Nanocrystalline Morphology Research Articles

Comparison between the structural characteristics and process activity of bulk and mesoporous Ni-Co-Ce/Al2O3 catalysts in the dry reforming of methane

Dry reforming of methane (DRM) is a potential way to exploit greenhouse gases and generate hydrogen. Catalyst deactivation is the biggest DRM commercialization obstacle. Lately, Ni-Co bimetallic catalysts have demonstrated improved carbon resistance over Ni-based catalysts. The aim of this research is not just to investigate the impact of Ni-Co catalysts on the DRM activity, but also to evaluate the Ni-Co alloy creation effect on the catalyst characteristics and activity. Mesoporous alumina (MA) was used as a catalyst support for Ni-Co particles in this process and its structure and activity were compared to those of bulk alumina (BA) supported catalysts. In addition, cerium was included into all of the catalysts developed as a suitable promoter for reducing the amount of deposited coke. The results obtained from the XRD and nitrogen adsorption/desorption analysis indicated the formation of a mesoporous structure and nanocrystalline morphology in the Ni-Co/MA samples, as compared to the Ni-Co/BA ones. The results showed that the bimetallic 2Ni-1Co-1Ce/MA sample had the best catalytic activity, with a CH4 conversion of 98.30 %, CO2 conversion of 96.35 %, and H2 yield of 96.30 % at 700 °C.

Structural Properties of Cs<sup>1+</sup> Doped H<sub>3</sub>PMo<sub>12</sub>O<sub>40</sub> Nanocrystalline Polyoxometalate Thin Films

The microwave assisted chemical bath deposition (MA-CBD) technique were used to deposite nanocrystalline thin films of polyoxometalates like phosphomolybdic acid (PMA) (H3PMo12O40) and Cesium (Cs+) doped phosphomolybdic acid (Cs-PMA) (Cs3-PMo12O40). Thermo gravimetric and Differential thermal analysis (TGDTA), Fourier transform infrared spectroscopy (FTIR), Energy dispersive X-ray analysis (EDAX), X-ray diffractometry (XRD) and Scanning electron microscopy (SEM) tools are used for the thermal, structural, morphological and compositional analysis of microwave treated H3PMo12O40 and Cs3- PMo12O40 thin films. The completion of decomposition process at 600 oC of Cs3-PMo12O40 compound is confirmed from TGDTA analysis. The polycrystalline spinel cubic crystal structure of H3PMo12O40 and Cs3-PMo12O40 thin films were confirmed from X-ray diffractometer. The crystallite size of H3PMo12O40 and Cs3-PMo12O40 compound found to be in the range of 50 - 53 nm. The formation of H3PMo12O40 and Cs3-PMo12O40 materials were confirmed from the presence of main four absorption peaks observed in the range from 800 cm-1 to 1100 cm-1. The SEM microphotographs analysis identify the microwave assisted H3PMo12O40 and Cs3-PMo12O40 films have spherical shaped porous nanocrystalline morphology. The grain size of H3PMo12O40 and Cs3-PMo12O40 synthesized material found to be in the range of 10 - 12 A˚ The stoichiometric preparation of H3PMo12O40 and Cs3-PMo12O40 thin films with presence of P, Mo, O and Cs peaks of metal ions is observed from EDAX spectra.

A study of the spinodal decomposition of AgC[sbnd]u alloy films using in situ transmission electron microscopy

We performed in situ transmission electron microscopy (TEM) investigations to understand spinodal decomposition in AgCu alloy thin films. The decomposition of a homogeneous nanocrystalline morphology into a heterogeneous two-phase structure when annealed in situ from room temperature to 400 °C was investigated with different imaging modes in the TEM. These studies reveal phase transformation proceeds in stages: between 180 and 200 °C, onset of phase separation via spinodal decomposition is observed. Then, prominent phase separation occurs between 200 and 250 °C with minimal grain growth. Next, between 250 and 300 °C, grain growth primarily occurs via coalescence, with no apparent phase separation. From 300 to 350 °C, we observe significant phase separation and Ostwald Ripening. Finally, between 350 and 400 °C, further coarsening occurs via coalescence. STEM-HAADF mode reveals the onset of phase separation from domains as small as 5 nm and these results are also supported by electron diffraction and compositional mapping.

