Synthesis and characterisation of zirconium oxide nanofibers by electrospinning

Article abstract of DOI:10.1080/15533170500471391

Nanometer-sized zirconium oxide (ZrO₂) fibers with diameters about 200 nm have been synthesized by calcination of the zirconium oxide/poly(vinyl acetate) (PVAc) composite nanofibres prepared by sol-gel processing and electrospinning technique. The general morphology of the nanofibers has been studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The crystalline phase evolution as a function of calcination temperature was studied by X-ray diffraction patterns (XRD) of the nanofibers, which showed that the samples after calcination at 500°C and 750°C showed the presence of tetragonal phase along with some traces of monoclinic zirconium oxide. After calcination at 1000°C, only monoclinic phase was identified in the XRD patterns. The formation of pure zirconium oxide was further confirmed by FT-IR spectra. Copyright

Full text of DOI:10.1080/15533170500471391

This article was downloaded by: [University of Memphis]
On: 17 September 2012, At: 12:13
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthesis and Reactivity in Inorganic, Metal-Organic,
and Nano-Metal Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsrt20
Synthesis and Characterisation of Zirconium Oxide
Nanofibers by Electrospinning
a b
b
b
N. Dharmaraj
, C. H. Kim & H. Y. Kim
a
Department of Chemistry, Government Arts College, Udumalpet, India
b
Inorganic/Organic Nanomaterials Research Laboratory, Department of Textile Engineering,
Chonbuk National University, Chonju, Republic of Korea
Version of record first published: 19 Aug 2006.
To cite this article: N. Dharmaraj, C. H. Kim & H. Y. Kim (2006): Synthesis and Characterisation of Zirconium Oxide Nanofibers
by Electrospinning, Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 36:1, 29-32
To link to this article: http://dx.doi.org/10.1080/15533170500471391
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to
anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representation that the contents
will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should
be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,
proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in
connection with or arising out of the use of this material.

Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 36:29–32, 2006
Copyright # 2006 Taylor & Francis Group, LLC
ISSN: 0094-5714 print/1532-2440 online
DOI: 10.1080/15533170500471391
Synthesis and Characterisation of Zirconium Oxide
Nanofibers by Electrospinning
N. Dharmaraj
Department of Chemistry, Government Arts College, Udumalpet, India and Inorganic/Organic
Nanomaterials Research Laboratory, Department of Textile Engineering,
Chonbuk National University, Chonju, Republic of Korea
C. H. Kim and H. Y. Kim
Inorganic/Organic Nanomaterials Research Laboratory, Department of Textile Engineering,
Chonbuk National University, Chonju, Republic of Korea
oxides have been demonstrated, notable examples include car-
[3]
[2]
2
Nanometer-sized zirconium oxide (ZrO ) fibers with diameters bothermal reduction, thermal evaporation, metallo-organic
[
4]
[5]
about 200 nm have been synthesized by calcination of the zirco-
nium oxide/poly(vinyl acetate) (PVAc) composite nanofibres
prepared by sol-gel processing and electrospinning technique.
The general morphology of the nanofibers has been studied by
scanning electron microscopy (SEM) and atomic force microscopy
decomposition, and anodic oxidation. New strategies are
still being developed. Nowadays, electrospinning technique has
been successfully employed in the preparation of metal oxide
[6]
[7]
fibers such as, zinc oxide, vanadium pentoxide, cobalt
[9]
AFM). The crystalline phase evolution as a function of calcination oxide, nickel oxide, copper oxide,
[8]
[10]
[11]
(
titanium oxide,
[12]
[13]
temperature was studied by X-ray diffraction patterns (XRD) of
the nanofibers, which showed that the samples after calcination
at 5008C and 7508C showed the presence of tetragonal phase
along with some traces of monoclinic zirconium oxide. After
calcination at 10008C, only monoclinic phase was identified in the
magnesium titanate, nickel titanate, etc. Electrospun nano-
fibers have approximately 1 to 2 orders of magnitude more surface
[14]
area than that found in thin films.
