Hexagonal Phase Structure Research Articles

Structural, optical and photocatalytic properties of pure and Pd-doped CdS thin films

Pure and palladium (Pd)-doped cadmium sulfide (CdS) thin films were deposited on glass substrate by successive ionic layer adsorption and reaction (SILAR) process with different doping concentrations. X-ray diffraction results confirmed the crystalline and hexagonal phase structure of prepared samples. The increase in the main diffraction peak (002) intensity with increasing Pd concentration revealed the substitution of Pd+2 with Cd+2 in the lattice. The crystallite size increased from 58.32 to 89.71 nm with Pd concentration. Morphology of the thin films shown that the average grain size increases by the agglomeration of nano-grains which become cluster of particles after Pd+2 incorporation. The energy bandgap of the CdS thin films is decreased from 2.44 to 2.37 eV with increasing Pd percentage. Photoluminescence (PL) spectra described that the pure and Pd-doped thin films show a broad PL emission peak associated to the transition of sulfur ion vacancy transfers to the valence band. Moreover, the Pd doping improved the film photostability as well as the photocatalytic degradation of methylene blue (MB).

The Green Synthesize of Zinc Oxide Catalyst Using Pomegranate Peels Extract for the Photocatalytic Degradation of Methylene Blue Dye

In this study, the zinc oxide NPs have been synthesized from the fresh pomegranate peels extract using the precipitation method. The ZnO nanoparticles were produced from the reaction of fresh peels extract with zinc acetate salt which was used as zinc source in the presence of 2 M NaOH. The green synthesized nanoparticles were characterized through X-ray diffraction (XRD), UV-Vis diffuse reflection spectroscopy, Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). The XRD patterns confirm the formation of hexagonal wurtzite phase structure for ZnO synthesized using pomegranate peels extract with average crystalline size of 28 nm. FTIR spectra identify the presence of many active functional groups for the pomegranate extract which is ideal to bind with zinc acetate to produce the ZnO nanoparticles during the preparation method. The reflection spectra of green synthesis ZnO with pomegranate extract observed a blue shift towards lower wavelength with (8 nm) difference compared to ZnO without the addition of any extract. The provenance of such blue shift towards shorter wave length was due to the quantum size effect. The Atomic force microscopic (AFM) result shows average roughness value for ZnO nanoparticles of 6.26 nm. The decolorization efficiency of the methylene blue dye was investigated using the ZnO nanoparticles under sun light irradiation and it was compared with the bare ZnO synthesized without the addition of extract. The catalytic activity was about 88% after 60 min of sunlight irradiation for both prepared catalyst however, the decolorization efficiency of ZnO with the addition of extract was higher at the first 16 min compared to bare ZnO.

The novel two step synthesis of CuO/ZnO and CuO/CdO nanocatalysts for enhancement of catalytic activity

In the present investigation, Copper oxide (CuO)/Zinc oxide (ZnO) and CuO/cadmium oxide (CdO) nanocomposites (NCs) were fabricated by a simple two-step process involving co-precipitation technique and hydrothermal approach for the first time. The Powder X-ray Diffraction (PXRD) pattern demonstrates the existence of monoclinic, hexagonal and cubic phase structure of CuO/ZnO and CuO/CdO NCs. The absorption spectrum of the material was obtained via UV–Visible Spectroscopy and the band-gap value is calculated using Tauc’s relation as 1.7 eV, 2.8 eV and 2.75 eV respectively for pure, CuO/ZnO and CuO/CdO NCs. The FESEM images gave the spherical and stone-like morphologies in the prepared CuO/ZnO and CuO/CdO NCs. At room temperature, CuO/ZnO and CuO/CdO NCs act as superior catalyst for the reduction of Rhodamine B (RhB) and Malachite Green (MG) dyes and degradation efficiency attained to be 77.26%, 73.15% for RhB and 79.82%, 74.69 for MG, respectively.

