How does calcium substitution affect the temperature range of barium titanate’s dielectric peak?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

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.

In barium titanate (BaTiO $_{3}$ ), the substitution of calcium (Ca $^{2 +}$ ) for barium (Ba $^{2 +}$ ) ions is used to modify the material's ferroelectric properties. Specifically, this chemical substitution broadens the temperature range at which the dielectric constant peak occurs.1

This modification is significant because pure barium titanate exhibits a sharp, large peak in its dielectric constant near the Curie point, a characteristic that is often undesirable for applications requiring stable capacitor performance. By broadening this peak, calcium substitution helps stabilize the material's dielectric response across a wider range of temperatures.1