS (cobalt, phosphorus, erbium, nickel, copper and sulfur), GeNiUS (germanium, nickel, uranium and sulfur) and three different ways of making bacon (BaCoN, BAcON and BaCON). However, the closest I’ve got to a catchphrase is an impossible molecule made of two argon atoms and hydrogen, creating Alan Partridge’s famous ‘Ar-H-Ar!’

Kat Arney