Materials Literature
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New experimental data on solid solutions of quantum paraelectrics with KTaO_3:Nb as an example are considered within a framework of a quantum theory of ferroelectric phase transitions. In order to describe the effect of local heterogeneities a percolation type theory together with a random field approach were employed.
A motion of neutral and charged particles located nearby a metal surface under joint action of time-periodic electric field E(t) directed normally to the surface and permanent magnetic field H directed along the surface has been considered. I has been shown that due to a nonlinearity of the system there exists a direc…
Some of (1-x)NaNbO_3-(x)ABO_3 perovskite solid solutions exhibit a dramatic diffusion of the dielectric permittivity epsilon' maximum and relaxor-type behavior when the second component concentration exceeds a threshold value x_0. The concentration phase transition to the relaxor-like phase is abrupt (of the first ord…
Finite-bandwidth effects on the temperature dependence of the mobility of injected carriers in pure organic crystals are explored for a simplifed case of impurity scattering. Temperature-dependent bandwidth effects are discussed briefly through a simplified combination of band and polaronic concepts.
KTaO_3-based solid solutions exhibit a variety of interesting physical phenomena. To better understand these phenomena, we performed first-principles calculations on [K_{1-x}, Li_x]TaO_3 (KLT) and K[Ta_{1-x}, Nb_x]O_3 (KTN) supercells. Our results show Li displacements and potential barrier heights in KLT that are in…
Ion implantation of Mn ions into hole-doped GaP has been used to induce ferromagnetic behavior above room temperature for optimized Mn concentrations near 3 at. %. The magnetism is suppressed when the Mn dose is increased or decreased away from the 3 at. % value, or when n-type GaP substrates are used. At low temperat…
A new method for preparation of single crystals of the superconducting intermetallic MgB2 compound from a Mg-Cu-B melt flux is presented. The high vapour pressure of Mg at elevated temperature is a serious challenge of the preparation process. The approximate thermodynamic calculations of the ternary Mg-Cu-B phase dia…
We demonstrate that room-temperature ferromagnetism in epitaxial Co-doped TiO2 anatase is driven by electron-mediated exchange interaction, and not by metallic Co clusters. Co(II) substitutes for Ti(VI) in the lattice and produces oxygen vacancies that do not contribute carriers. Free electrons originate with oxygen v…
Accounting for the anharmonicity of the real interatomic potentials in a model in 1+1 dimensions shows that coherent 3D islands can be formed on the wetting layer in a Stranski-Krastanov growth mode predominantly in compressed overlayers. Coherent 3D islanding in expanded overlayers could be expected as an exception r…
Resistivity and ac magnetic susceptibility measurements on Ba2Sn3Sb6 and SrSn3Sb4 indicate that these Zintl compounds display a transition to a superconducting phase at Tc = 3.9 K. The Meissner effect was observed for Ba2Sn3Sb6 under an applied field of 25 Oe. The signatures for superconductivity, such as high and low…
Close contacts between sulfur, selenium, and tellurium centers are used to construct nanotubes in the solid state which are able to host other molecules.
A separate family of enzymes within the metallo-beta-lactamase fold comprises several important proteins acting on nucleic acid substrates, involved in DNA repair (Artemis, SNM1 and PSO2) and RNA processing [cleavage and polyadenylation specificity factor (CPSF) subunit]. Proteins of this family, named beta-CASP after…
Bimetallic silver–gold clusters offer an excellent opportunity to study changes in metallic versus “ionic” properties involving charge transfer as a function of the size and the composition, particularly when compared to pure silver and gold clusters. We have determined structures, ionization potentials, and vertical…
Recent scanning tunneling microscopy studies of the intrinsic electronic properties of single-walled carbon nanotubes (SWNTs) are overviewed in this Account. A brief theoretical treatment of the electronic properties of SWNTs is developed, and then the effects of finite curvature and broken symmetry on electronic prop…
High quality InP nanocrystals without any size sorting were synthesized in a noncoordinating solvent by strictly controlling the reaction parameters. This synthetic method is much faster, less expensive, and “greener” than any current methods for the synthesis of high quality InP nanocrystals. Fatty acids with well-de…
We show that carbon nanotube transistors operate as unconventional "Schottky barrier transistors," in which transistor action occurs primarily by varying the contact resistance rather than the channel conductance. Transistor characteristics are calculated for both idealized and realistic geometries, and scaling behavi…
Abstract An improvement in the adhesion strength of polyimide/epoxy joints was obtained by (1) introducing a functional group on the polyimide surface, (2) improving the mechanical properties of the epoxy adhesive, (3) increasing the curing temperature, and (4) using polyamic acid as an adhesion‐promoting layer. The f…
We study the energy transport properties of one-dimensional nonlinear aperiodic lattice models in this paper. It is found that, compared with their periodic and disordered counterparts, the quasiperiodic and fractal models exhibit critical macroscopic behavior in the low-temperature region, while in the high-temperatu…
We have studied a system composed of a hydrophobic aerosil (R812) dispersed in the liquid crystal 4- n -octyl-4‘-cyanobiphenyl (8CB) using the spin probe electron spin resonance (ESR) technique, and in particular, we have determined, for different aerosil concentrations, the temperature dependence of the orientational…
X-ray diffraction, Raman scattering, and X-ray photoemission of SrBi 2 Ta 2 O 9 powder sample (the Curie temperature of 310 °C) synthesized from a precursor solution showed that the crystal structure of the SrBi 2 Ta 2 O 9 unit cell was preserved from bulk to surface, and the surface had never been covered with metall…