Br doping-induced evolution of the electronic band structure in dimorphic and hexagonal SnSe thermoelectric materials.

SnSe with its layered structure is a promising thermoelectric material with intrinsically low lattice thermal conductivity. However, its poor electronic transport properties have motivated extensive doping studies. Br doping effectively improves the power factor and converts the dimorphic SnSe to a fully hexagonal structure.

Contradicting Influence of Zn Alloying on Electronic and Thermal Properties of a YbCd Sb -Based Zintl Phase at 700 K.

Zintl compounds are promising thermoelectric materials for power generation as their electronic and thermal transport properties can be simultaneously engineered with anion/cation alloying. Recently, a peak thermoelectric figure-of-merit, zT, of 1.4 was achieved in a (Yb Mg )Cd Mg Zn Sb Zintl phase at 700 K.

Ultralow Water Permeation Barrier Films of Triad a-SiN:H/n-SiON/h-SiO Structure for Organic Light-Emitting Diodes.

Organic electronic devices such as organic light-emitting diodes (OLEDs), quantum dot LEDs, and organic photovoltaics are promising technologies for future electronics. However, achieving long-term stability of organic-based optoelectronic devices has been regarded as a crucial problem to be solved. In this work, a simple and reproducible fabrication method for ultralow water permeation barrier films having a triple-layered (triad) hydrogenated silicon nitride (a-SiN:H)/nanosilicon oxynitride (n-SiON)/hybrid silicon oxide (h-SiO) multistructure is presented.

Grain Boundary Interfaces Controlled by Reduced Graphene Oxide in Nonstoichiometric SrTiO Thermoelectrics.

Point defect or doping in Strontium titanium oxide (STO) largely determines the thermoelectric (TE) properties. So far, insufficient knowledge exists on the impact of double Schottky barrier on the TE performance. Herein, we report a drastic effect of double Schottky barrier on the TE performance in undoped STO.

Enhancing Thermoelectric Performances of Bismuth Antimony Telluride via Synergistic Combination of Multiscale Structuring and Band Alignment by FeTe Incorporation.

It has been a difficulty to form well-distributed nano- and mesosized inclusions in a BiTe-based matrix and thereby realizing no degradation of carrier mobility at interfaces between matrix and inclusions for high thermoelectric performances. Herein, we successfully synthesize multistructured thermoelectric BiSbTe materials with Fe-rich nanoprecipitates and sub-micron FeTe inclusions by a conventional solid-state reaction followed by melt-spinning and spark plasma sintering that could be a facile preparation method for scale-up production. This study presents a bismuth antimony telluride based thermoelectric material with a multiscale structure whose lattice thermal conductivity is drastically reduced with minimal degradation on its carrier mobility.

Phonon-glass electron-crystals in ZnO-multiwalled carbon nanotube nanocomposites.

We propose a strategy for enhancing thermoelectric performance through the realization of a 'phonon-glass electron-crystal' (PGEC) by interface control using multiwalled carbon nanotubes (MWCNTs). By the consolidation of undoped ZnO nanoparticles with MWCNTs (0.5, 1, and 2 wt%) using spark plasma sintering, we fabricated the interface-controlled ZnO-MWCNT nanocomposites, in which ZnO grains were surrounded with a MWCNT network.

A gigantically increased ratio of electrical to thermal conductivity and synergistically enhanced thermoelectric properties in interface-controlled TiO-RGO nanocomposites.

We report synergistically enhanced thermoelectric properties through the independently controlled charge and thermal transport properties in a TiO-reduced graphene oxide (RGO) nanocomposite. By the consolidation of TiO-RGO hybrid powder using spark plasma sintering, we prepared an interface-controlled TiO-RGO nanocomposite where its grain boundaries are covered with the RGO network. Both the enhancement in electrical conductivity and the reduction in thermal conductivity were simultaneously achieved thanks to the beneficial effects of the RGO network, and detailed mechanisms are discussed.

Effect of topographical control by a micro-molding process on the activity of human Mesenchymal Stem Cells on alumina ceramics.

Background: Numerous studies have reported that microgrooves on metal and polymer materials can affect cell adhesion, proliferation, differentiation and guidance. However, our knowledge of the cell activity associated with microgrooves on ceramics, such as alumina, zirconia, hydroxyapatite and etc, is very incomplete, owing to difficulties in the engraving of microgrooves on the hard surface of the base material. In this study, microgrooves on alumina were fabricated by a casting process using a polydimethylsiloxane micro-mold.

Spontaneous Growth of Ultra-Long SiO(x) Nanowires from SiC Thin Films by Thermal Annealing.

The use of a simple thermal treatment for growing ultra-long SiO(x) nanowires on silicon carbide (SiC) thin films is reported for the first time. SiC thin films with a thickness of 100 nm were prepared by sputtering at room temperature followed by annealing in an Ar/H2 gas atmosphere. The growth of SiO(x) nanowires started when the annealing temperature was at 1200 degrees C, and was rapidly and spontaneously grown at temperatures above 1250 degrees C.

