Materials Science and Engineering A 434 (2006) 19–22 Luminescence in semi-crystalline zirconium titanate doped with lanthanum G.F.G. Freitas a , R.S. Nasar b,∗ , M. Cerqueira b , D.M.A. Melo b , E. Longo c , J.A. Varela d a Escola T´ ecnica Federal de S˜ ao Luiz, EAFSL, S ˜ ao Luiz, MA 65095-460, Brazil b Departamento de Qu´ ımica, UFRN, Natal, RN 59072-970, Brazil c Departamento de Qu´ ımica, UFSCar, S˜ ao Carlos, SP 13565-905, Brazil d Instituto de Qu´ ımica, UNESP, Araraquara, SP 14800-900, Brazil Received 7 March 2006; received in revised form 30 May 2006; accepted 11 July 2006 Abstract This paper aims to describe the synthesis of the semi-crystalline and crystalline powder of lanthanum doped with zirconium titanate (65/35), LZT through Pechini method. The analysis done by Raman demonstrated that semi-crystalline phase at 550 ◦ C and crystalline phase after 600 ◦ C were formed. The XRD pattern shows the ZrTiO 4 phase formation demonstrating that La substitutions into the lattice take place. The calcined powder at different temperatures shows a semi-crystalline phase presenting photoluminescence effect when processed at low temperatures. From 300 to 400 ◦ C a broadband is observed at 563 nm and 568 nm, respectively. Defects creation such as: Zr 3+ · V O •• and Ti 3+ · V O •• , Zr and Ti replaced by La with vacancy formation, impurities and imperfections contributed to the photoluminescence effect. However, the main emission is due to a reverse Ti 4+ → O 2- or/and Zr 4+ →O 2- transition that occur within a regular titanate or zirconate eight-fold coordination [BO 8-δ ], B = Zr 4+ , Ti 4+ . © 2006 Elsevier B.V. All rights reserved. Keywords: Photoluminescence; Amorphous materials; Pechini method 1. Introduction Amorphous semiconductors exhibit absorption edges, which are usually situated in approximately the same energy range as the absorption edge of the crystalline form having a simi- lar short-range order. The development of new semiconductor materials with wide band gaps (2.0–4.0 eV) may give rise to new optoelectronic devices, particularly to materials to be applied in the development of green or blue light emission diodes (LED) or laser diodes. In many optoelectronic devices, amorphous semiconductors can replace single crystal semiconductors, par- ticularly when cost is an important factor. Absorption edges of amorphous semiconductors are often much more sensitive to the conditions of preparation, thermal history, and purity than the broad features of the whole optical absorption band [1]. Amorphous material of the ABO 3 family (A and B are cations and O is the oxygen anion), such as BaTiO 3 , Pb(Zr, Ti)O 3 and SrTiO 3 , has recently attracted a good deal of attention due to their ferroelectric [2,3] and electro-optic properties [4]. Photo- ∗ Corresponding author. Tel.: +55 84 3215 2828; fax: +55 84 3215 9224. E-mail address: nasar@terra.com.br (R.S. Nasar). luminescence (PL) in crystalline titanate is well known, but this property has only recently been identified in semi-crystalline and amorphous titanate synthesized at low temperatures for thin films and powder [5]. Pizani et al. [6] recently reported on efficient room tem- perature photoluminescence (PL) in both amorphous PbTiO 3 powder and thin film reported on silicon wafers. Pontes et al. [7] studied visible photoluminescence properties changing sur- face morphology and the structure of amorphous -PbTiO 3 thin films processed by the polymeric precursor method. The exper- imental results indicate that the nature of PL must be related to the disordered structure of PbTiO 3 thin films. The zirconium titanate is a semiconductor that is used as an intermediary phase in PZT and PLZT syntheses. It has an - PbO deformed structure at room temperature. Studies done by Haart et al. [8] shows that the SrZr 0.98 Ti 0.02 O 3 crystalline phase presents an excitation spectrum with a broadband at 280 nm. Only one emission band is observed peaking at 460 nm. The spectra closely resemble those of BaZr 0.99 Ti 0.01 O 3 reported by Macke [9]. This study aims to synthesize and optically characterize semi- crystalline and crystalline La(ZrTi)O 4 (LZT). The synthesis route is the polymeric precursor method developed by Pechini [10]. 0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.07.023