Eco-friendly ferroelectric oxides for energy applications

The growing global demand for sustainable technologies has driven the development of new functional materials capable of addressing current energy and environmental challenges. In this context, ferroelectric materials have gained special relevance due to their multifunctional capabilities, making them promising candidates for applications such as energy storage, actuators, sensors, and solid-state cooling systems. Among them, barium titanate (BaTiO₃) stands out as one of the most widely studied materials due to its ferroelectric behavior at room temperature, low cost, ease of synthesis, and especially for being lead-free, an increasingly important factor in the effort to reduce the use of toxic substances in electronic devices. 

The properties of pure BaTiO₃ can be improved by introducing dopants such as tin (Sn), which enable modifications in the crystal structure, expansion of the phase coexistence region, and optimization of the material's functional performance. Several studies have shown that the partial substitution of Ti⁴⁺ by Sn⁴⁺ in the perovskite lattice of BaTiO₃ enhances the functional response of the system, enabling new or improved applications. Therefore, the BaTi_1-xSn_xO₃ system represents a promising platform for the development of advanced ceramic materials with potential use in efficient electrical energy storage and environmentally friendly cooling technologies without moving parts.   
This thesis presents a detailed experimental study of the BaTi_1-xSn_xO₃ system for compositions with x = 0.03, 0.06, 0.09, 0.12, 0.15, and 0.20, synthesized using the conventional solid-state reaction method. The structural, dielectric, and ferroelectric properties of the materials were investigated with the aim of evaluating their potential for applications in energy storage and solid-state cooling. The phase transitions, electrocaloric response, and energy storage performance were analyzed, identifying the optimal compositions with high recoverable energy density and remarkable electrocaloric strength.