Materials Literature
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Sm{0.5-x}Pr{x}Sr{0.5}MnO{3} exhibits variety of ground states as x is varied from 0 to 0.5. At an intermediate doping of x = 0.3 a charge-ordered CE type antiferromagnetic insulating (AFI) ground state is seen. The transition to this ground state is from a paramagnetic insulating (PMI) phase through a ferromagnetic me…
A corner-overgrown GaAs/AlGaAs heterostructure is investigated with transmission and scanning transmission electron microscopy, demonstrating self-limiting growth of an extremely sharp corner profile of 3.5 nm width. In the AlGaAs layers we observe self-ordered diagonal stripes, precipitating exactly at the corner, wh…
A first-principles study of the electronic polarization of BN and AlN nanotubes and their graphitic sheets under an external electric field has been performed. We found that the polarization per atom of zigzag nanotubes increases with decreasing diameter while that of armchair nanotubes decreases. The variation of the…
Bottom-up fabrication by molecular self-assembly is now widely recognized as a potent method for generating interesting and functional nano- and mesoscale structures. Hydrogels from biocompatible molecules are an interesting class of mesoscale assemblies with potential biomedical applications. The self-assembly of a p…
Smart bases: By using a photochromic azobenzene-derived blocking group, a piperidine base can be switched between a sterically shielded, inactive form and an accessible, reactive form (see picture; C dark gray, H light gray, O red, N blue). Thus, light can be used for the reversible external modulation of ground-state…
Quantum dots (QDs) are being investigated as novel in vivo imaging agents. The leaching of toxic metals from these QDs in biological systems is of great concern. This study compared the cytotoxic mechanisms of two QD species made of different core materials (cadmium selenide [CdSe] vs. indium gallium phosphide [InGaP]…
A new method of synthesizing Mn-activated phosphor is presented. The method uses only chemical etching of Si wafer in HF/H2O solution with the addition of an oxidizing agent KMnO4. The luminescence centers of red emission are ascribed to Mn4+ ions in the octahedral sites of potassium hexafluorosilicate (K2SiF6). The l…
The two-dimensional multifractal detrended fluctuation analysis is applied to reveal the multifractal properties of the fracture surfaces of foamed polypropylene/polyethylene blends at different temperatures. Nice power-law scaling relationship between the detrended fluctuation function $F_{q}$ and the scale $s$ is ob…
Ultra-nanocrystalline diamond is a polycrystalline material, having crystalline diamond grains of sizes in the nanometer regime. We study the structure and mechanical properties of this material as a function of the average grain size, employing atomistic simulations. From the calculated elastic constants and the esti…
For the first time, the Fe-Fe interactions in the geometrically frustrated antiferromagnetic systems of zinc and cadmium ferrites are determined quantitatively by the first-principles methods of density functional theory. Both the generalized gradient approximation (GGA) as well as GGA plus the onesite Coulomb interac…
The mechanisms by which amorphous silica dissolves have proven elusive because noncrystalline materials lack the structural order that allows them to be studied by the classical terrace, ledge, kink-based models applied to crystals. This would seem to imply amorphous phases have surfaces that are disordered at an atom…
We have investigated the movement of electrons around the peripheries of dendrimers and between their redox termini and electrodes through studies of the electrochemistry of dendrimers presenting metallocenes (and other transition metal sandwich complexes) as terminal groups. Because these compounds can be stabilized…
A compact reaction cell is described for in-situ experiments requiring control of both the temperature of the sample and the atmosphere over the sample. The cell incorporates an optional furnace capable of temperatures of up to ∼1273 K. The compact design and ability of the cell to mount directly on a standard goniome…
Uniform red-phosphor spheres (∼60−300 nm in diameter) of Y 2 O 3:Eu 3+ binary and (Y,Gd) 2 O 3:Eu 3+ ternary systems exhibiting excellent emission at 610 nm have been converted from their colloidal precursor spheres synthesized via homogeneous precipitation. The precursor spheres (approximate composition: [(Y 1- x Gd…
The relationship between morphology and function of ZnO is demonstrated by investigating its polar planes, oxygen vacancies, and catalytic activity for N-formylation. ZnO with various morphologies is controllably synthesized via simple hydrothermal reactions. Scanning electron microcopy images exhibit a variety of the…
We investigate a generalized two-dimensional Weyl Hamiltonian, which may describe the low-energy properties of mechanically deformed graphene and of the organic compound $\ensuremath{\alpha}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\text{I}}_{3}$ $[\text{BEDT-TTF}=\text{bis}(\text{ethylene}\text{dithio)tetrathiaful…
The magnetic properties of disordered graphene and irradiated graphite are systematically studied using a combination of mean-field Hubbard model and first-principles calculations. By considering large-scale disordered models of graphene, I conclude that only single-atom defects can induce ferromagnetism in graphene-b…
The following article describes the coatings of both Fabry-Perot (FP) etalons to be installed in the integral field spectrometer 3D-NTT. This simultaneous use of two FP etalons of high and low resolution respectively is the new concept upon which the 3D-NTT is built. Design and fabrication of the coatings of those eta…
Special enhanced silver mirror coatings were designed and fabricated to minimize the polarization introduced by a three-mirror off-axis high-accuracy telescope. A system diattenuation of approximately 1% in the VIS-NIR was achieved by both reducing the diattenuation from each mirror individually and by balancing the d…
Mg 2 TiO 4 ‐doped Ba 0.60 Sr 0.40 Mg 0.15 Ti 0.85 O 3 (BSTM) thin films with different Mg 2 TiO 4 concentrations were deposited on a polycrystalline alumina substrate via the sol–gel method. With the addition of Mg 2 TiO 4 , MgTiO 3 , MgAl 2 O 4 , and BSTM phases were formed in these composite thin films. The dielectr…