Wurtzite Structure Of ZnO Research Articles

Highly tunning of dielectric and photocatalytic properties of crystalline ZnO semiconductor: functionality of Ba additives

Abstract In the present work, the concentration of Ba-additive played a significant role in advancing the dielectric properties and photo-removal activity of ZnO semiconductor for methylene blue dye. Ba doped ZnO semiconductor with different doping concentrations (Zn1-xBaxO, x = 0.003, 0.005, 0.007 and 0.009 wt.%) were grown by solid-state reaction route. The X-ray diffraction (XRD) data confirmed the formation of the wurtzite structure of ZnO along with the presence of BaO-based secondary phase (SP). The XRD peak intensity related to the SP was found to increase with the increase of Ba concentration. Microstructural analyses through scanning electron microscope (SEM) images and energy-dispersive X-ray analysis (EDS) showed that with the addition of Ba, a gradual increase in the grain size was observed. Furthermore, SP segregated at the grain boundary and showed an increasing trend with doping. The emergence of secondary phases with Ba concentration was confirmed with the help of supplementary spectroscopic characterizations including Fourier transform infrared spectroscopy (FTIR) and UV-Vis diffuse reflectance. The presence of BaO secondary phase has shown a benefit effect on the dielectric and photodegradation properties of ZnO material. The remarkable resistance reduction suggested that the higher Ba concentrations significantly enhance charge carrier mobility. For wastewater treatment uses, BZO9 photocatalyst exhibited a perfect degradation efficiency of 90.1% for methylene blue (MB) removal after 210 min of visible light illumination.

RGO‐Modified ZnO‐TiO2 Nanohybrids as Promising Antibacterial Agents for Biomedical Applications

AbstractThis study explores the synergistic antibacterial activity of ZnO nanorods (NRs) decorated with TiO₂ nanoparticles (NPs) and reduced graphene oxide nanosheets (rGO NSs). ZnO NRs and binary ZnO‐TiO₂ nanocomposites (ZT NCs) with varying TiO₂ content were synthesized using an in situ sol–gel method and subsequently modified with different amounts of rGO NSs. The nanocomposites were characterized using advanced techniques to assess their structure and antibacterial performance. X‐ray diffraction (XRD) confirmed the dominance of the hexagonal wurtzite ZnO structure, while Fourier transform infrared spectroscopy (FT‐IR) confirmed interconnectivity. A slight red shift in UV–vis diffuse reflectance spectra indicated changes in optical properties, and BET analysis showed an increase in surface area and pore volume due to rGO incorporation. The ternary ZT‐rGO (ZTR) NCs, particularly ZTR 4 (with 4 wt% rGO), exhibited significant antibacterial, antifungal, and antioxidant properties. ZTR 4 showed enhanced efficacy against both Gram‐positive (Staphylococcus aureus, Bacillus cereus) and Gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa), as well as Candida albicans. The results highlight the synergistic effects of ZTR NCs, making them promising candidates for applications in biomedical and environmental fields as effective antibacterial agents.

Characterization of ZnO nanoparticles synthesized using probiotic Lactiplantibacillus plantarum GP258.

The fundamental goal of our investigation is to employ a sustainable synthesis method for zinc oxide nanoparticles (ZnO NPs), utilizing lactic acid bacteria isolated from curd as the key biological agent. Bacteria function as agents for both reduction and capping processes, which aids the synthesis of ZnO NPs. Various characterization techniques including XRD, FTIR, UV-vis, TEM, SEM-EDX, and zeta potential measurements were employed to analyze the morphology, dimensions, and elemental composition of the generated nanoparticles. The experimental outcomes confirmed the presence of hexagonal wurtzite-structured ZnO NPs with an average size of 10 nm. The colloidal system demonstrated excellent stability with a zeta potential of -60 mV. Furthermore, the synthesized nanoparticles displayed significant antibacterial activity against selected human pathogens, with the biggest inhibition zone observed against Staphylococcus aureus (22 ± 0.57 mm) and the smallest inhibition zone observed against Salmonella enterica serovar typhi (3 ± 1 mm). MTT assay revealed the promising antiproliferative potential of ZnO NPs, with an average IC50 value of 98.53 µg/mL. Additionally, the NPs were photocatalytically and electrochemically analyzed, indicating their potential use in cancer research as well as in coating and drug delivery applications.

