Scientists produced new family of glass from metal-organic compounds

A metal-organic framework with ultrahigh glass-forming ability.

The comparison in Tg/Tm ratio between ZIF-62 and other types of glass-forming systems, including water (29, 30), oxide (33), metallic (34), and organic (35, 36)—good GFA typified by CPs, PMMA, B2O3, and SiO2 in contrast with the ultrahigh GFA of the ZIF-62.
The comparison in Tg/Tm ratio between ZIF-62 and other types of glass-forming systems, including water (29, 30), oxide (33), metallic (34), and organic (35, 36)—good GFA typified by CPs, PMMA, B2O3, and SiO2 in contrast with the ultrahigh GFA of the ZIF-62.

Since, prehistory, humans are using silicon dioxide to produce glass. Now an international team of researchers at Penn State has developed a new family of glass based on metals and organic compounds that stacks up to the original silica in glass-forming ability.

The glass is produced by melting the source materials and then somehow manage to cool them so that no crystals form. Rapid cooling or quenching are two most commonly used methods for this procedure. This shortens the time available for crystals to form due to the rapid temperature drop.

John C. Mauro, professor of materials science and engineering, Penn State said, “Glass-forming ability is the ability of a liquid to avoid crystallization during cooling. It is nothing but a liquid frozen into a solid-like material in noncrystalline form. Mechanically it behaves as a solid but it is somewhere between a liquid and a solid.”

The new metal-organic glass composed of two similar but different organic compounds at the corners — imidazolate and benzimidazolate. These organic molecules randomly take the place of the oxygen atoms at the tetrahedron corners.

Silica glass had the best glass-forming ability of all glasses until the researchers synthesized zinc-based ZIF-62 metal-organic glass, the researchers reported today (Mar. 9) online in Science Advances. They noticed that the more benzimidazolate incorporated into the metal/organic framework, the better the glass-forming ability.

The more viscous liquids with the bulkiest ligands tend to resist crystallization the best. ZIF-62 has the best glass-forming ability of 50 existing glasses and while standard silica glass is brittle, the metal-organic glass is far more pliable, which may also add to its glass-forming ability.

The zinc-based natural glass is harder to create than silica glass on the grounds that the natural mixes imidazolate and benzimidazole first should be incorporated, blended with hydrous zinc nitrate and a dissolvable. The blend at that point softens at around 800 degrees Fahrenheit. Temperature is imperative on the grounds that the blend needs to liquefy totally, however not achieve roughly 980 degrees Fahrenheit, and soon thereafter the liquid glass will vaporize.

Scientists observed some materials properties using a variety of spectroscopic approaches and x-ray diffraction. They also quantified molten glass’s mechanical properties and optical transmission.

Mauro said, “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. There also needs to be research into how to scale-up this process for manufacturing.”

The researchers would also like to identify other metallic-organic combinations to make different glasses. They next plan to look at a cobalt-based glass.