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Nano-sized tetragonal BaTiO3 (BT) particles that are well dispersed in solution are essential for the dielectric layer in multilayer ceramic capacitor technology. A hydrothermal process using TiCl4 and BaCl2, as source of Ti and Ba, respectively, or the precursor TiO2 as seed for the formation of BT, and poly(vinylpyrrolidone) (PVP) as a surfactant, was employed in this study to enhance both the dispersibility and tetragonality (c/a) simultaneously in a single reaction process. The process parameters, i.e., the ratio of TiO2 substitution of TiCl4, the reaction time, and PVP content were systematically studied, and the growth mechanism and relation between the tetragonality and the particle size are discussed. Dynamic light scattering (DLS) analysis was used to show that truncated pseudo-tetragonal BT-PVP particles with an average size of 100 nm, having a narrow size distribution and a coefficient of variation (CV) as low as 20% and being mono-dispersed in water, were produced. The narrow particle size distribution is attributed to the ability of PVP to inhibit the growth of BT particles, and the high c/a of BT-PVP to heterogeneous particle growth using TiO2 seeds. [ABSTRACT FROM AUTHOR]

Nano-sized tetragonal BaTiO3 (BT) particles that are well dispersed in solution are essential for the dielectric layer in multilayer ceramic capacitor technology. A hydrothermal process using TiCl4 and BaCl2, as source of Ti and Ba, respectively, or the precursor TiO2 as seed for the formation of BT, and poly(vinylpyrrolidone) (PVP) as a surfactant, was employed in this study to enhance both the dispersibility and tetragonality (c/a) simultaneously in a single reaction process. The process parameters, i.e., the ratio of TiO2 substitution of TiCl4, the reaction time, and PVP content were systematically studied, and the growth mechanism and relation between the tetragonality and the particle size are discussed. Dynamic light scattering (DLS) analysis was used to show that truncated pseudo-tetragonal BT-PVP particles with an average size of 100 nm, having a narrow size distribution and a coefficient of variation (CV) as low as 20% and being mono-dispersed in water, were produced. The narrow particle size distribution is attributed to the ability of PVP to inhibit the growth of BT particles, and the high c/a of BT-PVP to heterogeneous particle growth using TiO2 seeds. [ABSTRACT FROM AUTHOR]

In order to synthesize of high-dispersion and tetragonal BaTiO3 (BT) nanoparticle, a hydrothermal method is used in a mixture of chloride metal sources and KOH with polyvinylpyrrolidone (PVP). The properties of BT-PVPs prepared by different reaction temperature and time are investigated via XRD, FE-SEM, DLS, FT-IR, and TEM to clarify the changes of the crystal phase, dispersion, and particle structure. The reaction is finished at 230 °C for 24 h and the critical reaction condition for that the crystal phase of the obtained BT particle changed from the cubic to the tetragonal is found to be 190 °C fixed in reaction time 24 h, and 9 h. During reaction the PVP on the BT surface decomposed to different form, and the PVP plays the role of dispersant in aqueous solution. By the hydrothermal condition of 230 °C for 24 h almost monodisperse BT-PVP with sizes of 83 nm and tetragonality (c/a) of 1.0062 were synthesized. The structure of nanoparticle, core (BT)-shell (PVP) was investigated by FT-IR and direct observed by TEM and the mechanism of particle growth and dispersion was discussed. [ABSTRACT FROM AUTHOR]

Monodispersed, spherical nanoparticles of the BaTiO3-polyvinylpyrrolidone (BT-PVP) composite were synthesized through the surface modification of the oxide BT by the polymer PVP, using TiCl4, BaCl2, PVP, and KOH (as the mineralizer) in an aqueous solution. To reduce the size of the particles and ensure that they were monodispersed, the concentrations of the Ba and Ti sources were increased and the reaction parameters such as reaction temperature, reaction time, and KOH concentration were optimized. As a result, monodispersed BT-PVP particles with an average diameter of 114 nm (coefficient of variation, CV = 20.0%) were obtained from a Ba-rich solution ([Ti]/[Ba] = 0.2 M:0.3 M; [KOH] = 1.4 M), and their dynamic light scattering in an aqueous suspension demonstrated that the average diameter was 162 nm (CV = 26.6%). A higher KOH concentration resulted in smaller particles, but the excess KOH promoted particle aggregation and PVP gelation. The mechanism of dispersion and aggregation of BT-PVP will be discussed in detail. [ABSTRACT FROM AUTHOR]