Assessing the combined effects of chemical and mechanical parameters on silar-grown nanostructured ZnO thin films

In the literature, a comprehensive assessment of the combined impacts of chemical and mechanical parameters on the properties of thin films grown by SILAR is missing. In this work, ZnO film formation is investigated under variable precursor concentration, pH, withdrawal speed and number of cycles. Interestingly, the produced ZnO films displayed remarkable aspect ratio and morphological variability, ranging from the commonly obtained nanograins shape towards hexagonal nanorods, flower- like rods and nanoneedles, which to our knowledge have not yet been achieved by using single step SILAR process. More particularly, low concentration and intermediate pH and withdrawal rates were favorable for nanorods formation. In addition, increasing the withdrawal speed from 26 to 30 cm·min-1 resulted in a thinner film with improved rod uniformity and reduced crystallite size. This is the first study on the impact of substrate withdrawal speed on SILAR films. Among all studied parameters, the number of cycles was particularly useful for tuning film thickness, while preserving its target shape. In addition, the films grown under a higher number of cycles showed improved film crystallinity and rod orientation with reduced dislocation density, microstrain and bandgap energy. In our conditions, the most suitable combination of parameters required for exhibiting optimized nanorod-shaped coating are: a concentration of 0.07 M, pH of 10.5, speed of 30 cm·min-1 and 40 cycles. In this case, XRD, XPS, Raman and FTIR spectra displayed typical features of hexagonal Wurtzite structure of ZnO with no impurities within the film surface, whereas AFM measured a thickness of 1.4 μm with 243 nm surface roughness.

Mechanical, Thermal, and Photocatalytic Properties of TiO₂/ZnO Hybrid Composites Fabricated via Additive Manufacturing

This study explores the fabrication and characterization of TiO₂/ZnO hybrid nanocomposites using stereolithography (SLA), a cutting-edge additive manufacturing technique. Hybrid composites were prepared by incorporating 0.5 wt.% nano-TiO₂ and varying ZnO concentrations (0.1 wt.%, 0.3 wt.%, and 0.5 wt.%) into an epoxy/acrylate-based resin. All composite samples were designed in SolidWorks, printed with an LCD-based SLA printer, and UV-cured for structural stabilization. A series of analyses were conducted to evaluate their morphological, mechanical, thermal, and photocatalytic properties. SEM analysis showed uniform particle dispersion at lower ZnO concentrations, while higher addded caused agglomeration. XRD confirmed the anatase phase of TiO₂ and the wurtzite structure of ZnO, ensuring their structural stability. TGA results showed improved thermal resistance for the hybrid composites compared to the pure resin, highlighting the synergistic effects of TiO₂ and ZnO in mitigating thermal degradation. Mechanical tests showed significant improvements in flexural strength and hardness, with the TZ5 composite (0.5% w/w TiO₂ and ZnO) showing the best performance due to optimum filler distribution. Photocatalytic tests showed superior Methylene Blue degradation for the hybrid composites, with TZ5 achieving the highest efficiency (80.9%) due to the synergistic effects of TiO₂ and ZnO. These results highlight the potential of SLA-manufactured composites for environmental and energy applications.

Improvement of the Electrical Properties of ZnO Nanomaterials with Fe by Co-precipitation Method

Fe-doped ZnO nanomaterials were prepared by the co-precipitation method. The experiments used a solution of 0.5 M for ZnCl2, doped with FeSO4 in proportions of 0-100 wt.%, followed by the addition of 1 M for NaOH solution until a pH of 12 was reached. Next, the precipitated substances were calcinated at 550ºC for 3 h in air. SEM image analysis showed that the nanoparticles formed in the condition of pure ZnO and Fe2O3 whereas rod-shaped formed with Fe doping. Nanoparticles of ZnO transformed into nanorods when doped with Fe. EDS analysis detected Fe under the conditions of 3 and 5 wt.% doping. XRD patterns of ZnO and all doping of Fe in ZnO nanostructures were corresponded to a hexagonal wurtzite structure of ZnO which showed crystallite size in the range of 25-29 nm. The electrical properties of Fe-doped ZnO nanostructures were identified by the spectroscope measurements of fluorescence and ultraviolet-visible absorption, and the electrical conductivity was calculated. It was found that Fe doping at 3 wt.% produced the lowest energy band gap (based on spectroscopy results) and this condition was associated with the highest electrical conductivity of 0.21 x 10-3 (Ω.cm)-1 which was calculated from the measurement of electrical resistance by two probes. Therefore, Fe doping can improve the electrical properties of ZnO nanostructures.

Photothermal Laser Printing of Sub-Micrometer Crystalline ZnO Structures.

