Eu3+‐doped glass as a color rendering index enhancer in phosphor‐in‐glass

A new method for improving color rendering index (CRI) and low correlated color temperature (CCT) in high‐power white‐light‐emitting diodes (WLEDs) is proposed. We used a configuration of phosphor‐in‐glass (PIG) and studied light output changes with the increment in concentration of yellow‐emitting Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce³⁺) phosphor. The PIG was coupled on the top of blue‐light‐emitting diodes (LED) chip (465 nm). To compensate the lack of red emission in the phosphor, Eu³⁺‐doped tellurium glass with different europium content was employed as a red emitter. The suitable contents of YAG:Ce³⁺ and Eu³⁺ were 7.5 weight percent (wt%) and 3 mol percent (mol%), respectively. The CRI value went from 72 to 82, whereas the CCT was reduced from 24 933 to 6434 K. The proposed structure can improve CCT as well as CRI of WLEDs just by placing a glass on top.     

Model for corrosion of metals covered with thin electrolyte layers: Pseudo-steady state diffusion of oxygen

A one-dimensional mathematical model is presented for the free corrosion of a bare metal surface (devoid of any oxide film) under a thin electrolyte layer using mixed potential theory where anodic metal dissolution is controlled by oxygen diffusion through the electrolyte layer and by the oxygen reduction at the metal surface. A pseudo-steady state is considered wherein the oxygen diffusion is at steady state while the metal and hydroxyl ions keep accumulating in the thin electrolyte layer due to a decoupling arising from the assumed Tafel laws for corrosion kinetics. Under free corrosion the oxygen diffusion is shown to depend on a non-linear boundary condition with a non-integer power on oxygen concentration at the metal surface which makes the model non-trivial. Analytical and numerical results for the oxygen concentration at the metal surface, corrosion potential, and corrosion current density are reported which depend on several kinetic, thermodynamic and transport parameters in the system. The model is applied to iron and zinc systems with input data taken from the literature. The experimental utility of the model for gathering thin-film corrosion parameters from a study of the corrosion current and potential as a function of the thickness of the electrolyte layer is discussed. Precipitation and passivity, though not the main object of study in this work, are briefly discussed.     

Stress Effects on Stabilizing Antiferroelectric Phase in Multilayer Ceramics

Controllable phase transformation between antiferroelectric (AFE) and ferroelectric (FE) states suggests multifunctional properties valuable for many device applications. Compared to AFE bulk ceramics with large voltage required for driving electric field‐induced phase transition, implementation of structures comprising multiple thin AFE ceramic layers can realize applications by reducing the switching operation voltage in the feasible range. Here, it is found that a compressive residual stress is developed in multilayer (Pb_0.97,La_0.02)(Zr_0.66,Sn_x,Ti_0.34?x)O₃ (PLZST) ceramic co‐fired with multiple Pd/Ag electrode layers, and the compressive residual stress can stabilize AFE phase. AFE phase forms in the PLZST multilayer ceramic with composition corresponding to FE in the bulk materials. Thermodynamic analysis based on free energy of FE and AFE phases well explains the FE to AFE phase transformation observed in the multilayer ceramic under the compressive stress. The findings exhibit a new strategy to tune structure and functional properties of multilayer ceramics through stress engineering for achieving device applications.     

Thermal Oxidation Analysis of Forage Turnip (Raphanus sativus L. var. oleiferus Metzg.) Oil

In this work, the composition of fatty acids and the oxidative stability of the oil from Raphanus sativus L. var. oleiferus Metzg. are presented and analyzed with the Rancimat method, and by absorption and molecular fluorescence spectroscopy. The gas chromatography showed that the content of unsaturated fatty acids was 90.27 ± 6.10 %, with a predominance of oleic (C 18:1), linoleic (C 18:2), erucic (C 22:1), linolenic (C 18:3) and eicosenoic (C 20:1) acids. The induction period determined by the Rancimat method was 48.0 ± 1.0 h. In addition, the thermal degradation of the oil was monitored through its acid value, density, UV–Vis absorption and molecular fluorescence, and here we show the potential applicability of emission spectroscopy for R. sativus oil oxidation studies.     

Synthesis of Boron Carbide by Reactive‐Pulsed Electric Current Sintering in the Presence of Tungsten Boride

The method of pulsed electric current sintering (PECS) has been used to obtain dense boron carbide (B₄C) and B₄C‐based composite materials containing tungsten boride (W₂B₅). To elucidate the role of the sintering additives and the mechanism of reactive densification, three types of materials have been obtained by PECS at 1850°C and 1900°C: “pure” B₄C, B₄C doped with 10 wt% W₂B₅, and B₄C doped with 10 wt% tungsten carbide (WC). X‐ray diffraction and X‐ray photoelectron spectroscopy have been used to determine crystallite size, phase changes, and the peculiarities of the chemical bonds of the densified materials. Structural and mechanical properties of the materials have been investigated using scanning electron microscopy, optical microscopy, ultrasound velocity measurements, and hardness tests. The electrochemical impedance spectra have been used to investigate the electrical properties of the PECS‐ed materials.     

A sex attractant for the scarab beetle Anomala solida Er

(R,Z)-5-(-)-(Oct-1-enyl)oxacyclopentan-2-one (R-buibuilactone) attracted male Anomala solida Er. (Coleoptera: Scarabaeidae, Rutelinae), a vineyard and orchard pest in Southeastern Europe. The presence of the corresponding (S) enantiomer or of 2-(E)-nonen-1-ol (a frequently found pheromone component in other Anomala spp.) in the bait did not influence catches. Traps baited with (R,Z)-5-(-)-(oct-1-enyl)oxacyclopentan-2-one were successfully used for monitoring the flight of A. solida, and may have practical applications for detection, monitoring, and mass trapping of the pest.     

Solvothermal synthesis of a novel mixed valence Cu(I)/Cu(II) complex containing sulphate, malate and 4,4-bipyridine, [CuCu2(mal)(SO4)(bpy)2 · H2O]n. Unique binding mode of the malate anion

The reaction of CuSO₄ · 5H₂O with 4,4^′-bipyridine and malic acid at 140 °C under solvothermal conditions afforded a mixed valence three-dimensional coordination polymer [Cu^ICu^II₂(mal)(SO₄)(bpy)₂ · H₂O]_n, (1). The building unit consists of a Cu²⁺-dimer in which copper centers are bridged by malate and sulphate anions. SO₄²⁻ anion further connects dimeric unit with the Cu¹⁺ center. Building units are linked by 4,4^′-bipyridine ligands to form double chains, that are interconnected into 3D network through additional sulphate bridge.     

Ultrafast Microwave Hydrothermal Synthesis of BiFeO3 Nanoplates

We report the synthesis of {100}_c facets exposed single‐crystalline BiFeO₃ (BFO) nanoplates, with thickness ranging from 20 to 160 nm and lateral size of submicrometers, via a simple and very rapid (1–2 min) microwave‐assisted hydrothermal approach. We show that the microwave treatment gives comparable improvement in crystallinity of BFO nanocrystals with respect to traditional hydrothermal processes while requiring significantly less time and energy. In addition, we show that microwave radiation power, reaction time, and alkali concentration play important roles in the crystallinity and morphology of the products. We discuss a possible formation mechanism of the nanoplates based on our experimental results. Additionally, the BFO nanoplates exhibit weak ferromagnetic properties at room temperature, which we attribute to the size‐confinement effect on magnetic ordering. The present microwave hydrothermal method has great potential in large‐scale fabrication of BFO nanomaterials as well as other composite functional materials due to significantly reduced time and energy.