Characterization and synthesis of pure ZrO2 nanopowders via sonochemical method

Pure ZrO₂ nanopowders have been synthesized via sonochemical method, which is a simple and energy efficient way to synthesize inorganic materials. The as-synthesized samples (hydrous zirconia, ZrO₂·nH₂O) are characterized by several techniques: X-ray diffraction (XRD), thermogravimetric analysis (TGA), photoluminescence spectrometer (PLS) and Raman spectrometer (RS). It is shown that t-ZrO₂ samples have two photoluminescence (PL) bands corresponding to the wavelengths of excitations of 254 and 412 nm. The structure of as-synthesized samples (ZrO₂·nH₂O) and the formation mechanism of ZrO₂ nanopowders are also discussed.     

Hydrothermal synthesis of Fe3O4 nanoparticles and its application in lithium ion battery

Well dispersed Fe₃O₄ nanoparticles with a mean diameter of about 160 nm were synthesized by a simple hydrothermal method in the presence of sodium sulfate. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Raman spectrum, and Fourier transform infrared spectra (FTIR). Electrochemical properties of the nanostructured Fe₃O₄ as cathode electrodes of lithium ion battery were studied by conventional charge/discharge tests, showing a high initial discharge capacity of 1267 mA h g^− 1 at a current density of 0.1 mA cm^− 2.     

Morphology and crystal structure of CeO2-modified mesoporous ZrO2 powders prepared by sol–gel method

Mesoporous ZrO₂ powder modified by CeO₂ has been prepared by sol–gel method combined with novel heat-treatment without any templates. The morphology and crystal structure were characterized by Fourier transform infrared spectrophotometer (FT-IR), thermal gravimetry/differential thermal analysis (TG/DTA), X-ray diffraction (XRD), Raman spectroscope, N₂ absorption–desorption, scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM). It was demonstrated that the morphologies and crystal structures were varied with the CeO₂ content and calcination temperatures. Some circular grooves with diameter about 300–500 nm and thickness of 150–200 nm were observed for 30 mol% CeO₂ modified samples. Tetragonal ZrO₂ and cubic (Ce,Zr)O₂ solid solution were in turn observed with CeO₂ content increasing. The oxygen storage capacity (OSC) of the mesoporous powders was determined by thermalgravimetry (TG) under cyclic thermal treatments.     

Influence of sintering temperature on thermoelectric properties of Bi<Subscript>2</Subscript>Te<Subscript>3</Subscript>/Polythiophene composite materials

Bi₂Te₃/Polythiophene (PTH) thermoelectric bulk composite materials were prepared by a two-step method. Firstly, Bi₂Te₃ and PTH nanopowders were prepared by hydrothermal synthesis and chemical oxidative polymerization, respectively. Secondly, the mixture of the Bi₂Te₃ and PTH nanopowders (50:50 wt) was pressed under vacuum at 80 MPa and 298, 473, or 623 K. For comparison, Bi₂Te₃ powders were hot pressed at 623 K. The bulk materials were analyzed by conventional methods, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and field emission scanning electron microscopy equipped with electron dispersive X-ray spectroscopy. The XRD and TGA results showed that the PTH decomposed when the hot pressing temperature exceeded 473 K, and Bi₂Te₂S phase was formed. The thermoelectric properties of the bulk composite materials were investigated. The composite pressed at 623 K showed a higher power factor, ~2.54 μ Wm⁻¹ K⁻² at 473 K, which is as ~20 times as that of the composite pressed at 473 K, although, it is still much lower than that of the pressed Bi₂Te₃ material (~1,266 μ Wm⁻¹ K⁻² at 348 K).     

Controlled synthesis and possible formation mechanism of leaf-shaped SnS2 nanocrystals

A sort of novel leaf-shaped SnS₂ nanocrystals have been synthesized by controlled reaction of CH₃CH₂OCS₂K with SnCl₄·5H₂O in aqueous solution in the absence of surfactant. The leaf-shaped nanocrystals consist of very thin sheets with several microns in length and 100–300 nm in width. The structure, composition, and morphology of the as-prepared leaf-shaped SnS₂ nanocrystals were characterized by XRD, Raman spectra, XPS, and FE-SEM, respectively. Elemental analysis, FT-IR spectra, and TEM were further used to study the formation mechanism of the leaf-shaped SnS₂ nanocrystals. A possible mechanism of producing lamellae – breaking into nanosheets – rolling and assembling was suggested for the leaf-shaped SnS₂ nanocrystals formation based on experimental results.     

