Materials Literature
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The electrical conductivity, the thermoelectric power, and the electrical contribution to the thermal conductivity of superlattices have been studied within the envelope-function approach for the electrons. The effects of tunneling through the barriers due to finite potential offsets and of the thermal currents throug…
Highly (100)-oriented LaNiO3(LNO) thin films were grown on Si, SiO2/Si, Pt/SiSiO2/Si, as well as glass substrates by rf magnetron sputtering deposition at substrate temperatures ranging from 150 to 500 °C. As-deposited LNO films are metallic; those prepared at substrate temperature ∼150–250 °C have a resistivity of 0.…
Carbon nitride (CNx) films were prepared by reactive pulsed laser deposition at nitrogen partial pressure PN2varying from 0 to 300 mTorr. It is found that the atomic fraction of nitrogen f in the films first increases with increasing PN2, reaches a maximum of 0.32 at PN2=100 mTorr, and then decreases to a saturated va…
The metal-insulator transition of La 3 Ni 2 O 7-δ with 2-dimensional electrons has been studied. Various physical properties can be understood by introducing a model of charge orderings in the NiO 2 planes induced by oxygen orderings. Arguments on the non-occurrence of the superconductivity are also given.
A complete mapping in the Brillouin zone of the structural instability associated with the ferroelectric phase transitions of ${\mathrm{KNbO}}_{3}$ has been obtained by first-principles calculations using a linear response approach. The wave-vector dependence of the instability reveals pronounced two-dimensional chara…
The oxidation of sputtering deposited copper thin films has been investigated. Phase identification and surface morphology characterization were performed by x-ray diffraction, Raman spectroscopy, and atomic force microscopy (AFM). The copper film is first oxidized to Cu2O below 300 °C and then to CuO at higher temper…
Experimental and theoretical graphite valence-band photoelectron angular distributions are presented and compared. We observe a zone-selection effect, wherein interference between photoelectron amplitudes from the two atoms in each graphene unit cell cause both \ensuremath{\sigma} and \ensuremath{\pi} states to appear…
The response of an infinite, periodic, insulating solid to an infinitesimally small electric field is investigated in the framework of density functional theory. We find that the applied perturbing potential is not a unique functional of the periodic density change; it depends also on the change in the macroscopic pol…
The electronic structure of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ has been studied by photoemission and O 1s x-ray-absorption spectroscopy. Spectra of the Mn 2p core levels and the valence bands for ${\mathrm{LaMnO}}_{3}$ and ${\mathrm{SrMnO}}_{3}$ have be…
Using the self-consistent orthogonalized linear-combination-of-atomic-orbitals method in the local-density approximation, the electronic structure and the optical properties of three phases of titanium dioxide have been studied. For rutile, the calculated band structure, equilibrium lattice constant, and bulk modulus…
Insulator-metal phenomena depending on band filling (doping degree), temperature, and external magnetic field have been investigated for prototypical double-exchange ferromagnets, namely, crystals of ${\mathrm{La}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ (0\ensuremath{\le}…
Technical developments in the past few decades have led to scanners with greater accuracy and higher frequencies of operation at larger scan angles with wider apertures. The causes of this evolution of galvanometric and resonant scanners, whose attributes make sophisticated applications possible, are given in order to…
Fabrication issues of microlens arrays, made by first forming photoresist microlenses, by patterning and reflowing photoresist islands under temperature, and then transferring this into the substrate by a dry etch process, were studied. Photoresist microlenses were reliably fabricated within a range of aspect ratios.…
Linearized augmented plane wave (LAPW) calculations are performed for periodic (001) and (111) slabs of BaTiO$_3$ to understand the effects of surfaces on ferroelectric BaTiO$_3$. The (111) slab is found to be much less stable than the (001) slab. The average surface energies are respectively 3700 erg/cm$^2$ and 1600…
Motivated by recent experiments by Yuse and Sano (Nature, 362, 329 (1993)), we propose a discrete model of linear springs for studying fracture in thin and elastically isotropic brittle films. The method enables us to draw a map of the stresses in the material. Cracks generated by the model, imposing a moving thermal…
I present an informal discussion of various cases where two-dimensional surface metal-insulator structural and charge-density-wave instabilities driven by partly filled surface states have been advocated. These include reconstructions of clean semiconductor surfaces and of W(100) and Mo(100), as well as anomalies on t…
Carbon nanotube material can now be produced in macroscopic quantities. However, the raw material has a disordered structure, which restricts investigations of both the properties and applications of the nanotubes. A method has been developed to produce thin films of aligned carbon nanotubes. The tubes can be aligned…
The full set of high-energy spectroscopy measurements including X-ray photoelectron valence band spectra and soft X-ray emission valence band spectra of both components of FeSi (Fe K_beta_5, Fe L_alpha, Si K_beta_1,3 and Si L_2,3) are performed and compared with the results of ab-initio band structure calculations usi…
It has been shown previously that the magnetic field outside a spherically symmetric conducting body due to internal current sources does not depend on the profile of conductivity along the radius. It is demonstrated here that an arbitrary distribution of radial anisotropy superimposed on the symmetric conductivity, e…
Surface freezing is discovered in normal alcohol melts and studied using surface X-ray scattering techniques. A single crystalline bilayer is formed on the surface, at temperatures up to 1 °C above the bulk freezing temperature. The single bilayer persists down to bulk freezing. It is hexagonally packed, and the molec…