Green synthesis and characterization of zinc oxide nanoparticles using bush tea (Athrixia phylicoides DC) natural extract: assessment of the synthesis process.

Background: Nanoparticles are globally synthesized for their antimicrobial, anti-inflammatory, wound healing, catalytic, magnetic, optical, and electronic properties that have put them at the forefront of a wide variety of studies. Among them, zinc oxide (ZnO) has received much consideration due to its technological and medicinal applications. In this study, we report on the synthesis process of ZnO nanoparticles using Athrixia phylicoides DC natural extract as a reducing agent. Methods: Liquid chromatography–mass spectrometry (LC-MS) was used to identify the compounds responsible for the synthesis of ZnO nanoparticles. Structural, morphological and optical properties of the synthesized nanoparticles have been characterized through X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Results: LC-MS results showed that different flavonoids and polyphenols, as well as Coumarin, an aromatic compound, reacted with the precursor to form ZnO nanoparticles. XRD and UV-Vis analysis confirmed the synthesis of ZnO nanoparticles, with a spherical shape showed in SEM images. The quasi-spherical ZnO crystals had an average crystallite size of 24 nm. EDS and FTIR analysis confirmed that the powders were pure with no other phase or impurity. Conclusions: This study successfully demonstrated that the natural plant extract of A. phylicoides DC. can be used in the bio-reduction of zinc nitrate hexahydrate to prepare pure ZnO nanoparticles, thus, extending the use of this plant to an industrial level.

Tracking the changes in the structural, optical and photoluminescent properties of CuCo2O4/MnS nanocomposites with different composition ratios

(1−x)CuCo2O4/xMnS (x = 0, 0.25, 0.5) nanocomposite samples were formed using hydrothermal and thermolysis procedures. X-ray diffraction (XRD) phase analysis showed the formation of only CuCo2O4 phase necessitating the inclusion of Mn and S ions into the CuCo2O4 lattice. Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the presence of Mn and S ions in the nanocomposite samples. Rietveld refinement method was applied to determine the cation distribution of the different ions between different sites. The cell parameter (a) has no fixed trend of change. The average crystallite size is almost the same for all samples with an average of 15 nm. The effect of insertion of Mn and S ions into the CuCo2O4 on the diffused absorbance, extinction coefficient, refractive index, dielectric properties, and nonlinear optical parameters was discussed in detail. The pristine CuCo2O4 nanoparticles have two direct optical band gaps (1.65, 2.74) eV which are decreased to (1.59, 2.56) and (1.58, 2.54) eV for the MnS content x = 0.25 and 0.5, respectively. The two indirect optical band gaps of pristine CuCo2O4 changed irregularly as the MnS amount increased in the nanocomposite. The PL spectrum of CuCo2O4 is shifted to higher wavelength in the visible region upon alloying with MnS. The photoluminescence (PL) intensity of the nanocomposite samples is smaller than that of CuCo2O4 sample. The emitted PL colors depended on the amount of Mn and S ions in the CuCo2O4 matrix.

Сегнетоэлектрические свойства гетероструктуры Sr-=SUB=-0.5-=/SUB=-Ba-=SUB=-0.5-=/SUB=-Nb-=SUB=-2-=/SUB=-O-=SUB=-6-=/SUB=-/Ba-=SUB=-0.2-=/SUB=-Sr-=SUB=-0.8-=/SUB=-TiO-=SUB=-3-=/SUB=-/Si(001)

The properties of c-oriented thin films Sr0.5Ba0.5Nb2O6 grown on a Si(001) (p-type) substrate with a pre-deposited Ba0.2Sr0.8TiO3 layer were studied using scanning probe microscopy and dielectric spectroscopy. It is established that the films Sr0.5Ba0.5Nb2O6 are characterized by low surface roughness (less than 6 nm), average crystallite size 93 nm. It is shown that there is spontaneous polarization in the film directed from its surface to the substrate, which caused the manifestation of the field effect for the case of the Si substrate with p-type conductivity without external field effect. Differences in the magnitude of the surface potential signal for regions polarized by an external electric field of different polarities (+10 and −10 V), as well as in their relaxation to the initial state, are revealed. The reasons for the established patterns are discussed.

Insight into Structural and Optical Properties of Pristine and Sr2+ Doped La2NiMnO6

Double perovskites oxide (DPO) multiferroics La2-xSrxNiMnO6(x=0.0, 0.1, 0.2, 0.4, 0.6) are synthesized by sol-gel technique. The structural, optical and electrical (both DC and AC) properties of La2-xSrxNiMnO6 have been investigated by XRD and FTIR spectroscopy and two-probe resistivity and dielectric measurements as a function of temperature, respectively. The effect of doping of Strontium at A-site in double perovskites is discussed. XRD has revealed the formation of monoclinic structure of La2-xSrxNiMnO6 with space group P21 / n for x=0.0 and P21 for x=0.1, 0.2, 0.4, 0.6. The average crystallite size has been calculated to be in the range 31 to 46 nm as determined by Debye Scherrer equation. Infrared active optical phonons observed from reflectivity spectra have been analysed fitting the theoretical oscillators using Lorentz oscillator model. We have observed several well-resolved phonon modes in La2-xSrxNiMnO6 with increasing dopant concentration. Activation energy calculated using Arrhenius Plot is in the range of 0.31 to 0.18 eV, confirming the semiconducting nature of all samples. The dielectric constant and tangent loss as a function of temperature and frequency are also discussed for these multiferroics.

