Photoluminescence and electrical properties of Er3+-doped Na0.5Bi4.5Ti4O15—Bi4Ti3O12 inter-growth ferroelectric ceramics

Upconversion (UC) and electrical properties of Na0.5Bi8.5-xErxTi7O27 (NBT-BIT-xEr, 0.00⩽x⩽0.25) ceramics were studied. Structural analysis revealed that a single inter-growth structured phase exists in all samples and the Er3+ ion substituting for Bi3+ at the A-site increases the orthorhombic distortion. Under the 980 nm laser excitation, two characteristic green emission bands and one red emission band were situated at 527, 548 and 670 nm, corresponding to the transitions 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The optimal photoluminescence (PL) were found in the NBT-BIT-0.20Er sample, and the emission color transforms from green to yellowish green. Temperature dependence of fluorescence intensity ratio (FIR) for NBT-BIT-0.20Er was measured ranging from 290 to 440 K and its maximum sensitivity was calculated to be about 0.0020 K-1 at 290 K. Dielectric measurements indicated that TC slightly increased simultaneously with the decrease of tanδ. Therefore, this ceramic has potential applications for high-temperature multifunctional devices.