The Variation Effect of Mg-doped NPs Prepared by Sol-Gel Method on its Structural Properties and Biological Activities

In this paper, we reported the synthesis of NiO NPs and Mg doped-NiO NPs using the facile sol-gel method. Besides, the influence of the variation of Mg dopant on the structural, morphological and optical properties of the prepared Mg-NiO NPs was studied. The synthesized Mg-NiO NPs nanoparticles were characterized by X-Ray Diffraction Analysis (XRD), Energy Dispersive X-ray Spectroscopy (EDS), Fourier-Transform Infrared Spectroscopy (FTIR), Field-Emission Scanning Electron Microscopy (FE-SEM), and UV-Vis spectrophotometer. The X-ray diffraction confirmed the formation of the cubic structure of Mg doped-NiO NPs after doping with the magnesium. The increase in the crystal size was observed with the increase in the concentration of the Mg dopant element. The FESEM images reveal the formation of nickel oxide through the appearance of spherical clusters, while the hybrids appear as wrinkled surface covered with spherical particles of magnesium. The UV-Vis spectrum showed a shift towards shorter wavelengths with an increase in the concentration of the Mg dopant element due to the quantum confinement effect. The hemolysis activity study showed that NiO NPs had a low hemolysis percentage of 1.47% and increased with increasing concentration. While, increasing of the RBC hemolysis (5.9%) after NiO doped with Mg. The antibacterial activity was studied against S. aureus and P. aeruginosa bacteria, and indicated the highest growth inhibition zones of Mg-doped NiO NPs as compared with NiO NPs against of Staphylococcus aureus and Pseudomonas aeruginosa, respectively.

Production and Characterization of RE3+:Yb2O3 Nanoparticles

In this study, doped ytterbium oxide (Yb2O3) nanoparticles (NPs) with different dopant type (Eu and / or Tb) and undoped were synthesized by wet chemical method using nitrate salt as a starting source. Afterwards, they were calcined at 900 °C for 4 h. The crystal structure phase, size, and morphology of undoped and doped Yb2O3 nanoparticles (NPs) were characterized by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Undoped and doped NPs were exhibited cubic bixbyite-type crystal structure (Ia-3 space group). Lattice parameter changes caused by dopant element in NPs were examined using X-ray peak profile analysis. In order to investigate the occuring changes in the crystal structure, average crystallite size (CS) and lattice parameter (LP) values were computed with Williamson–Hall (W–H) and Cohen-Wagner (C–W) methods, respectively. It was observed that the crystal structure of the doped NPs expanded compared to the undoped Yb2O3 NPs, which explains the increase in the LP and CS values. The LP values of all the NPs were ranged from 10.444 Å (R2 = 94.9) to 10.453 Å (R2 = 81.8) while the CS of them were between 19 nm (R2 = 95.9) and 24 nm (R2 = 88.8). All the NPs exhibited nearly spherical and agglomerate structure and there were also few pores between the agglomerate particles in the structure. Besides, continuous agglomerate morphology formation was observed in particles containing Tb. The average nanoparticle size values were varied between 46 and 115 nm depending on the dopant element.

Improvement of Quality of Thick 4H-SiC Epilayers

The epitaxial growth of ~250 μm thick 4H-SiC epilayers has been demanded for ultra-high-voltage power devices. We have attempted to improve the quality of thick epilayers. At the edge of wafer, stacking faults, epi-crown and interfacial dislocations could be well suppressed by controlling the distribution of growth rate. Investigation of carrier concentration depth profile revealed that increasing surface roughness increased the carrier concentration during thick epitaxial growth. Under N2-doped growth condition, memory effect by accumulation of by-products containing dopant element is also one of the reasons of the carrier concentration increasing during the growth.