Degradation effect of temperature variation and dye loading g-C3N4 towards organic dyes

Graphitic Carbon Nitride (g-C3N4) have been synthesized through melamine by using hydrothermal method. In this paper work degradation organic dyes used such as MB, MO and Rh-B are used for water purification. Remarkably, it has been studied that the synthesis of (g-C3N4) along with factors of dye loading and temperature variation manipulating the photo-degradation process. We have prepared the g-C3N4 by hydrothermal method using a wide ranging of characterization techniques such as SEM, EDX, TEM, XRD, FTIR, UV, XPS and CV. The SEM morphology of g-C3N4 like nano spheres shapes are observed. EDX analysis are observed two peaks nitrogen and carbon. UV–visible analysis for the band gap calculated value is 2.74 eV. XRD observed the peak 27.9° that the hexagonal phase structure with the miller indices (002). FTIR analysis the functional groups. CV studied for the specific capacitance. Furthermore, we have studied the efficiencies in these organic dyes MO 97.3%, MB 91.1% and Rh-B 99.6%. These efficiencies was obtained vary the dye loading. Hence, g-C3N4 can be well-thought-out as a potential candidate these pollutants as MO, MB and Rh-B for the water purification.

Solar-Blind Photodetector with Lower Dark Current and Higher Ilight/Idark Ratio Based on Mg0.38Zn0.62O Film Deposited by Pulsed Laser Deposition Method.

In this study, pulsed laser deposition method (PLD) was employed to grow MgxZn1-xO films on quartz substrates. The optimal deposition temperature of 300 °C for MgxZn1-xO film was decided and Mg0.38Zn0.62O, Mg0.56Zn0.44O and Mg0.69Zn0.31O films were grown respectively using MgxZn1-xO targets with different Mg contents (x = 0.3, 0.5 and 0.7). As-deposited Mg0.38Zn0.62O film possessed the mixed-phase (hexagonal and cubic phase) structure, appropriate band gap of 4.68 eV and smaller surface roughness of 1.72 nm, and the solar-blind photodetector (PD) based on it was fabricated. The key features of our PD are the cutoff wavelength of 265 nm lying in solar-blind band, lower dark current (Idark) of 88 pA, higher peak responsivity of 0.10 A/W and bigger Ilight/Idark ratio of 1688, which provide the new idea for the application of solar-blind PDs based on MgxZn1-xO films.

Magnetic properties of Cu and Al doped nano BaFe12O19 ceramics

The BaCuxFe12-xO19 and BaAlxFe12-xO19 (x = 0.0, 0.4, 0.8, 1.2) materials were prepared via sol-gel auto combustion technique. Further, the X-ray diffraction patterns suggested the formation of single phase hexagonal structure. This work is aimed to study the effect of diamagnetic and paramagnetic elements on magnetic characteristics of BaFe12O19. The results established that in the case of diamagnetic (Cu) substitution, the saturation magnetization was increased and decreased alternatively. Furthermore, it was noticed that the coercivity values of all doped samples were lower than those of undoped samples. But the replacement of Fe3+ with paramagnetic (Al) element led to a decrease in saturation magnetization and to a significant increase in the coercive field.

Co-existence of Ferroelectric and Ferromagnetic Properties of Bi+3 Substituted M-type Barium Hexaferrites

Co-existence of ferroelectric and ferromagnetic nature in bismuth substituted M-type barium hexaferrites has been investigated in this current project. A series of samples with formula BaBixFe(12-x) (where x varies from 0.2 to 1.2 with step size of 0.2) have been prepared by conventional powder metallurgy route. The structural, functional group analysis, surface morphology, optical, dielectric, ferroelectric, and ferromagnetic properties of samples are characterized using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV-visible spectroscopy (UV-Vis), LCR meter, ZT-IA, and vibrating sample magnetometer (VSM) respectively. XRD and FTIR confirm the single phase of hexagonal structure of bismuth doped M-type barium hexaferrite. The platelet like structures is observed on the surface of the samples. The optical band gap energy decreases due to the formation of intermediate states between the valence and conduction bands as the concentration of Bi ions increases. The variation in dielectric constant and ac conductivity depends upon the frequency of the applied field as well as the composition of the samples. P-E loop shows clear ferroelectric behavior. The maximum saturation polarization of 5.42 μC/cm2 is observed. The presence of FeO6 octahedron at three (12 k, 2a, and 4f2) crystallographic sites in the hexagonal unit cell is the origin of induced polarization. Magnetic properties reveal the strong ferromagnetism of bismuth doped M-type barium hexaferrite at room temperature.

