The correlation of lattice constant with superexchange interaction in Bi-YIG fabricated by mechanochemical processing
Magnetic and structural properties of Bi substituted YIG with nominal formula of Bi x Y3 − x Fe5O12 (x = 0.0, 0.25, 0.5, 0.75, 1.00) prepared via Mechanochemical Processing (MCP) have been studied with Mossbauer spectroscopy, X-ray diffraction (XRD). The
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ginally published in the journal Hyperfine Interactions, Volume 184, Nos 1–3, 575–580. DOI: 10.1007/s10751-008-9783-9 © Springer Science + Business Media B.V. 2008
Abstract Magnetic and structural properties of Bi substituted YIG with nominal formula of Bix Y3−x Fe5 O12 (x = 0.0, 0.25, 0.5, 0.75, 1.00) prepared via Mechanochemical Processing (MCP) have been studied with Mossbauer spectroscopy, X-ray diffraction (XRD). The temperature dependence of sublattice magnetic hyperfine field for samples is analyzed. The a–d intersublattice superexchange found to be antiferromagnetic and increases from −21.97 to −25.79 kB as Bi increases from 0.0 to 0.25. The a–a and d–d intrasublattice exchanges for sample x = 0.0 are 13.18 and 10.55 kB respectively while for sample x = 0.25 a–a and d–d intrasublattice exchanges are 7.7 and 8.9 kB respectively. The correlation of lattice constant and superexchange interaction are discussed. Keywords Lattice constant · Superexchange interaction · Bi-YIG · Mechanochemical processing · Mossbauer spectroscopy
1 Introduction Yttrium iron garnet (Y3 Fe5 O12 ) has provoked great interest since their discovery. According to structure analysis of Menzer YIG belongs to space group Ia3d(O10 h ) [1] and cation are located at the center of corresponding oxygen polyhedral, i.e. Yttrium ions occupy center of dodecahedral {24c} site, a disturbed cube, and iron ions occupy center of octahedral [16a] and tetrahedral (24d) site [2]. The strongest magnetic interactions occur in the intersublattice exchange, superexchange interaction, between Fe+3 irons in octahedral and tetrahedral site through intervening O−2 ions [3, 4].
M. Niyaifar (B) · Ramani · M. C. Radhakrishna Physics Department, Bangalore University, Bangalore 560056, India e-mail: [email protected] A. Hassnpour · M. Mozaffari · J. Amighian Physics Department, University of Isfahan, 81746-73441, Isfahan, Iran
N. S. Gajbhiye and S. K. Date, ICAME 2007. DOI: 10.1007/978-3-540-78696-2_77
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G(842)
G(664)
G(840)
G(800)
G(640)
45
G(552) G(642)
40
G(444)
G(422)
G(400)
G(532)
Intensity (a. u.)
G(321)
x=1.00
G(521)
G(420)
576
x=0.75
x=0.50
x=0.25
x=0.00
30
35
50
55
60
65
70
2θ degree
Fig. 1 X-ray diffraction pattern of Bix Y3−x Fe5 O12 Fig. 2 Lattice constant as a function of Bi concentration
12.46
Lattice Constant (A)
12.44
12.42
12.40
12.38
12.36 0.00
0.25
0.50
0.75
1.00
Bi Concentration
Bismuth substituted YIG have been found to exhibit a very large Magneto-Optic property which will be good candidate material microwave devices and MagnetoOptic recording medium [5].
2 Experimental Polycrystalline substituted yttrium iron garnets of composition Bix Y3−x Fe5 O12 with x equal to 0.00, 0.25, 0.50, 0.75 and 1.00 are prepared by mechanical alloying and subsequent heat treatments. The raw materials; Fe2 O3 , Y2 O3 and Bi2 O3 are first weighed in different mole ratios and then milled for 5 h. The as-milled powders are
Correlation of lattice constant with superexchange interaction Fig. 3 Mos
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