Moessbauer study of a binary amorphous ferromagnet: Fe/sub 80/B/sub 20/

Journal Article · Tue Aug 01 00:00:00 EDT 1978 · Phys. Rev., B; (United States)

DOI:https://doi.org/10.1103/PhysRevB.18.1003· OSTI ID:6707086

Chien, C L

Binary amorphous ferromagnetic Fe/sub 80/B/sup 20/ has been studied by /sup 57/Fe Moessbauer spectroscopy from 4.2 to 1050 K. In the amorphous state at temperatures less than the Curie temperature T/sub C/ = 685 K, the spectra of Fe/sub 80/B/sub 20/ exhibit well-defined and essentially symmetric hyperfine-field distributions P (H). The analyses of P (H) were obtained by deconvoluting the spectra via a Fourier series. The shape of P (H) is practically independent of temperature. The values of the effective hyperfine field H/sub eff/(T) show a temperature dependence of H/sub eff/(0)(1-BT/sup 3/2/-CT/sup 5/2/xxx), indicative of spin-wave excitation. The values of B = (22 +- 2) x 10/sup -6/ K/sup -3/2/ and C = (1.4 +- 0.4) x 10/sup -8/ K/sup -5/2/ have been determined. The value of B/sub 3/2/ = BT/sub C//sup 3/2/ = 0.4 +- 0.05 is four times larger than those of crystalline Fe and Ni. rf sideband measurements of Fe/sub 80/B/sub 20/ at several frequencies under various field strengths indicate that Fe/sub 80/B/sub 20/ is highly magnetostrictive with a magnetostriction constant of about 45 x 10/sup -6/, which is comparable to the value of 30 x 10/sup -6/ obtained from static measurements. The amorphous state of Fe/sub 80/B/sub 20/ can not be preserved near T/sub C/ for more than a few minutes. The value of T/sub C/ = 685 K has been determined by the frquency-counting method. A very unusual crystallization behavior, which it both temperature and time dependent, has been observed. The onset of crystallization has been found at T/sub CR/ = 715 K under heating rates of 20 and 40 K/min. A highly unstable crystalline phase of Fe/sub 3/B with T/sub C/ = 820 K forms after crystallization. This Fe/sub 3/B phase transforms completely into Fe/sub 2/B and ..cap alpha..-Fe after heating at 1050 K for only 30 min.

• Research Organization: Department of Physics, The Johns Hopkins University, Baltimore, Maryland 21218
• OSTI ID: 6707086
• Journal Information: Phys. Rev., B; (United States), Vol. 18:3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON BORIDES
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AMORPHOUS STATE
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IRON 57
LOW TEMPERATURE
MAGNETOSTRICTION
MEDIUM TEMPERATURE
MOESSBAUER EFFECT
TEMPERATURE DEPENDENCE
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EVEN-ODD NUCLEI
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NUCLEI
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
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