During light-driven 3D additive manufacturing, an object represented in digital form is initially translated into a spatial distribution of light intensity (sequentially or in parallel), which then results in a spatial material distribution. To date, this process typically proceeds by photoexcitation of small functional molecules, leading to photochemically induced crosslinking of soft materials. Alternatively, thermal triggers can be employed, yet thermal processes are often slow and provide only low spatial localization. Nevertheless, sub-micrometer ZnO structures for functional microelectronic devices have recently been laser-printed. Herein, the photothermal laser-printing of ZnO is advanced by i) introducing single-crystalline rather than amorphous sub-micrometer ZnO shapes that crystallize in the hexagonal ZnO wurtzite structure, ii) employing dimethyl sulfoxide (DMSO) instead of water, enabling higher local process temperatures without micro-bubble formation, and iii) using substrates tailored for light absorption and heat management, resolving the challenge of light to heat conversion. Finally, the herein-demonstrated ZnO printing requires no post-processing and is a cleanroom-free technique for the fabrication of crystalline semiconductors.

Synthesis and Characterization of Optically Transparent and Electrically Conductive Mo-Doped ZnO, F-Doped ZnO, and Mo/F-Codoped ZnO Thin Films via Aerosol-Assisted Chemical Vapor Deposition.

Mo-doped ZnO (MZO), F-doped ZnO (FZO), and Mo/F-codoped ZnO (MFZO) films have been deposited using a simple, cheap, and effective thin-film preparation route, aerosol-assisted chemical vapor deposition (AACVD). ZnO was successfully doped with Mo and/or F, confirmed by X-ray photoelectron spectroscopy (XPS) and by a decrease in unit cell parameters from X-ray diffraction (XRD). XRD also confirmed that all of the films had hexagonal wurtzite ZnO structures. Scanning electron microscopy showed that all of the films had well-defined surface features. The undoped ZnO film had a high resistivity of ∼102 Ω·cm, determined by Hall effect measurements, and a visible light transmittance of 72%, determined by ultraviolet-visible (UV-vis)-IR spectroscopy. The transmittance of the doped and codoped films was improved to 75-85%. The ZnO film codoped with 6.2 atom% Mo and 3.6 atom% F, deposited at 550 °C achieved the minimum resistance (5.084 × 10-3 Ω·cm) with a significant improvement in carrier concentration (5.483 × 1019 cm-3) and mobility (21.78 cm2 V-1 s-1).

Impact of modified spin coating variations on electrical resistivity and UV detector responsivity in Mg-doped ZnO thin films

Impact of modified spin coating variations on electrical resistivity and UV detector responsivity in Mg-doped ZnO thin films

Synthesis of zinc oxide semiconductor nanoparticles using natural extract: a systematic evaluation of cationic dye photodegradation influenced by extract concentration, catalyst dose, and pH.

This work obtained zinc oxide nanoparticles (ZnO NPs) using organic components extracted from Waltheria americana at different concentrations. ZnO materials were subsequently applied in the photodegradation of two cationic dyes, Rhodamine B (RB) and methylene blue (MB), at different doses of catalyst and pH. The crystallinity and hexagonal Wurtzite structure of ZnO were established through XRD analysis. The Zn-O bond in the ZnO NPs was confirmed in the FTIR, with the characteristic signals observed in the fingerprint region at ~ 400cm-1. SEM and TEM revealed the formation of quasi-spherical particles with an average size ranging from 2 to 12nm, depending on extract concentrations during synthesis. UV-Vis studies indicated the optical bandgap of ZnO, with values below 3eV, also dependent on extract concentration. PL analysis revealed the recombination of free excitons and defects in ZnO. Photocatalytic studies of ZnO materials demonstrated excellent degradation efficiency of RB and MB dyes, which was influenced by the extract concentration of NPs, while the degradation of MB was enhanced with a 1:1 dye-to-catalyst ratio under acidic conditions. In contrast, due to RB more complex structure, an increased ratio of 1:1 to 1:3 and acidic pH conditions improved its degradation. Green-synthesized ZnO NPs using photocatalysis techniques exhibit significant potential as eco-friendly alternatives for removing contaminants from water.

Inverted Red Quantum Dot Light-Emitting Diodes with ZnO Nanoparticles Synthesized Using Zinc Acetate Dihydrate and Potassium Hydroxide in Open and Closed Systems.

