Evaluation of birefringence contribution to transparency in (1-x)KNN-xSr(Al0.5Ta0.5)O3 ceramics: A phase structure tailoring

Birefringence, intrinsic to anisotropic phase-structured ceramics, can cause severe light scattering hence low transmittance. In this work, by tuning the addition of Sr(Al0.5Ta0.5)O3 (SAT), we constructed a gradual phase structure evolution in K0.5Na0.5NbO3 (KNN) ceramics at room temperature (RT). Results exhibit that the KNN-0.16SAT ceramic with an isotropic phase structure shows the highest transmittance close to 70% at 2000 nm. The relationship between transparency and phase structure was then systematically investigated, and the contribution of birefringence to transparency was also evaluated in a proposed model. Our work confirms that the absence of birefringence benefits the transparency in the KNN-based transparent ceramics, and fills up the missing link between phase structure and transparency in related fields.