Investigation of crystallization and growth of oxides and metals towards sustainability

The present thesis summarizes the research activities conducted during the Ph.D. in Materials Science and Technology at the University of Parma, where the focus was on the study of fundamental mechanisms and innovative low-energy strategies in crystallization processes and metal production. The work primarily examined metal-induced crystallization (MIC) of silicon dioxide (SiO₂), aiming to lower energy requirements for the phase transformation from amorphous to crystalline states. The exploration involved how metal cations affect SiO₂ crystallization, employing alkali and alkaline-earth metal salts to drive crystallization at temperatures below those of conventional methods. The results provide evidence that alkali cations integrate into the SiO₂ crystal matrix, promoting cristobalite and tridymite formation, while alkaline-earth cations appear to act mainly as external catalysts, favoring quartz formation through a two-step mechanism involving silicate intermediates. This work offers insights into refining crystallization mechanisms to selectively and efficiently produce high-purity quartz, presenting the potential for reducing the energy footprint of SiO₂ production across various industries. A side project focused on the bulk synthesis of nanocrystalline iron using a homemade chemical vapor deposition (CVD) setup, which successfully produced iron films with nanometer-scale grain sizes and controlled morphologies. This study underscored the potential for producing dense, nanostructured materials with enhanced mechanical properties. These findings open further opportunities to optimize synthesis conditions for achieving the desired combination of small-scale features and bulk material applications, particularly in industrial sectors requiring high durability with reduced energy input. In conclusion, this thesis provides a step forward in understanding metal-catalyzed crystallization of SiO₂ and the synthesis of nanostructured metals, highlighting methods to reduce energy consumption and improve material performance that are critical for sustainable industrial development. The findings aim to contribute to the fundamental science behind these processes and pave the way for applied research to optimize production techniques, supporting a sustainable future for energy-intensive industries.