Materials Literature
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We have studied the adducts formed by eosin (E) with a fourth generation dendrimer (D) that comprises 30 tertiary amine units in the interior and 32 naphthyl and 32 trans azobenzene units in the periphery. We have found that: (i) the all trans dendrimer D(32t) can be converted by irradiation with 365 nm light (Phi=0.1…
Using the DFT+U method, i.e., first principles density functional theory calculations with the inclusion of on-site Coulomb interaction, the effects of Pd doping on the O vacancy formation energy (E(vac)) in CeO(2) has been studied. We find that E(vac) is lowered from 3.0 eV in undoped ceria to 0.6 eV in the Pd-doped…
The capillary force was measured by atomic force microscopy between a gold coated sphere mounted on a cantilever and gold surfaces with different roughness. For smooth surfaces the capillary adhesive force surpasses in magnitude any dispersion, e.g. van der Waals/Casimir, and/or electrostatic forces. A substantial dec…
Besides permitting an accurate determination of the ferromagnetic-to-paramagnetic phase transition temperature and the characteristic temperatures for the beginning and end of the growth of martensite (austenite) phase at the expense of austenite (martensite) phase while cooling (heating), the results of an extensive…
We present molecular dynamics simulations of a realistic model of an ultrathin film of BaTiO3 sandwiched between short-circuited electrodes to determine and understand effects of film thickness, epitaxial strain, and the nature of electrodes on its ferroelectric phase transitions as a function of temperature. We deter…
Compositional inhomogeneity is examined in Li‐ and Ta‐modified potassium sodium niobate (K,Na)NbO 3 perovskite ceramics. The inhomogeneous distribution of the A‐site (K and Na) and B‐site (Nb and Ta) cations is found to be correlative. The inhomogeneity could not be eliminated by prolonged high‐temperature annealing i…
The growth of water on thin SiO2 films on Si wafers at vapor pressures between 1.5 and 4 Torr and temperatures between -10 and 21 degrees C has been studied in situ using Kelvin probe microscopy and X-ray photoemission and absorption spectroscopies. From 0 to 75% relative humidity (RH), water adsorbs forming a uniform…
The synthesis and characterization of several highly ordered lanthanide complexes formed by the use of f-metal directed supramolecular synthesis is described. These unique self-assemblies or bundles are chiral as well as luminescent, where the lanthanide-based emission is observed upon excitation of the ligands (anten…
Magnetic entropy and adiabatic temperature changes in and above the room-temperature region has been measured for La0.7Sr0.3Mn1-xM'xO3 (M' = Al, Ti) by means of magnetization and heat capacity measurements in magnetic fields up to 6 T. The magnetocaloric effect becomes largest at the ferromagnetic ordering temperature…
In their paper [Opt. Mater. 24, 333, 2003], Feldman et al conducted an experimental study of the dynamics of chromium ion valence transformations in Cr,Ca:YAG crystals among the trivalent Cr3+ state, and two tetravalent Cr4+ ones, of octahedral and tetrahedral coordination. The temperatures used ranged between ~800 an…
Both hexagonal wurtzite and cubic zinc blend GaN phases were synthesized in GaAs by 50 keV N+ implantation at 400 deg C and subsequent annealing at 900 deg C for 15 min in N2 ambient. Crystallographic structural and Raman scattering studies revealed that GaN phases were grown for fluence above 2x1017 cm-2. Temperature…
We show which is the nanostructure required in granular Co20(ZrO2)80 thin films to produce an ac response such as the one that is universally observed in a very wide variety of dielectric materials. A bimodal size distribution of Co particles yields randomly competing conductance channels which allow both thermally as…
UV Raman scattering studies show longitudinal optical (LO) mode up to 4th order in wurtzite GaN nanowire system. Frohlich interaction of electron with the long range electrostatic field of ionic bonded GaN gives rise to enhancement in LO phonon modes. Good crystalline quality, as indicated by the crystallographic as w…
Ferromagnetic ordering is reported in the post-annealed samples of Co doped n-GaN formed by Co+ implantation. A maximum Curie temperature ~ 250K is recorded for the sample with 8 atomic percent Co. Particle induced x-ray emission-channeling study confirmed the substitutional Co in Ga lattice site. Local atomic arrange…
InN phase is grown in crystalline InP(100) substrates by 50 keV N+ implantation at an elevated temperature of 400 deg C followed by annealing at 525 deg C in N2 ambient. Crystallographic structural and Raman scattering studies are performed for the characterization of grown phases. Temperature- and power-dependent pho…
The ability of near-infrared fluorescence imaging to detect single-walled carbon nanotubes (SWNTs) in organisms and biological tissues has been explored using Drosophila melanogaster (fruit flies). Drosophila larvae were raised on food containing approximately 10 ppm of disaggregated SWNTs. Their viability and growth…
We demonstrate spatially resolved probing and imaging of pH in live cells by mobile and biocompatible nanosensors using surface-enhanced Raman scattering (SERS) of 4-mercaptobenzoic acid (pMBA) on gold nanoaggregates. Moreover, we also show that this concept of pH nanosensors can be extended to two-photon excitation b…
Carbon-coated Fe [Fe(C)] nanocapsules were synthesized by a modified arc-discharge method, and their microstructure and electromagnetic (EM) properties (2–18 GHz) were investigated by means of transmission electron microscopy, Raman spectroscopy and a network analyser. The reflection loss R of less than −20 dB was obt…
We determine the electronic structure of a graphene sheet on top of a lattice-matched hexagonal boron nitride $(h\text{\ensuremath{-}}\mathrm{B}\mathrm{N})$ substrate using ab initio density functional calculations. The most stable configuration has one carbon atom on top of a boron atom, and the other centered above…
Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC composites) are attractive materials for use in the blankets and divertors of fusion reactors due to their excellent thermo-mechanical properties and inherently low induced radioactivation. However, the brittle characteristics of SiC such as…