Hindawi Publishing Corporation
Journal of Spectroscopy
Volume 2013, Article ID 123519, 10 pages
http://dx.doi.org/10.1155/2013/123519
Research Article
Raman Spectroscopy, X-Ray, SEM, and DTA Analysis of
Alkali-Phosphate Glasses Containing WO
3
and Nb
2
O
5
L. Bih,
1
M. Azrour,
1
B. Manoun,
2
M. P. F. Graça,
3
and M. A. Valente
3
1
Equipe Sciences de Matériaux, FST-Errachidia, Errachidia, Morocco
2
Equipe Matériaux et Environnement, Laboratoire de Chimie Appliquée et Environnement, Université Hassan 1er, Settat, Morocco
3
Physics Department (I3N), Aveiro University, Campus Universitário de Santiago, Aveiro, Portugal
Correspondence should be addressed to L. Bih; bihlahcen@yahoo.fr
Received 11 June 2012; Revised 9 August 2012; Accepted 29 August 2012
Academic Editor: Christoph Kra
Copyright © 2013 L. Bih et al. is is an open access article distributed under the Creative Commons Attribution License, which
permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
New phosphate glasses in the quaternary system (50-x)A
2
O-x WO
3
-10 Nb
2
O
5
-40 P
2
O
5
, with x = 0; 30 and A = Li or Na were
prepared by the melt quenching method. e effect on the crystallization behaviour of the glass due to the introduction of WO3
into the glass composition and, consequently, the diminishing of the molar amount of the alkaline oxide and the decreasing of the
molar ratio between network modi�ers and network formers (M/F) was studied. e prepared glasses were heat-treated in air, at
550
○
C, 600
○
C, and 650
○
C for 4 hours. e structure, of the obtained samples, was studied by differential thermal analysis (DTA),
X-ray powder diffraction (XRD), and Raman spectroscopy and the morphology by scanning electron microscopy (SEM). It was
found that the replacement of Li2 O or Na2 O by WO3 reduces the number of the crystallised phases. In the lithium-niobiophosphate
glasses, the presence of WO3
promotes the formation of NbOPO
4
instead of the LiNbO
3
phase and reduces the formation of ortho-
and pyro-phosphate phases. e thermal treatments affect the arrangements of the network structure of the AW40-glasses.
1. Introduction
Glass-ceramic composite materials have been a subject of
intensive interest during the last decades. e goal for the
development of such materials has been to achieve a com-
bination of properties not achievable by any of the elemental
materials alone.
Phosphate glasses have received considerable attention
in the past few years due to the synthesis of new glass
compositions with high chemical stability. e improvement
of chemical stability [1–3] stimulated the application of phos-
phate glasses in several �elds of materials science, such as fast
ionic conductors [4], semiconductors [5], photonic materials
[6–9], hermetic seals [10], rare-earth ion host solid state lasers
[11], and biomedical materials [12]. e structure of these
glasses consists of PO
4
tetrahedra, which can be attached
to a maximum of three neighbouring tetrahedra forming a
three-dimensional network as in vitreous P
2
O
5
. e addition
of metal oxides to the glass leads to a depolymerisation of
the network, with the breaking of P–O–P linkages and the
creation of nonbridging oxygen. e modifying cations can
provide ionic cross-linking between the nonbridging oxygen
of two phosphate chains, thus increasing the bond strength of
this ionic cross-link and improving the mechanical strength
and chemical durability of the glasses [1]. Niobium phosphate
glasses have been investigated because they might be used in a
wide range of applications, such as waste form for radioactive
waste immobilization [13], rare-earth ion hosts for laser
glasses [14], glass �bers and optical lenses [15, 16], hermetic
sealing [17], electrodes [18], and agricultural applications
[19]. Besides that, phosphate glasses are easy to produce at
relatively low temperatures (900–1200
○
C).
Niobiophosphate glass compositions such as P
2
O
5
-
Nb
2
O
5
-V
2
O
5
-TiO
2
and P
2
O
5
-Nb
2
O
5
-V
2
O
5
-Fe
2
O
3
, investi-
gated by vibrational spectroscopy, exhibit structural features,
characterized by NbO
4
and NbO
6
units [20]. Since sev-
eral niobiophosphate glasses are Nb-rich and Li-rich, their
application as precursors to glass composites containing
embedded LiNbO
3
ferroelectric crystals has been proposed
[21]. Recently, Graça et al. [22] prepared LiNbO
3
glass-
ceramic materials from the Li
2
O-Nb
2
O
5
-SiO
2
glasses by
controlled crystallization. e dielectric properties of these