Materials Literature
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Mineral deposits in land-based woodlice (crustacea, Porcellio scaber) were analysed by high-resolution X-ray diffraction, X-ray absorption spectroscopy (EXAFS) and infrared microscopy. Calcium carbonate is stored within the first four anterior sternites before changing the cuticle (shell). These deposits consist of fu…
It is well known that ZnO generally has the wurtzite structure. We report the growth of both hexagonal and cubic ZnO on Pt(111)/Ti/SiO2/Si substrate by a solution deposition. The wurtzite structure of ZnO film is enhanced up to the annealing temperature of 600 °C, and disappeared for annealing temperatures above 700 °…
The transmission characteristics of two waveguides, one carrying a forward, the other a backward magneto-inductive wave, are investigated. The experimental results obtained are compared with the theoretical predictions. It is shown that there is excellent agreement for the frequency dependence of the propagation coeff…
Y 2 O 3 : Eu nanotubes were fabricated by a surfactant assembly mechanism. The tubular structure was characterized by transmission electron microscopy. Under an ultraviolet-light excitation, the nanotubes show a relatively intense emission peak at 618 nm besides the 610 nm peak, different from that of single Y2O3:Eu n…
An analysis of the optical response of a triangular-shaped photonic band-gap prism is presented. Numerical simulations have been performed in the framework of multiple-scattering theory, which is applied considering spot illumination to avoid diffraction effects. First of all, refractive properties in the frequency ra…
First-principles calculation and anharmonic dynamical theory were used in sequence to explain a large excess heat capacity observed in yttria-stabilized zirconia in comparison with the additive rule value. It is found that the excessive shape of heat capacity decays gradually with the Y$_{2}$O$_{3}$ doping when the nu…
We study the coupled rotation-vibration levels of a hydrogen molecule in a confining potential with cylindrical symmetry. We include the coupling between rotations and translations and show how this interaction is essential to obtain the correct degeneracies of the energy level scheme. We applied our formalism to stud…
We have analyzed the properties of a noncollinear magnetic phase obtained in the mean-field analysis of the model of two coupled Heisenberg subsystems. The domain of its existence and stability is narrow and depends on the ratio between the averaged over nearest neighbours microscopic exchange parameters.
An empirical potential with fluctuating charges is proposed for modelling (MgO)_n clusters in both the molecular (small n) and bulk (n->infty) regimes. Vectorial polarization forces are explicitely taken into account in the self-consistent determination of the charges. Our model predicts cuboid cluster structures, in…
We have studied the problem of phase stability in NiPt alloy system. We have used the augmented space recursion based on the TB-LMTO as the method for studying the electronic structure of the alloys. In particular, we have used the relativistic generalization of our earlier technique. We note that, in order to predict…
A mesoscopic model of a diblock copolymer is used to study the motion of a grain boundary separating two regions of perfectly ordered lamellar structures under an oscillatory but uniform shear flow. The case considered is a grain boundary separating lamellae along the so called parallel orientation (with wavevector pa…
Influences of point defects on the nonradiative processes in ZnO were studied using steady-state and time-resolved photoluminescence (PL) spectroscopy making a connection with the results of positron annihilation measurement. Free excitonic PL intensity naturally increased with the increase in the nonradiative PL life…
We present an approach for the efficient calculation of vibrational Raman intensities in periodic systems within density functional theory. The Raman intensities are computed from the second order derivative of the electronic density matrix with respect to a uniform electric field. In contrast to previous approaches,…
Following the experimentally observed Seebeck coefficient enhancement in PbTe quantum wells in Pb/sub 1-x/Eu/sub x/Te/PbTe multiple-quantum-well structures which indicated the potential usefulness of low dimensionality, we have investigated the thermoelectric properties of PbSe/sub x/Te/sub 1-x//PbTe quantum-dot super…
We have studied solutions of the surfactants cetyltrimethylammoniumbromide (CTAB) and dodecyltrimethylammoniumbromide (DTAB) in liquid ammonia with respect to the formation of lyotropic phases. For this purpose, a set-up for performing X-ray scattering experiments at temperatures up to 120 degrees C on samples contain…
The Defense Advanced Research Projects Agency (DARPA) initiated its program in advanced thermoelectric materials and devices in 1995 in response to a belief that these materials could play a significant role in the development of new and enhanced military capabilities. The current and future use of these all-solid-sta…
We evaluated the in-plane thermoelectric transport properties of self-supporting porous silicon samples which were prepared through anodization of degenerate silicon wafer. Rapid decrease of both electrical and thermal conductivity were observed alter the anodization. The thermal conductivities decreased by two orders…
Recent advances in our understanding of 1D and 2D thermoelectric materials in the form of quantum wires (1D) and quantum wells (2D) are reviewed, with emphasis given to the physical mechanisms responsible for the enhanced thermoelectric figure of merit (ZT) in these low dimensional systems. Starting with 2D superlatti…
This paper describes the thermo-mechanical performance of thermoelectric modules. A heat cycle test was performed in order to analyze the thermo-mechanical performance of modules of three different cross sectional area of elements. Modules of all the three types declined in generated output with the increase of heat c…
The structural and magnetic properties of the tris-dithiooxalato salts, A[M(II)Cr(C(2)S(2)O(2))(3)], have been investigated with A(+) = PPh(4)(+), N(n-C(n)()H(2)(n)()(+1))(4)(+), with n = 3-5, where M(II) is Mn, Fe, Co, and Ni. With the exception of A[MnCr(C(2)S(2)O(2))(3)], all the salts are ferromagnets with Curie t…