Cube-like Shape Research Articles

Role of cerium dopant in tuning the semiconductor-to-metal transition properties of magnesium zinc ferrite nanomaterials

In this research work, Magnesium zinc ferrite (CexMgZn1-xFe2O4) nanomaterials have been synthesized with various cerium concentrations (x = 0, 0.05, 0.1, 0.15) using the coprecipitation method. With no deformation as per structural analysis, cerium ions are doped in the spinel lattice of MgZnFe2O4 nanomaterials. The undoped MgZnFe2O4 with initial flake-like morphology is changed to cube-like shapes upon Ce (x = 0.15) addition. The DC resistivity exhibits a varying pattern in both ferromagnetic and paramagnetic regions as temperature increases. Furthermore, the samples with x = 0.15 exhibit a high resistivity on the order of 1.09∗1010 Ω cm, and an activation energy of 0.909 eV. The dielectric properties, such as dielectric constant, dielectric losses, and impedance, exhibit a progressive drop as the frequency increases from 1 MHz to 2 MHz. Furthermore, dielectric parameters reach their lowest value in the dopant x = 0.1. The highest Q values for x = 0.05 and 0.15 indicate that the mentioned materials are most suitable for use in high-frequency devices, likewise multi-layer chip inductors and resonant circuits. Growth inhibition of two types of bacterial extracts (E.Coli and S. aureus) has been studied. Results revealed MgZnFe2O4 enhanced growth inhibition against S. aureus bacteria with increasing Ce concentration, however, inhibition of E. Coli is hampered (50 % at maximum) by Ce incorporation into ferrite lattice.

PRODUCTION OF CuO/ZrO2 NANOCOMPOSITES IN POWDER AND FIBER FORMS

CuO/ZrO2 composite systems were synthesized in two different ways and comprehensively characterized with X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), transmission electron microscopy(TEM), and energy dispersive X-ray spectroscopy(EDX). These metal oxide samples were prepared by hydrothermal synthesis and electrospinning process. In these methods, the same metal salts were used as precursors. Separately produced ZrO2 nanoparticles(NPs) and CuO particles have spherical and cube-like shapes, and both morphologies have monoclinic structures. However, ZrO2 and CuO particles do not have uniform diameters, and the average size of these particles ranges between 6–17 and 215–847 nm, respectively. Moreover, CuO/ZrO2 nanocomposite particles(NCPs) were synthesized using a facile and one-pot hydrothermal technique. They have uniform, spherical, and monoclinic structures with a 15nm average diameter. Furthermore, ZrO2 fibers were produced with the electrospinning process as highly crystalline structures after annealing, with a 230 nm average fiber diameter. In addition, ZrO2 fibers were doped with hydrothermally synthesized CuO particles with a drop-casting method for the first time. This study clearly shows that particle-fiber structure allows the development of the efficiency of p-type counterparts by using only 0.5-1.5wt.% n-type. With these results, two methods can be used to produce heterostructure CuO/ZrO2 composite particles/fibers and as potential for photocatalytic degradation.

A novel electrospun nanofiber system with PEGylated paclitaxel nanocrystals enhancing the transmucus permeability and in situ retention for an efficient cervicovaginal cancer therapy

