Materials Literature
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The formation of the tetragonal compounds R2Fe14C (Nd2Fe14B structure) was studied as a function of the R component. At high temperatures the tetragonal R2Fe14C phase transforms mainly into a rhombohedral phase of the type of R2Fe17Cx in which the C atoms occupy an interstitial position. The transformation temperature…
The frequency, field, and temperature dependencies of core loss in rapidly quenched Fe-6.5 wt. %Si ribbons are reported. The annealed material exhibits (001)〈uv0〉 fiber texture, resulting in isotropic properties in plane; equivalent losses and B-H loops are seen in tape-wound toroids and in annuli punched from ribbon.…
Structure and magnetic properties of the rapidly quenched SmTiFe11 alloy ribbons fabricated under various quenching rates were systematically examined. Phase transformation from an equilibrium ThMn12-type structure (tetragonal) to a metastable TbCu7-type disordered structure (hexagonal) was found for the ribbons fabri…
Thermoelectric power of organic superconductors, β-(BEDT-TTF) 2 I 3 and (BEDT-TTF) 2 Cu(NCS) 2 (BEDT-TTF: bis(ethylenedithio)-tetrathiafulvalene) is calculated by the integration of the Boltzmann equation on the basis of the two-dimensional tight-binding band models. This calculation provides the interpretation of the…
Production of ferrite thin films is the key to integration of microwave ferrite devices (circulators for phased array antennas, for instance). The interesting materials are the usual microwave ferrites: garnets, lithium ferrites, barium hexaferrites. The required thicknesses are a few tens of micrometers, and it will…
The domain wall pinning model used previously by the authors to explain magnetic hysteresis and stress effects on magnetic hysteresis is used in conjunction with the Callen and Callen expression for magnetostriction λ to qualitatively explain magnetostriction hysteresis both with respect to magnetic intensity H and fl…
The ionic-conductivity (\ensuremath{\sigma}) and electric-modulus (${M}^{\mathrm{*}}$) data for melt-grown Na \ensuremath{\beta}-alumina in the ${10}^{2}$--${10}^{7}$-Hz frequency range have been previously interpreted with a formalism in which the decay of an observable, such as the time-dependent electric field in t…
Conventional grain-oriented silicon steels 0.3 mm thick were cold-rolled to thicknesses from 0.18 to 0.08 mm, and the magnetic properties and grain textures of these sheets were observed before and after annealing. The results indicated that the magnetic induction B8 and the coercive force Hc were 1.8 T and 25 A/m, re…
The hot working conditions were examined for Nd-Fe-B die-upset magnets. The Nd14Fe80B6 ternary composition has the best workability (die upsetting) from stress-strain curves for the initial stage of die upsetting at hot working temperature. The compression ratio defined as the inverse of reduction in height should be…
The large values of remanence observed in isotropic melt-spun R-Fe-Al-B-Si samples have been investigated by correlating the magnetic properties with the microstructure. Transmission electron microscope studies showed that the highest values of reduced remanence mR are obtained in samples with very fine Nd2Fe14B-type…
The pressure dependence of the HOMO–LUMO transition energy and the frequency of the longest wavelength longitudinal optical vibration of 45 Å diameter CdSe clusters in methanol–ethanol solution have been measured up to 50 Kbar. The LO mode shifts to higher frequency at a rate of 0.43 cm−1/Kbar, which corresponds to a…
Fragile glass-forming liquids are characterized by strongly non-Arrhenius temperature dependence of shear viscosity, and by unusually high heat capacity in the supercooled liquid above the glass transition. Using the inherent structure formalism, a theoretical model is developed to explain these characteristics. The v…
A time-of-flight inelastic neutron scattering study of Ca 0.4 K 0.6 (NO 3 ) 1.4 of the temperature dependence of the dynamic structure factor revealed a clear frequency-independent signature of the glass transition at the conventional transition temperature T g . Above T g the data combined with our previous neutron s…
A number of Nd15 Fe79−x Mgx B6 magnets with x up to 0.41 and pseudoternary Nd2(Fe1−yMgy)14B compounds with y up to 0.081 have been prepared by conventional powder metallurgy processes. Magnetic measurements indicate that for the magnet alloys i Hc increases as x increases up to 0.25 without a loss in Br, hence the (BH…
Oxygen plays a very important role in the magnetic properties of R-Fe-B-type alloys. As the oxygen content increases in Nd-Fe-B and Nd-Dy-Fe-Al-B alloys, the alloys gradually lose their magnetic and thermomagnetic properties: the Hci decreases and both the temperature coefficient of Hci and the irreversible temperatur…
Fe-rich and RE-containing phases with the ThMn12 structure show interesting intrinsic magnetic properties. The single-phase composition Fe80Mo12Sm8 has a saturation magnetization of 10 kG, a Curie temperature of about 200 °C, and an anisotropy field of about 90 kOe, with the saturation magnetization and the Curie temp…
Ultrafine subdomain particles of NiFe2O4, Ni0.5Zn0.5Fe2O4, and CoFe2O4 were prepared under mild hydrothermal conditions by precipitating from metal nitrates. Magnetic and Mössbauer effect measurements revealed the superparamagnetic nature of these ferrite particles. The crystallite sizes were in the range 5.0–20.0 nm…
High field magnetization and magnetoresistance of YbB 12 are investigated up to 550 kOe at low temperatures with special interest in the semiconductive band gap energy under the field. Very large negative magnetoresistance is found and the system is perfectly metallic around 500 kOe with anomalous increase in the magn…
A new process has been developed to produce high-energy bulk Pr-Fe-B magnets directly from the melt without the handling of magnetic powder or powderlike ribbons. The process mainly consists of only three steps—casting/hot pressing/annealing—and minimizes the oxygen contamination of magnets. A typical composition of c…
Experimental data are reported for depolarized and fully polarized components of the Raman spectra of variably ordered states of a-Ge and a-Si films. These spectra are compared to theoretical Raman calculations for relaxed Polk-model-derived structures with different degrees of bond-angle disorder. In addition, the ex…