Permittivity-Frequency Dependencies Study of Neutron-Irradiated Nanocrystalline Silicon Carbide (3C-SiC)

Nanocrystalline 3C-SiC was irradiated by neutron flux ([Formula: see text] n[Formula: see text][Formula: see text][Formula: see text]cm[Formula: see text]s[Formula: see text] up to 20[Formula: see text]h in the TRIGA Mark II type research reactor. The experiments have been conducted in the 0.1[Formula: see text]Hz–2.5[Formula: see text]MHz frequency and 100–400[Formula: see text]K temperature ranges. The frequency dependencies of real and imaginary parts of the permittivity of nanomaterial were analyzed comparatively before and after neutron irradiation. After neutron irradiation, there was increase in dopant element concentration in the nanocrystalline 3C-SiC particles. Concentration of new dopant elements in the 3C-SiC nanomaterial directly affects dielectric polarization and leads to increased permittivity. Simultaneously, after neutron irradiation, agglomeration and amorphous transformation influence on the polarization of nanocrystalline 3C-SiC. Moreover, 3C-SiC nanoparticle interface polarization gives rise to dispersion. It was found that ionic polarization was dominant in the nanocrystalline 3C-SiC particles.

Synthesis of Aluminum-Doped TiO2 Nanotubes by Anodization Method

We report the synthesis of Al-doped TiO2 nanotubes (Al-TNT) by DC anodization method at 50 volts. The method is simple, cost effective, environmentally safe and the samples produced are of good quality. The electrolytesolution was composed of ethylene glycol (EG), ammonium fluoride (0.3% wt NH4F), deionized water (2% vol H2O) and varying molar masses of aluminum nitrate - Al (NO3)3. The samples were analyzed XRD before and after annealing at 450 °C for 2 hours. The surface morphology and the elemental analysis of the annealed samples were characterized by SEM and ED-XRF respectively. The results show that phase transformation only occur after annealing. And that the surface organization, uniformity and structure are influenced by the concentration of the dopant element.

Characterization of Second-Phase Inclusion in Silicon Carbide Powders

A specific transition metal is used as a dopant element in silicon carbide powders to create the compensation effect. According to ab-initio simulation, vanadium, chromium, and manganese-induced compensation decrease the lifetime of the acceptor carrier and cause higher resistance when boron is the main impurity. Since the silicon carbide lattice has low solubility, excess metal precipitates on the surface of powders, particularly on the grain boundaries. The compositions of matrix and precipitation in the powders reveal obvious differences between the two areas. The X-ray diffraction (XRD) pattern shows the structure of VSi2, which indicates the existence of a second phase. Dual-beam focused ion beam (DBFIB) is used to further analyze the geography inside the powders. A cross-section view by DBFIB shows a second phase in the grains with a composition similar to that in the grain boundary. Metal-doped silicon carbide powders are used as starting materials to conduct crystal growth with better dopant element distribution.

Effect of Dopant Element on the Strength and Reliability of Ni-Base Superalloy at High Temperatures

In order to assure the reliability of advanced gas turbine systems, it is very important to evaluate the damage of high temperature materials such as Ni-base superalloys under creep and fatigue conditions quantitatively. The mechanism of the directional coarsening (rafting) of the γ′ phase (Ni3Al) of Ni-base superalloys under uni-axial strain at high temperatures was analyzed by molecular dynamics (MD) analysis. The strain-induced anisotropic diffusion of Al atoms perpendicular to the interface between the γ′ phase and the γ phase (Ni-matrix) was observed clearly at a Ni(001)/Ni3Al(001) interface. The strain-induced anisotropic diffusion was validated by the experiment using the stacked thin film structures with the (001) face-centered cubic (FCC) interface. The reduction of the diffusion of Al atoms perpendicular to the interface is thus, effective for improving the creep and fatigue resistance of the alloy. It was found by MD analysis that palladium was one of the most effective elements that restrain Al atoms from moving around the interface under the applied stress. The presence of the interaction between the different dopant elements was also clarified.

Correlations Between the Thermoelectric Power and Hall Effect of SN- or GE-Doped IN2O3Polycrystalline Ceramics

The thermoelectric power and Hall effect of Sn-or Ge-doped In2O3ceramics are investigated based on a comparative study. The metal-type conductivity in both the samples occurs when the carrier concentration exceeds ~1019cm-3. The carrier mobility is found to be higher for Ge-doped samples. The relation between the <<Lewis acid strength>> of the dopant element and its scattering cross section is also presented.