Overcoming the vaginal barrier to achieve sufficient drug penetration and retention is a huge obstacle for drug delivery in chemotherapeutics for cervical cancer. In this study, we investigate the feasibility of a novel composite nanocrystal/nanofiber system for improving the transmucus penetration and, thus, enhancing retention and drug delivery to the lesion of a cervicovaginal tumor. Herein, paclitaxel (PTX) was sequentially formulated in the form of nanocrystals, coated with polydopamine (PDA), and modified with PEG. The nanocrystals (NCs@PDA–PEG) were creatively fabricated to create a composite nanofibrous membrane (NCs@PDA-PEG NFs) by using an electrospinning technique. The morphology, size distribution, drug loading, encapsulation efficiency, X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectra, in vitro release, in vivo vaginal retention, apoptosis index, anti-tumor efficacy in a murine cervicovaginal tumor model, and local irritation were characterized. The NCs@PDA-PEG were formulated in a cube-like shape with an average size of 385.6 ± 35.47 nm; they were dispersed in electrospun nanofibers, and the drug loading was 7.94 %. The XRD curves indicated that the phase state of PTX changed after the creation of the nanocrystals. The FTIR spectra showed that the drug and the excipients were compatible with each other. In vitro delivery showed that the dissolution of PTX in the electrospun nanofibers was significantly faster than that when using bulk PTX. Compared with the PTX NC NFs, the NC@PDA-PEG NFs exhibited prolonged vaginal residence, superior transmucus penetration, minimal mucosal irritation, and significant tumor inhibition efficacy after the intravaginal administration of the NFs in tumor-bearing mice. In conclusion, by acting as novel pharmaceutical repositories, NCs@PDA-PEG NFs can be promising candidates for non-invasive local treatment, leading to efficient tumor inhibition in cervicovaginal cancer.

Poly(vinyl alcohol)-tragacanth gum/Titania bio-nanocomposite film for photodecomposition of malachite green

Concerned about the contamination as a consequence of untreated wastewater worldwide, nanomaterials have been utilized for purification. Nevertheless, their separation from water is difficult after the treatment. Herein, Titania nanomaterials were embedded in a poly(vinyl alcohol)-tragacanth gum (PVA-TG) matrix, due to easy separation. The polymer matrix was cross-linked by a green agent of citric acid, and the physicochemical properties of PVA-TG/Titania bio-nanocomposite (bio-NC) films were characterized, which displayed a high swelling ratio in the water because of the addition of TG. Further, Titania nanomaterials illustrated a cube-like shape in the PVA-TG/Titania bio-NC film confirming the complete dispersion. Afterward, the photodecomposition of malachite green (MG) over this bio-NC film was studied and optimized under ultraviolet (UV) irradiation. Scavenger agents determined that the electron was produced more than other radical agents. Ultimately, the photodegradation process of MG over bio-NC films was suggested by the hydroxyl addition, singlet oxygen, and UV irradiation transformation pathways.

Tunable Mie resonance in complex-shaped gadolinium niobate

Nanoscale particles described by Mie resonance in the UV–vis–NIR region are in high demand for optical applications. Controlling the shape and size of these particles is essential, as it results in the ability to control the wavelength of the Mie resonance peak. In this work, we study the extensive scattering properties of gadolinium niobate particles with complex bar- and cube-like shapes in the UV–vis–NIR region. We perform our experimental analysis by characterizing the morphology and extinction spectra, and our theoretical study by implementing a Mie scattering model for a distribution of spherical particles. We can accurately model the size distribution and extinction spectra of complex shaped particles and isolate the contribution of aggregates to the extinction spectra. We can separate the contributions of dipoles, quadrupoles, and octupoles to the Mie resonances for their respective electric and magnetic parts. Our results show that we can tune the broad Mie resonance peak in the extinction spectra by the nanoscale properties of our system. This behavior can aid in the design of lasing and luminescence-enhanced systems. These dielectric gadolinium niobate submicron particles are excellent candidates for light manipulation on the nanoscale.

Effect of synthesis route on the photoluminescence properties of SrTiO3:Pr,Al phosphor: Nanoparticles and microcubes

Sr0.998Pr0.002Ti0.998Al0.002O3 phosphors were prepared by hydrothermal (HT) and polymeric precursor (PP) methods. PP sample exhibits broadening of X-ray diffraction peaks due to the higher surface region of nanoparticles compared to HT sample. X-ray absorption spectroscopy results depicted defects associated with the formation of TiO5 octahedra for HT sample, which is ascribed to the rapid crystallization process in HT synthesis of the mesocrystals with cube-like shape. A quenching of 4f → 4f emissions in Pr3+ ions and a broad spectrum are observed for HT sample, which are attributed to structural disorder in the forming and modifying lattice due to charge compensation between Sr-O11 and Sr-O12 (or TiO5 and TiO6) clusters and intermediate levels in band gap states.

