Materials Literature
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Theoretical investigations of the electronic, magnetic and structural properties of LaTiO 3 and YTiO 3 have been made. In the framework of GGA and GGA+U scheme we analyzed the effect of the local Coulomb interaction ( U ) value on the atomic forces acting in the experimental structure. The optimal parameters of the el…
We report results of low-temperature thermodynamic and transport measurements of Pb1-xTlxTe single crystals for Tl concentrations up to the solubility limit of approximately x=1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude with the Tl concentration. The temperatur…
Crystallization at production scale is typically a poorly understood unit operation, with little implementation of the first principles aspect of crystallization in its design, optimization, and control. Problems with production crystallizers include the following: (1) inconsistencies of batch-to-batch in terms of the…
Polymeric methyltrioxorhenium (poly-MTO) is the first member of a new class of organometallic hybrids which adopts the structural motives and physical properties of classical perowskites in two dimensions. In this study we demonstrate how the electronic structure of poly-MTO can be tailored by intercalation of organic…
While isovalent doping of GaAs (e.g., by In) leads to a repulsion between the solute atoms, two Cr, Mn, or Fe atoms in GaAs are found to have lower energy than the well-separated pair, and hence attract each other. The strong bonding interaction between levels with t2 symmetry on the transition metal (TM) atoms result…
We present atomic-scale computer simulations in equiatomic L1$_0$-CoPt where Molecular Dynamics and Monte Carlo techniques have both been applied to study the vacancy-atom exchange and kinetics relaxation. The atomic potential is determined using a Tight-Binding formalism within the Second-Moment Approximation. It is…
We study spin transport in forward and reverse biased junctions between a ferromagnetic metal and a degenerate semiconductor with a delta-doped layer near the interface at relatively low temperatures. We show that spin polarization of electrons in the semiconductor, Pn, near the interface increases both with the forwa…
Quantum chemical calculations including embedding, scalar relativistic, and dynamic electron correlation effects on Cs2NaYCl6:(CeCl6)3- embedded clusters predict: (i) red shifts of the 4f->5d(t2g) transition with pressure and (ii) bond length shortening upon 4f->5d(t2g) excitation. Both effects are found to be connect…
Optical properties of nanocrystalline red-emitting phosphor, europium-doped yttria (Y2O3:Eu3+), of average particle size of 15nm are investigated. The intensity of the strongest emission line at 612nm is found to be highest in the nanocrystalline sample with 4at.wt% of europium. The narrow electronic emission spectrum…
There are many methods for analyzing solid-state kinetic data. They are generally grouped into two categories, model-fitting and isoconversional (model-free) methods. Historically, model-fitting methods were widely used because of their ability to directly determine the kinetic triplet (i.e., frequency factor [A], act…
We have identified, for the first time, the change in symmetry at the ferroelectric transition TFE near 1023K of the ferroelectromagnet YMnO3. This transition takes place 300K below the transition to the centrosymmetric state at TIP. Single crystal synchrotron diffraction coupled to a group theoretical analysis show t…
Large-scale alignment of lamellae in thin films of diblock copolymers containing polyacrylonitrile and poly(n-butyl acrylate) was achieved by casting copolymer solution on a silicon substrate moved away at a constant speed from the casting nozzle (zone-casting). Grazing incidence small-angle X-ray scattering revealed…
One ligand, five NIR-emitting complexes: Tropolonate (trp) ligands sensitize the near-infrared emission of several lanthanide (LnIII) ions upon formation of [Ln(trp)4]− complexes (Ln=Nd, Ho, Er, Tm, and Yb; see emission spectra). The solid-state structures and solution-state photophysical properties of the [Ln(trp)4]−…
Crystallization of the thermodynamically metastable β glycine is explained on the basis of its growth at the opposite poles of the crystal (see graph) and by considering the structure of the relevant surfaces of the three polymorphs and their interactions with solvent molecules.
Frequency-resolved femtosecond transient absorption spectra and kinetics measured by optical excitation of the second and first electronic transitions of the (8,3) single-walled carbon nanotube species reveal a unique mutual response between these transitions. Based on the analysis of the spectra, kinetics, and their…
Regenerated silk fibroin materials show properties dependent on the methods used to process them. The molecular structures of B. mori silk fibroin both in solution and in solid states were studied and compared using X-ray diffraction, FTIR, and (13)C NMR spectroscopy. Some portion of fibroin protein molecules dissolve…
We analyze the intrinsic geometric flexibility of framework structures incorporating linear metal--cyanide--metal $(\mathrm{M}\text{--}\mathrm{CN}\text{--}{\mathrm{M}}^{\ensuremath{'}})$ linkages using a reciprocal-space dynamical matrix approach. We find that this structural motif is capable of imparting a significan…
Thermolysis of benzoylacetonate complexes proved successful in the synthesis of rare-earth oxide nanocrystals. CeO2 nanopolyhedra, Eu2O3 nanodisks, and Pr2O3 nanoplates display 2D ordering on copper grids (see figure), and the former two show interesting optical properties arising from surface-modification effects.
Conjugated oligomers represent a prominent class of compounds from a viewpoint of their theory, synthesis, and applications in materials science. Push-pull substitution with an electron donor D at one end of the conjugation and an electron acceptor A at the other end results in them having outstanding optical and elec…
Recent theory has predicted a superlens that is capable of producing sub-diffraction-limited images. This superlens would allow the recovery of evanescent waves in an image via the excitation of surface plasmons. Using silver as a natural optical superlens, we demonstrated sub-diffraction-limited imaging with 60-nanom…