eV For Samples Research Articles

Chicken Eggshell Powder as Antibacterial Against Staphylococcus aureus and Escherichia coli Through In Vitro Studies

Identifying the most effective material with antibacterial properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) is a challenging task considering the rising concerns about drug resistance. Various experiments through in vitro and in vivo studies to obtain antibacterial agents using abundant and easily available raw material sources have been conducted. Therefore, this study aimed to acquire semiconducting nanoparticle material derived from purebred chicken eggshell waste that could effectively function as an antibacterial agent. The waste treatment was carried out using a top-down method applying the thermal decomposition method with calcination temperatures of 700 and 800 ºC for 30 hours. XRD analysis results showed CaO as a major phase and this was further supported by Rietveld calculation. The size of the crystalline phases obtained ranged from 10–45 nm, while FTIR analysis showed the appearance of CaO bond at a wave number of 715.65 cm-1. Furthermore, SEM analysis showed a rough folded particle surface with a pore percentage of 48.20%. Based on the UV-Vis DRS analysis results, chicken eggshell powder had band gap energy characteristics of 2.07, 2.74, 3.71, and 5.96 eV for sample B, as well as 4.60 and 5.82 eV for sample C. Activation of purebred chicken eggshell powder as antibacterial was performed both qualitatively and quantitatively using photocatalytic and non-photocatalytic methods. Qualitatively, both samples showed antibacterial activity, with a minimal inhibitory concentration (MIC) of 1,000 µg/mL.

Tuning structural, electrical, dielectric and magnetic properties of Mg–Cu–Co ferrites via dysprosium (Dy3+) doping

In current research work, Dy3+ substituted Mg0.5Cu0.25Co0.25Fe2‒xDyxO4 (0.0 ≤ x ≤ 0.04 with the step interval of 0.01) soft ferrites were synthesized by the sol–gel auto combustion method. The prepared samples were characterized by the techniques using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, current–voltage (I–V) measurement, LCR meter, vibrating sample magnetometer (VSM) and Raman. XRD data reveal that the average crystallite size is 49.71 nm and the lattice constant is 0.83703 nm for sample x = 0.03. The non-uniform grain growth was demonstrated by micrographs and impurity-free elemental composition was observed from EDX analysis. The DC resistivity has an increasing and decreasing trend in ferromagnetic and paramagnetic regions with an increase in temperature. Moreover, the high resistivity is observed with the order of 1010 Ω·cm, and the activation energy is 0.944 eV for samples x = 0.03. The dielectric parameters including dielectric constant, dielectric losses, and impedance gradually decrease with the increase in frequency from 8 Hz to 8 MHz. The minimum dielectric loss at high frequency is found for sample x = 0.03. The coercivity (Hc) and saturation magnetization (Ms) are found in the ranges of 520.82–544.02 Oe and 20.5841–21.1473 emu/g, respectively. These observations confirm that dysprosium (x = 0.03) doped MCC-soft ferrites may be applicable in transformer cores, microwave absorbance, and telecommunication devices.

Nano-SnO2/polyaniline composite films for surface plasmon resonance

Synthesized nanocomposites of protonated polyaniline with camphor sulfonic acid (PANI-CSA) doped with tin oxide nanoparticles (SnO2 NPs) were coated as films on fused silica substrates using the dip-coating technique. The optical, electrical, chemical and thermal properties of the produced (PANI-CSA)/SnO2 were investigated. The refractive index for (PANI-CSA)/SnO2 nanocomposite films increases with increasing SnO2 NPs mole fraction. The optical bandgap energy of undoped PANI-CSA thin films is 4.34 eV, being this value decreased in a monoexponentially decay to 4.08 eV for samples up to a 0.11-mol fraction of SnO2 NPs in PANI-CSA. For a 0.20-mol fraction the bandgap has a substantial decrease (3.93 eV) due to SnO2 NPs percolations. Upon inceasing SnO2 MPs content the electrical conductivity of the (PANI-CSA)/SnO2 nanocomposite films reaches a threshold of 2.25 [S.cm−1]. A surface plasmon resonance (SPR) theoretical model consisting in a prism with Au/(PANI-CSA)/SnO2 layers shows that the SPR sensitivity for particle detection increases with increasing SnO2 NPs concentration.