The Distorted Octahedral and Magnetocrystalline Anisotropy of FeMnO<sub>3</sub> by Stoner-Wohlfarth Model

Among magnetic materials, ferrites have significant attention due to their potential application, such as magnetic recording, sensors, radar-absorbent materials, catalysts, and energy-storage devices. One of the ferrites family, FeMnO3, has been synthesized by solid-state reaction using Fe2O3 powder with an excess of 0.02% MnO2 powder in the stoichiometric composition. The structural and morphological properties have been performed using XRD and SEM at room temperature. The diffraction peaks in the pattern were indexed as FeMnO3 with a cubic (bixbite, Ia3) crystal structure. It showed no additional peaks due to impurities. The SEM image reveals the grains nucleate in a cube-like shape. Some of the particles also seem to agglomerate into larger particles. The magnetic characterization was carried out using VSM at room temperature. The magnetic hysteresis loop (M-H curves) notices the ferrimagnetic behavior. The results show remnant magnetization (Mr), coercive field (Hc), magnetic moment (µB), and anisotropy constant of FeMnO3 are 0.296 emu/g, 299 Oe, 0.046 emu/mol, and 0.1 when the external field is 70˚-80˚ from the easy axis, respectively.

High optical modulation efficiency in perovskite CsPbI3/Br3 by ionic liquid ionization

An effective method to improve optical properties of perovskite CsPbI3/Br3 is a long-term goal pursued by researchers, such as incorporating, mechanism changing and structure optimizing. However, two significant problems still facing challenges including the complex fabrication process and low modulation efficiency. To contribute these, a method of ionic liquid modulation with respect to the photoluminescence PL intensity and peak position was demonstrated. The micro-structure including the information of crystal and bond in MAPbBr3/I3 soaking in C8H11F3N2O2 and C7H13N2∙ BF4 was supported by x-ray diffraction XRD patterns and Raman spectrum. A cube-like shape and size distribution mostly in 600–950 nm was imaged by scanning electron microscope. Then, compared with CsPbI3 before soaking in Hall measurement, the carrier concentration was improved about 46.1%, the mobility and resistivity were lowered around 39.2% and 40.2%, respectively. The modulation of intensity and peak position were confirmed by PL spectrum at room temperature. The absorption enhancement in excited state absorbs range was proved by transient absorption. Finally, the mechanism for optical modulation in this paper was systematically explained. The research method proposed in this paper can simplify the research process and improve the optical properties of the materials at the same time.

Morphology Control of PbZrxTi1-xO3 Crystallites under Alkaline Hydrothermal Conditions

Outstanding ferroelectric and piezoelectric properties of PbZrxTi1-xO3 (PZT) make nano and sub-micrometer particles of this material interesting for future nanotechnological applications as well as for fundamental studies of ferroelectricity at the nanoscale. In the present work, the prospects of a new hydrothermal approach were explored to control the particle size, aggregation stage, and composition of the PZT with the target composition of Zr/Ti = 60/40 (x = 0.6). Starting with water-soluble Zr-, Ti-, and Pb-precursors, the PZT formation was examined in the broad base (KOH) concentration range. The PZT particle size and composition were governed by the ratio of KOH with respect to Pb and not by the absolute KOH concentration (cKOH). The incorporation of Zr into the PZT perovskite phase began to decline at KOH:Pb ≤ 1.7 and at KOH:Pb > 20. In the concentration range of 20 ≥ KOH:Pb > 1.5, the PZT particles adopted a cube-like shape, the size of which decreased with a decrease in the KOH:Pb ratio. The smallest (<200 nm) and well-separated PZT particles were obtained at KOH:Pb = 1.7. The prevailing PZT crystal structure at a Zr/Ti composition of around 60/40 was rhombohedral; the tetragonal phase also began to appear in Ti-richer PZT compositions (Zr/Ti ≤ 50/50). The developed understanding established the basis for further tailoring of PZT particle morphologies for application-oriented or fundamental research.

