Mechanical properties of carbon nanotubes: theoretical predictions and experimental measurements
Mechanical properties of carbon nanotubes are discussed based on recent advances in both modeling and experiment.
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Anomalous low-temperature specific heat around the metal-insulator transition in ordered double-perovskite alloysSr2Fe(Mo1−yWy)O6(0<~y<~1)
Low-temperature excitation has been investigated for polycrystals of ordered double-perovskite alloys ${\mathrm{Sr}}_{2}\mathrm{Fe}({\mathrm{Mo}}_{1\ensuremath{-}y}{\mathrm{W}}_{y}){\mathrm{O}}_{6}$ $(0<~y<~1)$ by specific-heat measurements. Critical enhancement of excess low-temperature specific heat with anoma…
Perpendicular magnetic anisotropy of La0.67Sr0.33MnO3 thin films grown on CaMnO3 buffered SrTiO3
La 0.67 Sr 0.33 MnO 3 ( LSMO ) thin films were grown onto CaMnO3(CMO) buffered SrTiO3(100) by pulsed laser deposition. Because of the in-plane compressive strain induced by the lattice mismatch between CMO and LSMO, a perpendicular magnetic anisotropy (PMA) was obtained in the overlayer LSMO. Using the magnetic force…
Local structure of LiB3O5 single crystal from Li7 nuclear magnetic resonance
The local structure of LiB3O5 single crystal was investigated with Li7 (I=3/2) nuclear magnetic resonance measurements. We observed four different spectra, which could be divided into two groups corresponding to two kinds of lithium atoms, LiA and LiB, lying at crystallographically equivalent sites and magnetically in…
Optical properties of GaSe grown with an excess and a lack of Ga atoms
Measurements of the photoluminescence (PL) and photocurrent (PC) have been made on GaSe with excess Ga or Se atoms. The 1.77 eV emission band for the sample with excess Ga atoms is attributed to the transition from the donor level at 0.175 eV to the acceptor level at 0.152 eV. This donor level is considered to be rela…
“Rounding” of the sulfur living polymerization transition under spatial confinement
“Rounding” effects and other specific changes of liquid sulfur’s polymerization transition are studied using Raman scattering in the case of fluid’s spatial confinement in nanonoporous sol-gel glasses. Specifically, in this paper we demonstrate the smearing or “rounding” of the monomer↔polymer transition caused by geo…
Origin and implications of the observed rhombohedral phase in nominally tetragonal Pb(Zr0.35Ti0.65)O3 thin films
The structural and electrical properties of Pb(Zr0.35Ti0.65)O3 (PZT) thin films ranging in thickness from 700 to 4000 Å have been investigated. These (001)/(100)-textured films were grown by metalorganic chemical vapor deposition on (111)-textured Ir bottom electrodes. It was observed that, in the as-deposited state,…
Capillary condensation monitored in birefringent porous silicon layers
We performed studies on the capillary condensation of various substances in optically anisotropic porous silicon layers. Their strong in-plane form birefringence has been utilized to analyze the polarization state of the transmitted light when molecules penetrate into the pores. The polarization state of the transmitt…
Size scaling of intramolecular charge transfer driven optical properties of substituted polyenes and polyynes
The origin of dramatic variation in optical polarizabilities of push–pull conjugated chains with respect to the conjugation length is discussed. Ab initio calculations of intramolecular charge transfer (ICT)-driven dipole moment (μCT), polarizability (αCT), and first hyperpolarizability (βCT) show that the values of α…
Modeling the absorption spectra of Er3+ and Yb3+ in a phosphate glass
Absorption spectra of Er3+ and Yb3+ ions, codopants in a phosphate glass, are reported at 8 K and at wavelengths between 350 and 1600 nm. Detailed structure appearing in the spectra, associated with individual multiplet states, LJ2S+1, of Er3+(4f11) and Yb3+(4f13) is interpreted using a ligand-field coordination spher…
Transition metal ion implantation into AlGaN