Effect of TiO<sub>2 </sub>on Photocatalytic Activity of NiZnFe<sub>2</sub>O<sub>4</sub>/TiO<sub>2</sub> Nanocrystalline for Methylene Blue Degradation

The photocatalytic activity of NiZnFe2O4/TiO2 core-shell gg nanocrystalline was carried out. The NiZnFe2O4/TiO2 core-shell was synthesized using co-precipitation method with various concentrations 1:0, 1:1, 1:2, 1:3, 1:4, and 1:5. X-ray diffraction spectra pattern showed crystallite size at various concentrations 1:0, 1:1, and 1:3, which of 5.00 nm, 4.90 nm, and 10.81 nm, respectively. The morphology of NiZnFe2O4 nanocrystalline was characterized by transmission electron microscopy which confirmed that the sample undergoes agglomeration with not uniform particle shape. The average particle size of the nanocrystalline was 10.26 nm. Fourier transform infra-red showed functional groups such as Ti-O-Ti, M-Otetra, and M-Oocta at 1473.62, 563 - 586, and 401- 424 cm-1. In addition, the presence of Ti-O-Ti and M-O functional groups indicates NiZnFe2O4/TiO2 core-shell has been formed. The absorbance spectrum of the NiZnFe2O4/TiO2 core-shell has an energy band gap in the range of 2.1 – 3.3 eV. The results of the Vibrating sample magnetometer showed saturation magnetization and coercivity values ​​in the range of 12.4 – 22.9 emu/gr and 47 - 55 Oe, which were correlated as soft magnetic properties. NiZnFe2O4/TiO2 was successfully degraded Methylene Blue that reach 99.8% under UV light irradiation. The addition of TiO2 increases degradation, TiO2 acts as a trapping state that inhibits electron-hole recombination which can prolong the reaction time between free electrons and MB solution molecules. This study revealed the high potential of NiZnFe2O4/TiO2 core-shell nanocrystalline in photocatalytic application.

An Aqueous Route to Oxygen-Deficient Wake-Up-Free La-Doped HfO2 Ferroelectrics for Negative Capacitance Field Effect Transistors.

The crucial role of nanocrystalline morphology in stabilizing the ferroelectric orthorhombic (o)-phase in doped-hafnia films is achieved via chemical solution deposition (CSD) by intentionally retaining carbonaceous impurities to inhibit grain growth. However, in the present study, large-grained (>100 nm) La-doped HfO2 (HLO) films are grown directly on silicon by adopting engineered water-diluted precursors with a minimum carbonaceous load and excellent shelf life. The o-phase stabilization is accomplished through a well-distributed La dopant, which generates uniformly populated oxygen vacancies, eliminating the need for oxygen-scavenging electrodes. These oxygen-deficient HLOs show a maximum remnant polarization of 37.6 μC/cm2 (2Pr) without wake-up and withstand large fields (>6.2 MV/cm). Furthermore, CSD-HLO in series with Al2O3 improves switching of MOSFETs (with an amorphous oxide channel) based on the negative capacitance effect. Thus, uniformly distributed oxygen vacancies serve as a standalone factor in stabilizing the o-phase, enabling efficient wake-up-free ferroelectricity without the need for nanostructuring, capping stresses, or oxygen-reactive electrodes.

Anisotropy-Driven Crystallization of Dimensionally Resolved Quasi-1D Van der Waals Nanostructures.

Unusual behavior in solids emerges from the complex interplay between crystalline order, composition, and dimensionality. In crystals comprising weakly bound one-dimensional (1D) or quasi-1D (q-1D) chains, properties such as charge density waves, topologically protected states, and indirect-to-direct band gap crossovers have been predicted to arise. However, the experimental demonstration of many of these nascent physics in 1D or q-1D van der Waals (vdW) crystals is obscured by the highly anisotropic bonding between the chains, stochasticity of top-down exfoliation, and the lack of synthetic strategies to control bottom-up growth. Herein, we report the directed crystallization of a model q-1D vdW phase, Sb2S3, into dimensionally resolved nanostructures. We demonstrate the uncatalyzed growth of highly crystalline Sb2S3 nanowires, nanoribbons, and quasi-2D nanosheets with thicknesses in the range of 10 to 100 nm from the bottom-up crystallization of [Sb4S6]n chains. We found that dimensionally resolved nanostructures emerge from two distinct chemical vapor growth pathways defined by diverse covalent intrachain and anisotropic vdW interchain interactions and controlled precursor ratios in the vapor phase. At sub-100 nm nanostructure thicknesses, we observe the hardening of phonon modes, blue-shifting of optical band gaps, and the emergence of a new high-energy photoluminescence peak. The directional growth of weakly bound 1D ribbons or chains into well-resolved nanocrystalline morphologies provides opportunities to develop ordered nanostructures and hierarchical assemblies that are suitable for a wide range of optoelectronic and quantum devices.