Facile preparation of NiFe2O4/NaCl nanocomposites by wet chemical co-precipitation

In this work, we utilized various iron salts {Fe(NO3)3, FeSO4 and FeCl3} at the presence of aqueous solutions of NiCl2 and NaOH, respectively, to prepare NiFe2O4/NaCl nanocomposites using wet chemical co-precipitation. The dark-brown products were afterwards calcined for 3 h at 600 °C. All products were characterized using Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD results confirmed formation of the NiFe2O4/NaCl nanocomposites. The TEM results revealed that the particles are relatively similar in cube-like shape; however, the size was distinct.

PHYTOSYNTHESIS AND CHARACTERIZATION OF IRON NANOCOMPOSITES BY IRVINGIA GABONENSIS (OGBONO) AQUEOUS AND ETHANOL LEAF EXTRACTS

The need for emerging materials based on nano-composites from green plants, or non-useful materials for adsorption process is on the increase. The objective of this research was to evaluate the phytosynthesis and characterization of iron nano-composites (Fe.NCs) formed by aqueous and ethanol extracts of Irvingia gabonensis (Ogbono) tree leaves. The composites were characterized by visual observation, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Visual observation of the iron oxide nano-composites synthesized was confirmed by change in colour from yellow to brown within minutes of formation. The FTIR characterization showed that, phenolic groups were involved in the phytosynthesis of the iron nano-composites with the presence of –OH and –NH groups at 3348.54cm-1 and -C-N- group at 1635.69 cm-1 for aqueous extract and broad band of –OH and -NH stretch at 3363.97cm-1 and -C-H-stretch at 2978-2901.04cm-1 attributed to alkanes in alcohol extract. There was also –OH stretch at 2885.60cm-1 and Fe-O group at 671.25cm-1 in Fe. NCs with Fe-O stretch observed at 583.33cm-1 in I. gabonensis iron nano-composite. Cube-like structures, irregular shapes and sizes with individual, spherical particles forming aggregates and chains were revealed by the SEM micrographs, these are recognized attributes of strong magnetic properties of iron. The particle sizes are 30 and 45 nm for aqueous and alcohol extracts respectively, which could provide large surface area for contaminant adsorption. Conclusively, photosynthesis of Fe. NCs using water and ethanol extracts of I. gabonensis (Ogbono leaves) could be an effective one-step pathway for nano-composite production from eco-friendly, safe and less toxic green plant material.

Surfactant-Free Aqueous Dispersions of Shape- and Size-Controlled Zirconia Colloidal Nanocrystal Clusters with Enhanced Photocatalytic Activity.

Colloidal nanocrystal clusters (CNCs) are formed by clustering nanocrystals into secondary structures, which represent a new class of materials and have attracted considerable attention, owing to their unique collective properties and novel functionalities achieved from the ensembles in addition to the properties of each individual subunit. Here, we design a simple route to prepare aqueous dispersions of highly stable ZrO2 CNCs with tunable shape and size without modification. ZrO2 CNCs are composed of many ZrO2 nanocrystals each with a size of about 7 nm and possess a mesoporous structure. Both cube-like and star-like shapes of CNCs can be achieved by using different alkaline sources, while the size of CNCs can be adjusted by changing the hydrothermal time. The as-prepared aqueous dispersions of ZrO2 CNCs display an enhanced photocatalytic activity in the degradation of rhodamine B (RhB), compared with ZrO2 nanodispersions. More interestingly, star-like ZrO2 CNCs show better photocatalytic degradation properties than those of cube-like counterparts and even commercial P25. Furthermore, ZrO2 CNCs are easily recycled and can be used for the degradation of a range of dye systems.

