Effect of ZnO on sintering and microwave dielectric properties of 0.5CaTiO3-0.5 (Li0.5La0.5) TiO3 ceramics

The novel calcium titanate-lithium lanthanum titanate doped with zinc oxide (0.10, 0.30, and 0.50 mol. %) ceramic samples were prepared by solid-state reaction route. The phase formation, microstructure, densification, and microwave dielectric properties were investigated. It was found that the doping with zinc oxide led to a decrease in sintering temperature by 25 ^oC as compared with pure calcium titanate lithium lanthanum titanate due to the liquid phase effect. Also, the calcium titanate lithium lanthanum titanate (10ZCTLLT&30ZCTLLT)) doped with lower zinc oxide (0.10 and 0.30 mol. %) led to higher densification parameter. This was followed by increasing the zinc oxide doping up to (0.50 mol. %) which resulted in a decrease in densification and microwave dielectric properties which may be attributed to increase in porosity and grain growth upon the evaporation of zinc and oxygen vacancy. This led to the increase in dielectric loss (≈10 × 10^?4) value with 50ZCTLLT. Hence, the best result of microwave dielectric characteristics was obtained for 0.5CaTiO₃–0.5(Li_0.5La_0.5)TiO₃ with (0.10 and 0.30 mol. % ZnO) 10ZCTLLT and 30ZCTLLT ceramic samples sintered at 1175 ^oC/2h, with low dielectric constant (ε_r) = 4.4–10.5, very low dielectric loss = 1.07-2.23 × 10^?4 and high quality factor (Q x ?) ≈59-55 × 10⁴ at 8 GHz. Consequently, they can be used not only in wireless satellite communications technology but also can be used in the fifth-generation telecommunication 5G technology construction.     

Multi-length scale wear damage mechanisms of ultra-high molecular weight polyethylene nanocomposites

Ultra-high molecular weight polyethylene (UHMWPE) is reinforced with 1–3 wt % sliver (Ag) nanoparticles and zinc oxide (ZnO) micro-rods, and tensile strength as well as wear resistance of the samples is evaluated. Tensile strength was observed to increase with Ag and ZnO reinforcement up to 18% for 1 wt % ZnO and 1 wt % Ag, but in case of 3 wt % ZnO and 3 wt % Ag + 3 wt % ZnO, it decreases marginally by 4% when compared with neat polymer. The sliding wear rate for 1 wt % Ag + 1 wt % ZnO and 3 wt % Ag + 3 wt % ZnO decreases from 9.54 × 10⁻⁵ mm³ (neat polymer) to 7.49 × 10⁻⁵ mm³ and 5.65 × 10⁻⁵mm³, respectively, showing the synergistic effect of Ag and ZnO reinforcement. In scratch testing, minimum damage is obtained in 1 wt % ZnO reinforced polymer. On one hand, where micro-scratch damage is resisted by harder ZnO, whereas on the other hand, pin on disc wear (repeated surface damage) is protected by softer Ag tribolayer. The improved tensile strength (up to 9.7%) and wear resistance with synergistic addition of Ag and ZnO (both 1 wt %) opens a window in the development of bearing surface biomaterials providing improved longevity and durability, thus, may reduce the chances of revision surgery.     

Dielectric properties of poly(4‐vinylphenol) with embedded PbO nanoparticles

An organic/inorganic nanocomposite film was synthesized using poly(4‐vinylphenol) (PVPh) as an organic insulating polymer and PbO nanoparticles as a high‐k inorganic material to serve as an organic insulator with enhanced dielectric properties. PbO nanoparticles were dispersed into propylene glycol monomethyl ether acetate, and a solution of PbO/PVPh nanocomposite was prepared by adding a crosslinker. The PbO nanoparticle content within the PVPh polymer matrix was varied, and the effects of this variation upon the properties of the resulting nanocomposite films were studied, including the properties of surface morphology, surface bonding state and dielectric characteristic. The dielectric constant increased with increasing PbO content, reaching 9.2 at 1 MHz and with dielectric loss below 0.09 for the PbO content of 6 vol%. Furthermore, the leakage current increased to only 1.3 × 10^?8 A cm^?1 at the highest nanoparticle loadings, compared to the 7.2 × 10^?9 of pristine PVPh. The addition of PbO nanoparticles was found to effectively suppress the absorption of moisture on the surface of PbO/PVPh nanocomposite, although it also increased surface roughness, owing to the agglomeration and particulation of PVPh arising from an anchoring effect of the PbO nanoparticles. Copyright © 2015 John Wiley & Sons, Ltd.     

