Materials Literature
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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…
Both NMOS and PMOS light-emitting diodes and photodetectors are demonstrated. For the ultrathin gate oxide, the tunneling gate of metal oxide silicon (MOS) diodes can be utilized as both emitters for light emitting devices and collectors for light detectors. An electron-hole plasma model is used to fit the emission sp…
New kinds of yttrium-doped antimonic acid compounds with the compositional formula of H 1 - 3 x Y x SbO 3 · n H 2 O (0 ≤ x ≤ 0.22, n = 0.5) were successfully synthesized by solution processing using the reaction of an aqueous hydrogen peroxide solution with antimony and yttrium alkoxides, i.e., Sb(O- iso -C 3 H 7 ) 3…
This paper provides a review of the applications of thermoelectric devices to cooling electronics and prospects for the future. The need to accommodate increased module heat flux and reduce chip operating temperatures is discussed, along with the cooling technology developed within IBM to do this. A brief background d…
This communication presents a determination of the glass transition of polybutadiene under very high pressure, and raises the problem of the determination of the relative effects of temperature and density on the glass transition, depending on the pressure and temperature conditions. Local structure and slow dynamics…
A new misfit layer compound (EuS) 1.173 NbS 2 was synthesized, and its structure was solved in a (3+1) D superspace using the superspace group Xm 2 m( α 00 ) with X referring to a pseudo F centering. The cell parameters are a s = 3.3251(9) Å, b s = 5.7432(9) Å, and c s = 22.939(5) Å ( V s = 438.1(3) Å 3 ) with a modul…
It is well known that repetitive voltage surges from modern inverter fed drives (IFD) may age the insulation of motor stator windings, even on motors rated 440 V, leading to premature failure. Insulation aging seems to be correlated to the partial discharge (PD) activity of surges with very fast risetimes and high mag…