Preparation and luminescence properties of Mn-doped ZnGa2O4 nanofibers via electrospinning process

One-dimensional Mn²⁺-doped ZnGa₂O₄ nanofibers were prepared by a simple and cost-effective electrospinning process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), energy-dispersive X-ray spectrum (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and cathodoluminescence (CL) spectra as well as kinetic decays were used to characterize the samples. SEM results indicated that the as-formed precursor fibers and those annealed at 700 °C are uniform with length of several tens to hundred micrometers, and the diameters of the fibers decrease greatly after being heated at 700 °C. Under ultraviolet excitation (246 nm) and low-voltage electron beams (1–3 kV) excitation, the ZnGa₂O₄:Mn²⁺ nanofibers presents the blue emission band of the ZnGa₂O₄ host lattice and the strong green emission with a peak at 505 nm corresponding to the ⁴T₁–⁶A₁ transition of Mn²⁺ ion.     

Synthesis and characterization of spherical ZrO2:Eu phosphors by spray pyrolysis process

Europium doped zirconia (ZrO₂:Eu³⁺) powder phosphors consisting of spherical, dense and submicrometer size particles were successfully synthesized by a spray drying process followed by a post annealing treatment process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), scanning electron microscope (SEM), photoluminescence (PL) spectra as well as lifetimes were utilized to characterize the prepared samples. The results of XRD indicated that the samples began to crystallize at 500 °C, and the crystallinity increased with increasing the annealing temperature. The powders with metastable tetragonal symmetry were obtained at relatively low temperature. The effects of annealing temperature, the Eu³⁺ concentration as well as the morphology on the PL intensity were investigated in this work.     

Microwave accelerated synthesis of nanosized calcium deficient hydroxyapatite

Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca_10–x(HPO₄)_x(PO₄)_6–x(OH)_2–x) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16–39 nm and width 7–16 nm. The synthesized CDHA has the characteristic HPO^2–₄ vibration band at 875 cm^–1 in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600°C.     

Micro-Raman spectroscopy and X-ray diffraction studies of atomic-layer-deposited ZrO<Subscript>2</Subscript> and HfO<Subscript>2</Subscript> thin films

Raman spectroscopy and X-ray diffraction (XRD) methods were applied to characterize ZrO₂ and HfO₂ films grown by atomic layer deposition (ALD) on silicon substrates in chloride- based processes. A dramatic enhancement in spectral quality of Raman data resulted from the use of the film’s freestanding edges for experimental runs between 80 and 800 cm⁻¹. Both techniques detected a preferential formation of a metastable phase in ZrO₂ and HfO₂ films at 500 and 600^∘C, respectively, during the initial stages of ALD. In the case of ZrO₂ films this phase was identified as the tetragonal polymorph of ZrO₂ (t-ZrO₂). XRD and Raman spectroscopy data showed that, in contrast to the monoclinic phase (m-ZrO₂), the absolute amount of t-ZrO₂ remained approximately constant while its relative amount decreased with the increase of the film thickness from 56 to 660 nm. Neither XRD nor Raman spectroscopy allowed unambiguous identification of the metastable phase formed in otherwise monoclinic HfO₂ films.     

Hydrothermal preparation of boehmite-doped AgCl nanocubes and their characterization

A simple hydrothermal route to the preparation of the boehmite-doped AgCl nanocubes using AgNO₃, AlCl₃·6H₂O and NaOH at 200 °C for 24 h is reported. The products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), UV-vis, thermogravimetric analysis (TGA), and differential thermal analysis (DTA). FE-SEM and TEM micrographs showed that the obtained boehmite-doped AgCl had nanocube-like morphology. The influence of heating temperature on the phase, microstructure, morphology, and thermal stability of the products were also investigated. UV-visible results indicated that the absorption edge moved to higher wavelength with the increasing heating temperature. These materials would be a promising material for photocatalyst applications.     

Analyses of nano-crystalline LiCoVO4 prepared by solvothermal reaction

LiOH·H₂O, Co(NO₃)₂·6H₂O and NH₄VO₃ were used to prepare nano-crystalline LiCoVO₄ by 150 °C solvothermal reaction in isopropanol for 10–360 h and subsequent calcination at 300–500 °C for 6 h. XRD, TEM and selected area electron diffraction (SAED) revealed the presence of nano-crystalline LiCoVO₄ with inverse spinel structure. The V–O stretching vibration modes of VO₄ tetrahedrons were detected by FTIR over the range 617–835 cm^− 1 and by Raman spectrometer at 805.7 and 783.1 cm^− 1. Co, V and O were detected by EDX. TGA of solvothermal products shows weight loss due to the evaporation and decomposition processes at 40–648 °C.     

