Biosynthesis of silver nanoparticles by banana pulp extract: Characterizations, antibacterial activity, and bioelectricity generation

Here, green banana pulp extract (PE) has been used as a bio-reducing agent for the reduction of silver ions to silver nanoparticles (AgNPs). Bio-synthesized AgNPs were characterized by using UV, XRD, FEEM, TEM, and FTIR analysis. The face-centered cubic structures of AgNPs were formed with an average crystallite size of 31.26 nm and an average particle size of 42.97 nm. In this report, the electrical activities of green synthesized AgNPs have been evaluated along with the antibacterial activities. The antibacterial activities of AgNPs were evaluated against two pathogenic bacteria: Escherichia coli (gram-negative) and Staphylococcus epidermidis (gram-positive). AgNPs were added to the electrochemical cell and results demonstrated the improvement of power of the electrochemical cell. Green synthesized AgNPs showed excellent antibacterial activities against both gram-positive and negative bacteria and most importantly the NPs played an important role as an effective catalyst to enhance the electrical performance of bio-electrochemical cells. These significant findings may help in the advancement of nanotechnology in biomedical applications as well as in the creation of cheap and eco-friendly power generation devices

Structural, morphological and magnetic properties of Al3+ substituted Ni0.25Cu0.20Zn0.55AlxFe2−xO4 ferrites synthesized by solid state reaction route

Ni-Cu-Zn ferrite materials have been extensively used in electronic materials because of their outstanding properties at high frequencies. This work investigates the impact of Al substitution on the structure, morphology and magnetic properties of Ni0.25Cu0.20Zn0.55AlxFe2−xO4 (x = 0.00, 0.05, 0.10, 0.15 and 0.20) prepared by solid state reaction method. X-ray diffractometer (XRD), field emission scanning electron microscope (FESEM), impedance analyzer and Vibrating Sample Magnetometer (VSM) were used to characterize the properties of the samples. The XRD study confirmed the cubic spinel structure with single phase for all the samples. The lattice constant, X-ray density and bulk density decrease while the porosity and grain size increase with the increase of Al content in the samples. The frequency dependence of the complex permeability sintered at 1200 °C has been measured for toroidal samples in the frequency range between 1 kHz and 120 MHz at room temperature. The decrease in initial permeability has been explained on the basis of variation in grain size. The temperature dependence of the initial permeability has been measured in the temperature range between from 30 to 250 °C. Curie temperature (Tc) has been estimated from the temperature dependence of the permeability spectra for all samples. It is found that Curie temperatures and initial permeability (μi′) decrease on Al substitution. The saturation magnetization has been measured at room temperature and it was found to decrease with increasing of Al3+ ions. Keywords: X-ray diffractometry, Field emission scanning electron microscopy, Initial permeability, Curie temperature, Vibration sample magnetometer, Magnetizatio

Effect of Y substitution on magnetic and transport properties of Ba0.95La0.05Ti1−xYxO3 ceramics

Dielectric materials with giant dielectric constant are highly demanded for their many high-tech applications. While ferroelectric BaTiO3 inherently possesses polarization within it, high dielectric constant can only be obtained by structural as well as chemical modification. In this literature, we report the existence of high room temperature permittivity (≥103) in Ba0.95La0.05Ti1−xYxO3 (where x = 0.00–0.15) ceramics prepared by the pressureless conventional sintering method. Yttrium (Y) has been doped at the B site of Ba0.95La0.05TiO3 composition and their surface morphology, structural analysis, magnetic and transport properties have been investigated and discussed. XRD analysis confirms the formation of ABO3-type cubic perovskite structure of the studied compositions. The density of the prepared compositions is gradually increased with the increasing of Y content and porosity is decreased gradually. High dielectric constant and low dielectric loss with a wide range of frequency stability are observed. However, incorporation of Y in Ba0.95La0.05TiO3 gradually decreases the dielectric constant. The study of room temperature frequency dependent permeability indicates that 5% Y doped Ba0.95La0.05TiO3 possesses good magnetic properties. From the P-E loops, it is observed that Pr and Hc both are decreased with Y content. The present investigation is a fundamental step for the further improvement of the transport properties of BaTiO3 based ceramics. Keywords: Perovskite, Microstructure, Barium titanate, Yttrium, Dielectric, Magneti

