1. University of Dhaka, Bangladesh
Effect of dopants on the electromagnetic properties
of Ni-Cu-Zn Ferrites
Submitted by
S.M.Maksud-Ul-Alam
Exam Roll no. 3710
Session
Registration no.: HA-34096
Department of Physics
University of Dhaka, Bangladesh
Jun 2010

2. Objectives of the research work
Prepare series of Ni-Cu-Zn ferrite doped with CoO , Bi2O3 and Pbo by standard ceramic double sintering method.
Determine optimum sintering temperature by sintering the samples over wide range of temperature.
Decrease magnetic losses with optimum permeability.
Determination of ferromagnetic to paramagnetic transition temperature, TC
Determination of phases, structure, density, resistivity of the samples.
Correlate magnetic properties with appropriate composition and sintering temperature.

3. Ni-Cu-Zn Ferrites demands…
Ferrimagnetic cubic spinel ferrites demanded characteristics that make them technologically very useful are:
Used widely as high frequency ferrite because of their high electrical resistivity and high permeability in RF region.
Sufficiently low losses over wide range of frequencies.
High dielectric constant that makes them useful for microwave applications.
High mechanical hardness and environmental stability.
Low cost.
Exact mechanical dimensions.
Large number of controllable parameters.

4. Performances……
Ferrites are used today in radio and television, microwaves and satellite communications, audio, video and digital recording and as permanent magnets
They have been also used in high quality filters, inductor and transformer cores, humidity sensors.
The recent application, such as multilayer chip inductors, are currently used in notebook computers, hard disk drivers as memory core and other electronic products.
Widely used in Noise Suppression such as suppression of Electromagnetic Interferences to audio system.
Also perform as Deflection Yokes for CRT & Video Displays.

5. Methodology of Ferrite Preparation
Table 01: Composition of Ni0.27Cu0.15Zn0.58Fe2O4 ferrites.
Zn content, x
Weight% of CoO
(5mol%)
Weight% of Bi2O3
(0.5mol%)
Weight% of PbO
0.15
1.68
0.97
0.5
Sample identification
Table 02: Sample identification according to the substitutional doping level.
Ni0.27Cu0.15Zn0.58Fe2O4
Ni0.27Cu0.15Zn0.58Fe2O4 doped with 5mol% CoO
doped with 0.5mol% Bi2O3
doped with 0.5mol% PbO
Sample01
Sample02
Sample03
Sample04

6. Weighing by different mole percentage
Oxide of raw
materials
Weighing by different mole percentage
Wet mixing by ball milling
Dry mixing by agate mortar
Drying
Briqueting
Milling
Pre-sintering
Pressing to desired shapes
Sintering
Finished Product

7. Effect of Sintering Temperature
Sintering temperature has a great influence on the magnetic and electrical properties of polycrystalline ferrites such as:
Density significantly increases with the increase of sintering temperature.
Sintering temperature activates the grain growth of the microstructure.
Initial permeability increases with both the increase of density and grain size of the ferrites.
Therefore optimization of the sintering temperature corresponding to desire properties is very crucial in ferrite processing.

8. Effect of Additives…
The proper selection of additives /substitution have enormous influence on the properties of ferrites:
Change Curie temperature
Affect density/porosity
Reviews sintering temperature
Change resistivity/ dielectric properties

9. T0C
10000C 3h
2h 13min (1800C/h)
3h (2000C/h)
Room Temperature
6000C
Furnace cooling
1h 30min (2000C/h)
7000C
Time (h)
HEATING Cycle
Fig 01: Heating cycle of sintering the samples at 1000°C.
T0C
10500C 3h
2h 30min (1800C/h)
3h (2000C/h)
Room Temperature
Furnace cooling
1h 45min (2000C/h)
7000C
Time (h)
Fig 02: Heating cycle of sintering the samples at 1050°C.

10. T0C
11000C 3h
2h 46min (1800C/h)
3h (2000C/h)
Room Temperature
Furnace cooling
2h (2000C/h)
7000C
Time (h)
HEATING Cycle
Fig 03: Heating cycle of sintering the samples at 1100°C.
T0C
11500C 3h
3h 3min (1800C/h)
3h (2000C/h)
Room Temperature
6000C
Furnace cooling
2h 15min (2000C/h)
7000C
Time (h)
Fig 04: Heating cycle of sintering the samples at 1150°C.

11. HEATING Cycle
T0C
12000C 3h
3h 20min (1800C/h)
3h (2000C/h)
Room Temperature
Furnace cooling
2h 30min (2000C/h)
7000C
Time (h)
Fig 05: Heating cycle of sintering the samples at 1200°C.