Studies in structural characterization of silica–heteropolyacids composites prepared by sol–gel method

Heteropolyacids (HPAs) which are included in mesoporous silica, H₃PMo₁₂O₄₀/SiO₂ and H₄PMo₁₁VO₄₀/SiO₂ have been synthesized by a sol–gel technique that involves hydrolysis of ethyl orthosilicate. The effect of incorporation of heteropolyacids species on silica matrix was studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopy, thermo gravimetric analysis (TGA) and differential thermal analysis (DTA), N₂ adsorption–desorption, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).     

Green synthesis,characterisation and biological studies of AgNPs prepared using Shivlingi (Bryonia laciniosa) seed extract

Green synthesis of silver nanoparticles (AgNPs) using Shivlingi (Bryonia laciniosa) seed extract was carried out. Characterisation of synthesised nanoparticles was accomplished through the optical absorption and photoluminescence spectrum, X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The XRD analysis further confirmed the size of nanoparticles ∼15 nm. TEM images revealed homogeneous spherical ∼10 nm Bryonia extract capped AgNPs. The biological studies indicated that both Bryonia seed extract and the nanoparticles lack anti‐microbial activity; however, the nanoparticles had better cytotoxicity and total antioxidant activity. The Lethal concentration (LC)₅₀ value of water extract and the nanoparticles were found to be 1091 and 592 μg/ml, respectively. The lower LC₅₀ of nanoparticles indicates that it is more cytotoxic than the crude extract. The results indicate that the Bryonia seed is safe to be used as a medicine and the formation of their nanoparticle has further enriched the chemical reactivity, energy absorption and biological mobility.Inspec keywords: silver, nanoparticles, nanomedicine, particle size, microorganisms, cellular biophysics, nanofabrication, photoluminescence, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectra, Raman spectra, antibacterial activity, biochemistryOther keywords: green synthesis, biological studies, Shivlingi seed extraction, Bryonia laciniosa, silver nanoparticles, optical absorption, photoluminescence spectrum, X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, SEM, Fourier transform infrared spectroscopy, Raman spectroscopy, XRD analysis, nanoparticle size, TEM images, homogeneous spherical images, antioxidant activity, water extraction, chemical reactivity, energy absorption, biological mobility, Ag     

PANI/TiO2 nanocomposite‐based chemiresistive gas sensor for the detection of E. Coli bacteria

In the modern pace of the world, food safety is a major concern. In this work, a simple chemiresistive type gas sensor was fabricated to detect Escherichia Coli (E. coli) bacteria. Polyaniline (PANI) films were deposited on the indium tin oxide substrate by an electrochemical deposition method. TiO₂ nanoparticles were synthesised by facile hydrothermal method. PANI films were modified using hydrothermally prepared TiO₂ nanoparticles by a spin coating method. X‐ray diffraction (XRD), field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and ultraviolet– visible spectrophotometer techniques were used to characterise the PANI/TiO₂ nanocomposites. The peaks obtained in the XRD pattern confirmed the anatase phase of TiO₂ nanoparticles. FESEM analysis showed the nanofibrous structure of the nanocomposite. The FTIR characteristic peaks confirmed the formation of the nanocomposite. The electrical resistance of the sensors was evaluated as a function of the bacterial concentration. The PT2 (TiO₂ coated 5 times on PANI) in comparison with PT1 (TiO₂ coated 3 times on PANI) exhibited good sensitivity to the gas molecules at room temperature. The p‐n junction at PANI/TiO₂ interface improved the physical adsorption of gas molecules. Since no specific antibodies or receptors are used, the sensor has the potential for adaptation to real‐life applications. Thus low cost, real‐time, portable, reusable and sensitive bacteria sensors were fabricated and tested.Inspec keywords: conducting polymers, nanoparticles, nanocomposites, visible spectra, ultraviolet spectra, microorganisms, nanosensors, adsorption, gas sensors, nanofabrication, nanofibres, X‐ray diffraction, titanium compounds, spin coating, field emission scanning electron microscopy, Fourier transform infrared spectra, polymer films, electrodeposition, electrical resistivity, wide band gap semiconductors, biological techniques, nanobiotechnologyOther keywords: simple chemiresistive type gas sensor, polyaniline films, indium tin oxide substrate, electrochemical deposition method, TiO₂ nanoparticles, facile hydrothermal method, PANI films, spin coating method, gas molecules, portable bacteria sensors, reusable bacteria sensors, sensitive bacteria sensors, PANI‐TiO₂ nanocomposite‐based chemiresistive gas sensor, Escherichia Coli bacteria detection, X‐ray diffraction, XRD, field emission scanning electron microscopy, FESEM, Fourier transform infrared spectra, FTIR spectra, ultraviolet‐visible spectra, anatase phase, nanofibrous structure, electrical resistance, bacterial concentration, p‐n junction, physical adsorption, temperature 293.0 K to 298.0 K, TiO₂ , ITO     