Green synthesis and characterization of Fe doped ZnO nanoparticles and their interaction with bovine serum albumin

Herein we report an eco-friendly and cost efficient synthesis of Fe doped ZnO (TPFZO) nanoparticles using the extract of Thespesia polpulanea flowers as a stabilizing agent. The synthesized NPs have been characterized by XRD, FT-IR, UV-DRS, SEM, EDAX and TEM studies. The synthesized NPs were found to have the crystallite size in the range of 30–60 ​nm. The calculated band gap energies for ZO and TPFZO nanoparticles were 3.00 ​eV and 1.97 ​eV respectively. The size distribution of the ZO and TPFZO obtained from TEM were observed to be lying in the range 50–120 ​nm and 4–22 ​nm respectively. The interaction of TPFZO NPs with bovine serum albumin (BSA) has been studied using fluorescence and absorption titration methods. The results indicated that the nanoparticles quenched the BSA fluorescence at 340 ​nm via static quenching mode having a bimolecular quenching rate constant value of 6.21 ​× ​10¹³ Lmol⁻¹s⁻¹.     

Size-controllable synthesis of spherical ZnO nanoparticles: Size- and concentration-dependent resonant light scattering

A new and simple direct precipitation method assisted with ultrasonic agitation was proposed for the preparation of spherical ZnO nanoparticles. The size of the ZnO nanoparticles, 10 nm to 85 nm, was tuned through controlling the calcination temperature and changing the ratio of the reactants. The resonant light scattering (RLS) of the ZnO nanoparticles dispersed/suspended in aqueous solution of Triton X-100 was studied under room temperature. It was found that the ZnO nanoparticles of different size or concentration all have a characteristic RLS peak at 387 nm. Under optimal conditions, the RLS intensity was proportional to the ZnO concentration in the range of 7.3 × 10^?8–1 × 10^?4 mol L^?1, while the cubic root of the RLS intensity was found to be proportional to the size of ZnO nanoparticles. Further, the quantitative relationship of the size of the ZnO nanoparticles versus the calcination temperature was derived, and this could be used to forecast/control the nano-size in the nano-ZnO preparation.     

Development of electrochemical DNA biosensor for Trichoderma harzianum based on ionic liquid/ZnO nanoparticles/chitosan/gold electrode

Electrochemical DNA biosensor was successfully developed by depositing the ionic liquid (e.g., 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][Otf])), ZnO nanoparticles, and chitosan (CHIT) nanocomposite membrane on a modified gold electrode (AuE). The electrochemical properties of the [EMIM][Otf]/ZnO/CHIT/AuE for detection of DNA hybridization were studied. Under optimal conditions using cyclic voltammetry, the target DNA sequences could be detected in the concentration range of 1.0 × 10⁻¹⁸ to 1.82 × 10⁻⁴ mol L⁻¹, and with the detection limit of 1.0 × 10⁻¹⁹ mol L⁻¹. This DNA biosensor detection approaches provide a quick, sensitive, and convenient method to be used in the identification of Trichoderma harzianum.     

