Materials Literature
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To fully exploit the promise of molecular materials for NLO applications, inter- and supramolecular interactions must be accounted for. We review our recent work on electrostatic interchromophore interactions in multichromophores for NLO applications. The discussion is based on a bottom-up modeling strategy: each chro…
Abstract The bis(guanidine)‐stabilised zinc complexes [ N 1 , N 2 ‐bis(1,3‐dimethylimidazolidin‐2‐ylidene)ethane‐1,2‐diamine]dichloridozinc(II), [Zn(DMEG 2 e)Cl 2 ] ( C1 ), diacetato[ N 1 , N 2 ‐bis(1,3‐dimethylimidazolidin‐2‐ylidene)ethane‐1,2‐diamine]zinc(II),[Zn(DMEG 2 e)(CH 3 COO) 2 ] ( C2 ), and bis[ N 1 , N 2 ‐b…
The mechanical and electronic properties of hcp-ReB2 are calculated by a first-principles approach. The calculated extreme equilibrium mechanical properties are consistent with the available experimental and theoretical data. The calculated elastic moduli suggest that hcp-ReB2 has a low compressibility and is most lik…
The crystal structure and piezoelectric properties of ternary ceramics x(Bi1∕2Na1∕2)TiO3–y(Bi1∕2K1∕2)TiO3–zKNbO3 (abbreviated as BNT-BKT-KN100x∕100y∕100z) system have been investigated. Effects of BKT and KN on the crystalline structure were examined. The morphotropic phase boundary (MPB) phase diagram of BNT-BKT-KN t…
Thick wall mesoporous carbons (FDU-18) with ordered large pore structures were synthesized via an evaporation induced self-assembly (EISA) approach by using a novel amphiphilic diblock copolymer with a weakly hydrophobic segment as a template, soluble resol as a carbon source and THF as a solvent. The versatile atom t…
We study phase separation in a deeply quenched colloid-polymer mixture in microgravity on the International Space Station using small-angle light scattering and direct imaging. We observe a clear crossover from early-stage spinodal decomposition to late-stage, interfacial-tension-driven coarsening. Data acquired over…
We present results of detailed ac susceptibility, magnetization and specific heat measurements in Heusler alloys Ni 50 Mn 34 In 16 and Ni 50 Mn 34 Sn 16 . These alloys undergo a paramagnetic to ferromagnetic transition around 305 K, which is followed by a martensitic transition in the temperature regime around 220 K.…
Magnetically anisotropic cobalt and iron nanofibers (see figure) are obtained via oriented polymer-supported electrospinning and subsequent reduction and thermal treatment. The cobalt and iron nature of the fibers is confirmed by XRD analysis. Fibers of both metals show ferromagnetic behavior. Parallel aligned iron na…
It is shown that Ca2+ doping at Bi-site results in the release of weak ferromagnetism in BiFeO3. Structural transformation from rhombohedral to triclinic is observed with 10% Ca doping. Raman measurements show the presence of oxygen vacancies with Ca doping and no evidence of either intermediate valence or the tetrava…
An approach to further improve piezoelectric properties of (1−x)(K0.5Na0.5)NbO3–xLiNbO3 (KNLN) ceramics, i.e., the optimum poling temperatures (Tp) of KNLN ceramics should be chosen near the polymorphic phase transition temperatures, is proposed. This is contrary to conventional wisdom associated with electrical polin…
X-ray amorphous manganese oxides were prepared by reduction of sodium permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these materials are not amorphous, but nanostructured, with a prominent spinel substructure in Mn…
Dynamic micromagnetic simulation studies have been completed to observe the motion of a domain wall in a magnetic nanowire in an effort to increase the field-driven domain wall speed. Previous studies have shown that the wire dimensions place a cap on the maximum speed attainable by a domain wall when driven by a magn…
Diamond-based photonic devices offer exceptional opportunity to study cavity quantum electrodynamics at room temperature. Here we report fabrication and optical characterization of high quality photonic crystal microcavities based on nanocrystalline diamond. Fundamental modes near the emission wavelength of negatively…
We study a recently introduced model of one-component glass-forming liquids whose constituents interact with anisotropic potential. This system is interesting per-se and as a model of liquids like glycerol (interacting via hydrogen bonds) which are excellent glass formers. We work out the statistical mechanics of this…
The polarization of PbTiO3/SrTiO3 superlattices is experimentally tuned from 0–60 μC/cm–2 and the transition temperature from room temperature to 1000 K while maintaining a perfect crystal structure and low leakage currents (see figure). A simple model based on Landau theory is developed as a guide for the straightfor…
Using density-matrix theory, we microscopically calculate the relaxation dynamics of photoexcited electrons in graphene. Electron-phonon coupling leads to an initially ultrafast energy dissipation and to a nonthermal phonon occupation of the highest optical phonon modes. We also calculate the temporal evolution of the…
We use a multiscale procedure to derive a simple continuum model of multiwalled carbon nanotubes that takes into account both strong covalent bonds within graphene layers and weak bonds between atoms in different layers. The model predicts polygonization of crossections of large multiwalled nanotubes as a consequence…
Magnetite (Fe$_{3}$O$_{4}$), an archetypal transition metal oxide, has been used for thousands of years, from lodestones in primitive compasses[1] to a candidate material for magnetoelectronic devices.[2] In 1939 Verwey[3] found that bulk magnetite undergoes a transition at T$_{V}$ $\approx$ 120 K from a high temperat…
The electronic and vibrational contributions to the static dipole polarizability of C70 fullerene are determined using the finite-field method within the density functional formalism. Large polarized Gaussian basis sets augmented with diffuse functions are used and the exchange-correlation effects are described within…
The authors synthesized three new silole derivs. with incrementally flexible structure to tune their packing ability and therefore study the influence of the mol. organization in single-layer OLEDs. This architecture was chosen since the absence of org. layers interfaces allows a better evaluation of the role of the m…