Materials Literature
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The coherency of the domain walls forming between the a and c domains in epitaxial lead titanate films forces a tilt in the a-domains with respect to the surface normal of the (001)SrTiO3 substrate. It is shown that the measurement of the relative volume fraction of the domains requires mapping of the x-ray diffractio…
We propose a microscopic model without energy barriers in order to explain some generic features observed in structural glasses. The statics can be exactly solved while the dynamics has been clarified using Monte Carlo calculations. Although the model has no thermodynamic transition, it captures some of the essential…
Voltage offsets in the polarization-voltage characteristics of Pb(Zr,Ti)O3 capacitors can be induced by either thermal or optical processes. The thermally (optically) induced voltage shift occurs by heating (illuminating) the sample under remanence or a saturating bias. Generally speaking, the thermally induced voltag…
Two-particle calculations, which include the electron-hole Coulomb interaction nonperturbatively, are performed for excitons in surface passivated Si nanocrystals. The calculated exciton energies agree quantitatively with photoluminescence data. The exciton charge distributions differ markedly from those obtained in s…
The magnetism of an insulator, $\ensuremath{\kappa}$-(BEDT-TTF${)}_{2}$Cu[N(CN${)}_{2}$]Cl, situated near the 10 K superconducting phase in $\ensuremath{\kappa}$-type BEDT-TTF family, has been studied by ${}^{1}$H NMR for the first time. A commensurate antiferromagnetic ordering with a moment of (0.4--1.0) ${\ensurema…
It is shown that the local spin-density approximation describes well electronic structures of perovskite $\mathrm{La}M{\mathrm{O}}_{3}$ ( $M\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}$ Mn, Fe, Co, Ni) for the ground-state and single-electron excited-state properties. Inclusion of details of crystal structures…
We present a general scheme for the computation of the time dependent (TD) quadratic susceptibility ($χ^{(2)}$) of an extended insulator obtained by applying the `$2n+1$' theorem to the action functional as defined in TD density functional theory. The resulting expression for $χ^{(2)}$ includes self-consistent local-f…
Cubic structured CdS, CdSe, and CdTe, II–VI semiconductor nanoparticles have been synthesized using aqueous solution precipitation at room temperature. The ‘‘as-prepared’’ particles have a size of about 30 Å. Thermal annealing causes (a) an increase in particle size; (b) a structural transition from the cubic to the b…
We present results of temperature and magnetic field dependent resistivity ρ(H,T) and bulk magnetization M(H,T) measurements on post-annealed La0.7Ca0.3MnO3 thin films that were grown via pulsed-laser deposition. Both the resistivity and the anomalously large negative magnetoresistance peak near the ferromagnetic orde…
We propose a heterogeneous reaction-diffusion model for the hydration and setting of cement. The model is based on diffusional ion transport and on cement specific chemical dissolution/precipitation reactions under spatial heterogeneous solid/liquid conditions. We simulate the spatial and temporal evolution of precipi…
An extension of the evolution strategy for mixed-integer optimizationproblems is introduced. The resulting generalized evolution strategy is applied to the problem of optical multilayer coating design and the results are compared with results obtained by standard methods. The generalized evolution strategy as a synthe…
This paper explains the origin of the ferroelectric instability in LiNbO3 and LiTaO3 and compares the electronic structures and energetics of the two materials.
Resonant tunneling through semimetallic ErAs quantum wells embedded in GaAs structures with AlAs barriers was recently found to exhibit an intriguing behavior in magnetic fields which is explained in terms of tunneling selection rules and the spin-polarized band structure including spin-orbit coupling.
The band structures of 6H and 4H SiC calculated by means of the FP-LMTO method are used to determine the effective mass tensors for their conduction-band minima. The results are shown to be consistent with recent optically detected cyclotron resonance measurements and predict an unusual band filling dependence for 6H-…
A new method to obtain a local parameterization for the exchange term in the many--body electronic problem is presented. The approach amounts to the introduction of a coordinate dependent electron effective mass. Numerical results for metallic clusters in the jellium model are compared with other standard methods.
The results of study on dynamic dielectric properties of some H-bonded crystals are presented. It is shown that relaxational soft modes are responsible for the ferroelectric phase transition in RbD2PO4, PbHPO4 and NH4HSeO4 and their contribution accounts for the static permittivity. Glass-like dielectric relaxation wi…
Abstract The electromic behavior of polyaniline‐poly(sodium acrylate) composite films (CPAn‐PAcNa) combined with a polycation bound to the disulfonated bathophenathroline ligand‐Fe complex (QDM‐BPDS‐Fe) was investigated in a LiClO 4 CH 3 CN non‐aqueous aprotic solution. The combination was achieved by chemial deposit…
Low-frequency Raman scattering spectra of potassium nitrate, KNO3 are observed as a function of temperature in a range from room temperature up to 130 K above the melting point Tm (606 K), including its order-disorder phase transition point at 403 K (Tc ). A central peak grows drastically with increasing temperature b…
The solid phases which appear when heating crystalline bis n-decyl and n-dodecyl ammonium tetra-chlorozincates (C10Zn and C12Zn for short) were studied using differential scanning calorimetry, X-ray diffraction and infrared and Raman spectroscopies. The unit-cell parameters of the different phases were determined. For…
We report the effects of matrix impedance on the electrical and optical properties of polymer dispersed liquid crystal (PDLC) samples. It was found that the impedance of a PDLC sample is a function of the applied dc bias and the frequency of the superimposed ac perturbation signal. Using the Randles equivalent circuit…