mixeds oxides by nikhil betkiker
DESCRIPTION
Ferrites: Ferrites are mixed metal oxides of magnetic nature in which iron is the main component. In general, ferrites show four different types of crystal structures namely, 1] Ferrospinel Structure. 2] Hexagonal Structure. 3] Garnet Structure. 4] Orthoferrite structure. We are going to discuss about spinel structure as Co Ni ferrite is a spinel ferrite. Ferrospinel Structure. They have the general formula MeFe2O4, where Me is divalent metal ion or a mixture of ions having average valence of two. The unit cell is cubic. The oxygen ions forms a nearly close-packed face centered cubic structure and the metal ions are distributed over tetrahedral and octahedral holes. Normal ferrites:In which all-divalent metal ions occupy A sites and all the Fe3+ occupy B sites. e.x. Zn 2+ [Fe23+] O4 Zn 2+ ions have a very low octahedral preference; therefore they enter the A-sites of the lattice, resulting in normal ferrites. Inverse ferrites:In which all divalent metal ions and half the Fe3+ ions occupy B sites while remaining Fe3+ occupy A sites. e.x. Fe3+[ Fe3+ Ni2+] O4 Mixed ferrites:In which all divalent metal ions and Fe3+ ions are uniformly distributed over the tetrahedral and octahedral sites. Co - Ni ferrite is a mixed spinel ferrite, which has general formulae AII x BII 1-x Fe2O4TRANSCRIPT
Preparation, characterisation and solid state properties of
some
Mixed metal oxides
For the last several decades, the field of mixed metal oxides has served as a source of interesting and challenging research problems to technologists chemists and material scientists. Mixed metal oxides have distinct structural features which play important role in tailoring their electrical, magnetic, sensor, catalytic and other important properties which find applications in many important fields.
Mixed metal oxide of nano size show additional properties which finds applications in varied fields.
Ferrites are a class of mixed metal oxides of magnetic nature in which iron is the main component.
The ferrites with ferrospinnel structure have the general formula MeFe2O4 where Me is a divalent metal ion or a mixture of ions having average valence of 2.
INTRODUCITION
Preparation of mixed ferrospinnel ferrites :CoXNi(1-x)Fe2O4(where x= 0 , 0.5, & 1)
Characterization of the ferrites :>X-ray powder diffraction ( XRD) technique>Infra Red Spectroscopy(FTIR)
Study of Solid State Properties:A) Magnetic properties1) Saturation magnetisation2) Retentivity3) Coercivity4) Loss
B) Electrical properties1) Conductivity2) Dielectric constant
THE PRESENT INVESTIGATION INCLUDES
PREPARATION OF SAMPLES
COMBUSTION METHOD
Sr no. Ferrite Ni(NO3)2·6H2O gms
Fe(NO3)3·9H2Ogms
Co(CH3COO)2·4H2Ogms
1 NiFe 2O4 6.2031 17.2349 0
2 Co 0.5 Ni 0.5 Fe 2O 4 3.0998 17.2262 2.6553
3 CoFe 2O4 0 17.2175 5.3075
Quantity of each sample prepared: 5 gms.
Table :Stoichiometric quantities of different salts in each sample
SALT SOLUTION
NTA
GLYCENE
PASTY MASSRESIDUE
FINE POWDER SAMPLE
Powder X-ray diffraction patterns for the samples under investigation were taken on Rigaku D-Max IIC diffractometer.
The particle size has been calculated from X-ray patterns using Scherrer formula.
Characterisation
• X-ray diffraction (XRD) • Powder diffraction method
Background counts were taken using KBr pellet.
IR spectra of KBr and the sample in the ratio of 100:1 were recorded in the wave range 4000-300 cm-1; on Shimadzu IR spectrophotometer.
INFRA RED SPECTROSCOPY (FTIR)
SOLID STATE PROPERTIES:
• Magnetic properties
The measurements were done on the usual hysteresis loop tracer and also on automated high field magnetic loop tracer.
The hysteresis loop of the samples were recorded.
The magnetic parameters were estimated.
• Electrical properties
• Conductivity
Two- probe method.
The resistivity of the samples was measured from room temperature to 500° c .
The variation of resistivity with temperature was studied for the samples.
• Dielectric constant
The dielectric measurements were done on the samples at room temperature using HPCA 6440B
20 30 40 50 60 70 80
Inte
nsi
ty (a.
u.)
2degree)
CoFe2O
4
Co0.5
Ni0.5
Fe2o
4
NiFe2o
4
•The dhkl and 2Ɵ values are in agreement with the reported values in JCPDS data files.