The Effect of pH and Monomer Concentration on Polyaniline Thin Films Grown Using Electrodeposition

Polyaniline (PANI) thin films were successfully prepared from an aqueous electrolyte bath containing aniline and sulphuric acid (H2SO4) using electrodeposition method. The present study demonstrates that the properties of PANI thin film depends on the variation of pH and aniline concentration in prepared precursor. The optical and structural of PANI thin films were characterized using UV-Visible spectrometer (UV-Vis), X-ray diffraction spectrometer (XRD), Fourier Transform Infra-Red spectrometer (FTIR) and Raman spectrometer. PANI layer grown at pH 2.00 displayed green colour layer which denoted as emeraldine base (half oxidized state of PANI) while at pH 3.80 the colour of PANI layer was yellow representing the leucoemeraldine base (fully reduced state of PANI). Result obtained from FTIR confirmed the footprint of PANI and Raman spectrometer confirmed the half oxidized emeraldine base of PANI. Optical analysis using UV-Vis demonstrated the smallest energy band gap, Eg of PANI is 3.54 eV for sample with 0.50 M aniline concentration and pH 2.00. The trend shows that the bandgap of PANI is increased as the pH increased from 2.00 to 3.80. XRD result showed that all the deposited PANI layers were amorphous. Full characterization of this material is providing some information on PANI behavior due to pH and concentration in the prepared precursor.

Effects of helium implantation fluence on the crystal-ion-slicing fabrication of Y-cut lithium niobate film

In the present work, the contribution of Helium implantation fluence on the Crystal-Ion-Slicing fabrication (CIS) of Y-cut LiNbO3 film were systematically investigated. Y-cut Lithium niobate (LN) thin films with a submicron thickness on the Y-cut LN substrates were successfully fabricated by CIS technique by employing He implantation. By varying the implantation fluence, the structure evolution of the LN exfoliation layer was systematically investigated by Rutherford backscattering/channeling (RBS/C), X-ray Diffraction (XRD), Raman spectroscopy, as well as Atomic Force Microscopy (AFM). Upon gradually increasing the implantation fluence from 1.0 x 1016 to 4.0 x 1016 cm-2, the lattice damage together with the tensile strain in the as-implanted LN becomes intensive according to the Raman spectroscopy investigations. In addition to the crystalline quality, the root mean square roughness becomes 1.4 nm upon increasing fluence till 4.0 x 1016 cm-2. The blistering threshold fluence for Y-cut LN is found to be between 1.0 x 1016 and 2.0 x 1016 cm-2, and the Arrhenius plot of the blistering time as a function of reciprocal temperature shows that the activation of blistering is 2.14 eV, 1.77 eV and 1.44 eV for samples under fluence of 2.0 x 1016, 3.0x 1016 and 4.0 x 1016 cm-2, respectively. Our experimental results unambiguously contribute to exploring the avenue of achieving high-quality layer, particularly highly anisotropic ones, by CIS techniques.

FTIR Spectral Characterization, Mechanical and Electrical Properties of P2O5-Li2O-CuO Glass-Ceramics

In the present investigation, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were employed to study the crystallization of (50 P2O5–50 Li2O with different CuO concentrations) glasses. Both mechanical and electrical properties were studied. The results clarified the formation of LiPO3 phase along with Li2CuP2O7 one which became more pronounced with successive increase in CuO contents having in mind that these phases caused measurable increase in density values. Additionally, the fracture toughness, compressive strength and elastic modulus were positively affected by the increasing of CuO contents. Moreover, DC conductivity and activation energy were also dependent on CuO contents where the latter recorded 0.56 eV for sample contained the highest CuO content. On the other hand, AC conductivity was nearly the same at low frequencies for samples had the lowest and highest CuO contents. However, in high frequencies, it showed a noticeable enhancement.