We developed inverted red quantum dot light-emitting diodes (QLEDs) with ZnO nanoparticles synthesized in open and closed systems. Wurtzite-structured ZnO nanoparticles were synthesized using potassium hydroxide and zinc acetate dihydrate at various temperatures in the open and closed systems. The particle size increases with increasing synthesis temperature. The ZnO nanoparticles synthesized at 50, 60, and 70 °C in the closed system have an average particle size of 3.2, 4.0, and 5.4 nm, respectively. The particle size is larger in the open system compared to the closed system as the methanol solvent evaporates during the synthesis process. The surface defect-induced emission in ZnO nanoparticles shifts to a longer wavelength and the emission intensity decreases as the synthesis temperature increases. The inverted red QLEDs were fabricated with a synthesized ZnO nanoparticle electron transport layer. The driving voltage of the inverted QLEDs decreases as the synthesis temperature increases. The current efficiency is higher in the inverted red QLEDs with the ZnO nanoparticles synthesized in the closed system compared to the devices with the nanoparticles synthesized in the open system. The device with the ZnO nanoparticles synthesized at 60 °C in the closed system exhibits the maximum current efficiency of 5.8 cd/A.

Enhanced photocatalytic degradation of antiviral drugs lopinavir and ritonavir by Ni doped ZnO/SiO2 nanocomposites

Enhanced photocatalytic degradation of antiviral drugs lopinavir and ritonavir by Ni doped ZnO/SiO2 nanocomposites

Dual Eu3+ and Er3+ doping in ZnO nanoporous 2D frameworks for tuning photocatalytic activity, linear and non-linear optical response

Dual Eu3+ and Er3+ doping in ZnO nanoporous 2D frameworks for tuning photocatalytic activity, linear and non-linear optical response

Impact of Silver Incorporation and Flash-Lamp-Annealing on the Photocatalytic Response of Sputtered ZnO Films.

Thin films of silver-doped zinc oxide (SZO) were deposited at room temperature using a DC reactive magnetron co-sputtering technique using two independent Zn and Ag targets. The crystallographic structure, chemical composition and surface morphology of SZO films with different silver concentrations were correlated with the photocatalytic (PC) properties. The crystallization of the SZO films was made using millisecond range flash-lamp-annealing (FLA) treatments. FLA induces significant structural ordering of the wurtzite structure and an in-depth redistribution of silver, resulting in the formation of silver agglomerates. The wurtzite ZnO structure is observed for silver contents below 10 at.% where Ag is partially incorporated into the oxide matrix, inducing a decrease in the optical band-gap. Regardless of the silver content, all the as-grown SZO films do not exhibit any significant PC activity. The best PC response is achieved for samples with a relatively low Ag content (2-5 at.%) after FLA treatment. The enhanced PC activity of SZO upon FLA can be attributed to structural ordering and the effective band-gap narrowing through the combination of silver doping and the plasmonic effect caused by the formation of Ag clusters.

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

Effect of sputter power on red-shifted optoelectronic properties in magnetron sputtered Ag/ZnO thin films

This study explores Ag/ZnO thin films on glass (Corning 0211) substrates, which were deposited using dc/rf magnetron reactive sputtering at varying Ag-sputter powers. The impact of Ag-sputter power on physical properties, such as structural, surface, compositional, optical, and electrical properties, is systematically explored. Grazing angle x-ray diffraction affirms a single-phase hexagonal wurtzite ZnO structure in all films, predominantly oriented along (002) normal to the substrate. Thin films deposited at 90 W Ag-sputter power exhibit superior structural and morphological properties, including greatest crystallite and grain size, minimum stress, and roughness. Electrical studies indicate that the material exhibits a semiconducting nature, with its electrical resistivity decreasing to a minimum of 0.8 Ω cm at 95 W. At this level of Ag sputter power, the films demonstrate low resistivity, high mobility (0.49 cm2/V s), a charge carrier concentration of 9.6 × 1019 cm−3, and an optical transmittance of 79%, along with an optical band gap energy (Eg) of 3.06 eV. This underscores the influence of Ag sputter power in tailoring Ag/ZnO thin films for optoelectronic applications.

Investigating the dielectric and ferromagnetic behaviour of Ni and Co dual doped ZnO for diluted magnetic semiconductor

Herein, Ni/Co co-doped ZnO nanoparticles (NPs) were successfully prepared via chemical co-precipitation process. The structural, purity and crystallite size of as-prepared particles were confirmed by using x-ray diffraction (XRD). The results revealed the hexagonal wurtzite structure of ZnO without any impurity phase of as-prepared samples. The crystallite size decreased from 34.9 to 9.6 nm, whereas lattice strain reduced to 0.00086. The change in crystallite size, lattice parameters, strains and dislocation density further indicates the successful incorporation of dopants in ZnO host lattice. The dielectric properties, ac conductivity, and magnetic behaviour were steadily examined. The dielectric constant has been found to be 1070 with 5wt% at low frequency and become constant at higher frequency. It was revealed that dopant additions lead to attain high dielectric constant and low loss possibly attributed to interface polarization, and dipole polarization due to oxygen vacancy defects. M-H measurement observed that ferromagnetism at room temperature pure and doped ZnO samples. The ferromagnetic behaviour of pure ZnO NPs with Ms = 0.17 emu g−1, Mr = 0.11 emu g−1 and Hc = 67 which was increased to Ms = 0.85 emu g−1 and Mr = 0.65 emu/g for 5wt% Co. This improvement with increasing Co concentration indicates that oxygen defects may stabilize the ferromagnetic order. These interesting features encouraging to use this material for ultrahigh dielectric materials and spintronics.

