ABSTRACT
High-yield synthesis of four new fluorinated enaminones LH2 (RfC(O)C2H2NH)2C2H4 (Rf = CF3 (2a), C2F5 (2b), C3F7 (2c)) and (F3CC(O)C2H2NH)2C3H6 (2a') as dianionic ligands is described. The ligands were characterized in solution (via nuclear magnetic resoannce (NMR)) as well as in the solid state (via X-ray diffraction (XRD)). The ligating ability of the enaminones was verified by reacting them with [Ce2(O(i)Pr)8(HO(i)Pr)2], which resulted in monomeric cerium(IV) complexes [CeL2] (3a-c, 3a') based on tetradentate chelation of the ligands. Cerium enaminolates were comprehensively analyzed by NMR spectroscopy, mass spectrometry, and single-crystal XRD studies to verify their monomeric nature. High stability under ambient conditions and high volatility makes them a potential precursor for the gas-phase synthesis of CeO2. Complexes 3a and 3b were applied as precursors in thermal and plasma-enhanced chemical vapor deposition to obtain crystalline ceria films with different surface morphologies. The purity and surface states of the films were analyzed by X-ray photoelectron spectroscopy, which revealed a high amount of Ce(3+) on the subsurface of CeO2 films.
ABSTRACT
Hematite (α-Fe2O3) nanoparticles of two different shapes but of same size (ca. 40 nm) were dispersed in PEDOT:PSS matrices in various concentration ranges (0-7 wt%) to study the consequent changes in conductivity in the dark and under solar illumination conditions. Within a distinct range of concentration, a distinct increase in the conductivity was observed for both spherical and cubical particle population. We ascribed this effect to the generalized Poole-Frenkel theory of conduction in conjunction with the basic depletion width properties of heterojunctions and electrostatic dipole moments, and verified our assumptions through data fitting. A difference in conductivity between sphere- and cube-based α-Fe2O3-PEDOT:PSS nanocomposites was also observed and ascribed to the electrostatic edge effect on the nanoparticles. The dispersion of α-Fe2O3 nanocrystals was confirmed by high-resolution electron microscopy, whereas the electrical properties and modulations thereof were followed by recording current-voltage characteristics.
ABSTRACT
Methods of high-resolution, high-speed, optical beam deflection and scanning are reviewed with respect to resolution and scanning frequency capabilities. A general description is given of external deflector devices in the categories of variable reflectors, variable refractors, birefringent deflectors, and interference deflectors. The different techniques are then evaluated on the basis of their application to high-speed, high-resolution, precision scanning applications.