Effect of heat treatment on the structure and photocatalytic properties of BiYO3 and BiY0.995Ni0.005O3 ceramic powders

BiYO3 powders were synthesized by the Pechini method under low-temperature conditions. When the heat treatment was performed at T < 600 °C, a mixture of tetragonal and cubic phases was obtained, while for T ≥ 600 °C, only the fluorite-like cubic phase was observed. Based on the Rietveld refinement, approximately 2% and 1% of the tetragonal phase remained in samples calcined at 400 °C and 500 °C for 1 h, respectively. The crystal size calculated for these samples was 4.4–48.1 nm, depending on the calcination temperature. The specific surface area of the samples diminished with heat treatment and reached a minimum at 800 °C. The band gap of samples with mixed phases was close to 2.16 eV and was ~2 eV for samples with a cubic phase. Photocatalytic tests demonstrate that BiY0.995Ni0.005O3 calcined at 800 °C had the best performance: it degraded more than 80% of the antibiotic oxytetracycline when irradiated with visible light. The Ni-doped BiYO3 material could degrade the antibiotic in tap water at an environmentally relevant concentration (μg L−1 levels) and showed steady activity throughout four reaction cycles.

Observation of a 1.979-eV spectral line of a germanium-related color center in microdiamonds and nanodiamonds

Color centers in diamond are considered as a platform for quantum computing and communications, biomedical markers, and nanosensors. Negatively charged split-vacancy centers have outstanding properties due to bright and almost monochromatic luminescence, but they have poor spin coherence and relaxation times. This drawback is believed to be absent in the neutral charge state of the defects. So far only the neutral silicon-vacancy center has been observed in luminescence and absorption spectra. Here we report the observation of its germanium-based analog in luminescence spectra with the zero-phonon line (ZPL) at 1.979 eV in samples containing negatively charged ${\mathrm{GeV}}^{\ensuremath{-}}$ centers. The relationship between the center and Ge dopant is unambiguously confirmed by studies of $^{12}\mathrm{C}$ diamonds containing $^{70}\mathrm{Ge}$, $^{73}\mathrm{Ge}$, or $^{76}\mathrm{Ge}$ isotopes. The intensity ratio of the ZPL of these centers varies with the crystal size, and the intensity of the ${\mathrm{GeV}}^{0}$ centers reaches its maximum in samples 150 nm in size. In the vibronic sideband of this center the local vibrational mode with an energy of 23 meV was identified. The density functional theory calculations yield a ZPL energy value of the ${\mathrm{GeV}}^{0}$ center which is 150 meV higher than the experimentally observed one and matches the values of its relaxational energy as well as the local phonon mode frequency.

Structural, optical, magnetic and photoelectrochemical properties of (BiFeO3)1−x(Fe3O4)x nanocomposites

(BiFeO3)1−x(Fe3O4)x nanocomposites were prepared by dispersion of Fe3O4 nanoparticles (NP) into sol–gel synthesised BiFeO3 (BFO) matrix followed by calcination at 500 °C. Samples with x = 0.0, 0.2, 0.33 and 0.5 were investigated using X-ray diffractions (XRD), UV–vis spectroscopy, photoluminescence spectroscopy (PL), transmissions electron microscopes (TEM), electron spin resonance (ESR), vibrating sample magnetometer (VSM) and photoelectrochemical (PEC) measurements. Formation of nanocomposites was confirmed by XRD and TEM. The XRD patterns showed presence of both BFO and Fe3O4 phases without any secondary phases. The crystallite size of BFO (39.1–51.1 nm) is much bigger than that of Fe3O4 (10.1–12 nm). Microstrain of BFO decreased for sample x = 0.2 and 0.33 and then increased for x = 0.5. Optical band gap of samples decreased from 2.5 eV for x = 0.0–1.96 eV for sample x = 0.5. The PL emission which centred at 428.1 eV for x = 0.0 increased gradually for samples x = 0.2 and 0.33 and then decreased for x = 0.5. Exchange bias (HEB) was observed for hysteresis loops of all samples, and the highest value of HEB was 38.4 Oe for x = 0.5. The g-values of the nanocomposites, ranged between 2.23 and 2.20, were higher than that of the BFO and Fe3O4 components. The PEC measurement showed the photocurrent density increased with x. Finally, modulations of the physical properties of BFO/Fe3O4 system were analysed and discussed in detail.

