Materials Literature
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We show that the magnetoelastic coupling between the magnetization and the amplitude of a short wavelength phonon enables the existence of a first order premartensitic transition from a bcc to a micromodulated phase in ${\mathrm{Ni}}_{2}\mathrm{MnGa}$. Such a magnetoelastic coupling has been experimentally evidenced b…
We calculate the linear magneto-optical Kerr rotation for CeSb in the near-infrared spectral range. Using an exact formula for large Kerr rotation angles and a simplified electronic structure of CeSb we find at \hbar ω= 0.46 eV a Kerr rotation of 90 degree which then for decreasing ωjumps to -90 degree as recently obs…
The theory of the macroscopic field appearing in the Kohn-Sham exchange-correlation potential for dielectric materials, as introduced by Gonze, Ghosez, and Godby [Phys. Rev. Lett. 78, 294 (1997)], is reexamined. It is shown that this Kohn-Sham field cannot be determined from a knowledge of the local state of the mater…
Integral expressions are determined for the elastic displacement and stress fields due to stationary or moving dislocation loops in three dimensional, not necessarily isotropic, finite samples. A line integral representation is found for the stress field, thus satisfying the expectation that stresses should depend on…
Abstract The atomic flux divergence obtained from current density and temperature in metal lines undamaged by electromigration is useful to predict the formation of initial void. In this study, a new method to calculate the atomic flux divergence used for predicting the formation of initial void is proposed considerin…
The optical conductivity is studied numerically for the ferromagnetic metallic state close to the charge ordering observed in perovskite manganites. We focus on roles of the charge fluctuation on the incoherent component in the optical spectra, and consider the Coulomb interaction in the one- and twodimensional spinle…
Cationic polymerization of a seven-membered cyclic sulfite (7CS) was carried out with methyl trifluoromethanesulfonate as a catalyst in chlorobenzene. The final conversions of 7CS were 22, 41, 52, and 60% in the polymerizations at 25°C with the initial monomer concentrations of 3, 4, 5, and 6M, respectively. The calcu…
It is possible to polymerize good quality polyacrylonitrile (PAN) chains, typically 360 monomers long, inside the channels of a zeolite. After suitable pyrolysis, these chains become conducting, as proved by microwave measurements and by electron spin resonance. This behavior contrasts with our preceding work with pol…
A new hexagonal aluminium–chromium–nickel phase, Al14.4Cr3.4Ni1.1, is described. The structure includes 12 icosahedral clusters in a unit cell, each of which consists of a transition metal (TM) atom at the center and 11 aluminium and one TM atom on the fivefold vertices of the icosahedron. Pairs of the clusters are li…
The relationship between the polaron mobility and the fixed-spin-induced ESR linewidth is verified experimentally in HCl-doped polyaniline in which a controllable amount of Fe${}^{3+}$ paramagnetic ions have been incorporated. The polaron mobility has been varied by (a) decreasing the temperature, and (b) aging of the…
The linear and nonlinear optical response properties of crystalline DEANST, N,N-diethyl-4-(2-nitroethenyl) phenylamine, have been computed rigorously, using a large set of input data including modified neglect of differential overlap (MNDO) and ab initio theoretical estimates of molecular polarizability α and hyperpol…
The title compound, a new polymorphic phase of dicobalt diphosphate, Co2P2O7, was prepared by hydrothermal methods. The structure contains CoO6 coordination octahedra and P2O7 radicals. The CoO6 radicals, connected by edge sharing, form six-membered rings, which are further interconnected to form two-dimensional zigza…
Poly(silylenemethylene)s of the types [SiMeRCH2]n and [SiHRCH2]n were prepared by the ring-opening polymerization (ROP) of 1,3-disilacyclobutanes (DSCBs) containing n-alkyl substituents, such as C2H5, n-C3H7, n-C4H9, n-C5H11, and n-C6H13, or a phenyl group on the Si. These new polymers include a monosilicon analog of…
The nature of the insulating ground state in quasi-two-dimensional organic conductor lambda-(BETS)_2GaX_zY_{4-z}, where the existence of a spin gap is suggested by susceptibility measurement, has been studied theoretically. Hartree-Fock calculations at absolute zero temperature show that if the on-site Coulomb interac…
Spontaneous emission and absorption in an aggregate of π-conjugated oligomers are studied theoretically. Each oligomer is taken as a ring of N carbon atoms with average bond length a, and is treated using the Hückel Hamiltonian with bond alternation parameter δ. Coulombic interactions between rings are treated to firs…
New phthalide-containing bisphenols, phenolphthalein-N-(3-methylanilide) (3-PMA), and phenolphthalein-N-(4-methylanilide) (4-PMA), were synthesized from phenolphthalein and m- and p-toluidines. These bisphenols were polycondensed with terephthaloyl chloride (TPC) using an interfacial or solution polymerization techniq…
The frequencies, widths, and shapes of the one-phonon Raman spectra of isotopically enriched and highly isotopically disordered $\ensuremath{\alpha}$-Sn samples have been measured. The isotopically enriched samples show a frequency inversely proportional to the square root of the mass, in agreement with the harmonic a…
The conductance of single-shell carbon nanotubes is numerically calculated in the effective-mass approximation by treating scattering from impurities exactly. The magnetic-field dependence of the conductance depends sensitively on the mean free path. When the mean free path is sufficiently large, undoped metallic nano…
The miscibility and thermal properties of polyethylene oxide(PEO)/oligoester resin (OER) blends and PEO/crosslinked polyester (PER) blends were studied by differential scanning calorimetry (DSC). The effect of quenching process on the crystallization behavior of PEO for these two systems were investigated and discusse…
The crystal structure of antiferroelectric PbZrO 3 was re-examined by high resolution powder neutron diffraction. The structure obtained with assumed modulations associated with the lattice vibrational modes Σ 3 ( T O ) and R 25 x y is almost the same as that obtained previously with the same assumptions. However, one…