Lead-free perovskite and double perovskite solar cells

The toxicity and instability of lead-halide perovskite materials in the solar cells are yet demands must be resolved to vie to find alternatives of free lead-based halide perovskites and double perovskite materials. Here we report on the experimental synthesis of a new family of lead-free inorganic halide double perovskites Cesium copper antimony chloride (Cs2CuSbCl6) and perovskite Cesium copper chloride (CsCuCl3) as a based sensitizer of the solar cells and studies of its characterize and optical properties of the Photo-Voltaic (PV) device. The configuration structural of PV devices is (FTO/TiO2/CsCuCl3 or Cs2CuSbCl6/Cu2O/Al electrode). The double perovskite Cs2CuSbCl6 and Perovskite CsCuCl3 are successfully synthesized, performed of structural investigations by X-ray diffraction, and depicted of optical properties via optical absorption of UV−vis measurement. The perovskite (CsCuCl3) belongs to the space grope P6122 and the Hexagonal structure phase. The strongest peeks of the XRD diffraction pattern of the double perovskite Cs2CuSbCl6 are taken at the reflection points (-201), (-202), (-3-11), (220), (-223) and (-5-34). From UV−vis measurements obtained values of a direct gap of both (Cs2CuSbCl6) and (CsCuCl3) are (1.5 and 2.2) eV, respectively. The optimum power conversion efficiency (PCE) of the PV device which used Cs2CuSbCl6 as a sensitizer is 0.94%, the filling factor is 24%, the open-circuit voltage is 582.5 mV and the short circuit current was 2.656 mA. The measurement is carried out under one sun intensity illumination (1000 W/m2).

Structural, morphological and photoluminescence behaviour of Sr10-xBax(PO4)6(OH)2 hydroxyapatite

This paper reports synthesis of Sr10-x(PO4)6(OH)2 with different concentration of Ba2+ ion by co-precipitation method. To enhance the intensity of photoluminescence properties of strontium hydroxyapatite, barium (Ba2+) ions are incorporated into hydroxyapatite structure. XRD pattern analysis shows single phase hexagonal structure along with space group P63/m. SEM image depicts the deposition of apatite layer on the surface of agglomerated spheroidal grains. FTIR analysis reveals the presence of functional group (PO4) in the synthesized hydroxyapatite. Photoluminescence spectra shows an intense green light emission at 523 nm under 230 nm UV light irradiation.

A novel upconversion emission material based on Er3+ - Yb3+ - Mo6+ tridoped Hydroxyapatite/Tricalcium phosphate (HA/β-TCP)

In this paper, a novel material based on Er-Yb-Mo tri-doped HA/β-TCP phosphor for intense green up-conversion (UC) emission was successfully synthesized by solid-state reaction method. X-ray diffraction (XRD) measurements verified that the materials including a trace amount of HA phase has a hexagonal structure and main β-TCP phase has a rhombohedral structure, which is controlled by the doped ions. Under excitation wavelength of 976 nm laser diode, the HA/β-TCP:Er-Yb-Mo phosphor showed strong green UC emission band at 520/556 nm and weak red emission band at 656 nm which are attributed to (2H11/2, 4S3/2) - 4I15/2, 4F9/2 - 4I15/2 transition of the Er3+ ion, respectively. Remarkably, compared with the sample without Mo6+, the green emission intensities increased ∼650 times was achieved by using Er3+-Yb3+-Mo6+ doped phosphor. The high efficiency of the UC can be attributed to novel energy transfer process from |2F7/2, 3T2> state of Yb3+ - MoO42− dimer to the 4F7/2 of Er3+ ions. Moreover, the grain orientations due to the effect of Mo6+ ions doped in β-TCP phosphor could play an important role in the enhancement of UC emission intensity. These results indicate that the HA/β-TCP: Er-Yb-Mo phosphor has potential application in biological imaging and medicine.