Fabrication and characterization of a zirconia/multi-walled carbon nanotube mesoporous composite

A zirconia/multi-walled carbon nanotube (ZrO₂/MWCNT) mesoporous composite was fabricated via a simple method using a hydrothermal process with the aid of the cationic surfactant cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy (TEM), N₂ adsorption–desorption, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques were used to characterize the as-made samples. The cubic ZrO₂ nanocrystallites were observed to overlay the surface of MWCNTs, which resulted in the formation of a novel mesoporous–nanotube composite. On the basis of a TEM analysis of the products from controlled experiment, the role of the acid-treated MWCNTs and CTAB was proposed to explain the formation of the mesoporous–nanotube structure. The as-made composite possessed novel properties, such as a high surface area (312 m² · g^? 1) and a bimodal mesoporous structure (3.18 nm and 12.4 nm). It was concluded that this composite has important application value due to its one-dimensional hollow structure, excellent electric conductivity and large surface area.     

Synthesis of ZnO/Fe3 O4 /rGO nanocomposites and evaluation of antibacterial activities towards E. coli and S. aureus

Antibacterial activity of nanoparticles (NPs) and nanocomposites (NCs) has received wide spread attention in biomedical applications. In this direction, the authors prepared zinc oxide (ZnO), iron oxide (Fe₃ O₄), and their composite including reduced graphene oxide (rGO) by hydrothermal method. The structural and microstructural properties of the synthesised NPs and NCs were investigated by XRD, FT‐IR, UV‐Vis, TGA, and TEM analysis. PEG‐coated ZnO and Fe₃ O₄ form in hexagonal wurtzite and inverse spinel structures, respectively. ZnO forms in rod‐shaped (aspect ratio of ∼3) morphology, whereas well‐dispersed spherical‐shaped morphology of ∼10 nm is observed in Fe₃ O₄ NPs. The ZnO/Fe₃ O₄ composite possesses a homogeneous distribution of above two phases and shows a very good colloidal stability in aqueous solvent. These synthesised particles exhibited varying antibacterial activity against gram‐positive strain Staphylococcus aureus (S. aureus) and gram‐negative strain Escherichia coli (E. coli). The nanocomposite exhibits a better cidal effect on E. coli when compared to S. aureus when treated with 1 mg/ml concentration. Further, the addition of rGO has intensified the anti‐bacterial effect to a much higher extent due to synergistic influence of individual components.Inspec keywords: colloids, visible spectra, II‐VI semiconductors, thermal analysis, nanofabrication, X‐ray diffraction, nanoparticles, biomedical materials, wide band gap semiconductors, transmission electron microscopy, ultraviolet spectra, antibacterial activity, nanocomposites, zinc compounds, nanobiotechnology, Fourier transform infrared spectra, graphene compounds, iron compounds, crystal growth from solution, crystal morphologyOther keywords: antibacterial activity, E. coli, biomedical applications, iron oxide, hydrothermal method, structural properties, microstructural properties, PEG‐coated ZnO, hexagonal wurtzite, inverse spinel structures, gram‐positive strain Staphylococcus aureus, S. aureus, gram‐negative strain Escherichia coli, nanocomposites, nanoparticles, XRD, FTIR spectra, UV‐vis spectra, TGA, TEM, rod‐shaped morphology, spherical‐shaped morphology, colloidal stability, cidal effect, ZnO‐Fe₃ O₄ ‐CO     

Effects of ZrO2 addition on phase stability and photocatalytic activity of ZrO2/TiO2 nanoparticles

ZrO₂/TiO₂ nanoparticles with various Zr/Ti ratios (0–0.9) were prepared by a polymer complex solution method (PCSM). The prepared samples were characterized using transmission electron microscopy (TEM), the Brunauer, Emmett & Teller (BET) method, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The ZrO₂/TiO₂ photocatalyst showed a high specific area and small crystal size. The XRD pattern for the Zr/Ti = 0.1 sample indicated that the addition of ZrO₂ stabilized the anatase phase of TiO₂ up to 800 °C. The photocatalytic activity of Zr/Ti = 0.1 sample was higher than that of the TiO₂ sample and commercially available Degussa P25. The high photocatalytic activity can be attributed to stronger adsorption in the visible light region, higher specific area, smaller crystal size and increased surface OH groups.     