Preparation of Local Raw Material for α-Fe<sub>2</sub>O<sub>3</sub> Nanoparticles Powder from Mineral Extraction of Iron Sand

Synthesis and characterization of α-Fe2O3 nanoparticles were obtained from extraction of ilmenite iron sand with coprecipitation method and to obtain α-Fe2O3 nanoparticles, high energy milling (HEM) was used. Surface morphology and identification of the elements contained in the sample were analyzed using scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). For phase analysis and crystal structure, X-ray diffractometer (XRD) was used. Moreover a vibrating magnetometer sample (VSM) was used to characterize its magnetic properties, while tunneling electron microscopy (TEM) was used for particle size characterization. Ilmenite-type iron sand has a diverse particle shape with a size of more than 100 μm with ilmenite (FeTiO3) mineral content of about 64.7%. The results of extraction using coprecipitation method with sintering 750 °C, obtained hematite α-Fe2O3 material which has not been saturated to an external magnetic field of 1 tesla, the magnetic remanent value (Mr) is about 0.8 emu/g and the coercivity field value is Hc around 773 Oe. The average size of hematite α-Fe2O3 particles after being milled 50 hours is between 15-30 nm with a cube-like shape.

Synthesis of anatase TiO2 mesocrystals with highly exposed low-index facets for enhanced electrochemical performance

Cube-like anatase TiO2 mesocrystals have been fabricated successfully by using amorphous titanate as a precursor. The size and shape of the synthesized mesocrystals are uniform with an average size of 100 nm. Interestingly, the low index facets of (100), (010) and (001) are exposed completely, forming the special cube-like shape. When used as an anode for lithium-ion batteries, anatase TiO2 mesocrystals exhibit an excellent lithium storage ability. A capacity of 166 mA h g−1 can be remained after 800 cycles at 5C, demonstrating a good long-term cycling performance. Furthermore, an average reversible capacity of 148 mA h g−1 can be also maintained even at a rate as high as 20C. Such an excellent electrochemical performance can be attributed to the special cube-like shape of TiO2 mesocrystals with exposed facets, which facilitate lithium-ion diffusion.

The role of the reactive oxygen species and the influence of KBiO3 synthesis method in the photodegradation of methylene blue and ciprofloxacin

KBiO3 was synthesized by three methods: chemical substitution, hydrothermal and sonochemical. All reaction products were analyzed by X-ray powder diffraction and reveal that KBiO3 presents a cubic structure. The morphology of each sample was analyzed with scanning electron microscopy (SEM), and the micrographs show particles with cube-like (chemical substitution), spheres-like (sonochemical) and flakes-like (hydrothermal) shape. HR-TEM technique was used to confirm the crystal structure and to determine the particle size of the samples, also it was used to corroborate the morphology. The photocatalytic activity of KBiO3 was evaluated on the reactions of the degradation of methylene blue (MB) and Ciprofloxacin (CPFX). An almost 100% discoloration of MB was reached at 120 min with KBiO3 obtained by the sonochemical method and a 67% degradation of CPFX was obtained by KBiO3 synthesized by the hydrothermal method. These results were associated with the catalyst morphology and organic adsorption on the surface of the catalyst. With the aim for a further understanding of the photocatalytic degradation of MB and CPFX, scavengers such as benzoquinone, isopropanol, and catalase were added to the photocatalytic reaction in order to identify the reactive oxygen species (ROS) involved. It has been found that hydrogen peroxide (H2O2) was the primary oxidizing species for the degradation of MB; meanwhile in the case of the oxidation of CPFX occurred by the presence of the superoxide radical (O 2 −· ).

Investigation on the structures and magnetic properties of carbon or nitrogen doped cobalt ferrite nanoparticles

Carbon or nitrogen doped cobalt ferrite nanoparticles were synthesized in the air by a facile calcination process. X-ray diffraction, mapping, X-ray photoelectron spectroscopy, and mössbauer spectra results indicate that the nonmetal elements as the interstitial one are doped into cobalt ferrite nanoparticles. The morphologies of doped cobalt ferrite nanoparticles change from near-spherical to irregular cubelike shapes gradually with the increased carbon or nitrogen concentration, and their particles sizes also increase more than 200 nm. Furthermore, the saturation magnetization of carbon doped cobalt ferrite is improved. Although the saturation magnetization of N-doped cobalt ferrite is not enhanced obviously due to the involved hematite, they also do not drop drastically. The results reveal an approach to synthesize large scale ferrite nanoparticles, and improve the magnetic properties of ferrite nanoparticles, and also provide the potential candidates to synthesis co-doped functional magnetic materials.