Phase pure (Ba0.3Sr0.7)(Zn1/3Nb2/3)O3 nanocrystalline particles synthesized by sol–gel technique at low temperature and their application

Phase pure (Ba_0.3Sr_0.7)(Zn_1/3Nb_2/3)O₃ (BSZN) perovskite ceramic nanocrystalline particles were synthesized at low temperature with high reaction yield and high synthetic reproducibility using the sol–gel technique. The results showed that high-purity perovskite BSZN phase with high crystalline quality was obtained at 800 °C, that is, the volatilization of ZnO was successfully overcome. The nanocrystalline particles were about 20–30 nm in diameter with regular and uniform spherical shapes, high dispersive properties, and less aggregation. The pellets made by these nanoparticles had excellent dielectric properties: dielectric constant $ \varepsilon_{\text{r}} $ 40.5, temperature coefficient of resonant frequency $ \tau_{\text{f}} $  0.5 × 10^?6/ °C, and quality factor Q × f: 75,000 at 3.89 GHz, and a high relative density of 98.1 %.     

Synthesis of O6‐Corona[3]arene[3]pyridazines and Their Molecular Recognition Property in Organic and Aqueous Media

O₆‐Corona[3]arene[3]pyridazines were synthesized from the one‐pot macrocyclic condensation reaction of 3,6‐dichlorotetrazine with 1,4‐dihydroquinone derivatives followed by the inverse electron demand Diels‐Alder reaction of the tetrazine rings with a cyclopentanone‐derived enamine. Conversion of six ester groups within macrocycle into all sodium acetate moieties afforded a water soluble O₆‐corona[3]arene[3]pyridazine. The coronary macrocycle host formed complexes selectively with organic ammoniums and dinitrile guests in a 1: 1 stoichiometric ratio in organic solvents with association constants ranging from (2.96 ± 0.10) × 10¹ to (2.53 ± 0.33) × 10⁵ L·mol⁻¹. Water soluble O₆‐corona[3]arene[3]pyridazine was also able to complex strongly with organic ammoniums in water to give an association constant up to (2.67 ± 0.21) × 10⁴ L·mol⁻¹. The pseudo‐rotaxane and inclusion structures of the host‐guest complexes were revealed by the X‐ray crystallography.     

Co doped ZnO nanowires as visible light photocatalysts

High aspect ratio cobalt doped ZnO nanowires showing strong photocatalytic activity and moderate ferromagnetic behaviour were successfully synthesized using a solvothermal method and characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), vibrating sample magnetometry (VSM) and UV–visible absorption spectroscopy. The photocatalytic activities evaluated for visible light driven degradation of an aqueous methylene orange (MO) solution were higher than for Co doped ZnO nanoparticles at the same doping level and synthesized by the same synthesis route. The rate constant for MO visible light photocatalytic degradation was 1.9·10⁻³ min⁻¹ in case of nanoparticles and 4.2·10⁻³ min⁻¹ in case of nanowires. We observe strongly enhanced visible light photocatalytic activity for moderate Co doping levels, with an optimum at a composition of Zn_0.95Co_0.05O. The enhanced photocatalytic activities of Co doped ZnO nanowires were attributed to the combined effects of enhanced visible light absorption at the Co sites in ZnO nanowires, and improved separation efficiency of photogenerated charge carriers at optimal Co doping.     

Assessment of corrosion protection and performance of bio-based polyurethane acrylate incorporated with nano zinc oxide coating

In this study, a series of UV-curable anticorrosive PUA coatings embedded with varying concentrations of inorganic ZnO fillers have been successfully prepared from jatropha-based polyol. The electrochemical impedance spectroscopy (EIS) and Tafel polarisation analysis revealed that increasing fillers composition lead to the improvement of the anticorrosive property of the hybrid coatings. Meanwhile, the salt spray test results were found to correlate with the EIS of C_c (F cm⁻²) was 2.71 × 10⁻⁹, Bode plot - 10⁶ Ω cm² and Tafel polarisation results 7.56 × 10⁻⁶ MPY at 3 wt% of ZnO. Physical properties of 3 wt% loading of ZnO fillers in hardness test obtained 6H which was strongly attributed to the low interfacial interaction and poor dispersion of the fillers within the polymer matrix.     