Structural and electrical characterizations of hydrothermally grown hydroxyapatite polycrystals: A morphological hierarchy

Pure hydroxyapatite (HAp) semiconducting microrods with very low dielectric loss have been synthesized in aqueous media of pH values 6, 8, and 10 by the hydrothermal method. Samples are characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectra analyses. The optical bandgap energies of these samples are found to be within the semiconducting range (∼3–4 eV). FESEM and TEM image analyses reveal the formation of microrods and reduction of the average length of the rods with increasing pH values. A core-shell-like microrod structure has been observed in the sample with pH value 6. The charge carrier follows an adiabatic small polaron hopping mechanism. The dielectric loss values are very small compared to that of other ceramic oxides which is very advantageous for electronic applications. Correlated barrier hopping model is the dominant charge transport mechanism within the samples with maximum barrier heights of 0.25 eV, 0.26 eV, and 0.27 eV for samples with pH values 6, 8, and 10, respectively. Nonideal Debye type relaxation appears within the material when the AC field is applied for temperatures above 100 °C.

Synthesis, optical and magnetic behavior of (BiFeO3)1−x(α-Fe2O3)x nanocomposites

(BiFeO3)1−x(α-Fe2O3)x nanocomposites were synthesized from dried gels of BiFeO3 and α-Fe2O3. Samples with x = (0.00 (BiFeO3), 0.25, 0.50 and 1.00 (α-Fe2O3)) were studied using X-rays diffractions (XRD), UV–vis spectroscopy, photoluminescence spectroscopy (PL), electron spin resonance (ESR) and vibrating sample magnetometer (VSM). Amounts of α-Fe2O3 phase were 23 and 35% for samples x = 0.25 and 0.50, respectively. Microstrain of BiFeO3 phase tended to decrease with increasing α-Fe2O3. Optical band gap reduced from 2.42 eV for BiFeO3 to 2.35 eV for sample x = 0.25 and then increased to 2.56 eV for sample x = 0.50. From PL, intensity of near band emission peak of BiFeO3 increased with increasing α-Fe2O3 content. From ESR and VSM, the g-value and magnetization saturation were enhanced with embedding of α-Fe2O3 into BiFeO3.

Characterization of sodium lead silicate glasses containing low and high levels of Fe2O3 and effect of its replacement for Na2O

Glass of the composition (mol%) (25-x) Na2O−xFe2O3−25PbO−50SiO2,x = 0, 0.25, 0.5, 1, 3, 5, 7, 10, 15, 16 and 20 (mol%) were prepared by the melt quenching method. The effect of replacing Fe2O3 for Na2O on the optical, structural, electrical and dielectric properties was studied. Experimental and theoretical density and XRD of the samples were also reported. Pb2+, Fe2+ and Fe3+ ions contributed to the UV-cut off and the developed bands in the visible and near IR regions. FTIR revealed the decrease of the SiO4 and increase of FeO4 units. XRD indicated change in the glass structure above 15 mol% Fe2O3. The electrical conduction seems to occur by ionic and electronic controlled electron hopping between Fe2+ and Fe3+ sites. The activation energy of ionic conduction decreased from 1.74 eV for un-replaced Na2O sample to 0.16 eV for sample with 16 mol% Fe2O3 at 1 MHz. Samples with 16 and 20 (mol% Fe2O3) showed e′ values in the range from 115 to 186 and from 34 to 66, respectively. These results present promising candidates for the studied glasses to be used as energy storage materials in electronic devices.