The reaction or tetrabutoxyoctadehydrodibenzo[12]annulene 2f with iodine under aerobic conditions was reexamined. Contrary to previous reports, the present results revealed the formation of both anti-diiodoindenofluorenedione and its syn isomer through the oxidation of the respective tetraiodoindenofluorenes, indicating the occurrence of two modes of iodine-induced transannular cyclization. This was supported by the reaction of 2f with bromine, which gave anti- and syn-hexabromodihydroindenofluorenes through interception of indenofluorene intermediates by bromine. The hexabromides were transformed into the corresponding dibromodiones by hydrolysis. [ABSTRACT FROM AUTHOR]

A correction to the article "Control and induction of surface-confined homochiral porous molecular networks" by Kazukuni Tahara and colleagues that was published in the 2011 issue, volume threee and pages 714 to 719 where it failed to state that correct energy values.

Abstract: Ethyl cellulose (EC) was mixed with terpineol and conductive ceramic La0.6Sr0.4Ti0.3Fe0.7O3−δ to prepare pastes with different EC content. Viscosity of the vehicles was found to increase with EC content, and the intrinsic viscosity, hydrodynamic radius, and effective sphere of EC in terpineol were estimated to be 0.07L/g, 78.8nm, and 0.06L/g, respectively. For a ceramic paste of 70wt% powder and vehicle, shear thinning properties were observed for pastes of 0 and 1wt% EC. For EC contents above 3wt%, the pastes become Newtonian-like behavior and EC was considered to act effectively as a dispersant. Screen printing of the pastes was carried out. The relative densities of the sintered films were as low as 51.7% for the 0wt% EC paste, but increased to 67.6% for the 3wt% EC paste. The high density observed for the 3wt% EC paste was due to particles being well dispersed, which was also expected from the rheological results. [Copyright &y& Elsevier]

We have synthesized anthracene-acetylene oligomers, which contained one 10-substituted anthracene unit and one anthraquinone unit, by cyclization with Sonogashira coupling. X-ray analysis revealed an almost-planar framework and significant out-of-plane deformation around the inner carbonyl moiety because of steric hindrance. These compounds underwent self-association in solution and their association constants for monomer-dimer exchange were determined by variable-concentration (1)H NMR measurements in CDCl(3): 8 mol(-1) L (10-substituent: isopropyl), <5 mol(-1) L (methoxy), and 19 mol(-1) L (octyloxy). These results were discussed on the basis of spectroscopic and molecular-orbital analysis. A linear molecular assembly of the octyloxy compound at a liquid/graphite interface was observed by STM measurements., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Self-assembled monolayers of a series of tetraalkoxy-substituted octadehydrodibenzo[12]annulene (DBA) derivatives 1c-g possessing butadiyne linkages were studied at the 1,2,4-trichlorobenzene (TCB) or 1-phenyloctane/graphite interface by scanning tunneling microscopy (STM). The purpose of this research is not only to investigate the structural variation of two-dimensional (2D) monolayers, but also to assess a possibility for peri-benzopolyacene formation by two-dimensionally controlled polymerization on a surface. As a result, the formation of three structures, porous, linear, and lamella structures, were observed by changing the alkyl chain length and the solute concentration. The formation of multilayers of the lamella structure was often observed for all compounds. The selection of molecular networks is basically ascribed to intermolecular and molecule-substrate interactions per unit area and network density. The selective appearance of the linear structure of 1d is attributed to favorable epitaxial registry matching between the substrate lattice and the overlayer lattice. Even though the closest interatomic distance between the diacetylenic units of the DBAs in the lamella structure (approximately 0.6 nm) is slightly larger compared to the typical distances necessary for topochemical polymerization, the reactivity toward external stimuli (electronic-pulse irradiation from an STM tip and UV irradiation) was investigated. Unfortunately, no evidence for polymerization of the DBAs on the surface was observed. The present results indicate the necessity for further designing a suitable system for the on-surface construction of structurally novel conjugated polymers, which are otherwise difficult to prepare.