Dispersion and flame retardancy of ethylene vinylacetate/layered silicate nanocomposites using the masterbatch approach for cable insulating material

Ethylene vinylacetate (EVA) copolymer-based nanocomposites with maleic anhydride-grafted ethylene-vinylacetate (EVAgMA) and organically modified clay (o-clay) were prepared in a twin screw extruder by following a two-step melt compounding method. EVAgMA/o-clay masterbatches with various clay contents up to 50 wt% were examined, after which the masterbatch with the highest clay content was melt compounded with EVA for the preparation of EVA/o-clay nanocomposites containing specific amounts of clay. Further morphological dispersion of the clay particles by highly polar EVA and shearing was confirmed in the EVA/o-clay nanocomposites by X-ray diffraction (XRD) and transmission electron microscopy (TEM). These morphologies led to increased thermal properties in air as well as a considerable decrease in heat release rate (HRR). EVA/o-clay/MDH nanocomposites were also prepared using a high clay-bearing masterbatch to confirm the synergistic flame retardancy of clay as a co-additive in EVA/MDH composites. EVA/o-clay/MDH nanocomposites prepared by substituting o-clay for MDH showed significantly lower and wider HRR during combustion compared to EVA/MDH composite.     

Superhydrophilic Transparent Titania Films by Supersonic Aerosol Deposition

Photocatalytic and hydrophilic TiO₂ thin‐film applications include water purification, cancer therapy, solar energy conversion, self‐cleaning devices, and antifogging windows. We demonstrate superhydrophilicity of aerosol‐deposition (AD) TiO₂ films on a glass substrate without use of a carrier solvent, thereby removing the possibility of impurity contamination. AD films exhibit high visible light transmittance (greater than 80%) and superhydrophilicity (0° contact angle) with even minimal UV‐light irradiation exposure. This AD method represents a significant step toward the realization of economically viable, functional thin films for the aforementioned applications.     

Synthesis of high-purity silver colloids using a thermal decomposition method

A thermal decomposition method was employed to produce high purity Ag particles. Silver carbonate was dispersed in an H₂O solvent that was heated above 80°C, followed by rapidly injecting H₂O₂ into the solvent. Then, the silver carbonate was decomposed into nanosized Ag particles using the decomposition heat of hydrogen peroxide as follows: Ag₂CO₃→2Ag+CO₂+1/2O₂. The size of the synthesized Ag particles is approximately 100 nm. This method can be used to produce high-purity Ag colloids withuut impurities, unlike other methods.     

Synthesis of copper-based bulk metallic glasses in the ternary Cu–Mg–Ca system

This paper reports the discovery of novel copper-based bulk metallic glasses free of group IV transition metals (Zr, Hf and Ti) in the Ca–Cu–Mg ternary system. Alloys of compositions ranging from Cu-33–55 at.%, Mg-18–36 at.% and Ca-18–36 at.%, located far from eutectic reactions, were found to exhibit high glass-forming ability (up to 8 mm using conventional copper mold casting), high hardness (up to 328H_V) and low densities (2.9–4.0 g/cm³).     

A numerical calculation of auger recombination coefficients for InGaAsP/InP quantum well heterostructures

Auger recombination coefficients are calculated numerically for InGaAsP/InP quantum well heterostructures. In narrow quantum wells, the quasi-threshold and thresholdless mechanisms mainly contribute to the Auger recombination coefficient. For the processes involving two electrons and a heavy hole (CHCC) or an electron and two heavy holes with a transition of one of the holes to the spin-orbit split-off band (CHHS), the Auger recombination coefficients depend on temperature only slightly in a wide temperature range. The dependence of the Auger coefficient on the quantum well width is analyzed and found to be nonmonotonic.     

Inkjet-printed InGaZnO thin film transistor

We report inkjet-printed InGaZnO (IGZO) thin film transistors (TFTs). IGZO ink was prepared by dissolving indium nitrate hydrate, gallium nitrate hydrate and zinc acetate dihydrate into 2-methoxyethanol with additional stabilizers. The resulting films were inkjet-printed with a resolution of 300 dots per inch using droplets with a diameter of 40 µm, and a volume of 35 pl. The films exhibited high optical transparency in the visible range and had a polycrystalline phase of InGaO₃(ZnO)₂ after thermal annealing treatment. The chemical composition of this IGZO sample was also determined, and shown to have high stoichiometric characteristics of low oxygen deficiency. The TFTs with a conventional inverted staggered structure using inkjet-printed IGZO as an active channel layer had a field-effect mobility of ~ 0.03 cm²/Vs in saturation region and an on-to-off current ratio greater than ~ 10⁴.     

Transient measurements of lattice oxygen in photocatalytic decomposition of formic acid on TiO2

In the absence of gas-phase O₂, formic acid extracted lattice oxygen from TiO₂ during photocatalytic decomposition (PCD) at room temperature. The amount of oxygen extracted was determined by interrupting PCD of a monolayer of formic acid after various reaction times and measuring O₂ uptake in the dark. After surface oxygen was depleted by PCD, oxygen diffused from the bulk to replenish the surface oxygen vacancies. The rate of oxygen diffusion to the surface was determined by measuring O₂ uptake after various dark times. A small fraction of the CO₂ that formed during PCD remained on the reduced sites of the TiO₂ surface, but this CO₂ was displaced by O₂ adsorption at room temperature.     

Fabrication of Superjunction Trench Gate Power MOSFETs Using BSG‐Doped Deep Trench of p‐Pillar

In this paper, we propose a superjunction trench gate MOSFET (SJ TGMOSFET) fabricated through a simple p pillar forming process using deep trench and boron silicate glass doping process technology to reduce the process complexity. Throughout the various boron doping experiments, as well as the process simulations, we optimize the process conditions related with the p pillar depth, lateral boron doping concentration, and diffusion temperature. Compared with a conventional TGMOSFET, the potential of the SJ TGMOSFET is more uniformly distributed and widely spread in the bulk region of the n drift layer due to the trenched p‐pillar. The measured breakdown voltage of the SJ TGMOSFET is at least 28% more than that of a conventional device.     

Reverse‐Conducting IGBT Using MEMS Technology on the Wafer Back Side

In this paper, we present a 600‐V reverse conducting insulated gate bipolar transistor (RC‐IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC‐IGBT uses the deep reactive‐ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC‐IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.