A Strange Material That’s Not Quite Crystal, Not Quite Glass

Scientists at the University of Michigan have discovered that quasicrystals—unusual solids that look part-crystal, part-glass—can actually be the most stable arrangement of atoms for certain materials. This is surprising because for decades, quasicrystals were considered “impossible” structures that shouldn’t naturally form.

What Exactly Is a Quasicrystal?

In a normal crystal (like salt or quartz), atoms line up in a pattern that repeats over and over, like tiles on a bathroom floor.

Quasicrystals also have a structured pattern, but the pattern never repeats. It’s orderly, but not repetitive—something like a beautiful mosaic that never exactly copies itself.

They were first discovered in 1984 by Daniel Shechtman, who found a metal alloy whose atoms formed a shape resembling many 20-sided dice stuck together. This shape has five-fold symmetry (it looks the same from five different angles), which scientists once believed was impossible in solid matter. Shechtman received a Nobel Prize for this discovery, though at first many people didn’t believe him.

Why Are Quasicrystals So Odd?

Quasicrystals sit somewhere in between:
• They have orderly, crystal-like regions.
• But their structure never repeats, like glass.

For years, scientists didn’t know: Are quasicrystals stable because of low energy (like crystals) or because of high entropy (like glass)?

How the Researchers Solved the Puzzle

To answer this, the Michigan team built the first quantum-level computer simulations of quasicrystals.

The problem: the usual simulation method assumes the atomic pattern repeats forever. Quasicrystals don’t do that.

The solution: the researchers took small chunks (nanoparticles) from a simulated quasicrystal and calculated the energy of each chunk. By doing this for different sizes, they could work backward and estimate the energy of the full material—no repeating pattern needed.

Their results show that two well-known quasicrystals (one made of scandium and zinc, another of ytterbium and cadmium) are actually energy-stable, just like normal crystals.

In other words, quasicrystals aren’t mistakes or frozen-in glassy states—they are naturally stable structures.

A Big Computing Breakthrough Too

Running these simulations normally takes enormous computing power. If you double the number of atoms, the time can increase eightfold.

To get around this, the researchers developed a new algorithm that speeds things up by as much as 100 times. Instead of every computer processor talking to every other one, only neighboring processors communicate. They also took advantage of supercomputers’ graphics processors (GPUs).

This new method could help scientists simulate other tricky materials, like glass, disordered solids, defects inside crystals, and even materials for quantum computers.