Impact of Nd doping in Bi2S3 thin films coated by nebulizer spray pyrolysis technique for photodetector applications

In this study, cost effective & scalable nebulizer spray pyrolysis approach was used to produce varying concentrations of Bi2S3:Nd (0, 1, 3, 5 wt%) thin films on glass substrates and the effect of Nd dopants on the crystalline, morphological, optical and photo sensing properties of the Bi2S3 thin films were studied. From the XRD results, the diffraction pattern of the prepared Bi2S3:Nd thin films exhibits an orthorhombic structure for all concentrations of Nd dopants with a predominant peak along (130) plane. Upon increasing the concentration of Nd dopants up to 3 wt% the predominant peak intensity increases with an increase in crystallite size of 25 nm and decreases with a further increase in the incorporation of Nd dopant. The surface morphological studies showed uniform nanocrystalline morphology for all the Bi2S3 thin films. The UV–Vis absorption studies revealed higher absorption of the prepared thin films over UV region and narrowing of the energy gap from 2.18 to1.63 eV with the incorporation of Nd dopant from 0 to 3%, repectievely. The photo sensing properties of the fabricated devices showed higher responsivity (R), detectivity (D*), EQE, and rapid rise/fall time of 1.36 × 10−1 A/W, 3.05 × 1010 Jones, 43%, and 0.1/0.2 s for Bi2S3:Nd 3 wt% thin film photodetector confirming the suitability of the device for commercial photodetector applications.

Compositionally modulated multilayer Cu-Zn alloy coatings fabricated using eco-friendly non-cyanide pulse electrochemical deposition

Pulse electrodeposition of Cu-Zn compositional modulated multilayer alloy (CMA) coatings was carried out onto AISI 304 stainless steel substrate using an environmentally friendly alkaline non-cyanide electrolytic bath. Cu-Zn alloy multilayer coating was co-electrodeposited using a trapezoidal pulse current. Multilayer coatings can have two different metals in layers or two-phase mixtures. Different sets of multilayers of 10, 20, 50, and 100 were done using a trapezoidal pulse current. In the trapezoidal pulse current module, during the higher current stage (0.1 A) Zn was deposited as compared to the lower current module (0.02 A) where Cu was deposited. Microstructural and structural analysis of the coatings confirmed nanocrystalline morphology with peaks corresponding to crystallographic planes of (002), (111), (020), and (022). Deposited coatings are hydrophilic in nature. The microhardness of the coatings is decreased with an increase in the number of layers deposited.

Effects of Sm and Cr co-doping on structural, magnetic, optical and photocatalytic properties of BiFeO3 nanoparticles

In this paper, bismuth ferrite and co-doped nanoparticle were synthesized by the tartaric acid modified sol–gel method. The XRD and Raman spectroscopy indicated that the structural phase changed from rhombohedral to orthorhombic. The nanocrystalline nature, grain size and morphology of the samples were confirmed using field emission scanning electron microscopy (FESEM) techniques. The ferromagnetic parameters increase with an increase in Sm-Cr co-doping concentration. Improved ferromagnetic properties Bi0.85Sm0.15Fe1-xCrxO3 VSM studies match with the EPR studies. The optical band gap energy of BFO and Bi0.85Sm0.15Fe1-xCrxO3 is 2.24 eV to 1.96 eV using UV–Visible spectroscopy. Compared to pristine BiFeO3, co-doped BiFeO3 nanoparticles exhibited the outstanding photocatalytic properties of methylene blue (MB) exposed to UV–Visible light irradiation. Bi0.85Sm0.15Fe0.95Cr0.05O3 nanoparticles showed 99.16 percent degradation at 90 min of radiation. The enhancement in BFO and Bi0.85Sm0.15Fe1-xCrxO3 nanoparticles' photocatalytic behaviors are contributed to changes in ionic radii, oxygen vacancies and narrow bandgap.

