Properties and Mechanism of PEALD-In2O3 Thin Films Prepared by Different Precursor Reaction Energy

Indium oxide (In2O3) film has excellent optical and electrical properties, which makes it useful for a multitude of applications. The preparation of In2O3 film via atomic layer deposition (ALD) method remains an issue as most of the available In-precursors are inactive and thermally unstable. In this work, In2O3 film was prepared by ALD using a remote O2 plasma as oxidant, which provides highly reactive oxygen radicals, and hence significantly enhancing the film growth. The substrate temperature that determines the adsorption state on the substrate and reaction energy of the precursor was investigated. At low substrate temperature (100–150 °C), the ratio of chemically adsorbed precursors is low, leading to a low growth rate and amorphous structure of the films. An amorphous-to-crystalline transition was observed at 150–200 °C. An ALD window with self-limiting reaction and a reasonable film growth rate was observed in the intermediate temperature range of 225–275 °C. At high substrate temperature (300–350 °C), the film growth rate further increases due to the decomposition of the precursors. The resulting film exhibits a rough surface which consists of coarse grains and obvious grain boundaries. The growth mode and properties of the In2O3 films prepared by plasma-enhanced ALD can be efficiently tuned by varying the substrate temperature.

Improved NOx Reduction Using C3H8 and H2 with Ag/Al2O3 Catalysts Promoted with Pt and WOx

The addition of Pt (0.1 wt%Pt) to the 2 wt%Ag/Al2O3-WOx catalyst improved the C3H8– Selective Catalytic Reduction (SCR) of NO assisted by H2 and widened the range of the operation window. During H2–C3H8–SCR of NO, the bimetallic Pt–Ag catalyst showed two maxima in conversion: 80% (at 130 °C) and 91% (between 260 and 350 °C). This PtAg bimetallic catalyst showed that it could combine the catalytic properties of Pt at low temperature, with the properties of Ag/Al2O3 at high temperature. These PtAg catalysts were composed of Ag+, Agnδ+ clusters, and PtAg nanoparticles. The catalysts were characterized by Temperature Programmed Reduction (TPR), Ultraviolet Visible Spectroscopy (UV-Vis), Scanning Electron Microscopy (SEM)/ Energy Dispersed X-ray Spectroscopy (EDS), x-ray Diffraction (XRD) and N2 physisorption. The PtAg bimetallic catalysts were able to chemisorb H2. The dispersion of Pt in the bimetallic catalysts was the largest for the catalyst with the lowest Pt/Ag atomic ratio. Through SEM, mainly spherical clusters smaller than 10 nm were observed in the PtAg catalyst. There were about 32% of particles with size equal or below 10 nm. The PtAg bimetallic catalysts produced NO2 in the intermediate temperature range as well as some N2O. The yield to N2O was proportional to the Pt/Ag atomic ratio and reached 8.5% N2O. WOx stabilizes Al2O3 at temperatures ≥650 °C, and also stabilizes Pt when it is reduced in H2 at high temperature (800 °C).

Physicochemical properties, nutritional value, and sensory quality of cassava (Manihot esculenta Crantz) rice-like grains

Cassava is one of the staple food crops grown in tropical and subtropical countries, including the Philippines. It is a cheap source of energy-dense food packed with minerals and vitamins comparable to those of many legumes. The purpose of the study was to investigate the physicochemical, nutritional, and sensory properties of cassava utilized as rice-like grains (RLGs). Four cassava varieties namely Lakan 1, Lakan 2, Rajah 4, and Binulak were utilized in the study. Results revealed that the products fall under the category of hard gel consistency. Lakan 1 had high gelatinization temperature (>74°C) while the other three gelanitized within the intermediate temperature range (70- 74°C). Lakan 1 had the highest moisture content (46.70%), Lakan 2 had the highest fat content (8.95%), whereas varieties with highest carbohydrate content are Rajah 4 (52.09%) and Binulak (52.11%). While all four varieties were similar in terms of other nutritional qualities: protein (1.18-1.32%), ash (0.35-0.81%), fiber (0.99-1.32%), Calcium (27.56- 28.62%), and Zinc (0.23-0.32%). In terms of carbohydrate profile, Lakan 2 had the highest starch content (71.33%), lowest amylose (17.4%), highest amylopectin (53.93%), highest estimated glycemic index (60.49, moderate GI), and lowest total dietary fiber (4.4%). The rice-like grains made from cassava were superior to rice in terms of its higher calcium content (28 mg/100 g), lower glycemic index, greater total dietary fiber (4.4- 5.4%), and longer shelf-life (11 months). Among the varieties, Rajah 4 was found to be exceptional in terms of the properties mentioned and was most liked by panelists

Good stability and high thermoelectric performance of Fe doped Cu1.80S

By doping Fe in Cu1.80S, good stability and a high thermoelectric performance were simultaneously obtained in the intermediate temperature range.

