Successive crystallization of ferroelectric-based BaTi2O5 bulk glass studied by Raman scattering

Non-isothermal crystallization process of ferroelectric-based BaTi2O5 glass (BTO-glass) is investigated by in situ Raman scattering. The gradual change of Raman spectra clearly shows the successive crystallization of BTO-glass through metastable α and β phases. The increase of volume fractions obtained from the development of spectral intensities is analyzed by the Johnson–Mehl–Avrami formula. The results indicate homogeneous crystallization of α phase and subsequent inhomogeneous crystallization of β phase. Finally specially resolved observation reveals the phase separation of β phase on the surface and BaTi2O5 crystal phase in the inside.