ORIGINAL PAPER Microstructure, dielectric properties and optical band gap control on the photoluminescence behavior of Ba[Zr 0.25 Ti 0.75 ]O 3 thin films L. S. Cavalcante Æ J. C. Sczancoski Æ F. S. De Vicente Æ M. T. Frabbro Æ M. Siu Li Æ J. A. Varela Æ E. Longo Received: 14 March 2008 / Accepted: 2 October 2008 / Published online: 24 October 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Ba[Zr 0.25 Ti 0.75 ]O 3 (BZT) thin films were syn- thesized by the complex polymerization method and heat treated at 400 °C for different times and at 700 °C for 2 h. These thin films were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, field emission gun-scanning electron microscopy (FEG- SEM) and atomic force microscopy (AFM), Ultraviolet– visible (UV–vis) absorption spectroscopy, electrical and photoluminescence (PL) measurements. FEG-SEM and AFM micrographs showed that the microstructure and thickness of BZT thin films can be influenced by the pro- cessing times. Dielectric constant and dielectric loss of BZT thin films heat treated at 700 °C were approximately 148 and 0.08 at 1 MHz, respectively. UV–vis absorption spectra suggested the presence of intermediary energy levels (shallow and deep holes) within the band gap of BZT thin films. PL behavior was explained through the optical band gap values associated to the visible light emission components. Keywords Microstructure  Dielectric  Optical band gap  Photoluminescence  BZT thin films 1 Introduction Recently, barium zirconate titanate, Ba[Zr,Ti]O 3 (BZT), has been utilized as an alternative material to barium strontium titanate, [Ba,Sr]TiO 3 , in the preparation of thin films or ceramic bulks [1–3]. This material presents a perovskite-type structure with general formula ABO 3 (A = Ba and B = Ti, Zr). Generally, BZT are formed by solid solution between barium titanate (BTO) and barium zirconate (BZO) due to the substitution of Ti 4? ions (B site) (atomic weight of 47.9, ionic radius of 74.5 pm) by Zr 4? ions (atomic weight of 91.2, atomic radius of 86 pm). This substitution is possible because the Zr 4? is chemically more stable than the Ti 4? [4]. BZT presents good dielectric properties due to its low dielectric loss and reasonable dielectric constant [5–7]. The microwave dielectric properties of this material are inter- esting for the development of capacitive and nonvolatile memory cells (DRAM’s and FeRAM’s) [8–10]. Moreover, the dielectric properties and ferroelectric phase transition temperature (T m ) of BZT ceramics are strongly dependent of Zr content in the lattice. BZT bulk ceramics with Zr content up to x [ 0.08 exhibit a broad dielectric constant- temperature (e * T) curve near the T m . This behavior can L. S. Cavalcante (&)  J. C. Sczancoski  M. T. Frabbro LIEC,DQ-UFSCar, P.O. Box 676, 13565-905 Sao Carlos, SP, Brazil e-mail: laeciosc@bol.com.br J. C. Sczancoski e-mail: jcsfisica@gmail.com M. T. Frabbro e-mail: tete_fabbro@hotmail.com F. S. De Vicente  M. S. Li Instituto de Fı ´sica de Sa ˜o Carlos, USP, P.O. Box 369, 13560-970 Sao Carlos, SP, Brazil e-mail: fsdevicente@nin.ufms.br M. S. Li e-mail: maximo@if.sc.usp.br J. A. Varela  E. Longo IQ, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP, Brazil e-mail: varela@iq.unesp.br E. Longo e-mail: elson@iq.unesp.br 123 J Sol-Gel Sci Technol (2009) 49:35–46 DOI 10.1007/s10971-008-1841-x