Zirconium oxide or zirconia (ZrO ) is an important techno-
2
XRD patterns. The formation of pure zirconium oxide was logical material that can show a visible photoluminescence
further confirmed by FT-IR spectra.
(PL) under an excitation by UV light. The excellent optical,
mechanical, electrical, chemical and photochemical properties
Keywords zirconium oxide, scanning electron microscopy (SEM), of this material made it suitable for different applications such
[16]
[
15]
[17]
X-ray diffraction (XRD), electrospinning
as interferometric filter,
coating material,
catalysts
Though several reports are available on the
[18]
and sensors.
preparation of zirconium oxide films
[16,18]
and nanocrystalline
there seems to be no report on the preparation
[17–19]
powders,
and characterization of zirconium oxide nanofibers. Hence, for
the first time, we present herein that nanometer-sized zirco-
nium oxide fibers can be conveniently prepared by electrospin-
ning a composite solution that contains zirconium oxide
precursor sol and PVAc followed by high temperature calcina-
tion of the inorganic/organic composite nanofibers.
INTRODUCTION
One-dimensional (1D) nonostructural metal oxides and related
materials have been a subject of intense research because of their
potential applications in many fields that include electronics,
[1]
photonics and sensing. A number of synthetic methods for
generating nanoscale wires, belts and tubes of various metal
EXPERIMENTAL
Received 20 July 2005; accepted 28 October 2005.
Zirconium isopropoxide and N, N-dimethyl formamide (DMF)
were purchased from Aldrich and used without further purifi-
cation. PVAc (Mn ¼ 500,000) was obtained from Celanase Ltd.
This work was presented in the International Conference on
Nanomaterials (NANO 2005), held at Mepco Schlenk Engineering
College, Sivakasi, India, during July 13–15, 2005.
The Korean Federation of Science and Technology Societies
(
has supported this study by the award of Brain Pool Fellowship
KOFST), Ministry of Science and Technology, Republic of Korea, Preparation of the Nanofibers
Zirconium oxide sol was prepared as described below using
zirconium isopropoxide as the precursor. Then, 7.5 g of zirco-
nium isopropoxide was dissolved in 20 g of absolute ethanol
and 0.15 g of nitric acid and 0.21 g of hydrochloric acid were
(
2004) to one of the authors (N. Dharmaraj).
Address correspondence to N. Dharmaraj, Department of
Chemistry, Government Arts College, Udumalpet 642126, India.
E-mail: dharmaraj67@yahoo.com.
29

3
0
N. DHARMARAJ ET AL.
added and stirred for 4 h. PVAc (18 wt%) solution was
prepared in DMF. The solution required for electrospinning
was prepared by stirring the zirconium oxide sol and PVAc
(18 wt% in DMF) in the ratio of 0.75:1 (w/w), for 6 h at
room temperature. The viscous solution thus obtained was
placed in a hypodermic syringe. The positive terminal of a
variable high voltage power supply was attached to a copper
wire inserted into the solution in the syringe, whereas the
ground iron drum covered with an aluminium foil served as
counterelectrode. A schematic diagram of the electrospinning
process was given in Figure 1. The distance between the tip
of the syringe and collector was 16 cm. The syringe was
placed at an angle of 208 to horizontal in order to get
uniform flow of the solution. When the voltage applied
between the two electrodes reached 15 kV, dry, web of compo-
site nanofibers with several centimeter length accumulated on
the surface of the aluminium foil. The zirconium oxide/
PVAc composite nanofibers deposited were collected and cal- FIG. 2. SEM images of zirconium oxide nanofibers: (a) as-synthesised
cinated in air at high temperatures for 4 h to get pure zirconia zirconium oxide/PVAc composite fibers, (b) fibers calcinated at 5008C,
(
c) fibers calcinated at 7508C and (d) fibers calcinated at 10008C.
nanofibers.