Colossal dielectric constant in PrFeO3 semiconductor ceramics

The perovskite PrFeO₃ ceramics were synthesized via sol–gel method. The dielectric properties and impedance spectroscopy (IS) of these ceramics were studied in the frequency range from 100 Hz to 1000 kHz in the temperature range from 80 K to 300 K. These materials exhibited colossal dielectric constant value of ∼10⁴ at room temperature. The response is similar to that observed for relaxorferroelectrics. IS data analysis indicates the ceramics to be electrically heterogeneous semiconductor consisting of semiconducting grains with dielectric constant 30 and more resistive grain boundaries with effective dielectric constant ∼10⁴. We conclude, therefore that grain boundary effect is the primary source for the high effective permittivity in PrFeO₃ ceramics.     

Physical properties of suspension ZnO nanoparticles prepared by wet chemical method: Comparison study

In this work a suspension of Nano-crystalline of ZnO particle is prepared by wet chemical at different temperature and concentration. From FTIR spectral exhibit present of Zn–O bond which indicate to formation ZnO particles. While all suspension and nano films exhibit a high transmittance in visible region about 90% which falls sharply in the UV region. The particle size is measured by using effective mass approximation (EMA), which was approximation (1.7–1.96 nm), and the band gap changes from 3.95 to 4.52eV for nanoparticles in suspension, and change from 3.76 to 3.94 eV for nanoparticles in ZnO film, which is change as function of concentration, temperature and aging time. Hall Effect measurements for ZnO films exhibit n-type conductivity for films deposited with activation energy 0.742eV at high temperature and 0.178eV at low temperature which is different as prepared sample conditions. Also the nanoparticle suspension and nanoparticle film could be implemented as a filter with variable cut off (8.9 × 10¹⁴–1.28 × 10¹⁵) H_Z.     

Modified cotton fabrics with poly (3-(furan-2-carboamido) propionic acid) and poly (3-(furan-2-carboamido) propionic acid)/gelatin hydrogel for UV protection,antibacterial and electrical properties

This research aimed to prepare smart cotton fabrics with multi functions for antibacterial activity, UV protection and electrical conductivity via in situ coating with conductive polymer and conductive hydrogel. Therefore, 3-(furan-2-carboamido) propionic acid was synthesized followed by polymerization using ceric ammonium nitrate. In addition, cotton fabrics coated with 3-(furan-2-carboamido) propionic acid via in situ polymerization and by the hydrogel that based on poly (3-(furan-2-carboamido) propionic acid) and gelatin which have been performed via in situ gelation process. The chemical structure and morphology of the 3-(furan-2-carboamido) propionic acid (monomer) and the synthesized polymer (PFu) were investigated by H¹NMR, IR, SEM, TGA and DSC. Where, the treated fabrics (PFu-T and PFu-G-T) are characterized by SEM, FTIR and contact angle. Furthermore, the AC electrical conductivity and dielectric properties of PFu, PFu-T, PFu-G-T and blank were investigated over the frequency range of 20 Hz–10 MHz at room temperature using impedance spectroscopy where the electric conductivity values are 1.74 × 10^-5, 7.5 × 10^-8, 4 × 10^-7, 8.24 × 10^-11 (S·cm)^-1, respectively. In addition, the anti-bacterial activity of PFu-T, PFu-G-T and blank was assessed versus gram-positive and gram-negative bacteria where, PFu-G-T shows activity against Escherichia coli and Staphylococcus aureus. Moreover, PFu-T, PFu-G-T showed high UV protection especially for PFu-G-T.     

