Journal of Alloys and Compounds
Influence of annealing temperature on structural and optical properties
of SiO2:RE2O3 [RE = Y, Gd] powder
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Rachna Ahlawat
Department of Physics, Materials Science Lab., Ch. Devi Lal University, Sirsa 125055, Haryana, India
a r t i c l e i n f o
a b s t r a c t
Article history:
SiO2:RE2O3 [RE = Y, Gd] powder were prepared by wet chemical technique and the prepared binary oxi-
des annealed at 500 °C and 900 °C. The crystalline structure, phase transformation, and surface mor-
phologies of as-prepared and annealed samples were investigated by XRD and TEM. The normal
transmission was measured using FTIR spectroscopy. Optical properties have been studied with UV–
Vis spectroscopy and PL study. XRD results shows that the as prepared samples of SiO2:RE2O3 [RE = Y,
Gd] powder has mixed phases of RE(NO3)3 and Si(OH)3. However, cubic rare earth oxide phase alone is
found for annealed samples. The strain values are calculated from W–H plot for annealed samples.
TEM micrograph shows that the samples are composed of individual spherical nanocrystallites at
500 °C and aggregated nanocrystallites at 900 °C. From the UV–Vis spectra, it is found that the position
of the absorption peak is shifted toward the higher wavelength side when annealing temperature is
increased. In the PL spectra, the broad emission bands are observed between 570–600 nm and the pres-
ence of O–Si–O (silica) and metal oxide is confirmed by FTIR spectra.
Received 16 December 2014
Received in revised form 2 March 2015
Accepted 9 March 2015
Available online 20 March 2015
Keywords:
Binary oxide
Four step annealing
Structural properties
Optical properties
Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction
microelectronics, optical fiber and photonics, etc. [5,7]. In case of
photonics applications, silica with its high softening temperature,
Powder, ceramic and composites of oxides in the nanometer
size have received much attention due to their various properties
and they significantly used in fundamental and application ori-
ented fields. Since oxide nanoparticles are having very large sur-
face area, they are used in catalytic applications [1]. These
particles are acting as a sensor to detect the various gases present
in the environment and also help to reduce the air pollution [2].
Oxide nanoparticles embedded in a polymer matrix produce
nanocomposites which are useful for electronic applications [3].
From the basic physics point of view, these compounds exhibit
interesting optical, magnetic and electronic properties with poten-
tial applications either as powder or thin film like compact fluores-
cent lamps, light emitting diodes, plasma display panels, high
definition televisions, in biomedical applications, as sensors, as IR
windows, nano heaters, and latent fingerprint detection [4–6].
Also, rare earth oxides are used as high index oxide for dielectric
mirror for high powered lasers, refractory and ceramic material
for industries [7–9].
higher thermal shock resistance, and lower index of refraction than
the other oxide glasses, may be an ideal host matrix for the rare
earth elements and their oxides.
For the development of powder technology, in particular,
demands as a building blocks due to the increase in structural
and compositional complexity so that they can be produced with
ease, in abundance, at low cost and low temperature. The applica-
tion of nanocrystalline materials as a powder feedstock for thermal
spraying has been facilitated with a wide range of powder sources
such as vapor condensation, combustion synthesis, thermo chemi-
cal synthesis, and co-precipitation and mechanical alloying/milling
and sol–gel process. Among the various powder sources, sol–gel
process has the advantage of lower temperature, possibility of
making a finely dispersed powder, easy to make and at low cost
[10]. Cannas et al. [11] used sol–gel method to prepare Y2O3–
SiO2, after thermal treatment of samples at moderate temperature
T ꢀ 900 °C (0.5 h) and high temperature 1300 °C (0.5 h) in air. They
found Y2O3–SiO2 as an amorphous when it was sintered at moder-
ate temperature. In another case, Xiaoyi and Yuchun [12] used co-
precipitation technique to synthesize Y2O3/SiO2 samples around
T ꢀ 800 °C. Sahoo et al. [13] investigated that composite film of
SiO2:Gd2O3 have shown superior micro-structure and morphologi-
cal properties as compared to that of pure thin film. Martino et al.
[14] have tried to investigate the effect of concentration on the
In last decades, binary system containing nanocrystallites RE2O3
(RE, rare earth-Y, Gd) containing SiO2 are important in various
fields
of
technology,
including
laser,
optoelectronics,
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