Materials Literature
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Laser ablation deposition has been used to synthesize nanoscale ferrite structures. Our investigations were performed on NiZn and Zn ferrite films deposited on silicon(100) substrates. Films produced by laser ablation at room temperature were annealed at 550°C for 1h. Other films were deposited directly at a 550°C sub…
Thin films on substrate may crack due to tensile residual stress taking a mud crack like pattern. The pattern can be controlled by prescribing stress raisers that initiate, and arresters that terminate, cracks at desired locations. Here, we describe the mechanism by which stresses are amplified in plasma-deposited fil…
The atomic scale details of the pressure-induced polymorphism of ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ have been established by in situ x-ray powder diffraction. At room temperature, the monoclinic ${\mathrm{Gd}}_{5}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ phase $(\ensuremath{\beta})$ is transformed to the…
The addition of Cu(I) to the random-coil peptide, C16C19-GGY, produces a self-organized, metal-bridged 4-helix bundle which displays an intense room-temperature luminescence at 600 nm. Emission, UV, and CD titrations along with X-ray absorption studies indicate that the luminescent cofactor is likely a Cu4S4 cluster i…
We report ultraviolet Brillouin light-scattering experimental data on $v\text{\ensuremath{-}}\mathrm{Si}{\mathrm{O}}_{2}$ in an unexplored frequency region, performed with a newly available spectrometer, up to exchanged wave vector $q$ values of $0.075\phantom{\rule{0.3em}{0ex}}{\mathrm{nm}}^{\ensuremath{-}1}$, at dif…
An indentation fracture mechanics analysis is developed to characterize the toughening effects of a compressive surface layer in brittle materials. The analysis is used to describe the enhanced toughness of cordierite glass–ceramic laminate composites, in which thermal‐expansion mismatch effects induced uniform stress…
The electronic structure of LaxSr1−xFe12O19 (x=0, 0.25, 0.5, 0.75, 1) hexaferrite is calculated using the density functional theory and generalized gradient approximation (GGA). The GGA+U method is used to improve the description of strongly correlated Fe 3d electrons. Fe-sublattice preferences for the magnetic moment…
The saturation magnetization of the milled powders gradually decreased as the milling time increased due to the transformation of the magnetic τ phase into the amorphous phase. On the other hand, the coercivity of the milled powders increased to a peak value of 4.35kOe, then decreased with increasing milling time. Whe…
An interesting concept for achieving graceful failure in oxide composites is discussed. It is based on crack deflection in a weak interphase between a matrix and reinforcement (e.g. fiber), around a fibrous core in a fibrous monolith, or in an interphase in a laminated composite. The interphase can be phase transforma…
Manganese ferrite is a partial inverse spinel which, when prepared by conventional growth techniques, has ∼20% of the Mn2+ ions on the octahedral sublattice. Here we describe a layer–by–layer growth scheme at atomic scale by which the percentage of Mn2+ ions on the octahedral sublattice can be artificially controlled.…
The capacitance of the Na 2 O–SiO 2 glass was measured in situ during heat treatment at various frequencies, 20, 100, 1, 3, 10, and 30 kHz. It was found that the capacitance of the glass abruptly decreases after a certain duration. The glass was quenched at this stage. It was confirmed by the X‐ray diffraction and tra…
The first examples of high-dimensional mixed-valence homometallic cyano-bridged copper complexes were synthesized and characterized: net-structured [Cu(CN)(4){Cu(cyclam)}(1.5)](2)(n)()(H(2)O)(5)(n) (1), ladder-type double-chain-structured [Cu(CN)(2){Cu(CN)(2)Cu(cyclam)}](n)()(H(2)O)(n) (2), layer-structured [{Cu(CN)(2…
Magnetic properties, phase evolution, and coercivity mechanism of melt-spun CoxZr98−xB2 (74⩽x⩽86) nanocomposites were studied systematically. From x-ray diffraction analysis, nearly single magnetic phase, Co23Zr6, is found in Co74Zr24B2 ribbon (x=74). With increasing Co content x, an additional phase, Co5Zr, is found…
Synthetic type IIa diamonds were characterized using rocking curve measurements and x-ray topography with quasi-plane-wave incidence, and high resolution reciprocal space mapping. The rocking curves of the (111) crystals were comparable to the theoretical ones. Some crystals had wider rocking curves because of the hig…
Static and dynamic magnetic properties of cuboctahedrally truncated polydisperse, rf plasma torch synthesized NiZn ferrite nanoparticles have been studied. The transmission electron microscopy (TEM) determined nanoparticle size distribution was log-normal (mean=11.7nm, σ=10.9nm). Magnetic properties are interpreted us…
The shape of ferromagnetic hysteresis loops is described in terms of symmetric Brown and antisymmetric Bozorth stress fields. The magnetization and nonlinear stress dependence of stress fields are measured and plotted. The Brown field is found to exist in every magnetoelastic process and is manifested when hysteresis…
Resonance Raman and resonance hyper-Raman spectra of the "push-pull" conjugated molecule 1-(4'-dihexylaminostyryl)-4-(4"-nitrostyryl)benzene in acetone have been measured at excitation wavelengths from 485 to 356 nm (two-photon wavelengths for the nonlinear spectra), resonant with the first two bands in the linear abs…
Nanocrystalline soft magnetic materials possess higher magnetization and operation temperatures than amorphous alloys with similar compositions. For these reasons, they are good candidate materials for power electronics applications. As an indication of their performance, core losses have been measured for a nanocryst…
An effort to increase the impact toughness of Nd–Fe–B sintered magnets by adding small amounts of Al, Nd, Ga, Cu, and Nb was successful. No significant compromise to magnetic properties occurred. Based on this work, a series of sintered Nd–Fe–B magnets with improved toughness was developed, which we call ToughNEO™. Sm…
Functionalization of single-walled carbon nanotubes (SWNTs) by isotropic plasma treatment was studied using resonant Raman spectroscopy. It was shown that plasma-induced functionalization results in the uniaxial isotropic constriction of the nanotubes but preserves their overall structural integrity. It was demonstrat…