Effect of reaction temperature and reaction time on the structure and properties of MoS2 synthesized by hydrothermal method

AbstractIn this study, molybdenum disulfide (MoS2) nanostructures were synthesized by a facile hydrothermal process, using ammonium heptamolybdate tetrahydrate ((NH4)6Mo7O24.4H2O) and thiourea (CH4N2S) as the reactants. The effects of experimental parameters including reaction temperatures and reaction times on the structure and morphology of MoS2 have primarily been investigated. The morphology, microstructure, chemical composition and optical properties of as‐synthesized MoS2 were characterized using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), energy dispersive X‐ray spectroscopy (EDS), X‐ray diffraction (XRD), Raman and Photoluminescence spectroscopy. The FESEM and TEM results indicate that depending on the reaction temperature, the three types of morphologies of MoS2 crystals could be obtained. Morphologies of MoS2 changed gradually from aggregated particles to flake‐like structure, then finally to nanosheet morphology with increasing reaction temperature from 160 to 220 oC. However, it was found that the reaction time contributed significantly to the restacking and refinement of MoS2 crystal structure, rather than affecting the morphology of the investigated samples. Both XRD and Raman investigations reveal that the as‐synthesized MoS2 has a hexagonal phase structure (2H‐MoS2). Interestingly, the as‐prepared MoS2 nanosheets exhibit photoluminescence in the visible range with the emitted photon energy of ~1.81 and ~1.95 eV, these properties make MoS2 a promising candidate as the material of choice for next‐generation optoelectronic and photonic devices.

Thermally induced structural metamorphosis of ZnO:Rb nanostructures for antibacterial impacts

In this work, we report on the synthesis of pure and Rb doped ZnO (ZnO:Rb) nanoparticles by a simple combustion technique followed by thermal treatment in an open-air atmosphere. The prepared samples were characterized using UV–vis spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), photoluminescence, Raman spectroscopy and scanning electron microscopy. The wurtzite hexagonal phase structure of ZnO and a secondary phase of Rb2ZnO2 was observed after doping ZnO with Rb. FTIR and DSC confirmed the functional groups and the thermal stability of the ZnO samples. Field emission scanning electron microscope showed an irregular shaped agglomerated morphology for the ZnO:Rb samples. The chemical states of the undoped and Rb doped samples were identified using X-ray photoelectron spectroscopy for both pure and ZnO:Rb samples. In addition, ZnO:Rb samples exhibit good antimicrobial activities against Bacillus subtilis with a change in antibacterial behaviour as compared to pure ZnO structures indicating their multifunctional applications.

Microwave absorbing properties of Y2Fe16Si micropowders with broad bandwidth and strong absorption

The rare earth-Fe intermetallic compounds with planar magnetocrystalline anisotropy were deemed as hopeful candidates for microwave absorption owing to their higher Snoek’s limit as compared to the cubic spinel-type ferrites. In this work, The Y2Fe16Si alloy was massively produced through strip casting technique, and the microwave absorbing properties of Y2Fe16Si-paraffin composites were studied. The Y2Fe16Si alloy exhibits a single phase of hexagonal Th2Ni17-type structure with a planar magnetocrystalline anisotropy and has a saturation magnetization of 121 emu g−1. It was found that electromagnetic dissipation contributes to microwave absorption but is not the determinative factor in Y2Fe16Si-paraffin composites. Controlling the values of the complex permittivity and the complex permeability in a reasonable range can lead to proper impedance matching. Thus excellent microwave absorbing properties can be obtained. The sample with the mass ratio of 3:1 between Y2Fe16Si and paraffin displays high performance ascribed to its appropriate values of complex permittivity and permeability. A minimum reflection loss (RL) of −51.6 dB is obtained with a thickness of 1.8 mm. Full covers of the effective bandwidth (RL < −10 dB) on the X-band and the Ku-band are achieved when the thicknesses are 1.9 mm and 1.38 mm, respectively. Hence, Y2Fe16Si exhibits excellent potential as a high-performance microwave absorbing material.

