Piezoelectricity in non-ferroelectric Bi₁₂TiO₂₀-BaSnO₃ amorphous ceramics

Bi₁₂TiO₂₀-BaSnO₃ (BTO-BSO) amorphous ceramics, which contain approximately 39% volume fraction of Bi₁₂TiO₂₀ and approximately 61% volume fraction of BaSnO₃, were fabricated via an interfacial interaction between the presynthesized BaSnO₃ and the Bi₁₂TiO₂₀ phases. Although neither BaSnO₃ nor Bi₁₂TiO₂₀ are ferroelectrics, the as-sintered BTO-BSO amorphous ceramics were found to exhibit both direct and inverse piezoelectric effects. Using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Raman techniques, we determined a normal crystalline BaSnO₃ and an obviously deformed nearly amorphous Bi₁₂TiO₂₀ in these sintered composites. The present work confirms the macroscopic polar nature of the plastically deformed amorphous Bi₁₂TiO₂₀ in the non-ferroelectric BTO-BSO amorphous ceramics. The presynthesized crystalline BaSnO₃ can effectively suppress recrystallization of the Bi₁₂TiO₂₀, which is also a key factor to fabricate these non-ferroelectric semicrystalline polar materials.