n- and p-type AlxGa1−xN (x=0.38 for n-type, x=0.13 for p-type) layers grown on Al2O3 substrates were ion implanted with the transition metals Mn, Cr, and Co at high concentrations (peak doping levels ∼3 at. %). After implantation and annealing at 1000 °C, only impurity transitions at ∼2.9 and 3.9 eV and no band-edge p…
Beam fanning reversal in the ferroelectic relaxor Sr0.61Ba0.39Nb2O6 at high external electric fields
Beam fanning has been studied in the cerium-doped ferroelectric relaxor strontium–barium–niobate (Sr0.61Ba0.39Nb2O6:Ce, SBN:Ce) under the application of high external electric fields. Spatial reversal in the distribution of the scattered light is achieved both below and above the phase transition. It is shown that the…
Fictive temperature dependence of density fluctuation in SiO2 glass
Fictive temperature dependence of density fluctuation in SiO2 glass was investigated by the small-angle x-ray scattering measurement. The density fluctuation in SiO2 glass varies linearly to the fictive temperature. Contribution of structural relaxation to the density fluctuation is larger than that of phonons. Isothe…
The piezoelectric shear strain coefficient of 〈111〉-oriented Pb (Zn1/3Nb2/3)O3-PbTiO3 piezocrystals
The piezoelectric d15 coefficients of 〈111〉-oriented (1−x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 single crystals for x=0.045 and x=0.08 (PZN-4.5%PT and PZN-8%PT) have been measured as functions of dc bias field and frequency using a Zygo laser interferometer system. High d15 values (∼5500 pC/N for PZN-4.5%PT and ∼7500 pC/N for PZN-…
The Nd-nanocluster coupling strength and its effect in excitation/de-excitation of Nd3+ luminescence in Nd-doped silicon-rich silicon oxide
The Nd-nanocluster Si (nc-Si) coupling strength and its effect in excitation/de-excitation of Nd3+ luminescence in Nd-doped silicon-rich silicon oxide (SRSO) is investigated. Nd-doped SRSO thin films, which consist of nc-Si embedded inside a SiO2 matrix, were prepared by electron-cyclotron-resonance plasma-enhanced ch…
Supersymmetry in carbon nanotubes in a transverse magnetic field
Electron properties of carbon nanotubes in a transverse magnetic field are studied using a model of a massless Dirac particle on a cylinder. The problem possesses supersymmetry which protects low-energy states and ensures stability of the metallic behavior in arbitrarily large fields. In metallic tubes we find suppres…
Nanoengineering of carbon nanotubes for nanotools
We have developed a well controlled method for manipulating carbon nanotubes. The first crucial process involved is to prepare a nanotube array, named a nanotube cartridge. We have discovered ac electrophoresis of nanotubes by which nanotubes are aligned at the knife-edge. The nanotubes used were multiwalled and prepa…
Allowed mesoscopic point group symmetries in domain average engineering of perovskite ferroelectric crystals
In multivariant systems, several energetically degenerate low temperature domain states can be produced at the structural phase transition. Coexistence of these domain states can produce mesoscopic structures that possess symmetries distinct from the microscopic single domain crystal symmetry. Such engineered domain s…
Self-organized growth and optical emission of silicon-based nanoscale β-SiC quantum dots
Si-based β-SiC quantum dots (QDs) were fabricated for exploring efficient blue emission from β-SiC nanostructures. Microstructural observations and x-ray photoemission spectroscopy reveal that the β-SiC QDs with sizes of 5–7 nm are embedded in the SiO2 and graphite matrices, displaying a locally tetragonal symmetry. P…
Stress development in sputtered NiO thin films during heat treatment
Nickel oxide thin films with a thickness of 100 nm were deposited on oxidized silicon wafers by rf magnetron sputtering from a NiO target in an Ar (nonreactive case) and an Ar+O2 atmosphere with various oxygen contents (reactive cases). The as-deposited films possess high compressive stresses (up to 3700 MPa) which de…