bariumtitanium

Barium titanate, chemical formula BaTiO3, is a white crystalline ceramic that belongs to the perovskite family of oxides. In the ideal structure, Ba2+ ions occupy the larger A sites and Ti4+ ions sit on the smaller B sites within a framework of corner-sharing TiO6 octahedra. At room temperature BaTiO3 is a tetragonal ferroelectric, exhibiting spontaneous polarization that can be reversed by an external electric field. The material is insulating and has a relatively high dielectric constant for a ceramic, with a bandgap near 3.2 eV.

Temperature changes drive phase transitions in BaTiO3. As temperature increases, BaTiO3 moves from a low-temperature ferroelectric phase toward a cubic paraelectric phase above the Curie temperature, which is about 120°C. BaTiO3 also undergoes a sequence of structural changes at lower temperatures (from rhombohedral or orthorhombic to tetragonal to cubic) depending on composition and history, affecting its dielectric and piezoelectric properties.

Synthesis and processing typically involve solid-state reaction routes, starting from BaCO3 and TiO2, with calcination and high-temperature sintering to achieve dense ceramics. Doping and solid-solution strategies are widely used to tailor the dielectric constant, Curie temperature, aging behavior, and sintering characteristics. Common dopants include donor or acceptor elements to adjust electrical behavior and to enable lead-free piezoelectric or dielectric applications.

Applications for BaTiO3 are broad and include multilayer ceramic capacitors (MLCCs), pyroelectric and piezoelectric devices, electro-optic modulators, and temperature-sensitive components such as PTC thermistors. Its lead-free nature has contributed to ongoing research and commercial use in modern electronic and electromechanical systems.