Materials Literature
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The Preisach model is appropriately modified to describe the clockwise hysteresis with the positive saturation state achieved for some positive input value. It is demonstrated that this type of clockwise hysteresis may naturally appear in front propagation problems such as nonlinear diffusion of electromagnetic fields.
Phase evolution and magnetic properties of melt-spun Nd8Fe86B6−xCx (x=0, 2, 4, 5, 6) alloy ribbons have been investigated. Increasing the C content was found to decrease the glass-forming tendency of as-spun ribbons. For samples with low C content (x⩽4), the best magnetic properties were achieved by directly quenching…
Thermal expansion and magnetic properties of the YFe11−xCoxTi compounds have been investigated by various experimental methods. A large magnetovolume effect has been clearly observed below TC for the Fe-rich compounds. When the transition metal concentration changes from Fe to Co rich, the invar-like effect becomes le…
We report an enhanced negative magnetoresistance ratio of about 16% at 4.2 K at 1 T for CrO2/TiO2 composites, compared to CrO2 powder compacts and CrO2/RuO2 composite. The magnetoresistance ratio of 60% at 4.2 K is noted when TiO2 acts as tunneling barrier. The absence of substantial barrier heights with RuO2 grains d…
The effect of the atomic disorder–order transformation on remanence enhancement and coercivity in isotropic CoPt magnets has been studied by isothermal annealing at 675 °C, well below the transformation temperature, for 10–80 min after quenching from 900 °C. The results of x-ray diffraction, alternating-current suscep…
Ultrafine Co1−xZnxFe2O4 (0⩽x⩽1.0) particles are fabricated by a sol-gel method. The magnetic and structural properties of powders were investigated with x-ray diffraction, vibrating samples magnetometer and Mössbauer spectroscopy. The lattice parameter (a0) increases linearly with increasing Zn concentration (x) and f…
We observed high N contents inside BN fullerenelike multilayered nanocages (ca. 30–100 nm) formed by reacting CNx nanotubes (x⩽0.1) and B2O3 in a N2 atmosphere at 1985–2113 K. High-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy, energy dispersion x-ray spectroscopy, electron dif…
The La0.7Ca0.3−xBaxMnO3 (x=0; 0.03; 0.06…0.3) and La0.7Ca0.3−xSrxMnO3 (x=0.105, 0.12, 0.135, 0.15, 0.165, and 0.18) lanthanum manganites were synthesized and studied. The Curie temperature TC of Ba range showed a sharp change near the concentration structural orthorhombic–rhombohedral phase transition. The TC values f…
Abstract Hydroxy‐terminated polybutadiene (HTPB) prepolymer prepared by free‐radical mechanism at Chemical Engineering Complex, Vikram Sarabhai Space Center, Thiruvananthapuram was reacted with toluene diisocyanate (TDI), a curative at varying stoichiometric ratios ( r = [NCO]/ [OH]) equal to 0.7, 0.8, 0.9, 1.0, and 1…
The fringe-field switching (FFS) mode is known to exhibit both a wide viewing angle and high transmittance, owing to the approximated in-plane rotation of the liquid crystal (LC) director. However, in the bright state, the device shows bluish and yellowish color parallel and perpendicular to the LC director at off-nor…
Electron magnetic resonance (EMR) spectra were measured on different La1−xSrxMnO3 manganites at the interval 100⩽T⩽420 K for studying an influence of the synthesis conditions on the magnetic homogeneity of the sample. The micron-sized crushed crystals La0.833Sr0.126MnO3 and La0.7Sr0.3MnO3 grown by fused-salt electroly…
Recently, the giant magnetoimpedance (GMI) effect found in amorphous wires has been noticed as a method for sensing a magnetic field. The GMI sensor was applied to nondestructive evaluation of microstructural changes for reactor pressure vessel steels passing through the refining process. They were measured by using a…
In this work the magnetic properties of magnetite powders doped with Co and Ni are investigated as a function of dopant concentration. Two sets of Fe3−xTxO4 powders with T=Co and Ni, x=0–1 were prepared using a hydrothermal method, with particle sizes of about 1 μm. The Mössbauer measurements revealed that both Co2+ a…
Electronic structure of NdNiO3 and YNiO3 are calculated by using LSDA+U method with rotational invariance. No orbital order on Ni sites is observed in both systems but different charge orderings. In a small distorting system NdNiO3, all Ni ions are trivalent and oxygen sites have a particular ordering, both in charge…
Binding of protons and metal ions to dendrimers is investigated using a multishell model, in which concentric binding sites are approximated by continuous and uniformly charged shells. The electrostatic interactions among the shells are assumed to be the sole source of site-to-site interactions, and an analytical form…
A technique to perform nanofatigue experiments was developed. This technique utilizes a depth-sensing nanoindenter with harmonic force. The nanofatigue behavior of 20 nm thick amorphous carbon coatings was studied. The contact stiffness was monitored continuously throughout the test. The abrupt decrease in the contact…
We report a systematic study of ferromagnetic resonance (FMR) on thin films of the ferromagnetic semiconductor GaMnAs grown by low temperature molecular beam epitaxy. Pronounced shifts of the FMR line are observed towards fields above and below the g=2.00 resonance position for the magnetic field orientations perpendi…
As a model system for solid polymer electrolytes thin polyethylene oxide (PEO) films (0.6–30 μm) are prepared as Al–PEO–Al and as Al–PEO–Si structures with blocking electrodes. Dielectric measurements (capacitance and loss angle) are carried out in a frequency range of 3 mHz⩽f⩽1 MHz in atmospheres of different relativ…
Dynamic Monte-Carlo simulations of ionic space charge relaxations are carried out using a three-dimensional model for thermally activated ion hopping in a multiwell energy structure. In this model a solid polymer electrolyte is embedded between two ideal blocking electrodes. The polymer is subdivided into 100×100×100…
The intensive milling technique has been used to produce nanocrystalline isotropic PrFeB-based powders. Highly coercive powders were obtained using the base composition R16T76B8 (R: rare earth, T: transition metal) with Dy and Zr additions achieving a high value of μ0Hc=2.66 T for Pr15Dy1Fe75.9B8Zr0.1. The influence o…