Boron: The Tough Guy of the Periodic Table | Advantages of Boron in Borosilicate Glass | Corning

Boron is considered a “low-abundance” element in the solar system and makes up only 0.001% of the Earth's crust. Yet, despite its modest representation in the universe, it is extremely prevalent in Corning’s research and development labs. In fact, if you were to go through our inventory of glass compositions, you would find hundreds of borosilicates – i.e., glasses that feature boron and silicon dioxides, versus conventional soda-lime glass, which is used in windows and bottles.

Why is boron so popular? A big part is its tough guy appeal. Boron enables glasses with strong chemical durability. It also has a very low coefficient of thermal expansion. That means borosilicate glasses withstand faster temperature changes than soda-lime glass.

Corning’s first significant application of borosilicate glass is a product you’re probably familiar with: PYREX® glass. Like the world’s most-beloved superheroes, PYREX glass has a great origin story. In 1915, Corning physicist Dr. Jesse Littleton was trying to develop a heat-resistant glass. One night, he brought home a sawed-off battery jar made of an experimental glass composition. His wife Bessie used it to bake a sponge cake, proving the glass could be used in the oven… and giving birth to the legendary line of cookware and laboratory glass. 

What makes PYREX glass so temperature resistant?  It has to do with how glass expands and contracts when heated and cooled. When a material gets hot, its atoms vibrate more. The object then expands as the space between the atoms increases. Boron vibrates much less than alternative elements and expands less as a result.

But boron’s appeal doesn’t end there. It lowers the devitrification temperature of the glass (the temperature at which it forms crystals), which makes it easy to melt. In addition, it reduces the viscosity of a glass at any given temperature. That makes it easier to mix and allows bubbles to rise out of the glass. Those qualities also increase the manufacturability of new glasses by ensuring the glass flows smoothly through Corning’s systems. As a result, boron has made numerous technical glasses possible, including our new Corning® Astra™ Glass, a glass substrate that enables extremely high pixel density for high-performance displays.

But even though Corning appreciates the softer side of boron, we also keep coming back to it for its toughness. Case in point: Boron is one of the key ingredients in the early Corning® Gorilla® Glasses.

While boron’s temperature resistance was well known, our discovery of its damage resistance was more serendipitous. When developing new compositions, researchers routinely score the glass and break it along the score mark.  Research Fellow Dr. Matthew Dejneka recalls working on early Gorilla Glasses and experimenting with a formula that included boron. “I had to sit on the glass with all my weight to get it to break along the score line,” Dejneka says. “We had been using boron for bubble removal, and in the process, we discovered that it gave us this great damage resistance.” 

Some say long-term relationships lose their spark. But after more than 100 years, boron is still surprising us with its capabilities.