Optical dispersion and bandgap of pure and Mn-doped 0.92Na0.5Bi0.5TiO3-0.08K0.5Bi0.5TiO3 lead-free single crystals |
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| Authors: | Yang Wu Yuqing Hu Saidong Xue Xiangyong Zhao Feifei Wang Yanxue Tang Zhihua Duan Wangzhou Shi Haosu Luo Renbing Sun |
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| Affiliation: | 1. Key Laboratory of Optoelectronic Material and Device, Department of Physics, Shanghai Normal University, Shanghai, China;2. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China;3. School of Materials and Chemical Engineering, Ningbo University of Technology, Ningbo, China |
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| Abstract: | Optical properties of lead-free ferroelectric pure and Mn-doped 0.92Na0.5Bi0.5TiO3-0.08K0.5Bi0.5TiO3 (NBT-8KBT) single crystals have been investigated systematically. Refractive index and extinction coefficient were measured and the critical parameters are obtained by modified Sellmeier dispersion equations and single-oscillator dispersion relation. The decline of refractive index for Mn:NBT-8KBT could be related to the lattice distortion of the Mn ions doping. High transmittance (>70%) over the transparent region (>400 nm) was found in the pure NBT-8KBT, higher than that of Mn:NBT-8KBT, which could be caused by the increase of domain wall density. An about 100 nm red-shift of absorption edge was observed in the Mn:NBT-8KBT single crystal, which is located in the visible region. Optical bandgap energies calculated through Tauc equation and a large bandgap difference of 2.96 and 2.62 eV occurs in the NBT-8KBT and Mn:NBT-8KBT, respectively, which illustrates the modulation of the band structures by Mn doping. |
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| Keywords: | bandgap Mn dopant NBT-KBT single crystal optical properties |
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