Synthesis and characterization of dielectric, electric, and magnetic properties of vanadium doped-bismuth europium ferrites for multiferroic applications

Polycrystalline Bi0.90Eu0.10Fe1-xVxO3 (BEFVO) (where x = 0.00 to 0.10) ceramics were synthesized by the solid-state reaction method. The X-ray diffraction (XRD) pattern revealed that all the samples possess hexagonal crystal structures with some impurity peaks. Gold Schmidt’s tolerance factor of the samples was found 0.8436 to 0.8478 which represents more stability of the doped BiFeO3 (BFO) than parent BFO. The crystallite size was found in the range of 65–33 nm. The density gradually increases with increasing the V concentration and the maximum bulk density (ρB = 6.981 g/cm3) is obtained for the x = 0.10 sample. The obtained average grain size is found in the micrometer range and the values are in the range of 1.31–0.74 µm. The maximum dielectric constant of 2577 at 102 Hz is found for the x = 0.07 sample. The resistivity decreases with doping concentration as a result of ac conductivity increases. The highest transition frequency of long-range to short-range mobility of charge carriers is obtained for the x = 0.07 sample. The highest real part of the initial permeability of 25.24 is found for x = 0.07 multiferroic ceramics. For the x = 0.07 sample, the maximal saturation magnetization is found to be 1.91 emu/g. The studied samples comprise large electric polarization and the optimum polarization of 7.5 μc/cm2 is observed for the x = 0.07 composition

How does tree competition and stand dynamics lead to spatial patterns in monospecific mangroves?

info:eu-repo/semantics/publishedHexennial International Conference ‘Meeting on Mangrove ecology, functioning and Management – MMM3’, 2-6 juillet, Galle, Sri Lank

Structural effect on Magneto-electric properties in (1-x) BiFe0.9La0.1O3 + xNi0.6Zn0.4Fe1.94V0.06O4 composites

Enhancement of magnetic as well as electric properties in BiFe0.9La0.1O3 (BLFO) with the addition of Ni-Zn ferrite have been studied on the compositions (1-x)BiFe0.9La0.1O3 + xNi0.6Zn0.4Fe1.94V0.06O4 (where, x = 0, 0.1, 0.2, 0.3, 0.5, 0.7 and 1.0). The samples were synthesized by the conventional ceramic methods sintered at 850 °C for 2 h. XRD studies revealed a normal distorted rhombohedral phase (R3c space group), cubic phase (Fd-3 m space group) and some impurity phases like Bi2Fe4O9 and Bi25FeO39 in the synthesized composites. The addition of Ni0.6Zn0.4Fe1.94V0.06O4 (NZVFO) successfully eliminated Bi25FeO39 phase from the derived composites. The average grain sizes (Dg) were estimated from FESEM images and found to decrease with the increase of NZVFO content in the samples. There is a large increment in saturation magnetization (MS) from 0.1 emu/g to 50.5 emu/g for adding NZVFO in BLFO. The frequency-dependent magnetic permeability μ and dielectric constant ε and dielectric loss tanδε have been measured with an impedance analyzer. The addition of NZVFO results in decreasing the permittivity ε' and dielectric loss (tanδε). The composites with 0.7 NZVFO addition shows a stable matching impedance Z/η0≈0.5 over a wide frequency range (5–70 MHz), demonstrating its possible applications in miniaturizing devices such as microwave antenna

Investigation of the structural, magnetic and dielectric properties of NiFe2O4/nanoclay composites synthesized via sol-gel autocombustion

