Post on 10-Aug-2020
Synthesis and Characterization of Ferroic Nanocomposites of Spinel
Ferrites and Perovskites
Jacob Faucheaux, Amin Yourdkhani, Shiva Adireddy, and Gabriel Caruntu*
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In this research, 0-3 type ferroic nanocomposites have been fabricated using colloidal synthesis approaches. The zero dimensional (0D) magnetic phase (CoFe2O4) was synthesized by an elevated temperature hydrolysis reaction carried out in a three neck flask. The ferrites were incorporated into the matrix of the perovskite phases (ATiO3, A= Ba and Pb) by two methods. Lead titanate was deposited onto the ferrites in an aqueous solution via the liquid phase deposition (LPD) method. Alternatively, the ferrites were incorporated into an amorphous titanium dioxide matrix via a sol-gel method which was used as a precursor for the hydrothermal synthesis of perovskite-spinel nanocomposites. The nanocomposites were characterized by XRD, VSM, TEM, FE-SEM, Raman, and PFM.
Abstract
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Perovskites (ATiO3 A=Ba or Pb) are ferroelectric (they exhibit electric polarization) and Spinels (CoFe2O4) are ferro or ferrimagnetic (they exhibit spontaneous magnetic dipoles) Magnetoelectric composites consist of a ferroelectric phase coupled together with a ferromagnetic phase
Introduction
Spinel Crystal Structure Perovskite Structure 3
Applying a stimulus to either phase can transfer a physical strain to the coupled phase and induce a response These materials have a range of applications in electronics and computers specifically in sensors, transistors, and data storage devices
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Cobalt Ferrite (Negative Magnetostriction Coefficient)
Lead Titanate (Electrostrictive Phase)
Polarization:
N S
5 dHdM
dMdP
dHdP
M E
0)0( PHP
PPHP 0)(
Methods
220°C 3hours
CoFe2O4
The CoFe2O4 (CFO) nanoparticles are synthesized by a hydrolysis reaction The DEG and NMDA act as both the solvent and as capping agents The hydroxide groups on the capping agents make the particles dispersible in polar solvents
Synthesis of Magnetic Nanoparticles CoCl2 20 + FeCl3 20 + DEG + NMDA
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Ti4+ Pb2+
H3BO3
Synthesis of Nanocomposites by LPD
1. 45 C, 3hrs
CoFe2O4
2. Annealed at 750 C 6hrs
PbTiO3-CoFe2O4
MFn(n-‐2m) + mH20 MOm + nF-‐ +2mH+ (1) H3BO3 + 4HF BF4-‐ + H3O+ + 2H2O (2)
LPD involves an equilibrium reaction Addition of Boric Acid shifts the equilibrium to the product side
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Integration of CFO into TiO2 matrix
EtOH CoFe2O4
Ti(butoxide)4
Adjusting the pH 3 to by HCl Adding molar amout of H2O dropwise
TiO2-CoFe2O4 (powder)
Gelling Dry at 100 C for 3hrs
The CFO nanoparticles were integrated into amorphous TiO2 through a sol-gel method
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The TiO2-CFO powder was then used as seeds for the formation of PTO-CFO nanocomposites under hydrothermal conditions ATiO3-CoFe2O4
TiO2-CoFe2O4 (powder)
A2+ + KOH + 15 mL H2O 180 C 12hrs (A = Ba or Pb)
Synthesis of PTO-CFO by Hydrothermal Method
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X-Ray Diffraction
20 30 40 50 60 700
50
100
150
200
250
300
Inte
nsity
(a.u
.)
2 (°)
PDF: 00-022-1086 CoFe2O
4
20 30 40 50 60 700
300
600
900
1200
1500
1800
2100
2400
CoFe2O
4PDF: 00-022-1086
PDF: 01-070-0747 PbTiO3
Inte
nsity
(a.u
.)
2 (o)
PTO-CFO hydrothermal
PTO-CFO LPD
CFO nanoparticles
The XRD pattern confirmed that the CFO nanoparticles were single phase. XRD patterns of the nanocomposites showed single tetragonal phase PTO. The CFO nanoparticles did not appear due to the weak intensity they exhibit in XRD.
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Magnetic Properties
-15000 -10000 -5000 0 5000 10000 15000-0.04
-0.02
0.00
0.02
0.04
Mom
ent (
emu/
g)
Field (Oe)
CFO nanoparticles
VSM measurements of the CFO nanoparticles.
