Sains Malaysiana 25(1): 51-57 (1996)                                                                           Sains Fizik dan Gunaan/

Physical and Applied Sciences

 

Anomalous Temperature Dependence of Electrical

Resistivity in Mg0.6Zn0.4Fe2O4 Ferrite

 

 

 

Mustafa Hj. Abdullah & Ahmad Nazlim Yusoff

Jabatan Fizik

Fakulti Sains Fizis & Gunaan

Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor D.E. Malaysia

 

 

SYNOPSIS

 

The  electrical resistivity of Mg0.6Zn0.4Fe2O4 ferrite was measured as a function of temperature in the range 300-630 K. Two anomalies are observed in the resistivity curves for measurements during heating up. These anomalies are identified as a magnetic anomaly at the Neel temperature, TN = 598 K, while the other one at TOt = 445 K is discussed as due to the contribution of conduction from the tetrahedral sites. The anomaly at Tot was reduced in the measurements during recooling, while the anomaly at TN was disappeared completely during recooling and second cycle. These effects are discussed as due to the increase of Fe2+ ions at the octahedral sites as a result of cation redistribution at higher temperatures. A relatively small anomaly at Tot still can be observed during the second run. This is possible if the Fe2+ ions have a preference to be relocated at the tetrahedral sites at lower temperatures.

 

SINOPSIS

 

Kerintangan elektrik Mg0.6Zn0.4Fe2O4 ferit telah diukur sebagai fungsi suhu dalam julat 300 - 630 K. Dua anomali dapat dicerap pada lengkung kerintangan bagi pengukuran semasa pemanasan. Dua anomali tersebut dikenalpasti sebagai anomali magnet pada suhu Neel, TN = 598 K, manakala yang satu lagi pada Tot = 445 K dibincangkan sebagai berpunca daripada sumbangan kekonduksian pada tapak tetrahedron. Anomali pada Tot mengurang dalam pengukuran semasa penyejukan semula pada julat suhu yang sarna, manakala anomali pada TN terus lenyap dalam pengukuran semasa penyejukan semula dan juga semasa kitar kedua. Kesan ini dibincangkan sebagai disebabkan oleh peningkatan ion Fe2+ pada tapak oktahedron daripada proses taburan semula kation pada suhu tinggi. Anomali yang berkurang pada Tot masih boleh dicerap semasa pengukuran kitar kedua. Keadaan seperti ini adalah mungkin jika ion Fe2+ mempunyai kecenderongan untuk bertempat semula pada tapak tetrahedron apabila suhu menurun.

 

 

RUJUKAN/REFERENCES

 

Ahmed, M. A., El Nimr, M. K., Tawfik, A. & Abodata, A. M. 1988. Effect of magnetic order on the conductivity in Co-Zn ferrites. Journal of Material Science Letters 7: 639.

Brabers, V. A. M., Proykova, Y. G., Salerno, N. & Whall, T. E. 1987. Anomalous electrical properties of  MxFe3-xO4.  Journal of Applied Physics 61: 4390.

Gani, A. A. & Miryasov, N. M. 1972. Effect of transition from the ferrimagnetic to the paramagnetic state on the conductivity of Cu- Cd ferrites. Soviet Physics Solid State13: 2627.

Lotgering, F. K. 1964. Semiconduction and cation valencies in manganese ferrite. Journal of Physics and Chemistry of Solid 25: 95.

Mousa, M. A., Summan, A. M., Ahmed, M. A. & Badawy, A. M. 1989. Electrical conduction in  γ - irradiated and unirradiated Fe3O4, CdFe2O4 and CoxZn1-xFe2O4 (0 < x < 1) ferrites. Journal of Material Science 24: 2478.

 

 

 

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