Ferroelectric transition in an epitaxial barium titanate thin film: Raman spectroscopy and x-ray diffraction study
Abstract
We have performed x-ray diffraction and Raman spectroscopy measurements in the temperature range of 300-873 K on a single phase epitaxially oriented BaTiO3 thin film grown by pulsed laser deposition on a single crystal MgO substrate. The θ-2θ room temperature diffraction measurements and asymmetric rocking curves indicate that the film is very weakly tetragonal with the c-axis parallel to the plane of the film. X-ray diffraction measurements up to high temperature reveal only a change in slope in the perpendicular to the plane lattice parameter around 450 K (in bulk Tc=395 K) indicating that a diffuse-like of phase transition is taking place. Room temperature polarized Raman spectra show that the film is indeed tetragonal with C4v symmetry and with the a-axis perpendicular to the film plane. Monitoring of the overdamped soft mode and the 308 cm-1 mode confirms that the phase transition is taking place over a wide temperature range according to the x-ray results. The increase of the phase transition temperature is attributed to the stress effect induced by the substrate.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- September 2003
- DOI:
- 10.1063/1.1596720
- Bibcode:
- 2003JAP....94.3307E
- Keywords:
-
- 77.80.Bh;
- 77.84.Dy;
- 68.55.Jk;
- 77.55.+f;
- 78.30.Hv;
- 78.66.Nk;
- 61.66.Fn;
- Phase transitions and Curie point;
- Niobates titanates tantalates PZT ceramics etc.;
- Structure and morphology;
- thickness;
- crystalline orientation and texture;
- Dielectric thin films;
- Other nonmetallic inorganics;
- Insulators;
- Inorganic compounds