Glass - Back to the Future!



Presenting Author:
Alicia Durán
<aduran@icv.csic.es>

article posted 22 March 2016


Alicia Durán is Research Professor of CSIC in the Instituto de Cerámica y Vidrio, of Madrid and the leader of research group GlaSS (http://www.glass.icv.csic.es). She is also Vice-president of the International Commission on Glass and future President of this association for the period 2018–2021.






Nd3+ doped transparent oxyfluoride nano glass-ceramics obtained by melting and sol-gel

Alicia Durán1*, G. Gorni1, J. J. Velázquez1, L. Pascual2, Y. Castro1, M. J. Pascual1, J. Fernández3,4 & R. Balda3,4
1 Instituto de Cerámica y Vidrio (ICV-CSIC), Madrid, Spain


Rare Earth (RE) ions are very important for diverse technological application, as lasers, wavelength downconverters, lighting, etc. Nd3+ is one of the most studied ions due to its potential applications for infrared laser (4F3/2?4I11/2 transition). LaF3 crystals are relevant crystalline phases due to the possibility of including the RE ions inside them. For maintaining the good mechanical and chemical properties of the oxide glasses, and to exploit the good optical properties of fluoride crystals, oxyfluoride nano glass-ceramics (nGCs) have been prepared by melting-quenching (MQ) and by sol-gel (SG) to study the effect of processing on their properties and the new opportunities opened with alternative methods.
55SiO2–10La glass composition(1) has been prepared by MQ and doped with Nd3+ ions in different concentrations: 0.1, 0.5, 1, 2 mol%. The crystallization mechanism has been studied for all the doped glasses and LaF3 nanocrystals tend to grow in 2D and crystal growth is limited by diffusion. Dopants do not affect the crystallization mechanism but affect the crystallization kinetics. Starting from the 2 mol% Nd3+ doped glass, fibres have been also prepared and characterized by XRD, SAXS and HR-TEM.
On the other side, oxyfluoride thin films were prepared by SG. The SG method allows preparing materials with quite high fluorine content, otherwise impossible by MQ. Four different compositions of SiO2–LaF3 have been prepared: 90–10, 80–20, 70–30, 60–40 mol% as thin films and bulk materials doped with 2, 3 mol% of Nd3+ ions. HR-TEM measurements showed the presence of LaF3 nano-crystals.
Photoluminescence measurements which include excitation and emission spectra together with the lifetime of the 4F3/2 state show that whereas in the case of nGCs prepared by MQ there is a reduction of the quantum efficiency as concentration increases, the thin films present the highest emission intensity for the sample doped with 3 mol% of Nd3+.

Figure 1: (a) HR-TEM of thin film with composition 80SiO2–20LaF3 treated at 750°C-80 h. (b) Room temperature emission spectra for the thin films doped with 2 and 3 mol% of Nd3+ ions.
(1) A. de Pablos-Martín, N. Hémono, G. C. Mather, S. Bhattacharyya, T Höche, H. Bornhöft, J. Deubener, F Muñoz, A. Durán and M. J. Pascual, Crystallization Kinetics of LaF3 Nanocrystals in an Oxyfluoride Glass, Journal of the American Ceramic Society, 94 [8] (2011) 2420-2428.
(2) S. Bhattacharyya, T. Höche, N. Hemono, M. J. Pascual, P. A. van Aken, “Nano-crystallization in LaF3-Na2O-Al2O3-SiO2 glass, Journal of Crystal Growth, 311 (2009) 4350-4355.

2 Institute of Catalysis and Petrochemistry (ICP-CSIC), Madrid, Spain
3 Dep.Física Aplicada I, Escuela Superior de Ingeniería, UPV/EHU, Bilbao, Spain
4 Materials Physics Center CSIC-UPV/EHU, 20018 San Sebastián, Spain