Analysis of structural, dielectric, magnetic and impedance spectroscopy of ZnO/CuFe2O4 nanocomposites

The nanocomposites of ZnO/CuFe 2 O 4; abbreviated as (ZnO) x /(COF) 1-x (x; 10 ∼ 50 wt%) were prepared by powder mixing method. The x-ray diffraction pattern revealed the formation of nanocomposites (NCs) with inverse spinel structure of COF and hexagonal wurtzite structure of ZnO. The scanning electron microscope analysis depicts the nano-plates like morphology, non-homogenous mixing and agglomeration of particles. The dielectric properties and impedance spectroscopy of NCPs were measured by LCR meter in the frequency range of 1 kHz to 2 MHz. There is decrease in the real and imaginary parts of dielectric constant (ε′ and ε″) were observed with frequency, which is explained by Maxwell–Wagner’s polarization mechanism. The real and imaginary parts of impedance (Z′ and Z″) also show decreasing trend with frequency owing to increase in hopping of charge carriers that result in enhancement of a.c. conductivity (σ a.c ). The impedance spectroscopy shows a semicircular arc at higher frequency which is attributed to the conduction from grains. Finally, the vibrating sample magnetometer result showed the change in the magnetic nature of NCPs; as saturation magnetization (M s ) and coercivity (H c ) decreases substantially with incorporation of non-magnetic ZnO weight fractions.

3D printing flexible Ga-doped ZnO films for wearable energy harvesting: thermoelectric and piezoelectric nanogenerators

The 3D printing of energy harvesters using earth-abundant and non-toxic elements promotes energy sustainability and market competitiveness. The semiconducting behavior and non-centrosymmetric wurtzite crystal structure of gallium-doped zinc oxide (GZO) films make them attractive for thermoelectric and piezoelectric nanogenerators. This study investigates the thermal, structural, mechanical, thermoelectric, and piezoelectric properties of 3D-printed GZO nanocomposite films. Thermal analysis demonstrates the stability of the nanocomposite film up to 230 °C, making it suitable for wearable energy harvesters. The crystalline structure of the nanocomposite film aligns with the hexagonal wurtzite structure of ZnO and displays a bulk-like microstructure with a uniform distribution of elements. The presence of Ga 2p, Zn 2p, O 1 s, and C 1 s core levels confirms the development of the nanocomposite film, characterized by a fine granular structure and a conductive domain compared to the neat resin film. The inclusion of GZO nanofillers tailors the stress–strain behavior of the nanocomposite film, enhancing flexibility. The 3D-printed GZO nanocomposite films demonstrate a promising thermoelectric power factor and piezoelectric power densities, along with mechanical flexibility and thermal stability. These advancements hold significant potential for wearable and hybrid energy generation technologies.

Synthesis, Characterization, and Photocatalytic Activity of Magnetically Separable Fe3O4@SiO2@ZnO-Ag Composite Photocatalyst.

Magnetically separable Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO-Ag composites are synthesized using hydrothermal and wet chemistry methods. The samples obtained are characterized in terms of morphology, composition, optical, and magnetic properties using TEM, SEM-EDS, XRD, FTIR, VSM, XPS, and UV-vis, and the photodegradation of Acid Blue 161 dye under UV irradiation is investigated. As a result of SEM and TEM analyses, the diameters of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO-Ag composites are determined as 210, 220, 230 and 235nm, respectively. The magnetic properties of the samples are determined by VSM analysis. In VSM analyses, magnetization saturation values of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO-Ag composites are determined as 81, 64, 41 and 20 emus × g-1, respectively. In XRD analysis, the face-centered cubic structure of Fe3O4 particles and the hexagonal wurtzite structure of ZnO are determined and it is determined that they are compatible with standard diffraction cards. According to UV-Vis analysis, E g values for Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO-Ag composites are found as 1.3, 1.68, 2.21, and 2.15eV, respectively. Among the photocatalysts prepared, Fe3O4@SiO2@ZnO-Ag composite Acid Blue 161 shows superior removal and recyclability against photodegradation of the dyestuff.