Influence of Ca concentration on the electric, morphological, and structural properties of (Pb,Ca)TiO3 thin films

Abstract

Pb 1Ϫx Ca x TiO 3 (0.10рxр0.40) thin films on Pt/Ti/SiO 2 /Si(100) substrates were prepared by the soft solution process and their characteristics were investigated as a function of the calcium content ͑x͒. The structural modifications in the films were studied using x-ray diffraction and micro-Raman scattering techniques. Lattice parameters calculated from x-ray data indicate a decrease in lattice tetragonality with the increasing content of calcium in these films. Raman spectra exhibited characteristic features of pure PbTiO 3 thin films. Variations in the phonon mode wave numbers, especially those of lower wave numbers, of Pb 1Ϫx Ca x TiO 3 thin films as a function of the composition corroborate the decrease in tetragonality caused by the calcium doping. As the Ca content ͑x͒ increases from 0.10 to 0.40, the dielectric constant at room temperature abnormally increased at 1 kHz from 148 to 430. Also calcium substitution decreased the remanent polarization and coercive field from 28.0 to 5.3 C/cm 2 and 124 to 58 kV/cm, respectively. These properties can be explained in terms of variations of phase transition ͑ferroelectric-paraelectric͒, resulting from the substitution the lead site of PbTiO 3 for the nonvolatile calcium.

The influence of Calcium doping on structural and electrical properties of ferroelectric Lead Titanate ceramic

“…All the peaks were indexed with great care and lattice parameter "d" was calculated by using hkl values. The present data and published data are in excellent agreement and are listed in table no.1[17].The XRD study also shows that with the increase of Calcium concentration the lattice constant "c" decreases while that of "a" increases [18,19]. These results attribute that the Ca ions occupying Pb ions site with smaller ionic radius.…”

Structural phase evolution of strontium-doped lead titanate thin films prepared by the soft chemical technique

“…Details of the preparation method can be found in the literature. 16,17 The polymeric precursor solution was spin-coated on substrates [Pt (140 nm)/Ti (10 nm)/SiO 2 (1000 nm)/Si] by a commercial spinner operating at 6000 rev/min for 20 s (spin-coater KW-4B, Chemat Technology, Northridge, CA), via a syringe filter to avoid particulate contamination. After spinning, the films were kept in ambient air at 150°C on a hot plate for 20 min to remove residual solvents.…”

Ferroelectric and structural instability of (Pb,Ca)TiO3 thin films prepared in an oxygen atmosphere and deposited on LSCO thin films which act as a buffer layer

“…On the other hand, in a recent investigation, only the absence of splitting was observed in C-V curves for Pb 1 À x Ca xTiO 3 thin films on a platinum-coated silicon substrate in a composition near x¼ 0.40 [26]. Fig.…”

“…Details of the preparation method can be found in the literature [26]. LSCO buffer layers were prepared by a spin coating technique on Pt/Ti/SiO 2 /Si substrates at 6000 rpm for 30 s. Each spin-coated LSCO buffer layer was subsequently baked at 150 1C on a hot plate for 20 min to remove any residual solvents.…”