Materials Literature
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We report detailed shape measurements of the tips of three-dimensional ammonium chloride dendrites grown from supersaturated aqueous solution. For growth at small supersaturation, we compare two different models: parabolic with a fourth-order correction, and power law. Neither is ideal, but the fourth-order fit appear…
We have found that various Mn oxides have the universal resistivity and thermopower in the high temperature limit. The resistivities and thermopowers of all the samples go toward constant values of 7±1 mΩ cm and −79±3 μV/K, which are independent of carrier density and crystal structures. We propose that the electric c…
The effect of layer-by-layer heterostructuring and epitaxial strain on lattice instabilities and related ferroelectric properties is investigated from first principles for the $[001]\ensuremath{-}({\mathrm{PbTiO}}_{3}{)}_{1}({\mathrm{PbZrO}}_{3}{)}_{1}$ superlattice and pure ${\mathrm{PbTiO}}_{3}$ on a cubic substrate…
Polymer diodes require cathodes that do not corrode the polymer but do have low work function to minimize the electron injection barrier. First-principles calculations demonstrate that the work function of the (1000) surface of the compound Ca2N is half an eV lower than that of the elemental metal Ca (2.35 vs. 2.87 eV…
High-dielectric-constant CaCu3Ti4O12 (CCTO) thin films were prepared on Pt/Ti/SiO2/Si(100) substrates by pulsed-laser deposition (PLD). The 480 nm thick polycrystalline films have preferred orientation and show obvious crystallization on the surface. The temperature dependence of dielectric constant and loss of the Pt…
The domain structure of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 single crystals with composition x≈0.33 in the range of the morphotropic phase boundary (MPB) was studied. Based on the analysis of spontaneous strain compatibility and charge of domain walls, we have established the permissible domain arrangements for the ferroele…
A new parallel algorithm for simulating Ising spin systems is presented. The sequential prototype is the n-fold way algorithm cite{BKL75}, which is efficient but is hard to parallelize using conservative methods. Our parallel algorithm is optimistic. Unlike other optimistic algorithms, e.g., Time Warp, our algorithm i…
The magnetoresistance (MR) effect in metallic atomic-sized contacts is studied theoretically by means of first-principle electronic structure calculations. We consider three-atom chains formed from Co, Cu, Si, and Al atoms suspended between semi-infinite Co leads. We employ the screened Korringa-Kohn-Rostoker Green's…
Nickel zinc ferrite nanoparticles (Ni0.20Zn0.44Fe2.36O4) have been produced at room temperature, without calcination, using a reverse micelle process. Particle size is approximately 7 nm as determined by x-ray powder diffraction and transmission electron microscopy. Saturation magnetization values are lower than antic…
Room temperature ferromagnetism is found in (Sn1−xMx)O2 (M=Mn, Fe, Co, x=0.05) ceramics where x-ray diffraction confirms the formation of a rutile-structure phase. Room temperature saturation magnetization of 0.2 and 1.8 Am2 kg−1 for (Sn0.95Mn0.05)O2 and (Sn0.95Fe0.05)O2, respectively, corresponds to a moment of 0.11…
Fabrication of composite supraparticles and “Janus” particles via a novel, generic, gel trapping technique is presented. The method is based on templating particle monolayers at air–water or oil–water interfaces, followed by lifting of the particles with poly(dimethylsiloxane) and gold deposition. Replicating ordered…
We use a nonequilibrium molecular-dynamics method to compute the Kapitza resistance of three twist grain boundaries in silicon, which we find to increase significantly with increasing grain boundary energy, i.e., with increasing structural disorder at the grain boundary. The origin of this Kapitza resistance is analyz…
When holes of about 0.018% are induced into a conduction band (breakdown of critical on-site Coulomb energy), an abrupt first-order Mott metal–insulator transition (MIT) rather than a continuous Hubbard MIT near a critical on-site Coulomb energy U / U c =1, where U is on-site Coulomb energy between electrons, is obser…
Abstract An overview of recent advances in the application of non‐carbonaceous nanostructured and composite materials in hydrogen storage is presented in this review. The main focus is on complex hydrides, non‐graphitic nanotubes, and other porous composite and framework materials, since carbon nanotubes have been the…
During the past half-century, the nuclear fuel cycle has generated approximately 1400 metric tons of plutonium and substantial quantities of the “minor” actinides, such as Np, Am, and Cm. The successful disposition of these actinides has an important impact on the strategy for developing advanced nuclear fuel cycles,…
We propose a novel approach to continuum modelling of dynamics of crystal surfaces. Our model follows the evolution of an ensemble of step configurations, which are consistent with the macroscopic surface profile. Contrary to the usual approach where the continuum limit is achieved when typical surface features consis…
Abstract. The new generation gas turbines are to generate higher gas temperatures which may seriously affect the thermal stability of the state-of-the-art TBCs (e.g. Partially Yttria Stabilized Zirconia, PYSZ). The reasons for that is the occurrence of considerable phase transformation and/or sintering-induced volume…
Binder removal characteristics of injection molded zirconia (ZrO2) ceramics in the form of one-closed end tubes were studied by thermal analysis methods such as thermogravimetry and calorimetry. Only a thermal teratment for the binder removal from the molded parts with thin walls is not suitable because of deformation…
Abstract. Several ceramic materials have been chosen and synthesized by Selective Fusion by Laser (SFL). These materials have been selected because their refractory condition, high hardness and good colouring power, that make them useful to be used as ceramic pigments. In the present work it is shown the structural an…
Abstract. Fine ceramics such as SiC, Si3N4 and ZrO2 and hard ceramic coatings such as DLC and CNx show attractive tribological properties of low friction and low wear in vacuum, air or water which cannot be observed with metals. Some typical observations are introduced and mechanisms are discussed in this paper.