Zirconium dioxide nanopowders with incorporated Si4+ ions as efficient photocatalyst for degradation of trichlorophenol using simulated solar light

We present a hydrothermal method for synthesis of zirconia nanopowders: pure and with incorporated Si4+ ions. Zirconyl chloride and tetraethyl orthosilicate were used as precursors. As prepared powders were annealed at 600°C and characterized using structural (XRD), morphological (SEM and TEM) and optical techniques (UV/vis DR, FTIR and photoluminescence spectroscopy). Their textural properties (BET method) and photocatalytic activity toward degradation of model compounds (tricholophenol and Rhodamine B) using simmulated solar light were obtained. We showed that by using hydrothermal synthesis method pure monoclinic ZrO2 highly crystalline powder can be obtained. Incorporation of Si4+ ions induced stabilization of tetragonal crystalline phase at room temperature and decreasing of particle sizes. Incorporation of Si4+ ions in zirconia matrix also resulted in increase of specific area of nanopowders. FTIR measurements were used as proof for existence of ZrOSi bond. Effective band gap of zirconia powders was reduced from 5 (pure ZrO2) to 3.8eV for samples with Si4+ ions. All zirconia powders showed significant photocatalytic activity regarding degradation of triclorophenol and no activity regarding RB (Rhodamine B dye). Photocatalytic activity of zirconia was increased by incorporation of Si ions in the host matrix. The source of this observation is discussed correlating all obtained properties of pure and Si-incorporated nanopowders. Optimization of synthesis parameters and composition of zirconia samples obviously can lead to their photocatalytic activity comparable to Degussa TiO2 powder, famous and commercial photocatalyst.

Influence of Argon Ion Bombardment on Improvement of Surface Properties of Low Density Polyethylene (LDPE)

In this paper, low-density polyethylene (LDPE) was irradiated by argon ion with different fluences up to 1015 ions/cm2. The optical, chemical and mechanical properties have been investigated using UV-Vis spectroscopy, FTIR and Micro-indentation tester, respectively. The results showed the ion beam bombardment induced decreases in the transmittance of the irradiated polymer samples. This change in transmittance can be attributed to formation of conjugated bonds i.e. possible formation of defects and/or carbon clusters. The indirect optical band gap decreased from 3.0 eV for pristine sample to 2.3 eV for that sample irradiated with the highest fluence of Ar ion beam. Furthermore, the number of carbon atoms and clusters increased with increasing the Ar ion fluences. FTIR spectra showed changes in the chemical properties of the bombarded polymer samples. Argon ion beam inducing increasing in the Vicker's micro-indentation, which may be attributed to the increase in the carbon concentration on the irradiated surface samples and cross-linking effects in the irradiated polyethylene chains.

Growth and characterization of highly mismatched GaN1−xSbx alloys

A systematic investigation on the effects of growth temperature, Ga flux, and Sb flux on the incorporation of Sb, film structure, and optical properties of the GaN1−xSbx highly mismatched alloys (HMAs) was carried out. We found that the direct bandgap ranging from 3.4 eV to below 1.0 eV for the alloys grown at low temperature. At the growth temperature of 80 °C, GaN1−xSbx with x &amp;gt; 6% losses crystallinity and becomes primarily amorphous with small crystallites of 2–5 nm. Despite the range of microstructures found for GaN1−xSbx alloys with different composition, a well-developed absorption edge shifts from 3.4 eV (GaN) to close to 2 eV for samples with a small amount, less than 10% of Sb. Luminescence from dilute GaN1−xSbx alloys grown at high temperature and the bandgap energy for alloys with higher Sb content are consistent with a localized substitutional Sb level ESb at ∼1.1 eV above the valence band of GaN. The decrease in the bandgap of GaN1−xSbx HMAs is consistent with the formation of a Sb-derived band due to the anticrossing interaction of the Sb states with the valence band of GaN.

