Miniature Flowers of Chalk and Glass

By Selina Haefeli

Minerals assemble themselves into exquisite nanoscale flower bouquets.

The shapes that materials in nature take on are determined by some simple rules of chemistry.  Basically, if you can change a solution’s temperature, the amount of CO2 or its pH—that is, its acidity and alkalinity—you can actually alter the way a material grows. In an elegant study conducted by chemists at Harvard, tiny floral structures have been fashioned by manipulating these conditions in a beaker containing chalk, glass and water.

“When you look through the electron microscope, it really feels a bit like you’re diving in the ocean, seeing huge fields of coral and sponges,” described lead researcher Wim Noorduin in a Harvard press statement. “Sometimes I forget to take images because it’s so nice to explore.”

The scientists used an instrument called a scanning electron microscope (SEM) to see the tiny structures self assemble. They noticed some interesting patterns that occurred as a result of changing the conditions in the beaker. For example, when the concentration of carbon dioxide was increased, the minerals developed a “broad leafed” structure and reversing the pH gradient created curved, ruffled petal shapes. Each individual flower is roughly fifty micrometers high, which is around the width of a strand of human hair.

Source: [Science]