amorphous material

A sheet of paper left on a wet table warps and lifts its edges. No one controls that motion, but it follows the same laws as plant growth: some areas of the sheet shrink more than others, and the flat form becomes three-dimensional. Engineers have long dreamed of taming this process so that a flat blank folds itself into a desired sculpture. In the new work, that trick succeeded with accuracy down to one percent.

A slice of eucalyptus a tenth of a millimeter thick is placed under a polarized light microscope, and the wood suddenly blooms: blue, yellow, and pink bands twist into spirals, forming rings and swirls. This is not paint but the play of light: the cellulose fibers that make up cell walls transmit light differently depending on their orientation.

When light hits ordinary plastic, some of it reflects, like a glare on a window. To eliminate this glare, a special coating made of tiny structures is applied to the surface, which cancels out the reflection.

Glass lenses and mirrors appear perfectly smooth and still. But beneath the surface, a hidden life teems. Atoms in an amorphous material (a substance without a crystalline lattice) are packed haphazardly, and this disorder creates a complex energy landscape, like a mountainous region with countless hills and valleys.

Imagine a multilayered shell where metal and insulator layers alternate like pages in a book. Such a structure can make an object hidden inside invisible to an observer. Light bends around it as water smoothly flows around a smooth stone: no ripple, no splash — no reflection, no shadow.

A crystal is like a row of soldiers on a parade ground: every atom is in its place, and electrons march through it in neat waves. An amorphous material is like a crowd at a train station, where there is no order, just a jostling throng. In such a crowd, an electron usually gets stuck quickly, like a person trying to push through a dense mass of people.

Tile a floor with identical triangles, and you get a boring repeating pattern. But what if you want the pattern to never repeat, yet use just one tile? For a long time, mathematicians were sure it couldn't be done: you'd need at least two different shapes. The famous Penrose mosaic is a case in point: rhombi with acute and obtuse angles arrange into an infinitely varied but strictly ordered pattern.

Plutonium is a metal with attitude. One form shrinks when cooled, another swells. But at room temperature, the alloy behaves strangely: the ruler says one thing, X-rays say another. The ruler shows the sample barely grows, while X-rays see atoms in the crystal lattice moving further apart.

A wafer-thin film of organic molecules was grown on a silicon substrate. In this film, as if on a sheet of graph paper, tiny "pens"—artificial atoms — were laid out with the tip of a scanning tunneling microscope.

Ordinary window glass may seem frozen forever, but inside, atoms never stay still. In amorphous germanium telluride (GeTe)—a material used in rewritable discs and non-volatile memory — physicists have for the first time directly tracked how atomic bonds stretch and bend in trillionths of a second.

Cells on the surface of an embryo resemble grains of rice that can align in one direction. This order is called nematic. It arises when cells start acting in concert, like a school of fish swimming in the same direction.

Silicon is like a universal building block: it goes into the chips in your phone, solar panels, and lasers. But if you squeeze it with immense force, the atoms rearrange into new patterns: these forms are called allotropes. One of them, Si-XIII, was first spotted more than twenty years ago, but its exact pattern remained a mystery.

When you press your finger on a piece of soft putty, it obediently dents and then slowly returns to its original shape. But if you press on a window pane, it either holds or cracks — no smooth deformation. Both materials are amorphous: their atoms are not arranged in a strict crystal lattice like in metal. Yet they behave completely differently.

A handful of lead sulfide nanocrystals coated with charged molecules spontaneously assembles into a perfect crystalline lattice. Each nanocrystal is like a brick just a few nanometers across, while the charged molecules on its surface act as the mortar.

In the air of factory floors and laboratories, invisible solvent molecules drift. One of them, acetonitrile, has a faint smell, but at high concentrations it can harm health. Typical sensors for it are bulky and expensive, but here we have a thin crystalline film that responds on its own to the presence of vapor.

Open systems exchange energy with their surroundings, like a guitar string fading into the air. Scientists built such a system out of light, twisting the beams into corkscrews and forming an artificial lattice — a maze where losses can be controlled at every step. Light in this maze always moves at the maximum possible speed, but its energy can fade or grow.

In the world of microchips, where streams of photons, quanta of light, carry information, a fundamental problem arises: light passing through matter inevitably heats it. This heating spawns thermal fluctuations — chaotic, unpredictable jostling of atoms that disrupts precise device operation.