Sains  Malaysiana 37(2): 205-210(2008)

 

Microwave, Magnetic, Dielectric and Absorption Properties

of Some Cerium-Yttrium Iron Garnets

(Sifat Mikrogelombang,  Magnet Dielektrik dan Penyerapan

Beberapa Garnet besi Serium-Iterium)

 

Mustaffa Hj. Abdullah, Mardiana Ahmad, Noor Baa'yah Ibrahim & Ahmad Nazlim Yusoff

Physics Programme, School of Applied Physics, Faculty of Science and Technology

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor D.E. Malaysia

 

 

Diserahkan : 30 Mei 2007 / Diterima:  24 Oktober 2007 

 

ABSTRACT

 

This paper describes the microwave properties and application of some cerium-substituted yttrium-cerium iron garnets,  Y3-xCexFe5O12   (x  £ 0.15),  as microwave absorbing  materials. The complex scattering parameters due to reflection (S11* and S22*) and transmission (S21*  and  S12*),  relative dielectric  permittivity   (er* = er¢ - jer¢¢)  and  relative  magnetic  permeability (mr* = mr¢ - jmr¢¢) were measured using a microwave vector network analyzer by means of a coaxial two-port technique in the frequency  range of  0.30 – 13.51  GHz.  The microwave power absorption in the materials is discussed as due to the dielectric and magnetic losses. The dielectric losses are interpreted as due to orientational dielectric relaxation and direct current conductivity. The maxima in magnetic losses correspond to domain wall and internal or natural ferromagnetic resonances. Microwave absorbing properties based on a metal-backed absorber were studied and discussed.

 

Keywords: Yttrium iron garnet; Magnetic permeability; Dielectic permittivity; Microwave; Absorption

 

 

ABSTRAK

 

Kertas ini memperihalkan sifat mikrogelombang dan kegunaan beberapa garnet besi cerium - itrium berganti cerium,  CexY3-xFe5O12   (x  £ 0.15),  sebagai bahan penyerap mikrogelombang. Parameter penyerakan kompleks daripada pemantulan, (S11* and S22*),   dan penghantaran,  (S21*  and  S12*),  ketelusan dielektrik relatif (er* = er¢ - jer¢¢)     dan kebolehtelapan magnet relatif (mr* = mr¢ - jmr¢¢) diukur dengan sebuah penganalis rangkaian mikrogelombang vektor melalui teknik sepaksi dua-port dalam julat frekuensi 0.30-13.51 GHz. Penyerapan mikrogelombang di dalam bahan dibincangkan sebagai disebabkan oleh kehilangan dielektrik dan magnet. Kehilangan dielektrik ditafsirkan berpunca daripada relaksasi dielektrik orientasi dan kekonduksian arus terus. Keadaan maksimum dalam kehilangan magnet disebabkan oleh resonans dinding domain dan ferimagnet dalaman atau semulajadi. Sifat penyerapan mikrogelombang yang berdasarkan suatu penyerap berlapikkan logam dikaji dan dibincangkan.

 

Kata kunci: Garnet itrium besi; Kebolehtelapan magnet; Ketelusan dielektrik; Penyerapan mikrogelombang

 

RUJUKAN/REFERENCES 

Abdullah, M. H. & Yusoff, A. N. 1997. Frequency dependence of the complex    impedances and dielectric behaviour of some Mg-Zn ferrites. J. of Mat. Sci.  32: 5817-5823.

Gomi, M., Furuyama, H.  &  Abe, M. 1991.  Strong magneto-optical enhancement in  highly Ce-substituted iron garnet film prepared by sputtering.   J.  of  Appl.  Phys.   71 (11) : 7065-7067.

Hewlett-Packard HP8719D Microwave Vector Network Analyzer Manual and  Software.

Kim, H., Grishin, A. & Rao, K. V. 2001. Giant Faraday rotation of blue light in epitaxial   films grown by pulsed laser deposition. J. of Appl. Phys. 89(8): 4380- 4383.

Kum, J. S., Kim, S. J., Shin, I. B.  &  Kim, C. S. 2003. Magnetic properties and Mossbauer studies of of     Y3-xCexFe5O12  (x = 0.00, 0.1 and 0.3)  fabricated using a Sol-Gel method. IEEE Trans. on Magnetics 39 (5): 3118-3120.

Krauss,  J. D. (1991).  Electromagnetics. Fourth Edition. New York : McGraw-Hill Inc.

Mao, T. C. & Chen J. C,  2006. Influence of the addition of Ce02 on the microstructure and the magnetic properties of yttrium iron garnet ceramic. J. of Magnetism and Magnetic Materials  302: 74-81.

Nicolson, A. N.  & G. F. Ross, G. F. 1970.  Measurement of the intrinsic properties of materials     by  time domain technique.  IEEE Trans. Instrum. Meas.  IM-19: 377-382.

Sekijima, T.,   Itoh, H.,  Fujii, T., Wakino, K.  & Okada, M. 2001. Influence of growth atmosphere on solubility limit of Ce3+  ions in Ce-substituted fibrous yttrium irin garnet single crystals. J. of Cryst. Growth 229: 409- 414.

Srivastava, S. P. 1993. Microwave Dielectric Microscopy. Ed. G.P. Srivastava.   New Delhi: Narosa Publishing House.

Yusoff. A. N., Abdullah, M. H.,  Ahmad, S. H.,  Jusoh, S. F., Mansor, A. A. & .Hamid,  S. A. A. 2002.  Electromagnetic and absorption properties of some microwave absorbers, J. of Appl. Phys. 92: 876-878.

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