The destiny of a crystal is defined before it is born

New in situ X-ray scattering experiments reveal how additives act at the prenucleation stage. The research was carried out on ID15A with very challenging samples. The results could lead to more efficient and environmentally-friendly materials and are out now in Nature Communications.

Additives are small amounts of extra molecules mixed into a material as it forms crystals. They can slow down or speed up crystal formation, change the shape or size of the crystals, or even steer the process in a different direction. They do this by attaching to growing crystal surfaces or influencing how the first tiny crystals appear.

Although additives are widely used in areas like medicine and materials science, scientists still do not fully understand exactly how these small molecules exert such strong control over crystallisation. Until today, most studies have examined only one stage of the additive’s influence on the material, making it difficult to capture its effects throughout the entire non-classical crystallization pathway.

“If we had a better idea of how additives influence the different steps of mineral nucleation in a material, we could maybe tailor them to make materials, such as cement, more effective and environmentally friendly”,explains Alexander Van Driessche, researcher at the CSIC (Spain).

Now, Van Driessche, together with scientists at the ESRF, ISTerre in the University Grenoble Alpes, BASF and the University of the Basque country, studied the nucleation process of portlandite and gypsum, used in cement, using a multi-technique, in situ approach.

“We tracked the entire nucleation process, combining high-energy X-ray scattering on ID15A, potentiometric probes, and a co-titration routine, which allowed us to monitor the effects of additives from pre-nucleation clusters to amorphous intermediates”, says Annet Baken, first author of this study and former PhD student at ID15A.

The experiments on ID15A proved challenging, due to the very diluted samples.

“This led us to develop a new way to correct the scattering images, so we could extract the tiny amount of information hidden by charges accumulated in the detector. This method is also being published soon.”, explains Alejandro Fernandez-Martínez, researcher at ISTerre and visiting scientist at the ESRF.

The results showed that portlandite transitions gradually from a disordered to an ordered phase, whereas gypsum exhibits an abrupt transition. The researchers found that additive effects extend beyond the classical models, and they apply influence primarily during the prenucleation stage. They also simultaneously delay and accelerate the different stages of nucleation.

“Our work shows that by watching every stage of crystal formation in real time, we can start designing additives that guide the process instead of just reacting to it. It is a step towards making industrial crystallisation both smarter and hopefully more sustainable”, concludes Van Driessche.

Reference

Baken, A., Fernandez-Martinez, A., Lanson, M. et al. Additive-specific modulation of non-classical nucleation pathways. Nat Commun (2026). DOI : 10.1038/s41467-026-68583-1

This actuality was initially published by ESRF.

Updated on 29 janvier 2026