Raman Scattering Studies of Lead Free (1-x)K_0.5Na_0.5NbO₃-xSrTiO₃ Relaxors

Abstract

We present the first results of FT NIR Raman studies of (K _0.5 Na _0.5 NbO ₃ ) _{1 − x} (SrTiO ₃ ) _x (x = 0.25, 0.20, 0.15) relaxors made in wide temperature range. Although the crystal structure of the investigated relaxors exhibits a pseudocubic symmetry Raman spectra are observed. The Raman spectra of (K _0.5 Na _0.5 NbO ₃ ) _{1 − x} (SrTiO ₃ ) solid solution resemble those observed for orthorhombic K _0.5 Na _0.5 NbO ₃ . The results are discussed in the frame of molecular dynamics of NbO ₆ octahedral network. It was found that, the changes in dynamics of NbO ₆ molecular groups appear at T ≈ 196 K for x = 0.25, T ≈ 254 K for x = 0.20 and T ≈ 336 K for x = 0.15.

Keywords:

• (K_0.5Na_0.5NbO₃)_1−x (SrTiO₃) _x
• relaxors
• Raman scattering

Acknowledgments

The paper was supported by the Grant No. 1 P03B 03028 (2005–2007) from the budget funds for science in Poland.