Sintering-driven effects on the band gap of (Pb,La)(Ti,Ni)O3 photovoltaic ceramics

In this work, the influence of the sintering temperature on the physical properties of (Pb_0.8La_0.2)(Ti_0.9Ni_0.1)O₃ (PLT-Ni) ceramics is reported. The experimental data revealed that the energy band gap of PLT-Ni ceramics could be tailored from approximately 2.7 to 2.0 eV by changing the sintering temperature from 1100°C to 1250°C. It is demonstrated that the simple substitution of Ti⁴⁺ by Ni²⁺ cations is effective to decrease the intrinsic band gap while increasing the tetragonality factor and the spontaneous polarization. However, the additional red-shift observed in the absorption edge of the PLT-Ni with increasing the sintering temperature was associated with a continuous increase in the oxygen vacancies () amount. It is believed that the impact of the creation of these thermally induced is manifold. The presence of and Ni²⁺ ions generate the Ni²⁺- defect-pairs that promoted both a decrease in the intrinsic band gap and an additional increase of the tetragonality factor, consequently, increasing the spontaneous polarization. The creation of Ni²⁺- defects also changed the local symmetry of Ni²⁺ ions from octahedral to a square pyramid, thus lifting the degeneracy of the Ni²⁺ 3d orbitals. With the increase in the sintering temperature, lower-energy absorbing intraband states were also formed due to an excess of , being responsible for an add-on shoulder in the absorption edge, extending the light absorption curve to longer wavelengths and leading to an additional absorption in “all investigated” spectrum as well.     

Technical and economical assessment of energy-saving roof and wall construction in Thailand

This research assessed the economic impact and construction costs of buildings with solar chimneys in Thailand, called bioclimatic houses. A solar chimney uses a combination of air gaps between walls and roof, and effective ventilation to lower the indoor temperature and reduce the need for air conditioning. The study looked at small, medium, and large size houses and studied construction techniques, the materials used, and the time needed to build a residential structure. It also polled owners of bioclimatic houses about their satisfaction. The techniques employed in building bioclimatic houses take slightly longer and cost slightly more than those used in standard construction. However, the study found that bioclimatic houses use approximately 10–20% less electricity for air conditioning require less maintenance and have a payback period of 6–13 years, depending on the size. The lifespan of insulation material used in standard houses is about 20–25 years, while the lifespan of a solar chimney is about 40–50 years. The solar chimney concept can also be applied to standard houses with minimal renovation. The study found that this type of house was suitable for use in Thailand, and with increased consumer awareness, had a high probability for adoption.     

Thermodynamic Analyses on Nanoarchitectonics of Perovskite from Lead Iodide: Arrhenius Activation Energy

Amongst the different perovskites being investigated for application in solar cells, one of the most frequently scrutinized is methylammonium lead iodide CH₃NH₃PbI₃ (or MAPbI₃), which is usually obtained by the reaction of lead iodide (PbI₂) with methylammonium iodide (MAI). Although this perovskite has been extensively studied and utilized in the manufacture of high-efficiency solar cells, its formation chemistry is still not well understood. Reliable experimental determination of the activation energy between PbI₂ and MAI has been difficult due to the rapid reaction at room temperature. In this work, we determined the activation energy by adopting the Arrhenius equation. This was possible by controlling the reaction using MAI vapor, instead of liquid solution. This procedure allowed the reaction to be carried out at temperatures of up to 150 °C. The formation of MAPbI₃ films was obtained by a two-step process: deposition of thin PbI₂ film by thermal evaporation and subsequent conversion into perovskite by exposure to MAI vapor. The conversion of PbI₂ to MAPbI₃ as a function of temperature was probed by X-ray diffraction. An activation energy of 0.12?±?0.02 eV was obtained. This low value explains the ease of MAPbI₃ formation at low temperatures, and partially explains its instability in environmental conditions.

