Materials Literature
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All of the first-principles electronic-structure calculations for the martensitic structure of NiTi have used the experimental atomic parameters reported by Michal and Sinclair [Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. B37, 1803 (1981)]. We have used first-principles, full-potential, linear muffin…
Polycrystalline samples of dimeric cadmium tartrate, [(Cd,C4H4O6)2H2O)]3H2O [labeled CdT(I)], were studied using impedance measurements and x-ray powder diffraction. The dependence of the real part of the dielectric constant on temperature showed a sharp peak at about 65 °C, revealing a structural phase transition, wh…
Spin-lattice relaxation times of P1 centers in a suite of two natural type Ib, two synthetic type Ib, and one natural type Ia diamonds were measured at 9.6 GHz as a function of temperature in the range 300 K>T>4.2 K. An analysis of the results revealed that for three of the diamonds (two synthetic type I…
We present ab initio molecular-dynamics studies of the graphitization of flat and stepped diamond (111) surfaces. Fully self-consistent calculations were performed within the local-density-functional approximation with ultrasoft pseudopotentials and periodic boundary conditions. We investigated the effects of the syst…
The change of the electronic structure and lattice dynamics upon the charge-ordering (CO) transition has been investigated for a ${\mathrm{La}}_{1/3}{\mathrm{Sr}}_{2/3}{\mathrm{FeO}}_{3}$ crystal by measurements of optical spectra. The CO transition, as characterized by sequential 2:1 ordering of nominal ${\mathrm{Fe}…
Lattice constants, resistivity, and Raman scattering spectra have been investigated for ${R}_{1/2}{\mathrm{Ba}}_{1/2}{\mathrm{CoO}}_{3},$ where $R$ is a trivalent rare-earth ion, with systematically changing the averaged ionic radius ${r}_{R}$ of the rare-earth ion. For $R=\mathrm{Gd},$ Eu, Sm, prominent metal-insulat…
Single crystal samples of Ce3+-doped fluorides [LiCaAlF6 (LiCAF), LiYF4 (LYF), NaCaYF6 (NCYF)], and oxides [Ca2Al2SiO7 (CASM), CaYAlO4 (CYA)] have been grown in inert and reducing atmospheres, with the intent of studying the effects of symmetry and ligand coordination on the dopant energy levels. The optical absorptio…
Composites of water-soluble conducting polyaniline copolymers, poly(aniline-co-aminobenzenesulfonic acid) (PAOABSA), containing γ-Fe2O3magnetic particles with nanometer size, were synthesized by a chemical method. The ferromagnetic properties of the resulting PAOABSA composites were measured as a function of the pH va…
Using a many-body approach based on atomistic pseudopotential wave functions we show that the electron-hole exchange interaction in semiconductor quantum dots is characterized by a large, previously neglected long-range component, originating from monopolar interactions of the transition density between different unit…
A theoretical description is proposed of the kinetics of overall crystallization when the appearance of the stable crystalline (SC) phase is preceded by the formation of a metastable phase. A general formula is derived for the fraction αs of volume of the SC phase crystallized at time t. This formula is used for obtai…
We present an ab initio procedure for the construction of pseudopotentials accommodated to a crystal environment under study, which takes into account the response of the core charge density to the valence electrons of an atom in a bond. Within pseudopotential methodology, core electrons are treated differently from v…
We have investigated the characteristics of the charge carriers of the double-layered manganites, ${\mathrm{La}}_{2\ensuremath{-}2x}{\mathrm{Sr}}_{1+2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}(x=0.35,$ 0.40), using polarized O $1s$ x-ray absorption spectroscopy. When the system undergoes the insulator to metal transition, th…
We study the “prepeak” appearing in the static structure factor of the molecular glass-former m-toluidine by means of neutron scattering experiments and Monte Carlo simulations. The occurrence of this prepeak is interpreted as resulting from spatial organization of the molecules that goes beyond the usual short range…
Composites of polyaniline (PANI) with both conducting and ferromagnetic feature were synthesized by an improved method proposed by the authors. The electrical and ferromagnetic properties of the composites were measured as a function of the concentration of KOH solution used during polymerization. The conductivity of…
Pure ground tungsten trioxide WO3 and (1−x)WO3−y⋅xReO2 mixtures were studied by x-ray absorption spectroscopy, x-ray powder diffraction and Raman spectroscopy in comparison with hydrogen bronzes HxWO3 and hydrogenated calcium tungstate CaWO4:H. It was found that a grinding of pure WO3 leads to a decrease of the crysta…
A study of the magnetic properties of several (Gd1−xErx)NiAl alloys (where x=0, 0.30, 0.40, 0.46, 0.50, 0.55, 0.60, 0.80, and 1.00) was undertaken using both ac and dc magnetic and heat capacity measurements in an attempt to understand the table-like magnetocaloric effect previously observed in (Gd0.54Er0.46)NiAl. Res…
The Rehr-Albers (RA) separable Green's-function formalism, which is based on an expansion series, has been successful in speeding up multiple-scattering cluster calculations for photoelectron diffraction simulations, particularly in its second-order version. The performance of this formalism is explored here in terms…
Cavitation erosion is an especially destructive and complex phenomenon. In order to understand its basic mechanism, the dynamics of laser-induced vapor bubbles have been investigated. Special experimental devices have been used to record ultrafast visualizations and pressure measurements. From these measurements, the…
We report time-resolved studies of image-potential states on Cu(100) and Ag(100). Femtosecond ultraviolet-pump and infrared-probe techniques combined with two-photon photoemission have been used to measure relaxation dynamics of $n=1,$ 2, and 3 image-potential states. We found the lifetimes of these states on Cu(100)…
In this paper, the Raman spectrum of Ti3SiC2 is reported and compared with that of TiC0.67. All the TiC0.67 first order Raman disorder-induced modes are active, but shifted, in Ti3SiC2. Two additional peaks at 150 and 372 cm−1 are observed in Ti3SiC2. The former is ascribed to a shear mode between the Si and Ti planes…