1. Structural and Magnetic Properties of MgxSrxMnxCo1-3xFe2O4 Nanoparticle ferrites
Nadir S. E. Oman
School of Chemistry and Physics, University of KwaZulu-Natal, Westville campus, P/Bag X5400, Durban 4000, South Africa
BE SURE TO READ THE NOTES !

2. Outline Introduction Structure and properties of spinel ferrite
Synthesis and XRD measurements of the series
HRTEM & HRSEM analysis
Mössbauer spectroscopy measurements
VSM measurement
Conclusions

3. Ferrites and applications
Recording
Drug delivery
Toys
levitation
Cancer treatment

4. Spinel Ferrite Structure
Ferrite have different crystal types namely:
(a) Spinel ferrite
(b) Garent
(c) Magnetoplumbite
AB2O4
Normal spinel and inverse spinel
(M2+δFe3+1-δ)[M2+1-δ Fe3+1+δ]O4
Fig. 1

5. Synthesis and X-ray powder diffraction (XRD) of MgxSrxMnxCo1-3xFe2O4
Glycol – thermal method was used for the synthesis of the nanoferrites.
XRD patterns indicate single phase structures were formed.
The lattice parameters were calculated using Bragg’s law and the equation
a = d * (h2 + k2 + l2)(1/2)
ρ = 8 * M / NA a3
Crystallite size were estimate using Scherer’s equation

6. XRD results
Fig. 2

7. Structural parametersx
a (Å)
±0.003
DXRD (nm)
±0.01
DHRTEM (nm)
±1.69
ρXRD(g/cm3)
0.001
0.0
8.380
8.27
8.55
5.30
0.1
8.387
7.91
8.33
5.26
0.2
8.34
8.66
5.24
0.3
8.379
7.28
7.42
5.23
0.33
8.395
7.20
7.83
5.18
Table 1

8. High- resolution electron microscopy and scanning electron microscopy measurements
Typically HRTEM micrograph
images at different scales.
The images show the crystalline
and particles distribution of the series.
The crystallite size values endorsed the
ones from XRD measurements.
x = 0
x = 0.1
x = 0.2
x = 0.3
x = 0.33
Fig. 3

9. High- resolution electron microscopy and scanning electron microscopy measurements
Typically HRSEM micrograph
images.
The images show uniform
nanoparticle shape.
The particles are well distributed
with little agglomeration.
x = 0
x = 0.1
x = 0.2
x = 0.3
x = 0.33
Fig. 4

10. Mössbauer Measurements
At least two Ziman’s sextets related to Fe3+ ions on A-site and B-site, were used to fit the spectrum.
An additional sextet was used to fit sample x = 0.1
By omitting Co from the sample x = 0.33, the spectrum shows
super-paramagnetic behavior.
no notes
Fig. 4

11. Hyperfine Parameters Table 2 x δ (mm/s) H (kOe) Γ (mm/s) f (%) δA
±0.03 δB
±0.04 HA ±9 HB ±4
H3rd ±7 ΓA
±0.09 ΓB
±0.08 fA ±3 fB
0.31
453
485 -
0.32
0.24 50
0.1
0.30
0.34
473
493
439
0.26
0.21 41 24
0.2
442
480
0.42
0.17 49 51
0.3
419
467
0.55 70 30
0.33
0.38
161
409
0.94
1.35 47 53
Table 2

12. Magnetization Measurements
Substituting cobalt by Mg, Sr and Mn atoms rapidly increase the magnetization from emu/g to emu/g for the x = 0 and x = 0.1 respectively, and then decreased to emu/g for x = 0.33.
Room Temperature Hysteresis loops can be understood in term of cations distribution.
The coercivity decreases with increasing x value, as expected.
Fig. 6

13. Magnetization Measurements
Fig. 7

14. Low Temperature Measurements
M-H curves in revealed a distortion (kink) at 2 K for the samples x = 0.1 and x = 0.2.
The magnetization decreased dramatically as the temperature increases.
The coercivity increases with decreasing temperature.
Fig. 8

15. Low Temperature Measurements
Fig. 9

16. Conclusions
Glycol-thermal method was successfully used to synthesize single phase nanoferrites.
Subsisting Co in sample x = 0.1, increased the magnetization up to emu/g at room temperature.
Reducing Co content weakness the super-interaction

17. Co-workers
Dr T. Moyo Dr H. Abdallah

18. Acknowledgement
South Africa National Research Foundation (NRF)

19. THANK YOU FOR YOUR ATTENTION
no notes