Structural and Optical Properties of Mn doped ZnS Nanoparticles: Sol-gel and Quantum Chemical Studies

A bstract - In the present work, undoped and Mn-doped ZnS nanoparticles (ZnS:Mn) were growth by the spin coated method at room temperature. The concentration of the Mn ions was changed from 2 to 6%. Different analytical techniques including were used to investigate the influence of Mn concentration on optical properties of produced thin films. In summary, the influence of Mn doping on the optical properties of un-doped ZnS thin films was reported. These results were also compared to the ZnS:Mn thin films produced by different techniques. In UV-Vis. studies, the band gap energy was found to be 3.5–3.8 eV depending on the Mn doping ratio. In addition, undoped and Mn-doped ZnS nanoparticles were theoretically performed as a cluster by semi empirical calculations. In these calculations, the Zn 7 S 7 and Zn 5 Mn 2 S 7 were optimized as a hexagonal wurtzite phase structure by semi-empirical pm6 level. The theoretical band gaps for both molecules were calculated with same method.

Effect of anions on the structural,morphological and dielectric properties of hydrothermally synthesized hydroxyapatitenanoparticles

Synthetic nano hydroxyapatites (HA) have been considered aspotential biomaterials for bone tissue engineering applications because of itsexcellent biological properties. The present work deals with the synthesis of HAnanoparticles from different anion source materials via autoclave assistedhydrothermal method. All the prepared HA nanoparticles were characterized byX-ray diffraction (XRD), Fourier transformation infrared spectra, field emissionscanning electron microscopy, energy dispersive spectra and high resolutiontransmission electron microscopy. The XRD patterns reveal the pure and hexagonalphase structure with smaller crystallite size for HA obtained from variouscalcium salt precursors. HA particles prepared from nitrate precursors showspherical morphology with 32 nm grain size whereas those derived from theacetate, chloride and egg shell precursors respectively show needle-like,irregular and oval morphology. The effect of different anions on the dielectricproperties and alternating conductivity of HA is investigated, as a polarizedsurface can trigger biological reactions. For the particles obtained fromnitrate, acetate, chloride and egg shell precursors respectively give dielectricconstant (εʹ) values of 9.96, 13.22, 9.92 and 10.86 at 5 MHz. The εʹ anddielectric loss (εʹʹ) values for the HA nanoparticles decrease with increase inthe applied frequency as well. The alternating current conductivity valuesconfirm that the as-synthesized HA samples exhibit insulating behavior. In shortthis article provides the various applicability of HA particles inoptoelectronics and drug delivery.Graphic abstract

Enhanced maximum energy product of (Sm1–yYy)2Fe17Nx caused by abundant yttrium doping

Replacement of samarium (Sm) with abundant yttrium (Y) can help solve the potential shortage of Sm in the preparation of promising Sm2Fe17Nx magnets. In this article, phase composition, microstructure and magnetic properties of (Sm1–yYy)2Fe17Nx (y = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were investigated. Maximum energy product (BH)max is improved when less than 40 at% Y is doped in (Sm1–yYy)2Fe17Nx powder. In particular, when 20 at% Y replaces Sm, (BH)max of (Sm1–yYy)2Fe17Nx powder increases by 15.1% from 131.7 to 151.6 kJ/m3. The effect of annealing temperature on the structural properties of high Y doping (Sm0.6Y0.4)2Fe17 and the magnetic properties of the corresponding nitrides were subsequently investigated. In the RE2Fe17 phase grain combination process, the interlaced structure of the rhombohedral Th2Zn17-type structural phase and the hexagonal Th2Ni17-type structural phase is formed. Due to short-range exchange coupling, the nitride with the highest content of two interlaced RE2Fe17 phases has the highest magnetic properties: Br = 1.23 T, HcJ = 443.9 kA/m and (BH)max = 197.6 kJ/m3.

Biopolymer K-carrageenan wrapped ZnO nanoparticles as drug delivery vehicles for anti MRSA therapy

