*2.4. Powder X-ray Diffraction (PXRD)*

Powder X-ray diffraction data were collected using a Bruker D8 Advance Vαrio diffractometer (Bruker-AXS, Karlsruhe, Germany) equipped with a LYNXEYE detector and Cu-Kα1 radiation (1.5406 Å). All the profile fittings were conducted using the software Diffrac.TOPAS 6.0 [21]. The bulk phase purity was checked by Le Bail profile fitting, using cell parameters from structural crystallographic information of the constitutive phases—namely FUR, ETZ, and PRX—as well as the new reported phases. In these fittings, only the background, unit cell parameters and zero error were refined. Rwp values obtained in all cases demonstrate an excellent agreement between the structural model and the bulk phase measured by powder diffraction.