     

Nonlinear model predictive control of biodiesel production via transesterification of used vegetable oils

The economic performance of an industrial scale semi-batch reactor for biodiesel production via transesterification of used vegetable oils is investigated by simulation using nonlinear model predictive control (NMPC) technology. The objective is to produce biodiesel compliant to the biodiesel standards at the minimum costs. A first-principle model is formulated to describe the dynamics of the reactor mixture temperature and composition. The feed oil and mixture composition are characterized using a pseudo-component approach, and the thermodynamic properties are estimated from group contribution methods. The dynamic model is used by the NMPC framework to predict the optimal control profiles, where a multiple shooting based dynamic optimization problem is solved at every sampling time. Simulation results with the economic performance of an industrial scale semi-batch reactor are presented for control configurations manipulating the methanol feed flow rate and the heat duty.     

Klebtechnik – multifunktionales Fügen für den nachhaltigen Werkstoffeinsatz im 21. Jahrhundert

Adhesive bonding technology – multifunctional joining for the sustainable use of materials in the 21^st century Adhesive bonding meets the key requirements for the sustainable joining technology of the 21^st Century: different materials can be assembled with integrated additional functions in a weight saving manner. The review paper outlines introductory the origin and the commercial relevance of adhesive bonding technology. Methods of surface treatment and the meaning of adhesion and cohesion are discussed. The classification of the adhesives occurs according to the setting mechanism. The right selection is explained. The comparison with other joining technologies is important for the assessment of adhesive bonding. The geometric design of the joint is based on construction guidelines: one should avoid stress peaks and maximize the glue area. Simple notes for the strength calculation make dimensioning easier. Materials testing in adhesive bonding engineering is described. The thick‐adherend tensile shear test is suited for the in situ determination of mechanical characteristics. Applications of adhesive bonding in aviation and aerospace and transportation are presented. Besides these traditional industries, new markets in sectors like electronics and medicine are opened up. Due to high strength and deformability, chemically curing products solve demanding tasks in adhesive bonding and sealing technology.     

Antistatic packaging based on PTT/PTT-g-MA/ABS/MWCNT nanocomposites: Effect of the chemical functionalization of MWCNTs

Polymer/carbon nanotube nanocomposites have attracted high interest for a wide spectrum of applications, including antistatic packaging used to protect electronic devices against electrostatic discharge. Polytrimethylene terephthalate (PTT)/maleic-anhydride-grafted PTT (PTT-g-MA)/acrylonitrile butadiene styrene (ABS) blend-based multiwall carbon nanotubes (MWCNTs) nanocomposites were prepared through extrusion. It was conducted chemical functionalization on the MWCNTs by oxidation using nitric acid to introduce functional groups. The effect of the amount (0.5 or 1.0 wt%) and functionalization of MWCNTs on the nanocomposites was investigated. Despite the poor barrier properties of PTT/PTT-g-MA/ABS/MWCNT nanocomposites due to the presence of voids confirmed by scanning electron microscopy (SEM), the nanocomposites with functionalized MWCNT (MWCNTf) showed excellent barrier properties, indicating that the functionalization process improved the interaction between the MWCNTs and the matrix. The addition of MWCNTs into PTT/PTT-g-MA/ABS blend decreased the electrical resistivity by eight orders of magnitude. The use of MWCNTf may still disrupt the electrical network pathway and slightly decreasing the electrical resistivity, but the nanocomposites present the desired properties required for antistatic packaging.     

Review of quantitative structure‐activity/property relationship studies of dyes: recent advances and perspectives

Dyes have been applied and are playing an increasingly important role in many industries, including the textile, printing, medical and energy industries. Their wide applications imply that specific dyes possessing given properties need to be effectively designed. The present review aims to survey information related to activity/property research of dyes that has been published in the past two decades. Emphasis is laid particularly on studies based on quantitative structure–activity/property relationships that have contributed to the theoretical design and application of dyes. Finally, the perspectives of quantitative structure‐activity/property relationship studies are set out in order to show how this method may be used to design new dyes and to evaluate their different properties. The challenges facing these studies are also outlined.