Metal organic compounds produce a new class of glass, according to The Pennsylvania State University.
March 13, 2018
by Canadian Packaging staff
Human beings have been making glass made from silicon dioxide since prehistory, perhaps after seeing it formed via lightning strikes or volcanic activity.
With industrialization, humans created glass made from boron, polymers and metallic compounds.
But now, researchers from Penn State and labs across Asia, Europe and Australia have worked together to create a new type of glass, a metal-organic hybrid glass made of zinc, and imidazolate and benzimidazolate, two organic compounds.
Glass forming is the liquid avoiding crystallization during cooling.
“Glass is a liquid frozen into a solid-like material in noncrystalline form,” says Penn State professor of material sciences and engineering John C. Mauro. “Mechanically it behaves as a solid but it is somewhere between a liquid and a solid.”
For this new type of metal-organic glass, researchers substituted zinc in place of silicon, and then used similar but different organic compounds at the corners which randomly take the place of teh oxygen atoms at the tetrahedron corners.
According to Mauro, silica glass had the best glass-forming ability of all glasses until the researchers synthesized the zinc-based ZIF-62 metal-organic glass. The more the benzimidazolate organic compound incorporated into the metal-organic framework, the better the glass was able to form.
While standard silica glass is brittle as we are all aware, ZIF-62 not only has the best glass-forming ability of the existing 50 types of glasses but it is also far more pliable than the silica type, which lends to its glass-forming ability.
Making ZIF-62 is more difficult to manufacture than silica glass.
After having to synthesize imidazolate and benzimidazolate and mix it with hydrous zinc nitrate and a solvent, the whole mixture needs to be place within an 800F environment to melt it. At 980F—too hot—the mixture will vaporize.
“This family of glasses is so new that, while we have determined its glass-forming ability and a few other properties, we have not fully characterized all of its material properties,” says Mauro. “There also needs to be research into how to scale-up this process for manufacturing.”
Next up, the researchers plan on examining the creation of a cobalt-based glass.
Image at top shows the tetrahedral structure of ZIF-62. Ang Qiao / Penn State