Characterisation of the Nanofibers
5008C appeared to have the rough surface owing to crystalliza-
SEM images of the samples were recorded by JEOL GSM- tion of zirconium oxide at this temperature with cylindrical
5
900 scanning electron microscope. Tapping mode AFM morphologies (Figure 2b). But the samples obtained after cal-
images were obtained from Nanoscope(R)-III A instrument. cination at 7508C showed about 30–40% decrease in their
Powder X-ray diffraction patterns of the fibers were obtained diameters, which is due to the decomposition and removal of
from Rigaku X-ray diffractometer using Cu-Ka radiation in PVAc component that played the role as a template for fiber
the 10–70 2u values. FTIR spectra of the samples (as pellets formation during electrospinning process (Figure 2c).
in KBr) have been recorded in Bio-Rad Win instrument. The However, it can be seen from the SEM images of the nanofibers
as-synthesised inorganic/organic composite fibers were calci- after calcination at 10008C, that their morphology has changed
nated for 4 h at different temperatures ranging from 5008C to to one where the fibers appear to consist of linked particles or
1
0008C at a heating rate of 28C/min in air.
crystallites (Figure 2d).
RESULTS AND DISCUSSION
Atomic Force Microscopy
Atomic force microscopy (AFM) was used to obtain quali-
tative information about the surface morphology of the nanofi-
bers. Figure 3 represents the AFM images and the height
profiles of the corresponding as-synthesised zirconium
oxide/PVAc composite nanofibers marked on the images. It
can be seen from the AFM images that the as-synthesised zir-
conium oxide/PVAc composite fibers have uniform, smooth
surfaces with cylindrical structure and their diameter ranges
from 400–500 nm as found in the SEM images. Our attempt
to obtain the AFM photographs of the calcinated samples
went unsuceessful due to the surface roughness resulted from
crystallization of zirconium oxide.
Scanning Electron Microscopy
The nanostructure of the fibers was analysed by scanning
electron microscopy (SEM). Figure 2 shows the SEM images
of the various nanofiber samples. The as-synthesised zirconium
oxide/PVAc composite nanofibers were found to have smooth,
uniform surfaces with varying diameters in the 400–500 nm
range (Figure 2a). The fibers obtained after calcination at
X-ray Diffraction Patterns
The crystalline phase evolution of zirconium oxide nanofi-
bers has been examined by XRD measurements. Figure 4
shows the XRD patterns of various ZrO2 samples. Zirconia
[20]
has two crystalline phases, tetragonal and monoclinic.
Amorphous behaviour was observed in the XRD of the
FIG. 1. A schematic diagram of electrospinning process.

SYNTHESIS AND CHARACTERISATION OF ZIRCONIUM OXIDE
31
FIG. 3. 1-dimensional and 3-dimensional AFM images of as-synthesised zirconium oxide/PVAc composite fibers and corresponding height profiles.
as-synthesised ZrO /PVAc composite nanofibers (Figure 4a). small peaks centered at 24.608 (1,1,0)m 28.408 (21,1,1)m
2
The samples obtained after calcination at 500 8C exhibits the revealed the coexistence of some content of monoclinic crys-
[19,20]
diffraction peaks centered at 30.358 (1,0,1) , 35.308 (0,1,1) , talline phase also.
The diffraction peaks corresponding
t
t
5
the tetragonal zirconium oxide suggesting that the sample sharper and intense when the calcination temperature was
0.508 (2,1,1) and 60.408 (1,1,2) , and are characteristics of to the monoclinic zirconium oxide phase became more
t
t
present mainly in the metastable tetragonal phase increased to 7508C showing the presence of both tetragonal
(
reported in the case of nanocrysalline zirconia.
Figure 4b). This result is in accordance with the data and monoclinic phases considerably (Figure 4c). This indicates
[
19]
However, the gradual transformation of the metastable tetragonal phase
to the monoclinic structure. In the XRD pattern of the nanofi-
bers calcinated at 10008C (Figure 4d), only monoclinic phase
was observed as indicated by the absence of the characteristic
tetragonal peak at 30.358. The diffraction peaks corresponding
to the tetragonal and monoclinic phases were well matched
with database in JCPDS (Card No. 89-2843) and earlier
[19,20]
reports for zirconium oxide nanocrystals and films.
