Soft Magnetic Properties of Fe-Ni-Nb Alloy Films
The relation between the soft magnetic properties and local anisotropy fluctuation measured by the dynamic differential susceptibility method in Fe-Ni-Nb alloy films was clarified and discussed in comparison with Fe-Si-Al alloy films. Fe-Ni-Nb alloy films with excellent soft magnetic properties, 5 MHz values of ¿eff = 6500 for 1000 Å thick films were obtained. For Fe-Si-Al alloy films, the magnitude of ¿eff = 6500 is proportional to 1/S2 (where S is a structure constant) and independent of the value of Hk, while for Fe-Ni-Nb alloy films, the value of S is about one-tenth of that in Fe-Si-Al alloy films, and the magnitude of ¿eff 6500 does not depend on S. Rather, this magnitude is dependent on the value of Hk, and is almost equal to 4¿Ms/Hk, obtained from a rotational magnetization model in a uniaxial single-domain particle.
Local anisotropy fluctuation on the permeability of sputtered sendust alloy films.
Precise concentration dependence of μeff in films was clarified in a concentration area around bulk Sendust alloy. The dynamic differential susceptibility measurement proposed by H. Hoffmann was applied to the same films to evaluate the magnetic inhomogeneities normally represented as magnetic skew and ripple. Influence of the local magnetic anisotropy on μeff of the films is discussed in detail. To realize excellent soft magnetic properties, especially at high frequency, a high degree of preferred orientation of grains or of random orientation of grains is suggested.
The crystal structure of stilpnomelane. Part II. The full cell
Summary The structural formula of stilpnomelane averaged from 37 representative literature analyses and based on the determined structure is (Ca,Na,K)4(Ti0·1Al2·3Fe35·5Mn0·8Mg9·3)[Si63Al9](O,OH)216·nH2O. Ferrostilpnomelanes have up to 12 R 3+ cations in the octahedral sheet, ferristilpnomelanes commonly have between 24 and 30 R 3+ cations, rarely up to 37. The two groups can be distinguished by accurate X-ray powder diffraction, ferrostilpnomelanes having d 001 less and a greater than have ferristilpnomelanes. The unit cell is triclinic, a = b∼21·8 Å, γ = 120°, d 001∼12·2 Å, P . Hexagonal groups or ‘islands’ of 24 silicon-oxygen tetrahedra co-ordinate to the octahedral sheet, the centres of the ‘islands’ are displaced by 5a/12, 8b/12 on either side of the octahedral sheet as a result of warping of this sheet to permit articulation with the smaller tetrahedral sheet. The 24-tetrahedra ‘islands’ are linked laterally by 6-member rings of inverted tetrahedra, which in turn link at their apices to like rings connecting the next sheet of ‘islands’. Thus a single tetrahedral layer is 4 tetrahedra thick and has symmetry 6/m. The 6-member rings of tetrahedra act as hinges permitting up to 0·5 Å extension or contraction of the tetrahedral sheet to accommodate variations in the octahedral sheet dimensions with varying R 2+/R 3+ ratio.