Zeolites and zeotype materials are the most common micro-porous inorganic materials employed in industrial processes. The three-dimensional network structure of these materials is well understood and is typically formed by tetrahedral SiO44- building blocks. The idea to fine tune the material’s properties while maintaining its robustness has impelled researchers to selectively replace the tetrahedral units by other building blocks. Among others, mixed-polyhedra materials with pentahedral and octahedral units are today established worldwide, combining the well-known tetrahedral SiO44- building unit with mainly transition metal centers.
The research group at the University of Aveiro has pioneered these investigations focusing on the incorporation of rare-earth, preferably lanthanide, cations into inorganic networks. Similar to other zeotype materials the mixed-polyhedra materials are prepared using high temperature and high pressure techniques, mimicking nature’s approach. Materials with fascinating photoluminescent properties are usually obtained. To understand the nature of the photoluminescence the knowledge of the newly synthesized material’s crystal structure is of crucial importance.