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Why does barium titanate have a much higher dielectric constant than many common materials?

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Figure 1: Ferroelectric properties of barium titanate (BaTiO3). (Left) Above 120° C the structure of the BaTiO3 crystal is cubic, and there is no net polarization of charge; (right) below 120° C the structure changes to tetragonal, shifting the relative positions of the ions and causing a concentration of positive and negative charges toward opposite ends of the crystal. — capacitor dielectric and piezoelectric ceramics Figure 1: Ferroelectric properties of barium titanate (BaTiO₃). (Left) Above 120° C the structure of the BaTiO₃ crystal is cubic, and there is no net polarization of charge; (right) below 120° C the structure changes to tetragonal, shifting the relative positions of the ions and causing a concentration of positive and negative charges toward opposite ends of the crystal.

Barium titanate (BaTiO $_{3}$ ) possesses a significantly higher dielectric constant than many common materials primarily due to its ferroelectric properties, which arise from its unique perovskite crystal structure.12

At temperatures below its Curie point (approximately 120 °C), the crystal structure of barium titanate undergoes a transition from cubic to tetragonal symmetry. During this shift, the central titanium ion (Ti $^{4 +}$ ) moves away from the center of the unit cell, while the barium and oxygen ions also shift from their cubic positions. This displacement creates a permanent electric dipole within the structure.123

These dipoles spontaneously align in clusters known as domains. When an electric field is applied, such as in a capacitor, the boundaries between these domains shift, allowing domains aligned with the field to grow at the expense of others. This process produces a large net polarization, which directly increases the material's capacitance and results in an exceptionally high dielectric constant.134