Structurally nanocrystalline-electrically single crystalline ZnO-reduced graphene oxide composites.

ZnO, a wide bandgap semiconductor, has attracted much attention due to its multifunctionality, such as transparent conducting oxide, light-emitting diode, photocatalyst, and so on. To improve its performances in the versatile applications, numerous hybrid strategies of ZnO with graphene have been attempted, and various synergistic effects have been achieved in the ZnO-graphene hybrid nanostructures. Here we report extraordinary charge transport behavior in Al-doped ZnO (AZO)-reduced graphene oxide (RGO) nanocomposites.

Thermal stability of gallium-doped zinc oxide thin film on glass substrates by an RF sputtering process.

The effects of a heat treatment on the structural and electrical properties of GZO thin films grown by RF magnetron sputtering were investigated. The heat treatment involved temperatures in the range from 200 degrees C to 500 degrees C under air. As the temperature was increased, the electrical properties of GZO thin films increased exponentially and the surface morphology was drastically altered.

Thermoelectric performance of SrTiO3 enhanced by nanostructuring-self-assembled particulate film of nanocubes.

Self-assembled particulate films with a uniform structure over a large area were prepared from La-SrTiO3 nanocubes for thermoelectric applications. UV irradiation was used to assist the formation of particulate film for decomposition of the organic phase in situ to obtain a mechanically robust structure at high temperature. The thermoelectric properties of the particulate film were measured after calcination at 1000 °C under a reductive atmosphere (Ar/H2 = 60/40).

Interfacial structure and electrical properties of transparent conducting ZnO thin films on polymer substrates.

The effects of polymer substrates on the interfacial structure and the thermal stability of Ga-doped ZnO (GZO) thin films were investigated. The GZO thin films were deposited on polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates by rf-magnetron sputtering at room temperature, and thermal stability tests of the GZO thin films on the polymer substrates were performed at 150°C up to 8 h in air. Electrical and structural characterizations of the GZO thin films on the PET and the PEN substrates were carried out, and the origins of the stable interfacial structure and the improved thermal stability of the GZO thin film on the PEN substrate were discussed.

Hydrothermal synthesis of SrTiO3 nanoplates through epitaxial self-assembly of nanocubes.

SrTiO3 nanoplates are obtained by the precipitation of an aqueous gel suspension. The gel suspension is prepared by hydrolysis of a Titanium isopropoxide [Ti(OCH(CH3)2)4] solution with NaOH and the addition of Sr(NO3)2. The amount of additive oleic acid plays a significant role in the formation of pure SrTiO3 phase with specific morphologies.

Self-assembled-monolayers (SAMs) modified template synthesis and characterization of SrTiO3 nanotube arrays.

A self-assembled-monolayers (SAMs) modified anodic aluminum oxide (AAO) membranes were used to generate crystalline strontium titanate (SrTiO3) nanotube arrays, which have been characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), coupled with electron diffraction analysis. The possible formation mechanism can be explained by the induced nucleation effect of the functional headgroups in the SAMs.

Emissive ZnO-graphene quantum dots for white-light-emitting diodes.

Hybrid nanostructures combining inorganic materials and graphene are being developed for applications such as fuel cells, batteries, photovoltaics and sensors. However, the absence of a bandgap in graphene has restricted the electrical and optical characteristics of these hybrids, particularly their emissive properties. Here, we use a simple solution method to prepare emissive hybrid quantum dots consisting of a ZnO core wrapped in a shell of single-layer graphene.

Thermoelectric properties of Cu-dispersed bi0.5sb1.5te3.

A novel and simple approach was used to disperse Cu nanoparticles uniformly in the Bi0.5Sb1.5Te3 matrix, and the thermoelectric properties were evaluated for the Cu-dispersed Bi0.

Exfoliation of layers in NaxCoO2.

We proposed and developed an exfoliation process for layer-structured NaxCoO2 to prepare CoO nanosheets. Na+ ion exchange by acid treatment was utilized to expand the spacing between the two CoO2 layers in NaxCoO2. Ethylamine was then effectively utilized for the exfoliation of cobalt oxide sheets having nanometer-order thickness and high aspect ratio.

The formation mechanism of a textured ceramic of thermoelectric [Ca2CoO3](0.62)[CoO2] on beta-Co(OH)2 templates through in situ topotactic conversion.

We investigated the formation mechanism of thermoelectric [Ca(2)CoO(3)](0.62)[CoO(2)] (CCO) on beta-Co(OH)(2) templates with maintained orientations by identifying the intermediate phases and specifying the relationship between their crystallographic orientations. We mixed beta-Co(OH)(2) templates with the complementary reactant CaCO(3) and prepared a compact by tape casting, with the developed (001) plane of the templates aligned along the casting plane.

High-resolution transmission electron microscopy study of Ca(3)Co(4)O(9).

The crystal structure of Ca(3)Co(4)O(9) was investigated using high-resolution transmission electron microscopy (HRTEM) and the image-simulation method. The c(*) was 10.8A and the b parameters were 4.