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March 15th, 2012

Previews of the latest articles in the Journal of the American Ceramic Society

Published on March 15th, 2012 | By: pwray@ceramics.org

New papers that have been accepted for publication in the Journal of the American Ceramic Society are posted to “Early Viewon the Wiley website and can be read even before the issue is printed. Below are summaries of selected papers currently available via Early View.

All members of The American Ceramic Society receive free online access to JACerS To access any of the ACerS journals, or to become a member, visit www.ceramics.org.

owder X-ray diffractograms of (a) mc-BaTiO3 (BTO), (b) ns-TiO2 annealed at 500°C, (c) Degussa P25, (d) heterostructured mc-BaTiO3 core/ns-TiO2 shell annealed at 500°C, and (e) a sonomechanical mixture of mc-BaTiO3 and P25. All peaks in (a) correspond to those of BaTiO3. In (b) and (c), peaks associated with anatase (A) and rutile (R) are marked.

Powder X-ray diffractograms of (a) mc-BaTiO3 (BTO), (b) ns-TiO2 annealed at 500°C, (c) Degussa P25, (d) heterostructured mc-BaTiO3 core/ns-TiO2 shell annealed at 500°C, and (e) a sonomechanical mixture of mc-BaTiO3 and P25. Credit: JACERS; Wiley.

Heterostructured Ceramic Powders for Photocatalytic Hydrogen Production: Nanostructured TiO2 Shells Surrounding Microcrystalline (Ba,Sr)TiO3 Cores

Li Li, Gregory S. Rohrer and Paul A. Salvador
These researchers from Pittsburgh’s Carnegie Mellon University prepared and annealed heterostructured photocatalysts with (Ba,Sr)TiO3 microcrystalline cores surrounded by nanostructured TiO2 shells. They report that photocatalysts annealed at 600°C had rates of photochemical hydrogen production from water/methanol solutions much greater than those for TiO2 or (Ba,Sr)TiO3 alone. They also suggest that such heterostructured powders represent a new strategy for the design of efficient photocatalysts and for the use of nanostructured catalytic coatings.

Proposed reaction mechanism for molecular level interfacing of boron with poly(ureamethylvinyl)silazane liquid polymer. Credit: JACerS; Wiley.

Synthesis, Characterization and High-Temperature Stability of Si(B)CN-Coated Carbon Nanotubes Using a Boron-Modified Poly(ureamethylvinyl) Silazane Chemistry
Romil Bhandavat and Gurpreet Singh
Kansas State University researchers Bhandavat and Singh prepared a composite nanowire structure that consisted of a multiwalled carbon nanotube core and a polymer-derived silicon boron carbonitride shell. They report an amorphous Si(B)CN coating on individual nanotubes for all specimens processed below 1,400°C and high-temperature stability of the carbon nanotube core in flowing air up to 1,000°C.

Schematics of unit cell formation from powder packing. Credit: JACerS; Wiley.

Direct Multi-Scale Modeling of Sintering
Andrey Maximenko, Andrey Kuzmov, Evgeny Grigoryev and Eugene Olevsky
A research team from the Ukraine, Russia and the United States presents a new multiscale numerical approach for the modeling of sintering of macroscopically inhomogeneous materials that does not require the formulation of material constitutive equations. The new approach specifies material properties through the definition of macroscopic unit cells. Therefore, the influence of any number of material structure parameters on sintering kinetics and on specimen distortion can be investigated.

Block diagram of the starch-assisted sol-gel method for the preparation of K-doped Li2ZrO3 sorbents. Credit: JACerS; Wiley.

A Facile Starch-Assisted Sol-Gel Method to Synthesize K-Doped Li2ZrO3 Sorbents with Excellent CO2 Capture Properties
Qiang Xiao, Xiaodan Tang, Yijun Zhong and Weidong Zhu
This team of researchers from China’s Zhejiang Normal University used a facile starch-assisted sol-gel method and freeze-drying to synthesize potassium-doped Li2ZrO3 sorbents. The team reports that the sorbents exhibited excellent CO2 capture properties, and it confirmed good capture-regeneration stability.

Schematic diagram of the photovoltaic device: glass/ITO/oxide/P3HT/Au. Credit: JACerS; Wiley.

The Application of Bismuth-Based Oxides in Organic-Inorganic Hybrid Photovoltaic Devices
Zhike Liu and Feng Yan
Hong Kong Polytechnic University’s Liu and Yan used pulsed laser deposition to prepare BiFeO3, Bi2WO6 and BiVO4 ferroelectric oxide films with different band structure. They used them as n-type semiconductors and poly(3-hexylthiophene) as p-type organic semiconductor to form bilayer heterojunctions in photovoltaic devices. Liu and Yan report that the bismuth-based oxides exhibit wider absorption spectra and induce higher external quantum efficiency, open-circuit voltage and power conversion efficiency compared with bismuth-based oxides, indicating that bismuth-based oxides are promising materials for photovoltaic devices.

Schematic representation of a typical BaTiO3 particle. The outer shell layer and inner pores are suggested as a cubic phase.

Schematic representation of a typical BaTiO3 particle. The outer shell layer and inner pores are suggested as a cubic phase.

Synthesis and Size Control of Tetragonal Barium Titanate Nanopowders by Facile Solvothermal Method
Hyun-Wook Lee, San Moon, Chang-Hak Choi and Do Kyung Kim
This team of Korean researchers used diethanolamine and triethanolamine to suppress particle growth (from 100 to 80 nanometers) in a solvothermal process for the synthesis of nanosized barium titanate powders with tetragonal structure. The team reports that it was able to tune the particle size while retaining tetragonality by adjusting the experimental parameters. It also reports that the nanopowders exhibit a narrow size distribution with uniform morphology and tetragonal asymmetry dominant structures.

Pore morphology and 3D interconnectivity of as-fabricated foam reticulated porous Bioglass scaffolds sintered at 900°C. Credit: JACerS; Wiley.

Preparation and Characterization of Porous Bioglass and PLLA Scaffolds for Tissue Engineering Applications
Kajal K. Mallick and James Winnett
United Kingdom’s Mallick and Winnett used camphene-based freeze cast reticulation, polyurethane foam templates and solvent extraction to fabricate three-dimensional open, uniform and interconnected porous scaffold network structures of Bioglass® and poly-L-lactide. They report that the PLLA achieved a compressive yield strength close to the upper range of cancellous bone and that the mean compressive strength of Bioglass scaffolds compared favorably with the theoretical model of porosity variation with strength and was higher than reported values.

Flowchart illustrating the experimental procedure followed in this work. Credit: JACerS; Wiley.

A “Green Chemistry” Approach to the Synthesis of Rare-Earth Aluminates: Perovskite-Type LaAlO3 Nanoparticles in Molten Nitrates
Esmeralda Mendoza-Mendoza, Sagrario M. Montemayor, José I. Escalante-García and Antonio F. Fuentes
This team of researchers from Mexico proposes using alkali metal nitrates as low-temperature fluxes and a facile, rapid and environmentally friendly two-step (mechanically induced metathesis to generate in-situ alkali metal nitrate flux and to obtain suitable La- and Al-containing presursors, followed by short firing at temperatures above nitrate melting points) method to prepare perovskite-type LaAlO3 nanoparticles. The team reports that these LaAlO3 powders are composed of loosely agglomerated nanoparticles with very fine crystallite size and that the method considerably decreases previously reported synthesis times and temperatures.

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