Nanocrystal formation using laser irradiation on Nd 3+ doped barium titanium silicate glasses L.L. Martin a,⇑ , S. Ríos b , I.R. Martín a,c , P. Haro-González a , J.M. Cáceres d , A. Hernández-Creus e a Dpto. Física Fundamental y Experimental, Electrónica y Sistemas, Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez, s/n, E-38206 La Laguna, Tenerife, Spain b Dpto. de Física Básica, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez, s/n, E-38206 La Laguna, Tenerife, Spain c MALTA Consolider Team, Spain d Dpto. Edafología y geología, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez, s/n, E-38206 La Laguna, Tenerife, Spain e Dpto. de Química Física, Instituto de Materiales y Nanotecnología, Universidad de La Laguna, Av. Astrofísico Francisco Sánchez, s/n, E-38207 La Laguna, Tenerife, Spain article info Article history: Received 29 June 2012 Received in revised form 12 September 2012 Accepted 28 October 2012 Available online 6 November 2012 Keywords: Nd 3+ Laser irradiation Ba 2 TiSi 2 O 8 Nanocrystals Glass ceramic Glass abstract Two different thermal treatments were used to create nanocrystals from a precursor glass. The glass whose composition is Ba 2 TiSi 2 O 8 and doped with 3% of Nd 3+ was prepared using the melt quenching method. A conventional thermal treatment in an electrical furnace was used to obtain transparent glass ceramic samples, which contain Fresnoite nanocrystals with an average size of 35 nm. Moreover, these nanocrystals were obtained in a localized area of the precursor glass by irradiating with a continuous Ar + laser. Evidence of the changes induced by laser irradiation was confirmed by optical spectroscopic, X-ray diffraction, scanning electron and atomic force microscopy. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction The glass–ceramic materials are produced by a controlled devit- rification or crystallization from a precursor glass. This process dif- fers from the spontaneous crystallization that is a common problem in the glass production. After the devitrification process, the glass–ceramic material contains an amorphous phase of the remaining glass and one or more nanocrystalline phases, all result- ing in a mixture of properties. Transparent glass–ceramics containing rare-earth ions or non- linear optical crystals have received considerable attention, because such materials have high potential applications in photon- ics [1,2]. From the viewpoint of practical applications in integrated optics or photonic crystals, it is important to fabricate transparent glass–ceramics with controlled patterns as micro-scale dots or lines, which can be used as laser waveguides, gratings or wave- length conversion devices. Laser irradiation of glass materials has recently been successfully used as an effective technique to induce spatially selected structural modification and/or crystallization in glass [3,4]. This technique is of particular interest for performing various optical devices to form crystalline phases in glass through this laser irradiation. Fresnoite crystal, composed of barium–titanium silicate Ba 2 TiSi 2 O 8 (BTS), belonging to P4bm group, has TiO 5 square pyra- midal structure, which is the origin of the polarizability of this crystal [5]. BTS crystal shows piezoelectric, pyroelectric, ferroelec- tric, fluorescence and non-linear optical properties [6,7]. Recently Maruyama et al. [8] reported the possibility of synthesizing trans- parent glass ceramic samples by heat treatment of glasses using an electric furnace. These transparent nanocrystalline materials have important applications in photonic devices where complex struc- tures of small size, only obtained by laser irradiation, are required. Also, the possibility of fabricate high quality optical micro-resona- tors made from BTS glass have been shown [9] and the capability of modifying these structures is only possible by micro structuring with laser devitrification. The aim of this work is to analyze the changes produced in Nd 3+ doped BTS precursor glass under irradiation with continuous wave Ar + laser. In this work the effect of laser irradiation on glass sam- ples is compared to the behavior of glass ceramic samples obtained by thermal treatment in order to determine the optimal conditions to produce nanocrystalline material upon laser exposure. 0925-8388/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jallcom.2012.10.162 ⇑ Corresponding author. Tel.: +34 922 318 651. E-mail address: lmartin@ull.es (L.L. Martin). URL: http://lmartin.webs.ull.es/ (L.L. Martin). Journal of Alloys and Compounds 553 (2013) 35–39 Contents lists available at SciVerse ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jalcom