A Ray of Hope for Better UV Blocking

Jen Rygel in the XPS Lab
Graduate student Jen Rygel in the XPS Lab

Protection from ultraviolet (UV) radiation may get a little stronger, thanks to a glass innovation developed by researchers at Penn State. They have determined that adding cerium oxide to phosphate glass, rather than the silicate glass commonly used for eyeglasses and windows, makes a more effective UV blocking material.

Cerium exists in two states in glasses - cerium (III) and cerium (IV) - and both states strongly absorb ultraviolet light. Cerium has typically been added to silicate glass to enhance its ultraviolet absorbing capacity. However, silicate glass can only dissolve so much cerium before it becomes saturated and can hold no more, while also turning yellow with high concentrations of cerium.

Because of cerium's beneficial properties, the Penn State research team explored approaches to adding larger amounts of it into glass without discoloration. They focused on phosphate glasses, which have a more flexible structure then silicate glasses and can potentially incorporate higher percentages of cerium.

The researchers synthesized and compared 11 glasses with varying concentrations of cerium, aluminum, phosphorus, and silica and determined that they could make phosphate glasses with 16 times more cerium oxide than silicate glasses without discoloration.

In addition to more effectively blocking UV light, increasing a glass' cerium concentration also enhances its resistance to radiation damage from x-rays and gamma rays by capturing freed electrons, according to the researchers.

Authors on the article, - Synthesis and properties of cerium aluminosilicophosphate glasses, - which appeared in the 15 December issue of Non-Crystalline Solids were Jen Rygel, graduate student in materials science and engineering, and Carlo Pantano, distinguished professor of materials science and engineering.

Source - TMS (The Minerals, Metals & Materials Society) by Lynne Robinson. For more information visit http://live.psu.edu/story/43506

This article was featured in Focus on Materials - Winter 2010.