Materials Literature
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A series of Li–Zn mixed ferrites with composition formula Li0.5–0.5xZnxFe2.5–0.5xO4 is prepared by the solid-state reaction method. The variation of lattice parameter with composition is explained on the basis of tetrahedral ionic radius. Thermopower studies are undertaken over a temperature range 300 to 750 K by the…
Kinematical studies of glass transition and crystallization in glassy Se80−xTe20Inx are made using DSC technique. From the heating rate dependence of the glass transition and crystallization temperatures the activation energy, ΔEt, for the relaxation time controlling the structural enthalpy as well as the activation e…
Magnetostriction and magnetomechanical coupling coefficient have been measured on Ho0.85Tb0.15Fe2−xCox (x=0, 0.5, and 1.2) alloys. The alloys were prepared by arc melting as well as by arc melting followed by zoning using induction furnace. Saturation magnetostriction (λs) and magnetomechanical coupling coefficient ar…
On the basis of our recently suggested fan-shaped scattering model [J. Chem. Phys. 92, 5099 (1990)], a method to calculate the translational order parameter τ for the uniaxially oriented liquid crystalline smectic phase is suggested. Using this method, τ is determined from the scattering profiles of the two-dimensiona…
Analytical and numerical calculations of threshold behavior and electro-optical characteristics in twisted chiral nematic layers are presented, when weak anchoring in the tilt and twist angle of the director is assumed. An analytical expression for the effective twist angle and the Fréedericksz threshold voltage is de…
Stable compounds in microwave plasmas of various source gases for vapor-phase diamond growth have been measured by using in situ Fourier transform infrared spectroscopy. Each gas mixture of CH4+H2, C2H2+H2, C2H4+H2, CH3OH+H2, C2H5OH+H2, CO+H2, CCl4+H2, and CH4+O2+H2 was introduced into the plasma discharge region as a…
The ground-state as well as the excited-state absorption and fluorescence properties of single crystals of Cr3+ doped nonstoichiometric green spinels MgO–2.6Al2O3 have been studied at various temperatures and in a broad spectral range (300–1700 nm). Evidence is found of the existence of four distinct classes of Cr3+ s…
The Si2C ground state has been reinvestigated using various basis sets at the Hartree–Fock level as well as with the use of many-body perturbation theory to second order. In agreement with previous theoretical investigations, the ground state is found to be a closed-shell C2v symmetry structure, whereas a linear D∞h s…
Time-resolved OH(X 2Πi,v=1–9) populations have been measured and analyzed to determine parameters relating to formation mechanisms and vibrational relaxation. OH(v) was formed in electron-irradiated Ar/H2/O3 mixtures containing added O2 or CO2 as relaxer species. OH(v→v−1,v−2) emission was observed using time-resolved…
The temperature dependence of dielectric dispersion in [N(C 2 H 5 ) 4 ] 2 ZnCl 4 single crystal, whose transition temperature is 220 K, was measured in the temperature range from about 200 K to 300 K. A notable dispersion is found only along the a -axis. The relaxation time, which increases as the transition temperatu…
The local geometric and electronic structure around a zirconium atom substituted for yttrium in ${\mathrm{Y}}_{2}$${\mathrm{O}}_{3}$ was investigated both experimentally and theoretically. X-ray-absorption measurements were performed at the Y and Zr K and ${\mathit{L}}_{\mathrm{II}}$ edges, in the extended x-ray-absor…
Minimal-basis tight-binding theory, using free-atom term values and nearest-neighbor universal 1/${\mathit{d}}^{2}$ coupling, and an A/${\mathit{d}}^{3}$+B/${\mathit{d}}^{12}$ repulsion, is used to calculate elastic properties without further approximations. Specifically, the shear constants (${\mathit{c}}_{11}$-${\ma…
A Fourier transform infrared study of the vibrational spectrum of Si2C produced by vaporizing mixtures of silicon and carbon-12 or carbon-13 and quenching the products in Ar at 13 K has confirmed a previously observed vibration at 1188.4 cm−1 as the ν″3(b2), antisymmetric Si–C stretching mode, and resulted in the iden…
Frequency-dependent conductivity measurements are reported in the charge-density-wave state of ${\mathrm{K}}_{0.3}$${\mathrm{MoO}}_{3}$ and ${\mathrm{K}}_{0.3}$${\mathrm{Mo}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{W}}_{\mathit{x}}$${\mathrm{O}}_{3}$ alloys in the radio-frequency, microwave, millimeter-wave, an…
The relationship between the anionic groups of \ensuremath{\beta}-barium borate and lithium borate nonlinear optical (NLO) crystals and their bonding, electronic structure, and transmission cutoffs has been studied using the discrete variational self-consistent multipolar X\ensuremath{\alpha} method [B. Delley and D.…
Theoretical calculations show that inhomogeneous doping can increase the efficiency of thermoelectric generators and refrigerators.
A combination of magnetic and electron microscopic measurements on iron deposited in chemically widened anodic aluminum oxide films has allowed us to relate the coercivity of these materials to the dimensions of the metal particles. The coercivity is found to be highly anisotropic and to depend on the aspect ratio of…
We provide a comprehensive analysis of the microstructure of the porous glass, vycor. Using transmission electron microscopy, small-angle x-ray scattering, molecular adsorption, and the dynamic process of direct energy transfer, a consistent picture of the mass, pore, and interfacial features of this material is prese…
We report the polarized absorption ${\mathrm{\ensuremath{\alpha}}}_{\mathrm{\ensuremath{\theta}}}$(\ensuremath{\Elzxh}\ensuremath{\omega}) and photoluminescence ${\mathit{L}}_{\mathrm{\ensuremath{\theta}}}$(\ensuremath{\Elzxh}\ensuremath{\omega}) spectra of gel-processed blends of poly(2-methoxy,5-(2'-ethyl-hexoxy)-p-…
We propose an approach to the calculation of the cohesive and the structural properties of solids. This approach is based on the second theorem of Hohenberg and Kohn and allows one to obtain directly the charge density and the total energy without determining, at the same time, the band structure of the system. The me…