-15000 -10000 -5000 0 5000 10000 15000-1.5x10-4
-1.0x10-4
-5.0x10-5
0.0
5.0x10-5
1.0x10-4
1.5x10-4
Field (Oe)M
omen
t (em
u)
PTO-CFO hydrothermally
PTO-CFO LPD
VSM measurements of PTO-CFO nanocomposites.
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Morphology
TEM images of the CFO nanoparticles 12
TEM and FE-SEM of PTO-CFO nanocomposites formed by LPD.
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TEM and FE-SEM of PTO-CFO nanocomposites formed
hdyrdothermally 14
Magnetic Field Assisted Raman
800 700 600 500 400 300 2000
500
1000
1500
2000
Inte
nsity
(a.u
.)
Wavenumber (cm-1)
0 Oe 500 Oe 1000 Oe 1500 Oe 2000 Oe
A1g
A1(3
TO)
Si
B1+E
E(2
TO)
Spinel modesPerovskite modes
Raman Bands Ferrite Perovskite
Field (Oe) A1g A1(3TO) B1+E E(2TO) Si 0 713.5 584.2 290.3 207.1 525.2
500 677.3 574.8 291.9 199.4 525.3 1000 675.0 571.3 290.1 198.8 525.4 1500 684.0 566.5 287.1 197.7 525.4 2000 691.4 565.2 283.4 195.2 525.4
Raman Spectra of PTO-CFO powder prepared by LPD placed on a silicon wafer. Shifts in the perovskite
modes suggest a coupling between the magnetic and
piezoelectric phases.
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800 700 600 500 400 300 2000
1000
2000
3000
4000
5000
In
tens
ity (a
.u.)
Raman Shift (cm-1)
0 Oe 500 Oe 1000 Oe 1500 Oe 2000 Oe
Si
A1g
A1(3
TO)
B1+E
E(2
TO)Spinel modes
Perovskite modes
Raman Bands Ferrite Perovskite
Field (Oe) A1g A1(3TO) B1+E E(2TO) Si 0 709.8 577.7 289.4 199.7 508.3
500 710.8 579.6 289.4 199.7 508.3 1000 709.8 580.6 290.4 201.7 508.3 1500 710.8 578.7 290.4 200.7 508.3 2000 710.8 580.6 290.4 201.7 508.3
Raman Spectra of PTO-CFO powder
prepared hydrothermally
placed on a silicon wafer. Shifts in the perovskite modes suggest a coupling
between the magnetic and
piezoelectric phase.
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Magnetic Field Assisted Piezoresponse Force Microscopy
-20 -10 0 10 20
0.0
1.0x10-10
2.0x10-10
3.0x10-10
4.0x10-10
5.0x10-10
6.0x10-10
Am
plitu
de (m
)
Voltage (V)
0 Oe 500 Oe 1000 Oe 1500 Oe 2000 Oe
-20 -10 0 10 20
-100
-50
0
50
100
150
200
250
300
Pha
se (°
)Voltage (V)
0 Oe 500 Oe 1000 Oe 1500 Oe 2000 Oe
PFM measurements of PTO-CFO nanocomposites synthesized by LPD method.
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References
Yourdkhani, A.;; Perez, A.;; Lin, C.;; Caruntu, G. Chem. Mater. 2010, 22, 6075 6084 6075. Caruntu, D,;; Caruntu, G,;; Chen, Y.;; C.;; Goloverda, G.;;
Kolesnichenko, V. Chem. Mater. 2004, 16, 5527-5534. Liu, A.;; Zhang, X.;; Xu, Y.;; Niu , X.;; Zheng, X.;; Ding, X. Chemosphere
59, 2005, 1367 1371. Wang, Y.;; Xu, H.;; Wang, X.;; Zhang, X.;; Jia, H.;; Zhang, L.;; Qiu, J.;; J.
Phys. Chem. B 2006, 110, 13835-13840.
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Acknowledgements
This works was sponsored by Louisiana Board of Regents/National Science Foundation NSF(2010-15)-RII-UNO Thanks also goes to Dr. Daniela Caruntu for her help in the CFO nanoparticle synthesis and to Denny Lenormand for help with the VSM measurements.
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