Role of Al and Ti doping in modulating electrical properties of BIVOX system

The doubly-doped bismuth vanadate with Al and Ti having formula unit, Bi2V1−xAlx/2Titx/2O5.5-δ (0.10 ⩽ x ⩽ 0.25) was synthesized. The specimens were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), differential scanning calorimetric (DSC), UV-Vis, and electrochemical impedance spectroscopy (EIS) for their structural, thermal, optical, and electrical studies. Influence of both dopant cations (Al and Ti) was observed in the gradual stabilization of the tetragonal phase of Bi2VO5.5-δ with dopant amount. A non-uniform grain growth phenomenon was observed up to x = 0.175, with dopant addition. UV-Vis study revealed the comparatively higher order of oxide ion vacancies for the composition x = 0.175. Impedance spectroscopy measurements indicate a significant decrease of both the grain (Rg) and grain boundary resistances (Rgb) with the rise in temperature and the overall resistance is found to be dominated by the grain interior contribution. Enhancement of ionic conductivity was found in all the compositions in the intermediate temperature range as compared to the parent compound, and the single Al-doped system and the highest value were obtained for x = 0.175.

Controlled Coprecipitation of Amorphous Cerium-Based Carbonates with Suitable Morphology as Precursors of Ceramic Electrolytes for IT-SOFCs

To be suitable as electrolytes in intermediate temperature solid oxide fuel cell (IT-SOFC), ceramic precursors have to be characterized by high sintering aptitude for producing fully densified products which are needed for this kind of application. Therefore, synthesis processes able to prepare highly reactive powders with low costs are noteworthy to be highlighted. It has been shown that amorphous coprecipitates based on cerium doped (and codoped) hydrated hydroxycarbonates can lead to synthesized ceramics with such desired characteristics. These materials can be prepared by adopting a simple coprecipitation technique using ammonium carbonate as precipitating agent. As a function of both the molar ratio between carbonate anions and total metallic cations, and the adopted mixing speed, the coprecipitate can be either amorphous, owning a very good morphology, or crystalline, owning worse morphology, packing aptitude, and sinterability. The amorphous powders, upon a mild calcination step, gave rise to the formation of stable solid solutions of fluorite-structured ceria maintaining the same morphology of the starting powders. Such calcined powders are excellent precursors for sintering ceramic electrolytes at low temperatures and with very high electrical conductivity in the intermediate temperature range (i.e., 500–700 °C). Therefore, irrespective of the actual composition of ceria-based systems, by providing an accurate control of both chemical conditions and physical parameters, the coprecipitation in the presence of ammonium carbonate can be considered as one of the most promising synthesis route in terms of cost/effectiveness to prepare excellent ceramic precursors for the next generation of IT-SOFC solid electrolytes.

Влияние токового отжига на температурные зависимости магнитоимпеданса в аморфных микропроводах

Miniaturization of material’s size is the key feature in many technological applications, in particular, in sensor systems. To achieve this goal, Taylor-Ulitovski technique was employed to produce microwires with very small (from 0.2 up to 100 µm) diameters. Ferromagnetic amorphous microwires exhibit giant magnetoimpedance effect (GMI) which is useful to develop high performance magnetic sensors. Since the discovery of GMI, a considerable amount of interest was devoted to enhancing sensitivity with respect to various external stimuli (magnetic field, stress, temperature). On the other hand, GMI sensing elements should have high environment stability. In the present work, a comprehensive study of the temperature effects on the magnetoimpedance behavior in amorphous microwires is conducted. The wires under investigations of the composition Co60.51Fe3.99Cr12.13B13.53Si9.84 have a relatively high Curie temperature (>300 ℃) but may demonstrate considerable temperature dependence in the intermediate temperature range (<100 ℃) of dc and ac magnetic properties. We showed that the as-casted wires exhibited a notable change in magnetic anisotropy, from circumferential to an axial anisotropy, owing to the internal stress relaxation. This is accompanied by huge variation in the magnetoimpedance behavior: the impedance vs magnetic- field plots change shape: from two symmetrical peaks to a single central peak. Current annealing (dc current of 25 mA magnitude for 60 min) was proposed to achieve a thermal stabilization of the magnetization processes and magnetoimpedance in glass-coated amorphous wires.