Materials Literature
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The structural synergy between biominerals (CaCO(3), hydroxyapatite) and biosubstrates were examined for the first time. The templating effect of substrate and a newly identified supersaturation-driven interfacial structure mismatch effect were identified in the context of a new nucleation model. It follows that the h…
We have studied how the calculation of electronic and vibrational contributions to nonlinear optical properties of three representative π-conjugated organic molecules is affected by the choice of basis set and the inclusion of electron correlation effects. The 6-31G basis does not always provide even qualitative accur…
Ultrathin films of pyrrole were deposited on the surfaces of carbon nanotubes using a plasma polymerization treatment. High-resolution electron transmission microscopy images revealed that an extremely thin film of the polymer layer (2∼7 nm) was uniformly deposited on the outer and inner surfaces of the nanotubes. The…
p-type conduction in ZnO thin films was realized by the codoping method. Types of conduction and carrier density in codoped ZnO films were found to be dependent on the oxygen partial pressure ratios in the sputtering gas mixture. The lowest room temperature resistivity was found to be 11.77 Ω cm with a hole density of…
We report a numerical calculation of the melting point of NaCl. The solid–liquid transition was located by determining the point where the chemical potentials of the solid and liquid phases intersect. To compute these chemical potentials, we made use of free energy calculations. For the solid phase the free energy was…
The tunability of epitaxial barium strontium titanate films is analyzed theoretically using a phenomenological model. The relative dielectric constant of Ba0.5Sr0.5TiO3 (BST 50/50) films as a function of the applied external electric field is calculated and an electric field–misfit strain phase diagram is developed to…
This article addresses the development of a free energy model for magnetostrictive transducers operating in hysteretic and nonlinear regimes. Such models are required both for material and system characterization and for model-based control design. The model is constructed in two steps. In the first, Helmholtz and Gib…
Molecular-beam-epitaxy grown GaN:Mn and AlN:Mn layers with Mn concentrations around 1020 cm−3 were investigated by optical absorption and photoconductivity measurements. From electron spin resonance Mn is known to be mostly present in the neutral acceptor state in GaN without codoping. This leads to a reassignment of…
The role of the surface during polarization switching in constrained ferroelectrics is investigated using the time-dependent Ginzburg–Landau theory. The model incorporates the elastic and electrostrictive effects in the form of a long-range interaction that is obtained by eliminating the strain fields subject to the e…
We present a model calculation of the thermal conductivity of germanium nitride, silicon nitride, and carbon nitride in a temperature range in which intrinsic phonon scattering is dominant. We show that, in spite of the rather complex crystal structure of these nitrides, thermal conductivities exceeding 100 W m−1 K−1…
We have investigated the photoluminescence (PL) from anodic alumina membranes with an ordered nanopore array formed on bulk Al foils. Most of the membranes fabricated by anodization in oxalic acid showed a strong PL peak in the blue. Due to an obvious asymmetry, the PL peak can be Gaussian divided into two bands aroun…
It is shown that the well-known blueshift of the fundamental absorption edge in as-deposited compositionally modulated amorphous Si/Ge and As6Se94/Se80Te20 multilayers (with periods of 4–8 nm) is further enhanced due to the thermal or laser-induced intermixing of adjacent layers. The laser-induced intermixing process,…
Single ferroelectric lead titanate (PTO) grains down to 15 nm were fabricated by chemical solution deposition. Varying the dilution of the precursor solution leads to different grain sizes between 15 and 200 nm. The grain-size-dependent domain configuration was studied using three-dimensional piezoresponse force micro…
The thermal conductivity of solid parahydrogen crystal with methane admixtures has been measured in the temperature range 1.5 to 8 K. Solid samples were grown from the gas mixture at 13 K. Concentration of CH4 admixture molecules in the gas varied form 5 to 570 ppm. A very broad maximum of thermal conductivity with ab…
Analytical representations in the time and frequency domains are derived for the most frequently used phenomenological fit functions for non-Debye relaxation processes. In the time domain the relaxation functions corresponding to the complex frequency dependent Cole-Cole, Cole-Davidson and Havriliak-Negami susceptibil…
The activation energy, E, of nonisothermal crystallization of polymer melts has been frequently evaluated by the Kissinger equation with positive rates of temperature variation, β. It is demonstrated that reversing the sign for β is a mathematically invalid procedure that generally invalidates the Kissinger method. As…
Er 3+ doped Nb2O5–TeO2 (NT) glass suitable for developing optical fiber laser and amplifier has been fabricated and characterized. Intense and broad 1.53 μm infrared fluorescence and visible upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. For 1.53 μm emission band, the ful…
ZnS:Mn nanocrystals with sizes between 3 and 4 nm were synthesized via a competitive reaction chemistry method, where the surface capping organic species (p-thiocresol) is used as an inhibitor of the crystal growth. The x-ray diffraction and photoluminescent (PL) properties of ZnS:Mn bulk and nanocrystals were compare…
The thermoelectric properties of the p-type (Bi0.25Sb0.75)2Te3 doped with 8 wt. % excess Te and the n-type Bi2(Te0.94Se0.06)3 doped substantially with 0.07 wt. % I, 0.02 wt. % Te, and 0.03 wt. % CuBr which were grown by the Bridgman method at a rate of 6 cm/h were measured before and after annealing, where annealing w…
Ferromagnetic shape memory alloys with a body-centered-cubic ordered structure in a Ni–Ga–Fe system have been developed. The alloys with the composition range of Ni 27 at. % Ga (20–22 at. %)Fe exhibit a thermoelastic martensitic transformation from a B2 and/or an L21 parent to a martensite phase, with a seven-layer mo…