Nanorod-like nanocrystalline CsSnI3 and CNT composite thin film–based hybrid photodetector

An experimental detail on the morphology engineering and characterizations of the all-inorganic Sn-based perovskite (here CsSnI3) thin films and their application in photodetectors are presented. In particular, we demonstrated that the chlorobenzene anti-solvent treatment during thin-film spin coating could effectively optimize the morphology properties of the obtained CsSnI3 thin film. SEM and AFM measurements showed the uniform thin film with nanorod-like nanocrystalline morphology. In addition, EDS and XPS measurements confirmed the low level of oxidation of the thin film, indicating good ambient stability. A planar photodetector was also made with the prepared thin film, and electrical characteristics were taken. The dark current and photocurrent were found in the range of 10−9 A and 10−7 A, respectively, with an on/off ratio of 102. The photoresponsivity was 10−5 AW−1. A further experiment was conducted to make composite thin films between CsSnI3 and CNTs for additional morphological engineering. The SEM measurement and Raman mapping manifested the nanonet-like morphology of the composite thin film. The quenching of the photoluminescence curve indicated the efficient photo-generated carrier extraction from the CsSnI3 matrix to CNTs. The absorption spectra also showed enhanced absorption ability of the prepared composite thin film. A hybrid photodetector made from the composite thin film showed dark current and photocurrent in the range of 10−6 A and 10−4 A, respectively, with an on/off ratio of 102. The photoresponsivity was 10−2 AW−1. Due to the combination of the CNTs with CsSnI3, the photoresponsivity increased 1000 times. At the same time, the hysteresis of the hybrid photodetector also reduced significantly compared to the pristine CsSnI3-based photodetector.

Crystallization and microstructure in K2O substituted SiO2–MgO–Al2O3–Li2O–AlPO4 glass-ceramics

The substitution of K+ ion by Ca2+ or Sr2+ in K2O–SiO2–MgO–Al2O3–B2O3–MgF2–Li2O–AlPO4 glass is executed and the relevant effects on crystallization and microstructure are explored. The glass monoliths obtained by single-step melt-quenching at 1500 ± 10 °C were transparent in nature. Density of base glass was evaluated as 2.66 ± 0.03 g cm−3 and found to be decreased by in presence of CaO or SrO. Opaque glass-ceramics were derived from the transparent glasses by controlled heat-treatment at 1000 ± 10 °C and the predominant crystalline phase was identified as fluorophlogopite mica, KMg3AlSi3O10F2 by X-ray diffraction. Field emission scanning electron microscopy revel that the plate like fluorophlogopite mica crystals predominated in base glass-ceramic (without CaO or SrO doped) but changed to nanocrystalline morphology containing droplet like spherical shaped mica crystallites (average size 200–400 nm) on addition of CaO and SrO. Highest density (=2.74 ± 0.03 g.cm-3) observed for SrO containing glass-ceramic is attributed to the nanocrystalline morphology.

Influence of WC/C target composition and bias potential on the structure-mechanical properties of non-reactively sputtered WC coatings

Physical vapor deposited WC based coatings strongly vary in their microstructure ranging from multi-phased columnar-crystalline up to nanocomposite coatings in relation to the usage of reactive or non-reactive carbon sources. Within this study, we investigated in detail the influence of additional carbon implemented into WC based target mmaterials as well as bias potential on the structure-mechanical properties of non-reactively sputtered WC coatings. Providing additional graphitic carbon within WC targets promotes the formation of nanocrystalline morphologies. Increasing bias potentials dominate the transition from a nanocrystalline to a columnar-crystalline morphology obtaining also a mixed state in between. The change in morphology is accompanied by a large modification in mechanical properties with hardness values ranging from 27 to 39 GPa, respectively. In addition, high adatom mobility – caused by bias potentials up to −200 V – predominates the phase formation of crystalline WC coatings changing from face-centered cubic (fcc)-WCx to competing W2C based structures. The W—C phase formation is furthermore examined using DFT calculations.

