fabrication and characterization of bismuth ferrite nanofiber by electrospinning method
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Fabrication And Characterization Of Bismuth Ferrite Nanofibers By
Electrospinning Method
Under the guidance of Dr. S. Balakumar
Presented by M. HAKKEEM
Register No. 34211007National Centre for Nanoscience and Nanotechnology
University of MadrasGuindy Campus
Chennai – 600 025.
Outline Multiferroics – definition
Bismuth ferrite
Existing challenges with the material
Scope of the thesis
Experiment design
Synthesis
Result and discussion…..
Multiferroics – Definition
Multiferroics are single phase materials which simultaneously possess two or more primary ferroic properties.
Ferromagetic (anti-)
Ferroelectric
Ferroelastic
Ferrotoroidic
Bismath Ferrite Rhombohedral distorted
perovskite structure
Room temperature Magnetoelectric effect
Antiferromagnetic (Tn)= 643 K
Ferroelectric (Tc) = 1103 K
In homogenous spin structure
Application of BiFeO3
Transducers , Magnetic field sensors and information storage in industry .
The data can be written electrically and read magnetically.
The best aspect of ferroelectric random access memory (Fe RAM)
BiFeO3 potential application of spintronics and photo catalytic compound ……
Existing challenges with the
material at microscale High leakage current
Small remnant polarization
High coercive field
Ferroelectric reliability
Inhomogeneous magnetic spin structure
Goals at the Nanoscale…
Reduce the leakage current
Reduce the impurity phases
Reduce the oxygen vacancy
Suppress the inhomogeneous spin structure
Increase the values of Ps, Pr and Mr
Scope of the thesis Controlling the size of the particles in
nanoscale
Controlling dimensionalities of the material (particles, thinfilms, nanofibers, etc.)
Doping or substitution
Materials and methods Overview of the method :
BiFeO3 Nanofiber were fabricated in sol – gel based electrospinning method
The process of fabricating the electrospinning solution involved the sol gel method while the fabrication of naofibers involved the electrospinning method.
Further the process of annealing yielded the BFO phase nanofibers
Materials Metal precursors :
Bismuth (III) nitrate pentahydrate [Bi (NOᴣ)ᴣ.5H2O]
Iron (III) nitrate nonahydrate [Fe (NO ᴣ)ᴣ.9H2O]
Polyvinylpyrrolidone [(C6H9NO)n]
Solvent :
Glacial acetic acid [C2H4O2]
Double distilled water [DD H2O]
Experiment designS. No. Parameters Value
1 Distance between needle stage and collector 10 cm
2 Applied voltage 8, 10, 15 & 20 kV
3 Collector Plate type
4 Processing duration 6 hrs
5 Syringe capacity 2 ml
6 Flow rate 0.2 ml per hrs.
Synthesis flow chart
Result and discussion We have fabricated bismuth ferrite
(BiFeO3/BFO) nanofibers by electrospinning method.
The applied voltage is found to be a potential parameter in determining the diameter and mechanical property of the nanofibres.
Therefore we have fabricated BFO nanofibers by varying the applied voltage at 8 kV, 10 kV, 15 kV and 20 kV.
Continues . . . All the fabricated nanofibers were annealed at 450oC
for 2 hrs in order to form the BFO phase.
The fabricated nanofibers were characterized for their
Crystalline phase and structural property by XRD
Morphological property by SEM , HRTEM
Optical property by UV-Visible-DRS technique
Material phase formation by TGA.
Thermogravimetric analysis(TGA)
The weight loss material &solvent.
150 and 200 oC pvp evaporation
200 and 400 oC acetic acid solvent evaporation
450 and 1000 oC there were no residual elements to be evaporated.
10 kV-450oC
XRAY – Diffraction (XRD) Crystalline
phase and structural analysis
BFO nanofibers annealed at 450 and 550oC for 2 hrs.
550oC - secondary phases -as Bi2Fe4O9 and Fe2O3 were formed
450oC – no secondary and impurity phases
10 kV
10 kV
Continues . . . All the fabricated
nanofibers at 8, 15 and 20 kV were annealed at 450 oC for 2 hrs
All the other BFO samples contained the secondary phases (Bi2O3)
Then fabricated nanofibers at 10 kv Were controlled mechanism has to be Found out in order to fabricate the secondary phase free BFO nanofibers
Energy dispersive spectroscopy (EDS)
Compositional analysis
The graphs confirmed that All the elements such as Bi , Fe O of BFO compound
Scanning electron microscope (SEM)
(a) 8 kv it ‘s not sufficient Small diameter
(b) 10 kv large
diameter ,Poor mechanical strength.
(c) 15 kv excellent fiber, homogenous Size distribution, diameter of size 50-100 nm
(d) 20 kv very small length, were fibers are broken relatively inhomogenous.
High Resolution Transmission
Electron Microscope (HRTEM)
UV - DRS Optical studies
The diffuse reflectance peaks between 700 - 800 nm and 600 – 550 nm regions
optical property of the nanofiber prepared at 20 kV was significantly influenced .
The perhaps due to the well pronounced secondary peak Bi2O3
Continues . . .The change of band gap value of BFO nanofibers with respect to the applied voltage
S. No. Material Band gap (eV)
1BFO NF @ 8 Kv
2.47
2BFO NF @ 10 kV
2.42
3BFO NF @ 15 kV
2.45
4BFO NF @ 20 kV
2.44
Summary and conclusion Bismuth ferrite (BiFeO3) nanofibers were
fabricated by electrospinning method by varying the applied voltages 8 kV, 10 kV, 15 kV and 20 kV.
The minimum voltage of 8 kV where the nanofiber formation was occurred considered as the threshold energy
All the fabricated nanofibers were annealed at 450 oC for 2 hrs.
all the nanofibers were characterized for the XRD, EDS, SEM , HRTEM , UV-DRS technique .
Continues . . . From the XRD results, it was found that the
phase pure BFO was obtained for the nanofiber which fabricated at 10 kV.
The other nanofibers fabricated at 8, 15, and 20 kV were found to with secondary phase such as Bi2O3, Bi2Fe4O9.
Continues . . . The compositional analysis revealed that all the
samples did contain the element of bismuth ferrite composition with rational percentage.
From the microscopy graphs (SEM and HRTEM), it was found that all the BFO were possessed fiber morphology.
However, the fiber fabricated at 8 kV was found to
be aggregated structure.
Continues . . . On the other hand, the fibers fabricated at 10 and
20 kV were found to be broken structure
A well aligned and homogeneous size distributed nanofibers were found in the samples which fabricated at 15 kV.
Therefore, for the study it was evident that the overall qualities of the nanofibers in terms of their morphology, mechanical, size distribution of were processing applied voltage dependent.
Thanking to all