Kappa-Carrageenan wrapped ZnO nanoparticles (KC-ZnO NPs) was synthesized, physico-chemically characterized and evaluated their biocompatibility and antimicrobial therapy against MRSA. XRD showed the highly crystalline and hexagonal phase structure of ZnO NPs. FETEM confirmed the spherical and hexagonal shaped particle with the mean size of 97.03 ± 9.05 nm. The synthesized KC-ZnO NPs exhibited significant antibacterial activity against MRSA. The biofilm growth of MRSA was greatly inhibited at 100 μg/ml as observed through live and dead cell assay. KC-ZnO NPs have shown invitro anti-inflammatory activity (82%) at 500 μg/ml. KC-ZnO NPs was non-toxic to NIH3T3 mouse embryonic fibroblasts cell lines. Further, no apoptotic and necrotic mediated death in NIH3T3 mouse embryonic fibroblasts cells were noticed by flow cytometric analysis. KC-ZnO NPs have good biocompatibility as recorded by the least hemolysis percentage (<3%) up to 100 μg/ml, which is much lesser than the acceptable limit. In addition, ecosafety analysis has shown that KC-ZnO NPs and kappa karrageenan (0–500 μg/ml) caused no mortality of A. salina after 48 h. However, bare zinc acetate has shown 35% mortality of A. salina after 48 h. The results conclude that KC-ZnO NPs could be a novel antibacterial therapy for the treatment of MRSA associated infectious.

Studies on the catalytic activity of CuO/TiO2/ZnO ternary nanocomposites prepared via one step hydrothermal green approach

In the present investigation, CuO/TiO2/ZnO ternary nanocomposites (CTZ TNCs) were developed via one-step hydrothermal green approach using Delonix regia flower extract. The monoclinic, tetragonal and hexagonal wurtzite phase structures were observed from the CTZ TNCs, which was primarily identified by the PXRD pattern. The structural defects and crystal nature was demonstrated by the Raman analysis. The individual prominent Raman modes of CuO, TiO2 and ZnO were observed from the CTZ TNCs. The morphological study was investigated by using Field Emission Scanning Electron Microscope (FESEM) analysis. From the FESEM analysis, needle like structure was observed from the prepared material of CTZ TNCs and size was achieved around to be 50–200 nm. At room temperature, ternary CTZ NCs acts as an excellent catalyst for reduction of 4-nitrophenol (4-NP), Methylene Blue (MB) and Crystal violet (CV) dyes and degradation efficiency achieved to be 95.48%, 94.84% and 82.18%, respectively.

Discovering the root of the stability of hexagonal WO3 surfaces from a periodic DFT perspective

DFT periodic calculations were carried out in order to gain more insight in relation with the stability of the (0 0 1) and (1 0 0) surfaces of the hexagonal WO3. These surfaces display an uncommon instability which could be attributed to their high polarity and the intrinsic instability problems of the hexagonal phase. Indifferently of the slab thickness, the internal structure of the slabs suffers distortion even at levels of a total loss of the hexagonal phase structure. Stoichiometric and non-stoichiometric O reconstructions do not seem to be practical mechanisms to solve the instability problem of these surfaces, leaving only the partial frozen slabs an efficient way to model the hexagonal (0 0 1) and (1 0 0) surfaces. However, the surface energy of these surfaces is dependent of the optimized layers instead of the frozen ones. Results obtained for the CO adsorption on the (0 0 1) surface showed that a model with six layers and two internal layers frozen to the atomic position of the bulk structure is enough to reach the structural and energetic stability of the CO adsorption.

Effect of Sintering Temperatures on Structural, Magnetic and Microwave Properties of Barium Ferrites/Epoxy Composites

This research highlights the structural magnetic and microwave properties of nanoparticles of M-type hexagonal barium ferrites (BaFe12O19). The samples were sintered at varied sintering temperatures (800, 900, and 1000 °C). The effect of temperatures on the structural, magnetic and microwave properties was highlighted. Barium ferrites are well-known materials used for radar absorbing materials (RAM). RAM materials with good absorbing performance should have high permeability, small permittivity and high magnetic or dielectric loss at microwave frequency. High microwave absorption can be created effectively in magnetic materials, as well as wideband absorption. The structural, microstructural and microwave properties were analyzed via an X-ray Diffractometer (XRD), a Field Emission Scanning Electron Microscope (FESEM) and a Vector Network Analyzer (VNA), respectively. The XRD results showed a full phase hexagonal structure was formed in the samples sintered at 900 and 1000 ºC. BaFe12O19 composite with a thickness of 3 mm showed a minimum Reflection Loss (RL) at −9.01 dB at a frequency of 9.16 GHz at temperature 1000 ºC.