In the tungsten bronze family, one material was considered the quiet one. When cooled, its siblings rearrange their electrons into wave-like patterns, but it did not, or so it was thought until recently.

Now it turns out that this material also undergoes rearrangement. At 290 K, just below room temperature, a charge density wave emerges in the monoclinic compound (one crystal form). Electrons that were previously spread uniformly across the crystal gather into stripes, like sand on a beach after the tide goes out. The period of these stripes does not match the atomic lattice spacing — the pattern is incommensurate.

The discovery was made using X-ray scattering and resistance measurements. Both methods showed the same thing: at 290 K, the material changes its behavior. Above the transition, at higher temperatures, the crystal exhibited a 'trembling'—atoms oscillate in a peculiar way, foreshadowing the rearrangement. This trembling was observed via diffuse and inelastic X-ray scattering.

Previously, this material was thought to be an exception in the family. Now it is clear: there are no exceptions. The transition at 290 K is the highest-temperature one among similar compounds. This is important for understanding how electrons self-organize in crystals and could be useful in electronics, where such transitions are used to switch states.