12. Sintering Temperature,
RESULTS AND DISCUSSION
Density
Table 03: Variation of bulk density of the samples with sintering temperature
Set
Sintering Temperature,
TS/3h, (0C)
Bulk Density,
db (gm/cc)
Ni0.27Cu0.15Zn0.58Fe2O4
(Sample01)
1100
4.44
1200
4.95
Ni0.27Cu0.15Zn0.58Fe2O4+ CoO
(Sample02)
4.96
Ni0.27Cu0.15Zn0.58Fe2O4+ Bi2O3
(Sample03)
1150
4.94
4.93
Ni0.27Cu0.15Zn0.58Fe2O4+ PbO
(Sample04)
4.55
5.08

13. XRD
Fig 06: X-ray Diffraction (XRD) pattern of the of Ni0.27Cu0.15Zn0.58Fe2O4, doped with CoO, Bi2O3 and PbO.

14. Lattice Parameter Set Lattice Parameter, a0 (Å)
Sintering temperature: 12000C/3h
Table 04: Lattice parameter, theoretical density and bulk density of the samples sintered at 1200°C/3h.
Set
Lattice Parameter,
a0 (Å)
X-ray density, dx (gm/cc)
Bulk Density, db (gm/cc)
Ni0.27Cu0.15Zn0.58Fe2O4
(Sample01)
8.433
5.29
4.95
Ni0.27Cu0.15Zn0.58Fe2O4+ CoO
(Sample02)
8.408
5.43
4.92
Ni0.27Cu0.15Zn0.58Fe2O4+ Bi2O3
(Sample03)
8.405
5.4
4.93
Ni0.27Cu0.15Zn0.58Fe2O4+ PbO
(Sample04)
8.404
5.37
5.08

15. Curie temperature Sintering temperature: 12000C/3h
Fig 07: Curie temperature of
Ni0.27Cu0.15Zn0.58Fe2O4
Fig 08: Curie temperature of
Ni0.27Cu0.15Zn0.58Fe2O4 doped with CoO (5mol%)

16. Sintering temperature: 12000C/3h
Fig 09: Curie temperature of
Ni0.27Cu0.15Zn0.58Fe2O4 doped with BI2O3 (0.5mol%)
Fig 10:Curie temperature of
Ni0.27Cu0.15Zn0.58Fe2O4 doped with PbO (0.5mol%)

17. TC SUMMERY Sample Curie Temperature,TC0C Ni0.27Cu0.15Zn0.58Fe2O4
Sintering temperature: 12000C/3h
TC SUMMERY
Sample
Curie Temperature,TC0C
Ni0.27Cu0.15Zn0.58Fe2O4
(Sample01)
160
Sample02: doped with CoO
177
Sample03: doped with Bi2O3
161
Sample04: doped with PbO
156

18. CoO, Bi2O3 and PbO, sintered at 1200°C/3h.
Sintering temperature: 12000C/3h
Permeability
ln f
Fig 11: Complex Permeability (μ’) vs Frequency Ni0.27Cu0.15 Zn0.58 Fe2O4 doped with
CoO, Bi2O3 and PbO, sintered at 1200°C/3h.

19. Frequency dependence Permeability at different sintering temperature
Sample02: doped with CoO
Sample01: Ni0.27Cu0.15Zn0.58Fe2O4

20. Frequency dependence Permeability at different sintering temperature
Sample03: doped with Bi2O3
Sample04: doped with PbO

21. Density Resistivity Sample Resistivity, ρ (Ω-m)
Sintering temperature: 12000C/3h
Table 06: Room temperature resistivity for the samples sintered at 12000C for 3hours.
Sample
Resistivity, ρ (Ω-m)
Ni0.27Cu0.15Zn0.58Fe2O4
(Sample01)
99.02
Sample02: doped with CoO
24.24
Sample03: doped with Bi2O3
1044
Sample04: doped with PbO
41.13

22. This is the behavior of semiconductor.
Fig 12: Temperature Vs Resistivity at 100kHz
From Fig, the value of Resistivity decreases with increasing temperature.
This is the behavior of semiconductor.

23. Dielectric constant Temperature dependence Dielectric Constant
Sintering temperature: 12000C/3h
Fig 13:Temperature dependent Permittivity, є’
at 100kHz
Fig 14:Temperature dependent Permittivity (img), є’’
at 100kHz

24. Fig 15:Frequency dependent Permittivity, є’ for sample01
Frequency dependence Dielectric Constant at different sintering temperature
Fig 15:Frequency dependent Permittivity, є’
for sample01
Fig 16:Frequency dependent Permittivity, є’
for sample02

25. Fig 17:Frequency dependent Permittivity, є’ for sample03
Frequency dependence Dielectric Constant at different sintering temperature
Fig 17:Frequency dependent Permittivity, є’
for sample03
Fig 18:Frequency dependent Permittivity, є’
for sample03

26. Conclusion
The samples are characterized by X-ray Diffraction which confirmed the single phase cubic spinel structure
2. It was observed that the lattice parameter changes slightly when dopants were added.
The lattice parameter of pure and doped with Co, Bi and Pb are 8.433, 8.408, 8.405, and
8.404 Ǻ respectively.
3. Curie temperatures of pure(Ni0.27Cu0.15Zn0.58Fe2O4) and doped with Co, Bi and Pb are 160°C,
177°C, 161°C and 156°C respectively. The difference between the peak value of real and imaginary
part was observed at ± 3°C, which is very much appreciated.
4. For all the samples, permeability increases with increasing sintering temperature which is connected with the increased density and grain size.
5. The highest value of resistivity was obtained for Bi2O3 doped sample which is 1044Ω-m. Resistivity decreases with increasing sintering temperature. This may be related to the decrease of porosity.
6.The dielectric constant decreases with increasing frequency, which confirms the dielectric behaviour of the ferrite materials.
The temperature dependence of dielectric constant shows that the dielectric constant increases with increasing temperature, which is a normal dielectric behaviour, observed in most of the ferrite materials.

27. Prof. Shamima Karim Choudhury University of Dhaka.
Special thanks to my supervisor
Prof. Shamima Karim Choudhury
University of Dhaka.

28. Thank you. Have a nice day.