RESULTS AND DISCUSSION
• Particle size 33 nm
• Particle size 26 nm
• Particle size 21 nm
• XRD AND PARTICLE SIZE
1000 2000 3000 4000 5000
0
20
40
60
80
100
% T
ransm
itta
nce
Wavenumber (cm-1)
NiFe2o
4
1000 2000 3000 4000 50000
10
20
30
40
50
60
70
% T
ransm
itta
nce
Wavenumber (cm-1)
Co0.5
Ni0.5
Fe2O
4
1000 2000 3000 4000 5000
0
20
40
60
80
100
% T
ransm
itta
nce
Wavenumber (cm-1)
CoFe2O
4
IR SPECTRA
•IR spectra of the samples shows the absorption bands which are in agreement with the normal absorption bands of ferrites.
-8 -6 -4 -2 0 2 4 6 8
-58
-38
-19
0
19
38
58em
u/gm
x 1000 Oe -8 -6 -4 -2 0 2 4 6 8
-60
-40
-20
0
20
40
60
emu/
gm
1000xOe
-8 -6 -4 -2 0 2 4 6 8
-60
-40
-20
0
20
40
60
B
A
HYSTERESIS LOOPS
SAMPLE 1:NiFe2O4 SAMPLE 2: CO0.5Ni0.5Fe2O4
SAMPLE 3: CoFe2O4
TABLE: saturation magnetisation, retentivity, coercivity, loss of the samples.
Sample Saturation Magnetisation
emu/gm
Retentivityemu/gm
CoercivityOe
Losserg/cm3
1 51.52 15.985 287.5 163.1342 50.897 9.885 151.00 190.403 51.99 8.9 114.00 14.87
ELECTRICAL RESISTIVITY
1.0 1.5 2.0 2.5 3.0 3.51.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Log
1000/T (K-1)
1.0 1.5 2.0 2.5 3.0 3.51.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Log
1000/T (K-1)
1.0 1.5 2.0 2.5 3.0 3.51
2
3
4
5
6
Log
1000/T (K-1)
SAMPLE 1: NiFe2O4
SAMPLE 2: CO0.5Ni0.5Fe2O4
SAMPLE 3: CoFe2O4
•A semiconductor behavior is observed for all samples.A high value of resistivity 2.3659×105 ohm .cm is observed for sample 3 whereas for sample 1 and sample 2 it is 1.336×105 ohm .cm and 1.7322×105 ohm .cm respectively
DIELECTRIC CONSTANT
1 2 3 4 5 6 7
15
30
45
60
75
90
Die
lect
ric
Const
ant
Log f
1 2 3 4 5 6 70
20
40
60
80
100
120
140
Die
lectr
ic C
onsta
nt
Log f
1 2 3 4 5 6 7
0
50
100
150
200
250
300
350
Die
lect
ric
Const
ant
Log f
SAMPLE 1: NiFe2O4
SAMPLE 3: CoFe2O4
•It can be seen from the plots that dielectric constant is found to decrease with increase in frequency reaching a very low value at higher frequency for all the samples. This shows that ferrite acts as dielectric material at low frequency regions. The value of dielectric constant at 20 Hz for sample 1 is 84.52, sample 2 is 117.97 and sample 3 is 246.01
• The combustion method used for the preparation results in fine particle ferrite
• The samples prepared are highly magnetic with low values of Coercivity and loss.
• The hysteresis loss and Coercivity for the sample 3 is found to be low. This confirms that the magnetic properties are dependent on particle size.
• The nature of resistivity plot exhibits semi- conductor behavior .
• Ferrite acts as dielectric material at low frequency regions.
CONCLUSIONS
1. Smit and H. P. J. Wijn, Ferrite, Philips Technical Library, Eindhoven, The Netherlands, (1959) 137. 2. Solid State Chemistry by C.N.R.Rao 3. R. M. Cornell, U. Schertmann, The Iron Oxides: Structure, Properties, Reactions, Occurrence and Uses, VCH Publishers, Weinheim, 1996.4. K. J. Standley, ‘Oxide Magnetic Materials’ (Oxford: Claredon Press, 1972). 5. C. Kittel, Introduction to Solid State Physics, Wiley, New York, (1976).6. R.B. Tangsali, S.H. Keluskar, G.K.Naik and J.S.Budkuley, Journal of Material science (2007)42,878-882.7. Dependence of dielectric behavior of Mn-Zn ferrite on sintering temperature. M.A.Ahmed,E.H.EL-Khawas,F.A.Radwan Journal of Material science 36(2001)5031-50358. www.googlebooks.com
REFERENCES
ACKNOWLEGMENT
1.Dept. of chemistry-Goa university
2.N.I.O-Dona paul
3.Dept. of PHYSICS & CHEMISTRY P.E.S COLLEGE
THANK YOU