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Sains Ma1aysiana 25(4) 1996: 85-91 Sains Fizis dan Gunaan/ Physical and Applied Sciences
Kesan Komposisi Magnesium ke atas Pemagnetan dan Kerintangan Elektrik Ferit Mnx-zMgzZn1-xFe2O4 (Effects of magnesium composition on the magnetization and electrical resistivity of Mnx-zMgzZn1-xFe2O4 ferrites)
Ahmad Nazlin Yusoff, Mustaffa Hj. Abdullah, Sahrin Hj. Ahmab & Ng Lay Minn Jabatan Fizik, Fakulti Sains Fizis dan Gunaan Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor D.E.
ABSTRAK
Sampel ferit Mnx-zMgzZn1-xFe2O4 dengan x = 0.5, 0 < z < 0.5; x = 0.6, 0 < z 0.6 dan x = 0.7, 0 < z < 0.7, disediakan dengan tindak balas keadaan pepejal. Pengukuran pemagnetan sebagai fungsi medan magnet dilakukan pada suhu bilik (TR) dan suhu-suhu yang lebih tinggi tetapi di bawah suhu Neel bilik (TR) dan suhu-suhu yang lebih tinggi tetapi di bawah suhu Neel (TN) serta histerisis magnet pada suhu bilik dan 373 K diperolehi untuk semua sampel menggunakan magnetometer sampel bergetar (VSM). Kerintangan elektrik pada suhu bilik diperolehi dengan kaedah dua terminal. Ketiga-tiga siri ferit Mn-Mg-Zn itu masing-masing menunjukkan suatu pemagnetan maksimum pada suatu kadar penggantian Mn oleh Mg. TN meningkat dengan kandungan Mg tetapi kerintangan elektrik berubah sebaliknya. Perubahan pemagnetan seperti yang tersebut disebabkan Mg mula menggantikan Mn pada tapak tetrahedron (A) menyebabkan momen magnet paduan meningkat. Penambahan Mg seterusnya menyebabkan Mn pada tapak oktahedron pula diganti, sehingga momen magnet paduan mengurang. Koersiviti yang kecil menunjukkan sampel bersifat magnet lembut dengan kehilangan tenaga yang sangat kecil. Pengurangan kerintangan dengan penambahan Mg mungkin disebabkan oleh peningkatan kelincahan pembawa cas yang melompat di antara ion-ion Fe2+ dan Fe3+ dan juga di antara Mn2+ dan Mn3+.
ABSTRACT
Sampels of Mnx-zMgzZn1-xFe2O4 ferrites, with x = 0.5, 0 < z < 0.5; x = 0.6, 0 < z 0.6 and x = 0.7, 0 < z < 0.7, were prepared by solid state reaction. For all samples, magnetization as a function of applied magnetic field was measured at room temperature (TR) and several temperatures above TR but below the Neel temperature (TN); while magnetic hysteresis was obtained at TR and 373 K using a vibrating sample magnetometer (VSM). Electrical resistivity at TR was measured by a two terminal method. The three series of Mn-Mg-Zn ferrite indicate a maximum ,agnetization at certain substitution of Mg. TN increased with the increase of Mg content while resistivity varied in the opposite manner. The variation of magnetization is interpreted as due to Mg started to replace the Mn at the tetrahedral sites (A) so that the resultant magnetic moment increased. However further substitution occurred at the octahedral sites (B), thus lowering the magnetic moment. A small coercivity indicates that the samples are soft ferrites with a small energy loss. A reduction in the electrical resistivity with Mg content probably due to an increase in the mobility of charge hopping between the Fe2+ and Fe3+ ions and also between Mn2+ and Mn3+ ions.
RUJUKAN/REFERENCES
Brabers, V.AM. 1987. Anomalous electrical properties of MnxFe3-xO4. J. Appl. Phys., 61(8): 4390. Cullity, B.D. 1972. Introduction To Magnetic Materials. USA: Addison-Wesley Publishing Company, Inc., 181. Epstein, D.J. & Franckiewicz, B. 1958. Some properties of quenched magnesium ferrites. J. Appl. Phys., 29(3): 376. Hastings, J.M. dan Corliss, L.M. 1956. Neutron diffraction study of manganese ferrite. Phys. Rev. 104(2): 328. Lotgering, F.K. 1964. Semiconduction and cation valencies in manganese ferrites. J. Phys Chem. Solids 25: 95. Syemyakov, A.A Kote'va, A.M., Paschenko, V.P., Kunevich, A.V., Turro, L.G. & Brovlina, G.T. 1990. NMR study of the distribution of manganese and iron ions of different valence in manganese-zinc ferrites. Neorganicheskie Materaly 26(7): 1533. Tanaka, T. 1978. Effect of the oxygen nonstoichiometry on the domain structure and the initial permeability in Mn-Zn ferrites. Jap. J. Appl. Phys. 17(2): 349.
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