Dielectric spectroscopy of aluminum oxide (γ-Al2O3)

Aluminum oxide (Al2O3) are continuously demonstrating the functional characteristics in devices. The physiochemical properties of hydrothermally as-grown Aluminum oxide (Al2O3) have been investigated in this research article. The as-prepared material was confirmed as γ- phase formation of Al2O3. The average crystallite size was found ∼ 78 nm, whereas the particles were found in nano scale too. Moreover, the absence of impurity in EDS analysis, and the presence of the bending vibrations of Al-O-Al and Al-O band in FTIR characterization further confirmed the absence of impurity in the material. Evaluated dielectric properties such as a relatively high dielectric constant, and low dielectric loss indicated the good optical quality of γ- Al2O3. Impedance and modulus spectroscopic studies showed the non-Debye type relaxation in γ- Al2O3 with an average relaxation time of 5.8 μs. Overall, the dielectric spectroscopy analysis of γ- Al2O3 indicates the promising applications of γ- Al2O3 in devices as dielectrics.

Thermally driven structural phase transformation and dislocation density of CdS nanoparticles precipitated without surfactant in KOH alkaline medium

The present research demonstrates a detailed discussion for the effect of annealing temperature on the structural transformation and surface morphology of the CdS nanoparticles synthesized using the precipitation method without surfactant in KOH alkaline medium. The annealing temperature used was in the range of 160 – 480 oC. The samples structural, functional group and morphological properties were investigated by using XRD, FTIR and SEM techniques. XRD analysis reveals that the CdS has gradually been transformed from the pure cubic to hexagonal polycrystalline structure as well as improved crystallinity upon increasing the temperature. Besides, the parameters of average crystallite size and dislocation density were calculated using the established Debye- Scherrer equation. The average crystallite size was in nano-dimension and increases gradually with temperature. The FTIR spectra indicate that the characteristic vibration band of CdS emerged in the lower wavenumber region of 650 and 500 cm-1, and the band becomes stronger as the temperature rises. Also, the SEM images demonstrate that the CdS exhibits uniform spherical morphology and the particle size grows larger at elevated temperatures. The improved crystallinity and structural properties tuning ability against temperature allows beneficial optical applications as solar cells, photocatalysts, non-linear optics, light emitting diodes and optoelectronic devices.

Sol-Gel Synthesis, Structure, Morphology and Magnetic Properties of Ni0.6Mn0.4Fe2O4 Nanoparticles Embedded in SiO2 Matrix

The structure, morphology and magnetic properties of (Ni0.6Mn0.4Fe2O4)α(SiO2)100−α (α = 0–100%) nanocomposites (NCs) produced by sol-gel synthesis were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM) and vibrating sample magnetometry (VSM). At low calcination temperatures (300 °C), poorly crystallized Ni0.6Mn0.4Fe2O4, while at high calcination temperatures, well-crystallized Ni0.6Mn0.4Fe2O4 was obtained along with α-Fe2O3, quartz, cristobalite or iron silicate secondary phase, depending on the Ni0.6Mn0.4Fe2O4 content in the NCs. The average crystallite size increases from 2.6 to 74.5 nm with the increase of calcination temperature and ferrite content embedded in the SiO2 matrix. The saturation magnetization (Ms) enhances from 2.5 to 80.5 emu/g, the remanent magnetization (MR) from 0.68 to 12.6 emu/g and the coercive field (HC) from 126 to 260 Oe with increasing of Ni0.6Mn0.4Fe2O4 content in the NCs. The SiO2 matrix has a diamagnetic behavior with a minor ferromagnetic fraction, Ni0.6Mn0.4Fe2O4 embedded in SiO2 matrix displays superparamagnetic behavior, while unembedded Ni0.6Mn0.4Fe2O4 has a high-quality ferromagnetic behavior.