Thermo-crosslinkable molecular glasses towards the low k materials at high frequency

Two molecular glasses having allyl side chains and thermo-crosslinkable benzocyclobutene (BCB) groups have been successfully synthesized. These molecules display good solubility in common organic solvents and show a typical glass-forming behavior of having no melting point and keeping a complete amorphous state. The thermally cured molecular glasses exhibit low dielectric constant (D_k) and dielectric loss (D_f) at 10 GHz, as well as low water uptake (Wa) even when they are immersed in boiling water for 72 h. Among them, a fluoro-containing molecule exhibits the best properties, showing D_k of 2.53, D_f of 1.93 × 10^?3 and Wa of 0.19%, respectively, indicating that fluoro groups can efficiently improve the dielectric properties of the molecules. A controlling test indicates that the allyl side chains make the molecules possessing glass-forming properties.     

Facile synthesis of ZnO and Co3O4 nanoparticles by thermal decomposition of novel Schiff base complexes: Studying biological and catalytic properties

In this paper, a novel Zn(II) and Co(II) Schiff base complexes were synthesized by template method via refluxing 2,3-Naphthalenedicarboxaldehyde, Metal(II) chloride (Metal = Zn or Co), and L-phenylalanine. ZnO and Co₃O₄ nanoparticles were synthesized by thermal decomposition of Zn(II) and Co(II) complexes, respectively. The products were characterized using different instruments such as CHN, Conductivity, FT-IR, XRD, HR-TEM, and UV–Vis spectrophotometer. The experimental results of elemental analysis for Zn(II) and Co(II) complexes, agree with the calculated results, indicating that the Zn(II) and Co(II) complexes have 1:1 ligand/metal ratios. The molar conductance of the Zn(II) and Co(II) complexes, is less than 5 Ω^?1cm^?1mol^?1, confirming the non-electrolytic nature of the synthesized complexes. The average crystallite diameter of the ZnO and Co₃O₄ samples is 39.64 and 30.38 nm, respectively. The optical energy gap of the ZnO and Co₃O₄ samples are 2.75 and 3.25 eV, respectively. Methylene blue dye was utilized to examine the photocatalytic properties of the synthesized nanoparticles using UV irradiations in the absence and presence of hydrogen peroxide. The % degradation of the methylene blue dye in the presence of hydrogen peroxide using ZnO and Co₃O₄ samples after 40 min is 94.55 and 98.98, respectively. Six pathogenic microbes were utilized to examine the antimicrobial properties of the synthesized Schiff base complexes and their nanoparticles: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus species, Aspergillus species, and Candida species. Zn(II) and Co(II) complexes display inhibition towards all the studied microbes. Besides, ZnO and Co₃O₄ nanoparticles exhibit less inhibition towards Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Streptococcus species. Moreover, ZnO and Co₃O₄ nanoparticles have no activity towards Aspergillus and Candida species.     

Determination of Catechol by a Novel Laccase Biosensor Based on Zinc-Oxide Sol-Gel

A biosensor was fabricated by incorporating laccase in a ZnO sol-gel with chitosan as a matrix for the determination of catechol. The ZnO nanoparticles were characterized by X-ray diffraction and atomic force microscopy. The conductivity of the chitosan/ZnO/glassy carbon electrode film was investigated by alternating current impedance. The biosensor was employed to monitor the reduction of catechol, and the peak current increased linearly with concentration between 1.0 × 10^?6 and 1.0 × 10^?4 mole per liter with a limit of detection of 2.9 × 10^?7 mole per liter. The laccase biosensor exhibited good stability, reproducibility, and some selectivity.     

Bi1.5ZnNb1.5O7 cubic pyrochlore ceramics prepared by aqueous solution–gel method

Bi_1.5ZnNb_1.5O₇ cubic pyrochlore ceramic was successfully prepared by the aqueous solution method. The preparation, microstructure development and dielectric properties of ceramics were investigated. Homogeneous precalcined ceramics powders have a cubic pyrochlore phase after thermal treatment at the temperature as low as 450 °C. The aqueous solution–gel method, which Bi, Zn and Nb ions are chelated to form metal complexes, leading to the formation of cubic pyrochlore phase at low firing temperatures. No detectable intermediary phase such as BiNbO₄ or pseudo-orthorhombic pyrochlore is observed in the XRD patterns of ceramics at the sintering temperature range from 850 to 1,000 °C. The dielectric properties study revealed that the ceramics sintered at 900 °C show excellent performance with dielectric constant of 111 and dielectric loss of 2.3871 × 10⁻⁴ under 1 MHz at room temperature.     

