Investigation of phase transition in ferroelectric Pb0.70Sr0.30TiO3 thin films

Abstract

We have carried out dielectric and Raman spectroscopy studies at the 298 -623 K temperature range in polycrystalline Pb 0.70 Sr 0.30 TiO 3 thin films grown by a soft chemical method. The diffuse phase-transition behavior of the thin films was observed by means of the dielectric constant versus temperature curves, which show a broad peak. Such behavior was confirmed later by Raman spectroscopy measurements up to 823 K, indicating that a diffuselike phase transition takes place at around 548 -573 K. The damping factor of the E(1TO) soft mode was calculated using the damped simple harmonic oscillator model. On the other hand, Raman modes persist above the tetragonal to cubic phase transition temperature although all optical modes should be Raman inactive. The origin of these modes was interpreted in terms of a breakdown of the microscopic local cubic symmetry by chemical disorder. The lack of a well-defined transition temperature and the presence of broad bands at some temperature interval above the ferroelectric-paraelectric phase-transition temperature suggested a diffuse nature of the phase transition. This result corroborates the dielectric constant versus temperature data, which showed a broad ferroelectric phase transition in this thin film.

Study of phase transition in (Pb,Ba)TiO3 thin films

“…5 and 7, the temperature dependence of the damping factor of the E͑1TO͒ mode was not well fitted; therefore, it was impossible to fit the data over 573 K. Fu et al 33 reported similar phonon mode behaviors for PbTiO 3 thin films deposited on Pt/Si substrates, whose transition phase temperature was estimated by the damping factor. Pontes et al 34 reported similar behaviors in Pb 0.7 Sr 0.3 TiO 3 thin films.…”

Structural transition on Pb1−xSrxTiO3 produced by chemical method

“…Polycrystalline Pb1−xSrxTiO3 (0 ≤ x ≤ 1) (PST) powders were prepared by the complex polymerization method, which provides samples with high composition accuracy and homogeneity [30][31][32]. To prepare the samples, we used commercially available reactants such as lead acetate trihydrate [Pb(CH3COO)2·3H2O] (>99% purity, Aldrich), strontium carbonate (SrCO3) (>98% purity, Aldrich), titanium isopropoxide [Ti(OCH(CH3)3)4] (>97% purity, Alfa Aesar).…”

Effect of Ba2+ – Sr2+ co-substitution on the structural and dielectric properties of Lead Titanate

“…From the family of perovskite structured ferroelectrics, A 2+ B 4+ O 3 type compounds that contain Ti 4+ , solid solutions of BariumStrontium Titanate, Lead-Barium Titanate, Lead-Strontium Titanate have been investigated extensively [7,8]. Perovskite materials based on lead titanate (PbTiO 3 -PT) are especially relevant as functional layers in piezoelectric, ferroelectric, pyroelectric and other devices and are found to emerge as materials of great importance due to their rich physical properties [9]. Recently lot of efforts have been taken to synthesize PT based bulk samples and thin films; and are extensively studied by modifying their properties with various techniques, employing suitable method of preparation, selecting appropriate substitution of cations etc.…”