Boost the Crystal Installation and Magnetic Features of Cobalt Ferrite/M-Type Strontium Ferrite Nanocomposites Double Substituted by La3+ and Sm3+ Ions (2CoFe2O4/SrFe12−2xSmxLaxO19)

Spinel cobalt ferrite/hexagonal strontium hexaferrite (2CoFe2O4/SrFe12−2xSmxLaxO19; x = 0.2, 0.5, 1.0, 1.5) nanocomposites were fabricated using the tartaric acid precursor pathway, and the effects of La3+–Sm3+ double substitution on the formation, structure, and magnetic properties of CoFe2O4/SrFe12−2xSmxLaxO19 nanocomposite at different annealing temperatures were assayed through X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. A pure 2CoFe2O4/SrFe12O19 nanocomposite was obtained from the tartrate precursor complex annealed at 1100 °C for 2 h. The substitution of Fe3+ ion by Sm3–+La3+ions promoted the formation of pure 2CoFe2O4/SrFe12O19 nanocomposite at 1100 °C. The positions and intensities of the strongest peaks of hexagonal ferrite changed after Sm3+–La3+ substitution at ≤1100 °C. In addition, samples with an Sm3+–La3+ ratio of ≥1.0 annealed at 1200 °C for 2 h showed diffraction peaks for lanthanum cobalt oxide (La3Co3O8; dominant phase) and samarium ferrite (SmFeO3). The crystallite size range at all constituent phases was in the nanocrystalline range, from 39.4 nm to 122.4 nm. The average crystallite size of SrFe12O19 phase increased with the number of Sm3+–La3+ substitutions, whereas that of CoFe2O4 phase decreased with an x of up to 0.5. La–Sm co-doped ion substitution increased the saturation magnetization (Ms) value and the subrogated ratio to 0.2, and the Ms value decreased with the increasing number of double substitutions. A high saturation magnetization value (Ms = 69.6 emu/g) was obtained using a La3+–Sm3+ co-doped ratio of 0.2 at 1200 for 2 h, and a high coercive force value (Hc = 1192.0 Oe) was acquired using the same ratio at 1000 °C.

Thermal and optical behavior of novel phosphate-based inorganic mixtures containing Fe and Na and their application as solar reflective coating

Herein, the synthesis of the novel and inexpensive phosphate mixtures (calcined and non-calcined) of iron (Fe) and sodium (Na) and their application as reflective coating with building envelope materials is reported. The main objective of this work is to determine the effect of hydrated mixtures as a reflective coating. To obtain different hydrated mixtures, samples were synthesized as both calcined and non-calcined mixtures. Various measurement techniques were used to characterize and study the thermal behavior of mixtures. From the thermal behavior of the mixtures, it is noticed that the mixtures can be used as heat-dissipating materials. The average crystallite size was found 40.18 nm and 25.48 nm for the calcined and the non-calcined mixtures, respectively. The calculated band gap for the calcined mixture is 3.71 eV and the non-calcined mixture is 3.73 eV. According to Reddy's equation, the refractive index of the calcined and the non-calcined mixtures is 2.61 and 2.60, respectively. Both the calcined (1A) and the non-calcined (1B) mixtures were fabricated with commercial white paint to develop aesthetic light gray coatings. Both coatings were painted and tested on two building material slabs separately. Then, the highest reflective coating material between these two was painted on a house prototype and tested against commercial gray paint available in the market. An average temperature reduction of 3.8 K was observed in modified gray coating compared to commercial building paint. The reflective coating of the calcined mixture blended with white paint was observed to be better than the non-calcined mixture blended with white paint.

Investigation of the Optical, Structural and Compositional Properties of Electrodeposited Lead Manganese Sulfide (PbMnS) Thin Films for Possible Device Applications

The properties of PbMnS semiconductor thin films deposited on fluorine-doped tin oxide (FTO) substrate using an electrodeposition method are investigated to determine their possible device applications. Lead acetate, manganese sulfate, and thiourea were used as precursors for sources of lead, manganese, and sulfur ions respectively. The concentration of lead, manganese, and sulfur ions sources with deposition voltage of 1.8 V was kept constant. The films were deposited using three electrodes system of electrodeposition method by varying deposition time. The films were characterized for optical, structural, morphological, and compositional properties and results showed that the absorbance, refractive index, and optical conductivity of the films are high in the visible (VIS) and near-infrared (NIR) regions but decreases in the NIR. These three properties initially increased with an increase in deposition time up to a time of 70 s which has the highest values of these properties before decreasing to lower values. The transmittance and extinction coefficient of the films are low in both VIS and NIR regions. The bandgap energy of PbS was found to be blue shifted with values of 1.51 eV, 1.54 eV, 1.60 eV, 1.45 eV, and 1.35 eV for the films deposited at 30 s, 50 s, 70 s, 90 s, and 110 s respectively. XRD analysis showed that the films are crystalline with sharp peaks positions indexable to crystalline planes of (111), (200), (211), (220), (311) and (400) with average crystallite size in the range of 16.110 nm to 17.218 nm. Energy-dispersive X-ray spectroscopy (EDX) results showed that the films are composed of lead, manganese, and sulfur but there are some impurity elements present mostly as a result of the substrate used. These properties exhibited by the deposited thin films of PbMnS showed that they can be used for many optoelectronic applications such as photovoltaic cells, sensors, photoconductors, etc.