In-vitro hemolytic activity and free radical scavenging by sol-gel synthesized Fe3O4 stabilized ZrO2 nanoparticles

Zirconia ceramics have attained much consideration owing to the amazing mechanical strength and white color. These properties provide an opportunity for the use in biomedical applications. In the present study, an application oriented sol-gel route was adapted for synthesis of zirconia nanoparticles. ZrOCl₂·8H₂O was used as a precursor, iron oxide (Fe₃O₄) nanoparticles (pH 2 & pH 9) as a stabilizer and de-ionized water was used as a solvent. Sol-gel synthesized iron oxide stabilized zirconia nanoparticles were prepared by varying concentrations of iron oxide nanoparticles in the range of 2–10 wt%. X-ray diffraction results showed mixed phases at all wt% with acidic pH value, while pure tetragonal phase of zirconia was observed for stabilization with 6 wt% basic iron oxide. Maximum value of dielectric constant (~80 at log f = 4) and minimum value of tangent loss (~0.66 at log f = 4) were observed for zirconia stabilized with basic 6 wt% iron oxide. Maximum value of hardness (1410 ± 10 HV) along with high fracture toughness were observed with optimized stabilization. Very weak hemolytic activity and maximum scavenging (~76) antioxidant activity was observed under optimized conditions. Thus, it can be suggested that optimized nanoparticles, i.e. tetragonal zirconia stabilized with 6 wt% of basic Fe₃O₄, can be further useful for therapeutical and pharmaceutical applications.     

Structure and ion transport in an ethylene carbonate-modified biodegradable gel polymer electrolyte

The influence of ethylene carbonate (EC) addition on 85poly(ε-caprolactone):15Lithium thiocyanate (85PCL:15LiSCN) polymer electrolyte is investigated using X-ray diffraction, impedance spectroscopy, Wagner's polarization and electrochemical measurements. The results reveal that the amorphicity of the 85PCL:15LiSCN system increases with increase of EC content up to an optimal level of 40 wt.%. This is reflected in the electrical properties of the gel polymer electrolytes, i.e., the 40 wt.% EC-incorporated gel polymer electrolyte exhibits both high amorphicity and high electrical conductivity as compared to the other samples. The EC concentration dependences of dielectric constant and electrical conductivity show a similar trend, indicating that these properties are closely related to each other. The total ionic transference numbers of EC-incorporated gel polymer electrolytes are in the range 0.989–0.993, demonstrating that they are almost completely ionic conductors. The electrochemical stability window of the 40 wt.% EC-incorporated gel polymer electrolyte is ∼4.1 V along with the electrical conductivity of 2.2 × 10⁻⁴ S cm⁻¹, which is significantly improved as compared to the 85PCL:15LiSCN system (3.0 V and 1.04 × 10⁻⁶ S cm⁻¹). Consequently, the addition of EC in the 85PCL:15LiSCN polymer electrolyte leads to a promising improvement in its various properties.     

Synthesis and physical characterization of electrically conducting polymers of polynuclear aromatic sulfonyl compounds

Potentially useful conducting polymers of sulfonyl substituted phenanthrene derivatives and non-conducting linear polymers, such as, polystyrene and poly(N-vinylcarbazole) have been synthesized and characterized using IR, thermogravimetric and dielectric measurements. The phenanthrene-based benzene, naphthalene and biphenyl copolysulfones have also been prepared and characterized through these techniques. These pendant and backbone polymer sulfones have exceptionally high thermal stability and electrical conductivity, such that dc conductivity in the range 2.80 × 10^?16 to 2.82 × 10^?7 Ω^?1 cm^?1 and ac conductivity in the range 1.69 × 10^?7 to 2.10 × 10^?6 Ω^?1 cm^?1.