Ultra-wide bandgap β-Ga2O3 films: Optical, phonon, and temperature response properties

Optical and phonon interactions of Ga2O3 thin films with nanocrystalline morphology were studied at extreme temperatures. The films were grown using a sputtering technique and analyzed via temperature response transmission, Raman scattering, and high-resolution deep-UV photoluminescence (PL). Raman modes indicated that the structure corresponds to the β-phase. The optical-gap at the range of 77–620 K exhibited a redshift of ∼200 meV, with a temperature coefficient of ∼0.4 meV/K. The optical-gap at room-temperature is 4.85 eV. The electron–phonon interaction model at that temperature range pointed to a low energy phonon, ∼31 meV, that is involved in the thermal properties of the optical-gap. Detailed Urbach energy analysis indicated that defects are the dominant mechanism controlling the band-edge characteristics even at an elevated temperature regime where phonon dominance is usually expected. Defects are attributed to the disordered forms of graphite that were detected via Raman scattering and to the granular morphology of the film. A deep-UV laser with an above-bandgap exaction line of 5.1 eV was employed to map the PL of the films. The highly resolved spectra, even at room-temperature, show a strong emission of ∼3.56 eV attributed to self-trapped holes (STHs). The STH is discussed and modeled in terms of the self-trapped exciton. Moreover, a very distinct but low-intensity emission was found at 4.85 eV that agrees with the value of the optical-gap and is attributed to bandgap recombination. The intensity ratio between the STH and that of the bandgap was found to be 6:1.

Wide thermal expansion in Ag0/Au0 nanoparticle doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass-ceramics

This report demonstrates high temperature sealing tendency of alumino-silicate glasses (ASG) on the system SiO2-MgO-Al2O3-B2O3-K2O-MgF2 doped with silver (Ag) and gold (Au) nanoparticles. Density of the melt-quenched (1550 °C) glasses were in 2.51–2.55 g.cm−3. The glasses were heat-treated at 900 ± 10 °C over which the opaque glass-ceramics were obtained with major crystalline phase (XRD) fluorophlogopite mica [KMg3(AlSi3O10)F2] with secondary phase norbergite (Mg2SiO4.MgF2). FESEM study indicated the development of Rod-like and rock-like crystallite particles (size ∼1–4 µm) randomly dispersed in mother glass–ceramic which was restructured into nanocrystalline morphology (crystallite size ∼100–400 nm) with the aid of Ag- or Au- nanoparticles. The significant change in microstructure influenced the corresponding density (2.51–2.55 g.cm−3) and thermal expansion characteristics. Coefficient of thermal expansion (CTE) for ASG was estimated to be 9.96 ± 0.10×10−6/K (50–800 °C), which increased to 10.46–11.01×10−6/K when doped with Ag- or Au- content. Such wide CTE (11.01 ± 0.11×10−6/K) value matches well with the CTE of ceramic/metallic materials used for high temperature application thus Ag- doped SiO2-MgO-Al2O3-B2O3-K2O-MgF2 glass can be a suitable for high temperature sealing application (like SOFC).

Synergistic effect of Cux/Mgx and Zn1−xO for enhanced photocatalytic degradation and antibacterial activity

Metal-doped zinc oxide nanostructures (ZONSs) of schemes CuxZn1−xO and MgxZn1−xO (x = 0, 0.01, 0.1 and 0.5 M) were synthesized via co-precipitation technique. The structural parameters of as-prepared ZONSs were investigated from XRD technique and doping concentration limit for both types of dopant was found, causing a shift in the Eg value based on the availability of density of states for that dopant. SEM analysis confirmed thin sheet-like nanocrystalline morphologies of all samples within size range 78–450 nm. Optical analysis revealed that higher concentration of Cu in the sample resulted in overlapped impurity states following a considerable increase in its Eg value. Among all samples, Cu0.1 and Mg0.01 samples with reduced PL emission, exhibited maximum degradation of MB dye under direct-sunlight exposure of few seconds. As positively charged metal-doped ZONSs attract more toward Gram-negative bacterial membrane, the suggested samples have shown improved antibacterial performance against Klabsiella strains.

