Structure and Dielectric Behavior of Yb2O3-MgO Co-Doped 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3 Ferroelectric Relaxor

Dielectric properties and structure of 0.015Yb2O3-xMgO doped 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3 ceramics with x = 0.0–0.025 have been investigated. As Yb2O3-MgO was added into the BT-NBT, the phase changes from tetragonal to pseudo-cubic, with the tetragonality c/a decreases from 1.011 to 1.008 and XRD peaks broadened. The combined study of XRD and TEM image revealed a formation of core–shell structure in grains with core of 400–600 nm and the shell of a thickness 60–200 nm. There is a slowly phase transition against temperature from the variable temperature Raman analysis. The ferroelectric relaxor peak of BT-NBT decreases from ~4000 to ~2000 and a new broad dielectric peak with an equivalent maximum (εr′~2300) appears in the temperature dependent dielectric constant curve (εr′-T), which produces a flat εr′-T curve. Sample 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3-0.015Yb2O3-0.005 MgO and 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3-0.015Yb2O3-0.01MgO give a εr′ variation within ±14% and ±10% in 20–165 °C. The core–shell microstructure should take account for the flattened εr′–T behavior of these samples.

Synthesis and blue emission properties of Co-doped CdS semiconductor nanoparticles

Background: Cadmium sulfide (CdS) based semiconductors are of great interest for different high-end applications because it poses direct bandgap (2.42 eV). CdS are the primary constituent material in many applications, namely solar cells, electroluminescent, and quantum dot light-emitting diodes. Transition metal-doped CdS revealed considerable influence in the bandgap, photoluminescence properties, and peak energy upon increasing the metal content. Objective: In this work, we study the single-phase cubic structure of CdS. Photoluminescence spectra revealed a strong blue emission peak located at about 445 nm. Methods: We investigate the Co-doping CdS semiconductor nanoparticles prepared via the chemical co-precipitation method using thiophenol as a template, 300 °C/2h in vacuum optimum temperature, and annealing period to yield nanosized particles. Morphology and structural studies of the particles were using XRD and TEM, respectively. Results: XRD and TEM studies for the calcined samples revealed a cubic structure. The crystalline size was in the range of 10-17 nm. Thermo gravimetric analysis (TGA) was employed to stabilize the temperature of annealing for the samples. Photoluminescence spectra revealed a strong blue emission peak around 445 nm, indicating surface states within the band gap region, a characteristic feature of nanoparticles. The blue shift in the spectra and the band gap value of Co-doped CdS nanoparticles was estimated using UV-vis absorption spectra. Conclusion: XRD analysis indicated zinc blende structure, and the intensity decreased with increasing Co content. TEM images show that the particles are spherical with average sizes around 13 nm. Luminescence of the synthesized nanoparticles exhibited blue emission between 400 – 500 nm, with the peak located at about 445 nm. The emission intensity increased with the increase in Co concentration.

Photocatalytic Activity of Heavy Metal Doped CdS Nanoparticles Synthesized by Using Ocimum sanctum Leaf Extract

Green chemical approaches for the production of nanomaterials are currently attracted to research and industry development to minimize the use of hazardous chemicals and reduce industrial pollution. A green reagent Ocimum sanctum leaf extract was used to synthesize doped and undoped CdS nanoparticles in this work. The as-synthesized nanoparticles were characterized by using different characterization techniques such as UV-Vis spectroscopy, XRD, and TEM. The effect of doping on physicochemical properties was analyzed. Photocatalytic properties of these nanoparticles were investigated by sunlight-based photodegradation studies of methylene blue dye. The doping of these green synthesized CdS nanoparticles with heavy metals has improved photocatalytic efficiency over a given time.