FT-IR Spectral Study
In order to confirm the formation of pure zirconium oxide
nanofibers after calcination at high temperature with the
complete removal of poly(vinyl acetate) templates, we
recorded the FT-IR spectrum of the various nanofiber
samples. The FT-IR spectrum of the as-synthesised inor-
ganic/organic hybrid nanofibers (Figure 5, curve a) showed
2
1
some strong absorptions in the region 1000 to 1750 cm , cor-
responding to the stretching and bending vibrations of PVAc
molecule. After calcinations at 5008C, the intensity of those
peaks due to PVAc were decreased or almost disappeared, indi-
cating the removal of PVAc molecules from the fibers, and
FIG. 4. XRD patterns of zirconium oxide nanofibers (a) as-synthesised
zirconium oxide/PVAc composite fibers, (b) fibers calcinated at 5008C,
21
21
21
(c) fibers calcinated at 7508C and (d) fibers calcinated at 10008C (
the diffraction peak characteristic of tetragonal zirconium oxide).
ꢀ
denotes new peaks appeared around 750 cm , 550 cm and 430 cm
due to the formation of zirconium oxide (Figure 5, curve b).

3
2
N. DHARMARAJ ET AL.
4
. Wang, Y.; Santiago-Aviles, J. J. Synthesis of lead zirconate
titanate nanofibres and the Fourier-transform infrared characteriz-
ation of their metallo-organic decomposition process. Nanotech-
nology 2004, 15, 32–36.
5
6
7
8
. Zhao, J.; Wang, X.; Chen, R.; Li, L. Fabrication of titanium oxide
nanotube arrays by anodic oxidation. Solid State Commun. 2005,
1
34, 705–710.
. Viswanathamurthi, P.; Bhattarai, N.; Kim, H. Y.; Lee, D. R. The
photoluminescence properties of zinc oxide nanofibres prepared
by electrospinning. Nanotechnology 2004, 15, 320–323.
. Viswanathamurthi, P.; Bhattarai, N.; Kim, H. Y.; Lee, D. R.
Vanadium pentoxide nanofibers by electrospinning. Scripta
Mater. 2003, 49, 577–581.
. Guan, H.; Shao, C.; Wen, S.; Chen, B.; Gong, J.; Yang, X. A novel
3 4
method for preparing CO O nanofibers by using electrospun
PVA/cobalt acetate composite fibers as precursor. Mater.
Chem. Phys. 2003, 82, 1002–1006.
9
. Guan, H.; Shao, C.; Wen, S.; Chen, B.; Gong, J.; Yang, X.
Preparation and characterization of NiO nanofibres via an electro-
spinning technique. Inorg. Chem. Commun. 2003, 6, 1302–1303.
FIG. 5. FT-IR spectra of zirconium oxide nanofibers (a) as-synthesised
zirconium oxide/PVAc composite fibers, (b) fibers calcined at 5008C and
1
0. Guan, H.; Shao, C.; Chen, B.; Gong, J.; Yang, X. A novel method
for making CuO superfine fibres via an electrospinning technique.
Inorg. Chem. Commun. 2003, 6, 1409–1411.
(c) fibers calcined at 7508C.
1
1. Li, D.; Xia, Y. Fabrication of titania nanofibers by electrospin-
ning. Nano Lett. 2003, 3, 555–560.
The formation of pure zirconium oxide is indicated by the IR
spectra of the samples calcinated at 7508C, which displayed
intense peak at 520 cm and at 750 cm (Figure 5, curve c)
2
1
21
12. Dharmaraj, N.; Park, H. C.; Lee, B. M.; Viswanathamurthi, P.;
Kim, H. Y.; Lee, D. R. Preparation and morphology of mag-
nesium titanate nanofibres via electrospinning. Inorg. Chem.
