Preparation and studies on surface modifications of calcium-silico-phosphate
ferrimagnetic glass-ceramics in simulated body fluid
K. Sharma
a
, A. Dixit
a
, Sher Singh
b
, Jagannath
a
, S. Bhattacharya
a
, C.L. Prajapat
a
, P.K. Sharma
c
, S.M. Yusuf
b
,
A.K. Tyagi
d
, G.P. Kothiyal
a,
⁎
a
Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
b
Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
c
Analytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
d
Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
abstract article info
Article history:
Received 18 February 2009
Received in revised form 24 April 2009
Accepted 14 May 2009
Available online 22 May 2009
Keywords:
Glass ceramic
XPS
Magnetite
Simulated body fluid (SBF)
Bioactivity
The structure and magnetic behaviour of 34SiO
2
–(45 -x) CaO–16P
2
O
5
–4.5 MgO–0.5 CaF
2
-x Fe
2
O
3
(where
x =5, 10, 15, 20 wt.%) glasses have been investigated. Ferrimagnetic glass-ceramics are prepared by melt
quench followed by controlled crystallization. The surface modification and dissolution behaviour of these
glass-ceramics in simulated body fluid (SBF) have also been studied. Phase formation and magnetic behaviour
have been studied using XRD and SQUID magnetometer. The room temperature Mössbauer study has been
done to monitor the local environment around Fe cations and valence state of Fe ions. X-ray photoelectron
spectroscopy (XPS) was used to study the surface modification in glass-ceramics when immersed in simulated
body fluid. Formation of bioactive layer in SBF has been ascertained using X-ray photoelectron spectroscopy
(XPS) and scanning electron microscopy (SEM). The SBF solutions were analyzed using an absorption
spectrophotometer. The magnetic measurements indicated that all these glasses possess paramagnetic
character and the [Fe
2+
/Fe
3+
] ions ratio depends on the composition of glass and varied with Fe
2
O
3
concentration in glass matrix. In glass-ceramics saturation magnetization increases with increase in amount of
Fe
2
O
3
. The nanostructure of hematite and magnetite is formed in the glass-ceramics with 15 and 20 wt.% Fe
2
O
3
,
which is responsible for the magnetic property of these glass-ceramics. Introduction of Fe
2
O
3
induces several
modifications at the glass-ceramics surface when immersed in SBF solution and thereby affecting the surface
dissolution and the formation of the bioactive layer.
© 2009 Published by Elsevier B.V.
1. Introduction
Calcium-silico-phosphate glasses have potential as implant mate-
rials for human body because of their bioactivity and biocompatibility.
Hench [1] has reported the first bioactive glass having composition
(wt.%) 45% SiO
2
, 24.5% Na
2
O, 24.5% CaO and 6% P
2
O
5
commonly known
as 45S5. The bioactivity of these materials is composition dependent.
Addition of alumina tends to decrease the bioactivity of these glasses
[2]. These glasses and glass-ceramics having Fe
2
O
3
show an important
application in cancer treatment by elimination of cancerous cells in
bones; by means of hyperthermia [3]. The magnetic properties arise
from magnetite [Fe
3
O
4
] that is produced from the Fe
2
O
3.
When this
material is placed in the region of the tumor and is subjected to an
alternating magnetic field, heat is generated by hysteretic losses [4].
The tumor is effectively heated and the temperature locally rises to 42–
45 °C. As a result, the cancerous cells perish while the healthy ones
survive [5–7]. Synthesis of glass-ceramics in SiO
2
–CaO–Fe
2
O
3
, SiO
2
–
CaO–Fe
2
O
3
–B
2
O
3
–P
2
O
5
, SiO
2
–Al
2
O
3
–Fe
2
O
3
–P
2
O
5
–Li
2
O and CaO–SiO
2
–
P
2
O
5
–Na
2
O–Fe
2
O
3
bioglasses, have been reported [8,9]. However,
the distribution and the bonding environment of Fe
2
O
3
on these
glasses and glass-ceramics have not been studied in great details.
Since the magnetic properties of the material depend on the envi-
ronment of Fe, therefore the knowledge of structure and oxidation
states of iron ions is beneficial for synthesis of magnetic glass and
glass-ceramic.
Since these materials are in contact with living tissues when
implanted in the body, they should not elicit any harmful response
from the host tissues. Therefore, the surface chemistry of materials
needs to meet the requirements of host tissues. In fact, surface of the
material has a critical influence on the biological response, therefore,
most of the applications of these biomaterials are dictated by the way
in which a given material interacts with body fluids. Therefore, a study
of the surface interactions with body fluid is needed to improve the
understanding of chemistry and physics taking place on surfaces/
interfaces of glasses/glass-ceramics. In this regard, XPS spectroscopy
is useful in understanding the surface interactions with body fluids as
Materials Science and Engineering C 29 (2009) 2226–2233
⁎ Corresponding author. Tel.: +91 22 25595652; fax: +91 22 25505296.
E-mail address: gpkoth@barc.gov.in (G.P. Kothiyal).
0928-4931/$ – see front matter © 2009 Published by Elsevier B.V.
doi:10.1016/j.msec.2009.05.009
Contents lists available at ScienceDirect
Materials Science and Engineering C
journal homepage: www.elsevier.com/locate/msec