Mo–V–O nanocrystals synthesized in the confined space of a mesoporous carbon

Ternary Mo–V oxide nanocrystals (Nano-MoVO) were hydrothermally synthesized in the confined space of a mesoporous carbon template and tested in the oxidative dehydrogenation (ODH) of ethane and propane. The synthesized nanocrystals are approximately 60 nm in length, 20 nm in diameter on average, and possess a structure resembling orthorhombic MoVO (Orth-MoVO) as indicated by spectroscopic and microscopy characterization. The Nano-MoVO catalyst has a 5-fold higher mesopore volume and a 4-fold larger external surface area than an Orth-MoVO synthesized by a conventional method (Orth-MoVO) as characterized through N2 adsorption analysis. Nano-MoVO shows similar activation energy in the ODH of ethane compared with other conventional MoVO catalysts. However, Nano-MoVO exhibits significantly higher propane/ethane activation rate ratio and higher propene selectivity even in the absence of elements such as Te and Nb that suppress overoxidation of propane-derived species to COx. The results suggest the benefits of the nanocrystalline morphology to limit overoxidation.

Ex Situ Residual Stress Analysis of Chemical Vapor Deposited Diamond Coated Cutting Tools by Synchrotron X‐Ray Diffraction in Transmission Geometry

When machining difficult‐to‐cut, nonferrous materials, chemical vapor deposited (CVD) diamond–coated cutting tools are applied. The tools’ favorable mechanical property profile is based on the hardness of the coating as well as the adaptability of the substrate. Nevertheless, the reproducibility of machining results and process stability are limited by insufficient coating adhesion. The resulting cutting tool failure is based on coating delamination initiated by crack development. By assessing residual stress as an influence of coating adhesion, an analysis of CVD diamond–coated tools is performed using synchrotron X‐ray diffraction in transmission geometry. Investigation of a nanocrystalline and multilayer morphology on cobalt‐based tungsten carbide (WC‐Co) and a silicon nitride–based ceramic (Si3N4) provides the distribution of the principal in‐plane residual stress tensor component σ22 depending on the coating morphology and substrate material. Contrary to microcrystalline CVD diamond, nanocrystalline layers decrease the compressive residual stress. In addition, the CVD diamond coating deposited on the Si3N4 substrate material tends to induce an overall initial tensile residual stress that leads to increased tool performance compared to WC‐Co‐based coated tools. Variation of the coating morphology as well as the substrate material offers the possibility to extend the current model for residual stress–dependent tool failure.

Controlling the morphology of nanocrystalline Y(OH)3 powders synthesized by microwave-hydrothermal route and effect of annealing

Y(OH)3 is the main precursor material to inherit desirable morphologies for Y2O3. The Y(OH)3 and Y2O3 are an important substitution for luminescent matrix and useful in temperature sensing applications. Nanostructured and phase-pure Y2O3 is also used as an essential dispersoid for the oxide dispersion strengthened steels which are candidate materials for future fast breeder reactors. In the present work, the nanostructured Y(OH)3 is prepared indigenously by the microwave-hydrothermal route which is appropriate to provide-uniform heating to the material and the hydrothermal-pressure environment plays a major role in the growth kinetics of morphology. The synthesis was carried out at various microwave powers of 700 and 800 W to obtain the different morphologies of tubular and rod-like structures, respectively. The morphology is attributed to the influence of heat-rate on the variation in hydrothermal pressure governed by microwave power. The morphologies remain the same on calcination 800 °C. As-synthesized powder samples showed hexagonal structure whereas the cubic structure was observed for those calcined at 800 °C for both morphologies. The hydroxide vacancies lead to form a cubic structure that has a larger unit cell. The yttrium oxides showed lattice compaction for the rod-like structure but yttrium hydroxides did not depict any difference in the lattice for the tubular and rod-like morphologies. Likewise, Raman spectroscopy analysis confirmed the formation of hexagonal and cubic phases for the as-synthesized and calcined nanopowder samples, respectively.

