First Realization of Transparency of Polycrystalline SrZrO₃ Perovskite Ceramics: Insights into Structural, Optical, and Dielectric Performances

Abstract

Transparent dielectric ceramics endowed with excellent optical, electrical, and photoelectric properties have attracted considerable attention in the past decade. The development of SrZrO₃ transparent dielectric ceramics in this work is pioneered for the first time. Combining the pore‐free microstructures with the highly symmetrical crystal structures, the dielectric properties of SrZrO₃ ceramics are improved significantly, including extremely large dielectric constants of ≈195–236 and quite low dielectric losses of ≈0.001–0.056 in the frequency scope from 1 kHz to 1 MHz. The transparent SrZrO₃ ceramics crystallize in a primary face‐centered cubic structure together with a trace of orthorhombic phase. The best SrZrO₃ specimen exhibits a high in‐line transmittance of ≈71% at 633 nm, a high refractive index of ≈2.02, a fine average grain size of ≈2.3 µm, a wide indirect bandgap of ≈5.7 eV, an oxygen ion polarizability of 2.42 ± 0.07 ų, and optical basicity of 0.978 ± 0.019. The chemical bonds of Zr─O and Sr─O in SrZrO₃ both pertain to ionic bonds, where the Zr─O bond is more stable than the Sr─O bond. The low‐level antisite defects are readily formed, which in turn cause selected optical absorption and reflectivity to partial visible and ultraviolet light.