P' A' Joy

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Combustion Synthesis and Properties of
Nanocrystalline Spinel Oxides
P. A. Joy National Chemical Laboratory Pune,
India pa.joy_at_ncl.res.in
SHS2008, IISc, November 27-29, 2008
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Solid State or Ceramic Method
La2O3 MnO2 NiO ? La2MnNiO6
Heating in a furnace at 1000-1400 oC for 7
days with many intermediate grindings. Total time
duration for synthesis 2 weeks
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Glycine-Nitrate Combustion Synthesis
La0.84Sr0.16CrO3
Glycine-Nitrate Process As-syntheized, on a hot
plate Residual carbon 0.36 High surface
area Compositional homogeneity
Citrate Gel method Calcined at 1060 oC Low
surface area Compositional inhomogeneity
Chick et al, Mater. Lett. 10, 6 (1990)
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Combustion synthesis using Glycine and metal
nitrates
2La(NO3)3
Mn(NO3)2
Water Solution
La2MnNiO6
200 oC
Ni(NO3)2
4Glycine
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La2MnNiO6 Combustion method
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Synthesis of nanocrystalline spinel ferrites
using glycine
9M(NO3)2 18Fe(NO3)3 40NH2CH2COOH ?

9MFe2O4 56N2 80CO2 100H2O
Glycine/Nitrate ratio 5/9 0.55,
Glycine/Metal ratio 1.5
Chick et al, Mater. Lett. 10, 6 (1990)
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Lithium Ferrite, Li0.5Fe2.5o4
G1
dXRD 0.9?/ßcos? 4 nm dTEM 3 nm
G3
100 nm
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G1 (4 nm) , G2 (7 nm) - Superparamagnetic
Langevin function
For H ? 0,
Magnetic particle size 2.5 nm (G1)
2.6--5.6 nm (G2)
For H ? 8,
Uniform size, narrow distribution
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Nanomagnetism
Blocking temperature, TB
Field Cooled Zero Field Cooled
Super Spin Glass (SSG)
Superparamagnetic (SPM)
Sasaki etal, Phys. Rev. B 71, 104405 (2005)
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Inter-particle interactions
Fe3O4
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de AlmeidaThouless eqn for a spin glass system
J. Appl. Phys. 98, 124312 (2005)
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Zinc ferrite is paramagnetic ZnFe2O4 Nano Zinc
ferrite (Zn1-xFex)ZnxFe2-xO4
17 nm
8 nm
ZNF1 1 mole glycine ZNF2 2 moles glycine
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Nano zinc ferrite
J. Nanosci. Nanotech. 8, 3955 (2008)
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27Al Solid State NMR of spinel aluminate
ZnAl2O4
Glycine (20-30 nm)
Carbohydrazide
Urea
MgAl2O4 by citrate method
Montouillout et al, J. Am. Ceram. Soc., 82, 3299
(1999)
T. Mimani, J. Alloys. Compounds 315, 123 (2001)
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Surface contributions
27Al solid State NMR ZnAl2O4 MgAl2O4
Nanoparticles
MgAl2O4
3 nm 5 nm 15 nm
ZnAl2O4
J. Phys. Chem. C112, 14737 (2008)
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Magnetostriction of sintered CoFe2O4
A change in the physical dimensions of a
ferromagnet when the state of magnetization
changes
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Bulk Sintered CoFe2O4, Microstructure and
Magnetostriction
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A Citrate gel method, Calcined at 500 oC B -
Co-precipitation method, Calcined at 100 oC C -
GNP Combustion method, As-prepared D Ceramic
method, calcined at 1100 oC
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TMA
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Citrate
Copptn
Combustion
Ceramic
Sensors Actuators 137, 256 (2007) J. Amer. Cer.
Soc. 91, 1976 (2008)
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Ni0.5Zn0.5Fe2O4 sintered at 1200 oC
J. Am. Ceram. Soc. 90, 1494 (2007)
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Conclusions

• Glycine-nitrate combustion method of synthesis
  is a simple, convenient and fast method for the
  synthesis of nanosized single phase spinel
  oxides
• Particle size can be easily controlled by
  adjusting the fuel/oxidizer ratio
• Almost uniform sized nanoparticles can be easily
  synthesized
• The nanocrystalline particles can be sintered at
  high temperatures without considerable grain
  growth
• Sintered ferrite from combustion synthesized
  nanocrystallites show exceptional properties

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Thanks to
Dr. Seema Verma Dr. Joseph Joly Dr. Sasanka
Deka Dr. Shekhar Bhame Dr. Raj Sankar
Mr. Vijayanand Ms. Sreeja Mr. Mangesh Mr. Pankaj
NCL CSIR DST SHS2008