Electron Momentum Density of Nanoparticles ZrO2: A Compton Profile Study

This work investigates the electronic momentum density (EMD) distribution in nanosize zirconia (ZrO2) using the technique of Compton scattering. The ZrO2 nanoparticles (11.2[Formula: see text]nm) are synthesized of mechanical milling and characterized by SEM, XRD and TEM probes. The Compton profile [Formula: see text] of nanoZrO2 is measured by Compton spectrometer 59.54[Formula: see text]KeV Gamma rays (Americium-241) source. The study finds out that EMD in nanoZrO2 is narrower comparing in case bulk ZrO2. This study adopts the ionic-model-based free atom [Formula: see text] calculation for many configurations (Zr)[Formula: see text](O[Formula: see text])2 ([Formula: see text]) to measure the charge transfer (CT) on the compound formation. According to this study’s findings, CT values in these materials are ranged from 1.5 to 1.0 electrons from Zr to O atom.

Preparation and Characterization of Composite from Poly(vinyl chloride) Hydrochar and Hydrolyzate of Keratin from Chicken Feather by Hydrothermal Carbonization

Poly(vinyl chloride) and chicken feather wastes considered as the dangerous wastes. This study aimed to characterize the prepared composite from poly(vinyl chloride) hydrochar and keratin hydrolyzate from chicken feather to get possibility the usage of this composite as soil amendment. The poly(vinyl chloride) hydrochar-keratin hydrolyzate composites (HKHC) had been produced with the hydrothermal carbonization process. The composites were made from different composition of poly(vinyl chloride):chicken feather (5:95% (HKHC5), 10:90% (HKHC10) and 15:85% (HKHC15)). The hydrothermal carbonization process would break and fracture the CHCl bond of poly(vinyl chloride). Moreover, this process would also hydrolyze keratin from chicken feather into small protein. The composite structure was formed from aromatic carbon and amino acids aggregate along with other organic substances. The solid composites and liquid residues formed in this process. The composites were characterized by FTIR, XRD and TEM and the composite of char-Fe3O4 was characterized by SEM. Meanwhile, the liquid residues were analyzed for its organochlorine by GC-MS and amino acid contents by HPLC. The results showed that all products have similar properties but the composite with ratio 5:95% (HKHC5) had the highest aromatic structure, paramagnetic (Fe3O4) crystallinity and amino acid contents.

Synthesis, properties, and activity of MoVTeNbO catalysts modified by zirconia-pillared clays in oxidative dehydrogenation of ethane

Composites comprising MoVTeNbO mixed oxide and zirconia-pillared montmorillonite clays (PilCs) were prepared. XRD and TEM with EDX studies confirmed the preservation of M1 MoVTeNbO phase in these composites responsible for high activity and selectivity in ethane oxidative dehydrogenation into ethylene. For composites with PilC content of 10 wt%, the best ethylene yield exceeding that of bulk MoVTeNbO oxide was demonstrated for clays with zirconia pillars doped with Ce and Al possessing the highest specific surface area. This is explained by optimized chemical interaction of these clays with MoVTeNbO mixed oxide improving its bulk oxygen mobility and reactivity by structure disordering while blocking surface sites responsible for combustion due to the stabilization of the reactive terminal oxygen species.

A Study of Low Young’s Modulus Ti–15Ta–15Nb Alloy Using TEM Analysis

The microstructural characteristics and Young’s modulus of the as-cast Ti–15Ta–15Nb alloy are reported in this study. On the basis of the examined XRD and TEM results, the microstructure of the current alloy is essentially a mixture (α + β+ α′ + α″ + ω + H) phase. The new H phase has not previously been identified as a known phase in the Ti–Ta–Nb alloy system. On the basis of examination of the Kikuchi maps, the new H phase belongs to a tetragonal structural class with lattice parameters of a = b = 0.328 nm and c = 0.343 nm, denoting an optimal presentation of the atomic arrangement. The relationships of orientation between these phases would be {0001}α//{110}β//{1¯21¯0}ω//{101¯}H and (011¯0)α//(11¯2)β//(1¯010)ω//(121)H. Moreover, the Young’s modulus of the as-cast Ti–15Ta–15Nb alloy is approximately E = 80.2 ± 10.66 GPa. It is implied that the Young’s modulus can be decreased by the mixing of phases, especially with the presence of the H phase.