Temperature dependent Raman scattering in polycrystalline Bi4Ti3O12 thin films

Polycrystalline Bi4Ti3O12 thin films were prepared on quartz substrates by pulsed laser deposition. The films were crystallized in the orthorhombic layer perovskite structure confirmed by X-ray diffraction and Raman spectroscopy. The Raman spectra are strongly dependent on temperature. A subtle phase transition in the temperature range 473–573 K exists in polycrystalline BTO thin films, which is evidenced by the disappearance of the Raman band at 116 cm−1 and appearance of a new Raman band at 151 cm−1. The two broad Raman bands centered at the 57 and 93 cm−1 at 300 K break up into clusters of several sharp Raman peaks at 77 K, due to monoclinic distortion of orthorhombic structure at low temperature in the as-prepared Bi4Ti3O12 thin films.