Ho Sueb LEE1, Hyo-Eun KIM1, Jin Soo KIM*1, Kwang-Sei LEE2
1 Department of Physics and Center for Research Facilities, Changwon National University, Changwon 51140, Korea
2 Department of Nano Science & Engineering, Center for Nano Manufacturing, Inje University, Gimhae 50834, Korea
Correspondence to: kimjjin@changwon.ac.kr
Received August 16, 2017; Revised September 12, 2017; Accepted September 27, 2017.
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Abstract
We have synthesized lead-free (Na$_{0.5}$K$_{0.5}$)NbO$_3$ (NKN) ceramics and used Raman spectroscopy to investigate the temperature dependences of the internal vibrational mode. With increasing temperature, the Raman peaks broadened and the peak frequency shifted to lower frequency. Especially, changes in the Raman peak's frequency were observed at the phase transitional temperatures of $T_{O-T}$ (orthorhombic-tetragonal) and $T_c$ (tetragonal-cubic). We discuss the temperature dependences of the Raman spectra related to the internal vibrations of NbO$_6$ octahedra and compared the results to dielectric behavior.