NiFe2O4 nanoparticles supported with 0, 2, 4, and 6 wt% of dodecylalkylammonium intercalated montmorillonite (DDA-MMT) are synthesized by sol-gel autocombustion method. The structural and morphological properties have been analyzed by XRD, FTIR and SEM techniques. The dielectric, magnetic, optical and electrical properties of the prepared samples have been evaluated. XRD analysis confirmed the formation of MMT layers exfoliated NiFe2O4 nanoparticles by showing the absence of 001 reflection of DDA-MMT in NiFe2O4/DDA-MMT compounds. The crystallite size is determined to be 31.32 nm for naked Ni ferrite and decreases with increase of DDA-MMT content, which revealed crystallization of NiFe2O4 is influenced by DDA-MMT. The saturation magnetization of Ni ferrite is found to be increased from 29.84 emu/g to the range of 30.78–38.45 emu/g when supported with DDA-MMT up to 6 wt%. A significant enhancement of dielectric constant, from 2.7 to 4.2, is observed when Ni ferrite is supported with 2 wt% DDA-MMT which could be accounted for interfacial polarization between MMT layers and ferrite nanoparticles. Optical band gap increases from 1.67 to 1.76 eV with application of 2 wt% DDA-MMT as supporting material in Ni ferrite. Present work indicates that the magnetic, dielectric, optical as well as electrical properties of Ni ferrite nanomaterial may be modified by adding the right quantity of DDA-MMT as a supporting material, which will ultimately assist in broadening the uses of Ni ferrite

Synthesis of Sr-doped Ni0.5Zn0.5SrxFe2-xO4 and the study of its structural, mechanical, magnetic, and electrical properties for high-frequency applications

The solid-state reaction method has been used to mold the spinel Ni–Zn ferrites with doped strontium (Sr) [Ni0.5Zn0.5SrxFe2-xO4; x = 0.00, 0.01, 0.03, 0.05, and 0.10]. The powder X-ray diffraction approach was driven to investigate the crystal lattice of the studied samples. By using a variety of methods, including the Debye-Scherrer (D-S) formula, the Williamson-Hall (W–H), the Halder-Wagner (H–W), and the size-strain plot (SSP), where broadening of the XRD peaks are used, we have calculated the crystallographic features of Ni–Zn ferrites to ascertain the crystallite size and lattice strain. With doped Sr contents in samples, the lattice constants of the studied ferrites were decreased. Scanning electron microscopy (SEM) was used to analyze the sample's surface. Using the Image J software, the samples' grain size was calculated. We also performed the FTIR calculation, which confirmed that the ferrites we studied were spinel ferrites. The stiffness constants and elastic moduli were enumerated using the FTIR data to evaluate the mechanical behavior of the studied samples. Important thermal parameters such as Debye temperature (ΘD) and melting temperature (Tm) were also calculated. The magnetic behavior characterizing parameters have been analyzed via a vibrating sample magnetometer (VSM). Our studied samples are soft magnetic materials. We found the magnetic and electric losses to be negligible. Over a wide frequency extent, from 102 to 106 Hz at ambient temperature, an impedance analyzer was utilized to examine the samples' dielectric properties and AC resistivity. In the high-frequency region, the dielectric constant is frequency independent and the values of the dielectric constant are decreased with doped materials. Resistivity is increased with Sr-doped materials

Synthesis of Mn3O4 nanoparticles via a facile gel formation route and study of their phase and structural transformation with distinct surface morphology upon heat treatment

Mn3O4 nanoparticles (NPs) were synthesized from the reduction of KMnO4 with glycerol at 80 °C in aqueous media via a gel formation route. In order to investigate the thermal stability and phase transformation, Mn3O4 NPs were subjected to heat treatment from 200 °C to 700 °C. The formation of different MnOx species observed by X-ray diffraction (XRD) measurements showed temperature dependent phase transformation occurring during the heat treatment process. XRD patterns showed that Mn3O4 NPs were formed at a temperature of 80 °C and two new phases Mn5O8 and Mn2O3 were appeared at 350 °C and 700 °C respectively. The three different oxides having their distinct surface morphologies viz., spherical, rod and cube shape respectively, were observed. Detailed morphological and structural investigations using Field Emission Scanning Electron Microscopy (FESEM), XRD, Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) revealed the temperature dependent phases, crystal structures, lattice constants, particle sizes and surface morphologies of the MnOx species