Electrochemical Performance and Mechanisms of NaSn2(PO4)3/C Composites as Anode Materials for Li-Ion Batteries

NaSn2(PO4)3/C composites obtained by solid-state and pyrolysis reactions present high capacity retention and high-rate capability as anode materials for Li-ion batteries. The structure of NaSn2(PO4)3 was analyzed by combining X-ray diffraction and density functional theory to confirm the R3 space group. The composite is formed by submicrometer particles with a cube-like shape coated by pyrolytic carbon that improves the electronic percolation. The 119Sn Mossbauer spectroscopy shows the existence of Sn4+ with a more ionic character than SnO2, which can be related to the inductive effect of the phosphate groups. This technique was used in the operando mode to follow the reaction with lithium during the first discharge that is a crucial step for improving the performance. A two-step mechanism has been identified that consists of the irreversible transformation of the pristine material into Sn0 species for the first half of the discharge followed by reversible Li–Sn alloying reactions. The Mossbauer spectra ...

Fabrication, Densification and Thermionic Emission Property of Lanthanum Hexaboride

An effective way to improve sintering densification of LaB6 was proposed and confirmed experimentally. Firstly, LaB6 nanopowders with a cube-like shape of ~ 94.7 nm were fabricated by molten salt synthesis route at 800 °C for 1 h. Then, LaB6 bulk material of 98% density was prepared by hot pressing sintering of as-synthesized LaB6 nanopowders under 1800 °C/50 MPa/30 min. The acquired LaB6 bulk material had a work function of 2.87 eV and exhibited an excellent thermionic emission property. The saturation emission current density at 1500 and 1600 °C reached 37.4 and 44.3 A/cm2, respectively.

Rapid fabrication and phase transition of Nd and Ce co-doped Gd2Zr2O7 ceramics by SPS

A series of Nd and Ce co-doped Gd2-xNdxZr2-yCeyO7 (0.0 ≤ x, y ≤ 2.0) ceramics were rapidly fabricated through spark plasma sintering (SPS) within 3 min. The effects of Nd and Ce contents on the phase composition, lattice parameter, active modes, microtopography and microstructure have been investigated in detail. XRD studies reveal that the compositions corresponding to 0.0 ≤ y ≤ 1.0 show a single phase and beyond 1.0 exhibit multiphase. The lattice parameters increase with elevated Nd and Ce content. The grains are densely packed on each other with cube-like shape, and the elements are almost homogeneously distributed in the compound. This synthetic method provides a simple pathway for the preparation of highly densified single phase ceramic at 1600–1700 ℃ for 3 min under pressure of 80 MPa.

A Novel Hydrothermal Approach for the Synthesis of Flower-Like Fe2O3/Fe Foam Nanocrystals and Their Superior Performance in Fisher–Tropsch Synthesis

A novel and facile hydrothermal approach was developed for the synthesis of three-dimensional flower-like α-Fe2O3 nanocrystals grown directly on Fe substrate using Fe(NO3)3 and hexamethylenetetramine as precursors in aqueous medium. A reaction mechanism for the synthesis and growth of the flower-like α-Fe2O3 nanocrystals was proposed to explain the effects of reaction time and temperature on the morphology and structure of the as-synthesized nanocrystals. Moreover, cube-like shapes of Fe2O3 nanocrystals were produced when urea used as hydrolysis reagent during the synthesis process. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction were employed to confirm the unique morphology, high crystallinity and pure phase structure. The as-synthesized flower-like α-Fe2O3 nanocrystals displayed a higher activity and C2–4 olefin/paraffin ratio in Fisher–Tropsch synthesis than the cube-like shape of α-Fe2O3 nanocrystals, possibly due to their high specific surface area as well as diversity of catalytic active sites. The produced flower-like Fe2O3 nanocrystals sample displayed high catalytic activity and C2-4 olefin/paraffin over the cube-like Fe2O3 nanocrystals for Fischer-Tropsch synthesis, due to the high specific surface area and diversity of catalytic active sites.