Synthesis of Microstructured ZnO in Hydrazine Hydrate Using a Hydrothermal Method and its Optical Properties

Microstructured ZnO have been synthesized by a simple hydrothermal approach, using ZnCl2as the zinc source and N2H4·H2O as the amine precursor in water-ethylene glycol solution at 120 °C for 8 h. The X-ray diffractrometer pattern indicates the pure phase formation of ZnO. Scanning electron microscope images show that the aspect ratio of the ZnO microrod increases by the amount of N2H4·H2O ranging from 0.5 to 1mL, but continuing to 3ml, the aspect ratio of the ZnO microrods decreases. Moreover, the optical band gaps calculated through UV spectroscopy are found to increase from 2.94 (±0.02) to 3.0 (±0.02) eV for samples synthesized at different amounts of hydrazine hydrate ranging from 0.5 to 1mL, respectively.

Correlation between Si doping and stacking fault related luminescence in homoepitaxial m-plane GaN

Si-doped GaN layers grown by metal organic vapor phase epitaxy on m-plane GaN substrates were investigated by low-temperature cathodoluminescence (CL). We have observed stacking fault (SF) related emission in the range of 3.29–3.42 eV for samples with moderate doping, while for the layers with high concentration of dopants, no CL lines related to SFs have been noted. Perturbation of the SF potential profile by neighboring impurity atoms can explain localization of excitons at SFs, while this effect would vanish at high doping levels due to screening.

Synthesis, structural and optical characterizations of cadmium oxide (CdO) thin films by chemical bath deposition (CBD) technique

Thin films of cadmium oxide (CdO) were synthesized and characterized using chemical bath deposition (CBD) technique. The XRD studies revealed amorphous CdO thin films which upon annealing at 623K transformed to polycrystalline structure. The optical studies showed that the CdO films have high average transmittance over 60% in the visible region and direct optical bandgaps of 2.02 ± 0.05 eV, 2.03 ± 0.05eV and 2.05 ± 0.05eV for samples X, Y, Z respectively. These characteristics make them good candidates for applications in photodiodes, phototransistors, photovoltaics, transparent electrodes, liquid crystal displays, IR detectors and anti-reflection coatings. Key words: Thin films, chemical bath method, cadmium oxide, characterizations, bandgap.

Highly mismatched N-rich GaN1−xSbx films grown by low temperature molecular beam epitaxy

We have grown N-rich, dilute Sb GaN1−xSbx alloys by low temperature molecular beam epitaxy. At low growth temperature of &amp;lt;100 °C the material loses crystallinity and becomes primarily amorphous with small crystallites of 2–5 nm at a Sb composition of &amp;gt;4 at. %. Despite the different microstructures found for GaN1−xSbx alloys with different composition, the absorption edge shifts continuously from 3.4 eV (GaN) to close to 1 eV for samples with Sb content &amp;gt;30 at. %. GaN1−xSbx alloys with less than 5 at. % Sb show sufficient bandgap reduction (∼2 eV), making them suitable for photoelectrochemical applications.

Effects of Post-Deposition Annealing Temperature on Band Alignment and Electrical Characteristics of Lanthanum Cerium Oxide on 4H-SiC

ABSTRACTInvestigation of lanthanum cerium oxide as a gate oxide on 4H-SiC was performed by varying post-deposition annealing temperature from 400 to 1000°C. Energy band alignment and band gap of bulk oxide and interfacial layer (IL) with respect to SiC were extracted using X-ray photoelectron microscopy. Two band alignment structures were proposed and the change of band alignment was affected by the changes in chemical composition in bulk oxide and in IL that may induce lattice strains and dipoles. A conduction band offset of IL/SiC was 0.97 eV for sample annealed at 1000°C, which was comparable to the value extracted from Fowler-Nordheim model. The acquisition of sufficient conduction band offset, coupled with the lowest slow trap density, effective oxide charges, interface trap density, as well as total interface trap density, yielded the lowest leakage current density for this sample.