Colossal dielectric anisotropy in Nb-doped SrTiO3 single crystal: Superior comprehensive performance of the [310] orientation

First systematic study of dielectric anisotropy in Nb:SrTiO 3 single crystals across seven orientations. • [311] shows the highest permittivity (2.35 ×10 5 ) but poor stability; [100] shows the lowest loss (<0.056) and excellent stability. • [310] orientation best balance defect concentration, electron binding, and dynamic response for orientation engineering. High-quality Nb-doped SrTiO 3 single crystals were successfully grown via the Verneuil method, and their dielectric properties were systematically investigated with respect to crystallographic orientation. The [311] orientation achieves the highest permittivity of 2.35 × 10 5 , accompanied by high Ti 3 ⁺ and oxygen vacancy concentrations, but exhibits poor frequency and temperature stability. In contrast, the [100] orientation shows the lowest permittivity of 6.0 × 10 4 , the lowest dielectric loss (<0.056), and excellent stability, attributed to its low defect concentrations and strong electron binding capability. Remarkably, the [310] orientation achieves an optimal balance, delivering a permittivity of 1.63 × 10 5 , a capacitance temperature variation of less than 8.5% from room temperature to 300 °C, and a high-frequency loss below 0.085, exhibiting outstanding thermal stability in the tested temperature range for capacitor applications. These findings provide direct guidance for designing textured polycrystalline ceramics and demonstrate that orientation engineering is a viable strategy for developing high-performance colossal dielectric materials. Download: Download high-res image (160KB) Download: Download full-size image