Vermiculites irradiated with ultraviolet radiation

• This work reports for the first time UV irradiation of commercial vermiculites.
• The changes induced by UV-radiation were studied by using X-ray diffraction (XRD)
• These changes occurred in a similar way to as temperature and vacuum do.
• UV radiation could be used to induce structural order in vermiculites in thin sheet

The present work reports the effects of ultraviolet radiation on commercial vermiculites for the first time. The changes induced by UV-radiation, dehydration–hydration and structural order–disorder, were studied by using X-ray diffraction (XRD). The results of XRD analysis indicated that these changes occurred in a similar way as temperature and vacuum do and they were more significant for vermiculites in powder form than in thin sheet. The larger crystallite size in the thin samples implied the presence of lower amounts of defects, improvement in the crystallinity and therefore increasing the structural order. Furthermore, ultraviolet radiation, being less penetrating and easier and cheaper to obtain than the gamma radiation, could be used as an alternative to induce structural order in thin sheet vermiculites. This success could be very important to solve some aspects related with the dimensionality of magnetic interactions, which plays a central role in controlling the critical dynamics of spin-glass systems (disordered magnet, where the magnetic spins of the component atoms — the orientation of the north and south magnetic poles in three-dimensional space — are not aligned in a regular pattern), and it is still not resolved in vermiculite due probably to its disordered structure. Also, the ultraviolet radiation as with gamma radiation probably might allow to enhance the physical properties of vermiculite as optoelectronic properties which would make it suitable for optoelectronic devices, although more investigation is needed.