Cellulose-precursor synthesis of nanocrystalline Co0.5Cu0.5Fe2O4 spinel ferrites

Nanocrystalline Cu_0.5Co_0.5Fe₂O₄ powders were prepared via a metal-cellulose precursor synthetic route. Cellulose was used as a fuel and a dispersing agent. The resulting precursors were calcined in the temperature range of 450–600 °C. The phase development of the samples was determined by using Fourier transform infrared (FT-IR) spectroscopy and powder X-ray diffraction (XRD). The field-dependent magnetizations of the nanopowders were measured by vibrating sample magnetometer (VSM). All XRD patterns are of a spinel ferrite with cubic symmetry. Microstructure of the ferrites showed irregular shapes and uniform particles with agglomeration. From XRD data, the crystallite sizes are in range of 16–42 nm. Saturation magnetization and coercivity increased with increasing calcining temperature due to enhancement of crystallinity and reduction of oxygen vacancies.     

Effects of β-alanine on morphology and optical properties of CoAl2O4 nanopowders as a blue pigment

In this paper, we have synthesized cobalt aluminate (CoAl₂O₄), nanopowders as blue pigments by the combustion method, which metal nitrates were used as precursor materials and mixture of urea and glycine as fuel. The effect of β-alanine weight percentage as a novel excess fuel on some physical characteristics (e.g. crystallite size and color) of powders has been investigated. The synthesized powders were characterized by means of X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), Transmission electron microscope (TEM), Fourier transform infrared (FT-IR) and Ultraviolet–visible (UV–Vis) spectroscopies. XRD patterns and FT-IR spectra confirmed the formation of pure nanocrystalline CoAl₂O₄ powders after calcination of the metal-fuel gel precursors at 600 °C for 2 h. Optical band gap of 2.3 eV observed for the prepared powders. The crystallite sizes were estimated of 20–30 nm by means of TEM images and Williamson–Hall method. UV–Vis spectra of the blue metal oxides were characteristics of Co²⁺ metal ions located in tetrahedral sites. CIE L¹a¹b¹ chromatic coordinates indicated that the bluest color was obtained for β-alanine = 5.5 and 35.6 wt.%.     

Samarium-decorated ZrO2@SnO2 nanostructures,their electrical,optical and enhanced photoluminescence properties

In the present work, pure ZrO₂@SnO₂ and Samarium (Sm_x) (x?=?1%, 8% and 12%)-doped ZrO₂@SnO₂ nanoparticles (NPs) successfully synthesized by facile low-cost co-precipitation technique. As-synthesized nanostructures (NS) were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), UV–visible, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller (BET) spectroscopic investigation. The tetragonal crystal phase of the as-synthesized Sm_x:ZrO₂@SnO₂ NS confirmed by XRD analysis. The observed peak shift in the XRD patterns confirmed incorporation of dopant into host lattice. The Sm_x:ZrO₂@SnO₂ NS present irregular spherical morphology and high agglomeration confirmed by FESEM microscope analysis. The presence of functional groups, chemical bonding, chemical constituents and valence state of the NS confirmed by FT-IR and XPS analysis. The Sm_x:ZrO₂@SnO₂ NS showed higher surface area and smaller optical band gap (454 cm²/g and 2.12 eV) than the pure ZrO₂@SnO₂ NS (189–196 cm²/g and 2.84 eV). Photoluminescence (PL) spectra of undoped ZrO₂@SnO₂ and Sm_x:ZrO₂@SnO₂ NS exhibited oxygen vacancies. Undoped ZrO₂@SnO₂ NS exhibited emission intensity at 370.6 nm (λ_excitation?=?300 nm) whereas, Sm_x:ZrO₂@SnO₂ NS showed emission intensities at 453.4 nm, 476.3 nm, 601.3 nm (λ_excitation?=?300 nm). Electrical property studies of Sm_x:ZrO₂:SnO₂ (1%, 8% and 12%) NS showed large variation in Hall constant (0.125?×?10⁶ cm²/coulomb to 0.647?×?10⁶ cm²/coulomb) with proportionately large variation in the resistivity (147.8 Ω-cm to 456.8 Ω-cm) for all the doped samples as compared with pure ZrO₂@SnO₂ NS. The Sm³⁺-doped ZrO₂@SnO₂ NS showed higher stability, intense PL emission and enhanced electrical properties.