Spectroscopic ellipsometry and morphological studies of nanocrystalline NiO and NiO/ITO thin films deposited by e-beams technique

The current article reported a new data on the structural, surface morphology and optical properties of multi-thickness nanocrystalline NiO/glass substrate and NiO/ITO/glass substrate semiconductor thin films prepared by electron beam deposition technique. Structural investigation shows that the as-deposited multi-thickness NiO films deposited on a glass substrate crystallize in the form of cubic NaCl type structure. However, ITO thin film has a cubic type structure. Besides, the increase in the crystallite size was observed with increasing the thickness of NiO film, this behavior was confirmed by AFM micrographs. In the spectral range 280 nm–1800 nm, the optical properties of the NiO/glass substrate and NiO/ITO/glass substrate thin films have been investigated using spectroscopic ellipsometry (SE) technique. For NiO/glass substrate sample, the SE results providing direct energy E g d i r ≈ 3.954 eV, indirect energy E g i n d i r ≈ 2.855eV and phonon energy of order 200 meV. In addition, the analysis of the refractive index dispersion gives the atomic number density to be N f i j = 2.213 x 10 22 c m − 3 . On the other hand, for the NiO (410 nm)/ITO (99 nm)/glass substrate thin film sample, a reduction in the direct transition energy to E g d i r ≈ 3.24eV and also in the factor N f i j to 1.6 x 10 22 c m − 3 was observed. Additionally, the values of the oscillator parameters were calculated for NiO/glass substrate and NiO/ITO/glass substrate thin films using the Wemple-DiDomenico single oscillator model (WDD). Finally, it was found that the values of Urbach energy for NiO/glass substrate and NiO (410 nm)/ITO (99 nm)/glass substrate are very small relative to the energy gap values which indicates that the region of localized sates is very narrow compared to the width of the energy gap. • The D/nm of NiO film increase from 16.86 to 22.75nm and for NiO/ITO from 15 to 26nm with increasing thickness from 75 to 410nm. • Good correlation between the increase in D/nm and reduction of dislocation density (δ) is found. • SE provides E g d i r ≈ 3.954 eV, E g i n d i r ≈ 2.855eV and E phon 200meV. For NiO/glass film a reduction in E g d i r to 3.24eV for the NiO(410nm)/ITO (99 nm)/glass. • The refractive index of NiO film is independent of the film thickness and atomic number density is found to be N f i j = 2.213 x 10 22 c m − 3 • The values of E o = 6.828eV, E d = 19.3eV for NiO film and E o = 4.56eV, E d = 15.1eV for (410 nm)/ITO (99nm)/glass substrate film are found.

Interactions of zinc aqua complexes with ovalbumin at the forefront of the Zn2+/ZnO-OVO hybrid complex formation mechanism

The present research is focused on experimental and computational mechanistic study of the nanocomplexes formation through Zn2+(aq)-ovalbumin (OVA) binding. The determination of processes occurring at Zn2+(aq)-OVA interfaces and mechanism of hybrid complexes formation involved the modeling of kinetics and isotherm of Zn2+(aq) binding. Scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction were employed to characterize the nano-crystalline structure and morphology of the Zn2+/ZnO-OVO hybrid complex. Formation of hybrid complex was monitored using Fourier transform infrared spectroscopy. Specific Zn2+(aq) binding sites were pointed using MD simulations. Large-scale MD analysis was carried out to sample conformational space of the formed Zn2+(aq)-OVA complexes. Density functional theory (DFT) calculations were used to investigate the structures of the interaction complexes between zinc(II) and Asp−/Glu− and predict their respective IR spectra, and for mechanistic modeling of oxidation processes involved in the formation and stabilization Zn2+/ZnO-OVO hybrid complex. Negatively charged ovalbumin surface was locally neutralized through rapid Zn2+(aq) adsorption and formation of monolayers via 1:1 Asp−/Glu−/-Zn2+(aq) complexes. The ovalbumin monomer species began to agglomerate, stabilized with Asp−/Glu−-Zn2+(aq)-Glu−/Asp− interface complexes that promoted the formation of nanocomplexes. Finally, antimicrobial assays have shown that Zn2+/ZnO-OVO hybrid complex exhibit an inhibition effect against bacteria (A. baumanii, K. pneumonia) and yeast (C. albicans) strains.