Hybrid Crystal Keeps Boosting Light Signals Even Under Extreme Pressure

A special kind of crystal, made from both organic and inorganic parts, can change how it interacts with light when squeezed. Scientists usually expect that squeezing such materials will weaken their ability to produce a second‑harmonic signal, a process where incoming light doubles its frequency. This happens because the lone‑pair electrons on certain atoms lose their activity when the material is compressed. In a surprising turn, researchers found that one crystal, built from thiomorpholine and antimony bromide units, actually gets stronger at producing this doubled light as pressure rises. Over a pressure span from nothing to almost nine gigapascals, the crystal’s signal grew more than twice its original strength. Even when the crystal changed its internal structure around 3. 5 gigapascals, the enhancement kept going.

By looking closely at the crystal’s structure and using computer simulations, scientists discovered that new bonds form between antimony atoms and sulfur when pressure increases. These bonds link small pyramidal groups of bromine and antimony into longer, zigzag chains. The new connections make the electron orbitals overlap more, spreading electrons across the crystal and boosting its optical response. The key point is that the improved bonding and electron sharing outweigh any loss in the activity of the lone‑pair electrons. In other words, the way atoms connect and share electrons becomes more important than the traditional lone‑pair effect when it comes to maintaining a strong second‑harmonic signal under pressure. These findings open up new possibilities for designing materials that can keep performing well even when subjected to extreme conditions, which could be useful in high‑pressure optical devices and sensors.

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