Journal of Physics and Chemistry of Solids 69 (2008) 1951–1956 Improvement of electrical properties of Sr-modified (Pb,Ca)TiO 3 thin films grown by soft chemistry route D.S.L. Pontes a , E. Longo a , F.M. Pontes b,Ã , M.S. Galhiane b , S.R. Rissato b , L.S. Santos b , E.R Leite c a Chemistry Institute, Universidade Estadual Paulista (UNESP), P.O. Box 355, 14801-970 Araraquara, Sa˜o Paulo, Brazil b Department of Chemistry, Universidade Estadual Paulista (UNESP), P.O. Box 473, 17033-360, Bauru, Sa˜o Paulo, Brazil c LIEC–CMDMC - Department of Chemistry–UFSCar, Via Washington Luiz , km 235, CP-676, CEP-13565-905, Sa˜o Carlos, Sa˜o Paulo, Brazil Received 13 March 2007; received in revised form 10 January 2008; accepted 1 February 2008 Abstract Strontium and calcium-modified lead titanate (Pb 0.70 Ca 0.15 Sr 0.15 )TiO 3 soft chemistry-derived thin films were prepared on platinum- coated silicon substrate by spin-coating method. Investigations were made on the structure, surface morphology and electrical properties of the film. The results by XRD and FE-SEM showed that the film exhibits a pure tetragonal perovskite phase and an average grain size of about 50–60 nm, respectively. Electrical measurements of a metal–ferroelectric–metal type capacitor exhibited a stable and switchable electrical polarization in the film. The structure of the Au/PCST/Pt capacitor showed well-saturated hysteresis loops at an applied voltage of 300 kV/cm with remanent polarization and coercive field values of 22 mC/cm 2 and 100 kV/cm, respectively. At 100 kHz, the dielectric constant and the dielectric loss of the (Pb 0.70 Ca 0.15 Sr 0.15 )TiO 3 thin film with thickness 240 nm were 528 and 0.05, respectively. r 2008 Elsevier Ltd. All rights reserved. Keywords: A. Thin films; B. Chemical synthesis; D. Dielectric properties; D. Ferroelectric; D. Microstructure 1. Introduction Nowadays, ferroelectric thin films are emerging as a key material for widespread applications in both electronic and optical fields, i.e., non-volatile memory storage. The integration with silicon electronics could be an important pathway for the next generation of device miniaturization. One of the challenges of this approach is the difficulty found in the preparation of multicomponent oxide systems, i.e., (Bi,Tb,La)FeO 3 , (Pb,Ba)TiO 3 , (Pb,Sr)TiO 3 , (Pb,Ca)- TiO 3 or (Ba,Sr)TiO 3 . Although there are various methods for manufacturing thin films, for example ion beam sputtering [1], molecular beam epitaxy [2] and pulsed laser ablation [3], the chemical methods have been used extensively, and they have the advantages of precise composition control and homogeneity, low cost, and short fabrication process [4,5]. Unfortunately, physical deposi- tion methods to grow thin films present problems in the stoichiometry, because of the different vapor pressure of the multiple elements system involved. Among the ferroelectric, the more studied, doped PbTiO 3 (PT) is a perovskite-type compound desirable for pyroelectric infrared detectors because of its relatively large pyroelectric coefficient and spontaneous polarization [6,7]. However, the inherent anisotropy of PbTiO 3 along the c- axis causes a large tetragonal strain and makes PbTiO 3 thin films poling difficult. Meanwhile, it is well known that many physical properties of materials vary significantly with a small change in chemical composition through doping or substitution. On chemical substitution with Ba, La, Sr, Sm or Ca, the system should undergo a series of structural transitions from a tetragonal to a pseudocubic or orthorhombic phase and, finally, to a cubic phase [8–10]. Calcium-modified lead titanate (PCT) thin films have recently raised interest as a good candidate because of their applications as piezo and pyroelectric sensors and due to their good ferroelectric and dielectric properties. Studies ARTICLE IN PRESS www.elsevier.com/locate/jpcs 0022-3697/$ - see front matter r 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jpcs.2008.02.004 Ã Corresponding author.: Tel.: +55 14 3103 6135; fax: +55 14 3103 6088. E-mail address: Fenelon@fc.unesp.br (F.M. Pontes).