Commun. 2004, 7, 431–433.
[21]
assigned as due to Zr-O stretching of zirconium oxide.
In
addition, the disappearance of the absorptions corresponding
to the PVAc molecule indicated the complete removal of
them at this temperature and the fibers formed were consisting
of only zirconium oxide.
1
3. Dharmaraj, N.; Park, H. C.; Kim, C. K.; Kim, H. Y.; Lee, D. R.
Nickel titanate nanofibers by electrospinning. Mater. Chem.
Phys. 2004, 87, 5–9.
1
4. Gibson, P.; Schreuder-Gibson, H.; Rivin, D. Transport properties
of porous membranes based on electrospun nanofibers. Colloids
Surf. A 2001, 187, 469–481.
CONCLUSION
Pure zirconium oxide nanofibers with about 200 nm
diameter were prepared by electrospinning technique. The
surface morphology of the fibers has been studied by
scanning electron microscope (SEM) and atomic force
microscopy (AFM). The observed X-ray diffraction patterns
1
5. Mcleod, H. A. Thin Film Optical Filters, 2nd Edition; Adam, H.,
Ed.; Bristol, 1986; pp. 519–542.
1
6. Lopez Ibanez, R.; Ramos Barrado, J. R.; Martin, F.; Brucker, F.;
Leinen, D. Oxide barrier coatings on steel strip by spray pyrolysis.
Surf. Coatings Tech. 2004, 188, 675–683.
(
XRD) of the fibers showed the presence of both tetragonal
1
1
1
7. Reddy, B. M.; Sreekanth, P. M.; Reddy, V. R. Modified zirconia
solid acid catalysts for organic synthesis and transformations.
J. Molec. Catal. A 2005, 225, 71–78.
and monoclinic phases after calcination at 5008C and 7508C.
However, the samples obtained after calcinations at 10008C,
showed the presence of only monoclinic phase in the XRD
patterns. The formation of pure zirconium oxide was also con-
firmed by FT-IR spectra.
8. Ansori, Z. A.; Karekar, R. N.; Aiyer, R. C. Humidity sensor using
planar optical waveguides with claddings of various oxide
materials. Thin Solid Films 1997, 305, 330–335.
9. Cordova-Martinez, W.; De La Rosa-Cruz, E.; Diaz-Torres, L. A.;
Salas, P.; Montoya, A.; Avendano, M.; Rodriguez, R. A.;
Barbosa-Garcia, O. Nanocrystalline tetragonal zirconium oxide
REFERENCES
1
2
3
2 3
. Zhang, J.; Jiang, F. Catalytic growth of Ga O nanowires by
3þ
physical evaporation and their photoluminescence properties.
Chem. Phys. 2003, 289, 243–249.
stabilization at low temperatures by using rare Earth ions: Sm
3
and Tb . Optical Mater. 2002, 20, 263–271.
þ
. Park, J. H.; Choi, Y. J.; Park, J. G. Synthesis of ZnO nanowires 20. Salas, P.; De La Rosa-Cruz, E.; Mendoza-Anaya, D.; Gonzalez-
Martinez, P.; Catano, V. M.; Rodriguez, R. A. High temperature
and nanosheets by an O -assisted carbothermal reduction
2
process. J. Cryst. Growth. 2005, 280, 161–167.
. Sun, S. H.; Meng, G. W.; Zhang, G. Z.; Gao, T.; Geng, B. Y.;
thermoluminescence induced on UV-irradiated tetragonal ZrO
2
prepared by sol-gel. Mater. Lett. 2000, 45, 241–245.
Zhang, L. D.; Zuo, J. Raman scattering study of rutile SnO nano- 21. Yu, J. J.; Zhang, J. Y.; Boyd, I. W. Formation of stable
2
belts synthesized by thermal evaporation of Sn powders. Chem.
Phys. Lett. 2003, 376, 103–107.
zirconium oxide on silicon by photo-assisted sol-gel proces-
sing. Appl. Surf. Sci. 2002, 186, 190–194.