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A Novel Study: The Effect of Graphene Oxide on the Morphology, Crystal Structure, Optical and Electrical Properties of Lanthanum Ferrite Based Nano Electroceramics Synthesized by Hydrothermal Method
摘要： Lanthanum Ferrite based nanocomposites were prepared with various Graphene oxide contents by the hydrothermal method. The crystalline structure, morphological properties, electrical and optical properties of samples were investigated. X-ray diffraction results indicate that all the nano electroceramics are polycrystalline with an Orthorhombic structure. Results from scanning and transmission electron microscopes indicate that the Bismuth ferrite/Graphene oxide powders have nanostructure. The optical band gaps of the nano electroceramics were calculated for the various amount of Graphene oxide. The electrical properties of samples were investigated with the temperature depend on conductivity measurements. The measurement shows that the electrical conductivity changes with increasing temperature and graphene oxide dopants of all samples. Activation energy values of the nanocomposites decrease with increasing graphene oxide content. The dielectric properties of Lanthanum Ferrite/Graphene Oxide nanocomposites (real and imaginer) with respect to frequency variation (1 KHz–5 MHz) were measured at room temperature. The relative permittivity, dielectric loss and alternating current conductivity values of the samples were estimated. It is show that relative permittivity, dielectric loss and alternating current conductivity increase with increasing frequency. The polarization-electric field hysteresis loop of all Lanthanum Ferrite/Graphene Oxide nano electroceramics was measured at the room temperature. The loop shows proper saturation with enhanced saturation polarization and coercive electric field. The obtained findings suggest that the physical and electrical properties of Lanthanum Ferrite/Graphene Oxide nano electroceramics can be changed by Graphene Oxide doping. These materials can be used for a variety of technological applications in the field of dielectric and ferroelectric.
关键词： Dielectric Properties,Graphene Oxide,Lanthanum Ferrite,Ferroelectric,Hydrothermal Method
更新于2025-09-09 09:28:46
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Tuning visible emission from red to yellow of PbWO4:Yb3+/Ho3+ nanophosphor by modulating activator ion concentration
摘要： Lanthanide doped upconverting nanophosphors possesses a great appulse in many emerging applications due to their stupendous luminescence property, photostability, effective quantum efficiency, etc. In this article Yb3+ and Ho3+ doped lead tungstate synthesized by hydrothermal method has been reported. The synthesized materials were characterized by XRD, FTIR, HRTEM and photoluminescence study was carried out with the help of spectroflurophotometer. The synthesized nanophosphor is an exposition of a strong red emission which was tuned to yellow emission by increasing the concentration of Ho3+ based on green emission at 542 nm due to 5S2/5F4→5I8 transition of Ho3+ and red emission at 657 nm due to 5F5→5I8 transition of Ho3+ upon excitation at 980nm. The study of dependency of emission intensity with pump power as lnP vs lnI curve corroborate that the upconversion mechanism involves two photon process. The radiative lifetimes measured for the emission were 23.31 μs for green emission (5S2/5F4→5I8) and 50.96 μs for red emission (5F5→5I8). The club-shaped nanophosphor which we have synthesized can be bestowed in different sectors as it has a tuneable red to yellow emission characteristics and hence, it could be exercised in many applications.
关键词： Lead tungstate,Hydrothermal,Rare-earth,Upconversion,Nanophosphor
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) 6TH INTERNATIONAL CONFERENCE ON PRODUCTION, ENERGY AND RELIABILITY 2018: World Engineering Science & Technology Congress (ESTCON) - Kuala Lumpur, Malaysia (13–14 August 2018)] - Synthesis of carbon dots and their optical properties
摘要： In this paper, carbon dots were synthesized from glucose, soot and ethylene glycol by hydrothermal treatment. The resulting carbon dots were characterized by luminescent spectrometry and spectrophotometry. The spectra exhibit bright luminescence in the blue region and strong absorption in the ultraviolet region. All samples exhibit typical excitation wavelength-dependent properties.
关键词： optical properties,hydrothermal treatment,luminescence,absorption,carbon dots
更新于2025-09-09 09:28:46
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Synthesis and Characterization of ZnO Nanorods as an Adsorbent for Cr(VI) Sequestration
摘要： Zinc oxide (ZnO) nanorods were fabricated through hydrothermal route and employed for the adsorption of Cr(VI) ions from aqueous medium. Zinc nitrate hexahydrate (Zn(NO3)2.6H2O) was used as a zinc precursor and Triton-x 100 was used as a capping agent. As synthesized ZnO nanorods were characterized by UV-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive X-Ray spectroscopy (EDX) techniques. The adsorption affecting parameters were investigated for maximum adsorption of Cr(VI) onto ZnO nanorods. The adsorption kinetics, isotherms, and thermodynamics were applied for adsorption mechanism evaluation. Maximum adsorption of Cr(VI) ions (250 mg/g) was achieved using 0.055 g/L ZnO dose at pH 2.0 for the contact time of 30 min. Pseudo-second-order kinetic model and Langmuir isotherm explained well the Cr(VI) adsorption onto ZnO nanorods. The Cr(VI) adsorption onto ZnO was spontaneous and endothermic in nature. In view of promising adsorption efficiency, ZnO nanorods could possibly be used for Cr(VI) ions removal from wastewater and also extendable for the adsorption of other heavy metals ions.
关键词： ZnO nanorods,Cr(VI) adsorption,hydrothermal synthesis,Cr(VI) removal,wastewater
更新于2025-09-09 09:28:46
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High-fluorescent carbon dots (CDs) originated from China grass carp scales (CGCS) for effective detection of Hg(II) ions
摘要： Carbon dots (CDs) as a kind of environment-friendly fluorescent nanomaterial has been actively studied because of wide and potential applications, such as bioimaging and biosensors. It is worth mentioning that preparing CDs from the recycling of carbonaceous waste has received considerable research interest. We proposed a simple carbon dots synthesis technique, that is, using China grass carp scales (CGCS) as original and green materials by a one-step microwave hydrothermal method to prepare CDs. Since the mercury ion has strongly sulphophile, S atoms display higher thermodynamic affinity and faster integrating process with Hg2+ ions. Due to the presence of large amount of cysteine-containing sulfhydryl groups, the obtained CGCS-CDs can be used as a specific fluorescence probe for detecting Hg2+ ions. Subsequently, CGCS-CDs were characterized by HR-TEM, XRD, FT-IR and XPS analyses. The optical properties of CGCS-CDs were elucidated by fluorescence and UV–vis spectra. Additionally, the effects of pH values and salt concentrations on optical properties of CGCS-CDs were also researched by fluorescence spectra. Under optimal conditions, the decrease of fluorescence intensity displays a good linear relationship with allowable Hg2+ ion detection concentration range of 0.014–30 μmol/L and a limit of detection (LOD) of 0.014 μmol/L is acquired. Meanwhile, the effect of other metal ions on the detection of Hg2+ ions by using CGCS-CDs as fluorescence probe was studied, suggesting that the CGCS-CDs could be an excellent fluorescence probe for the detection of Hg2+ ions. Eventually, the CGCS-CDs were proven to be low toxicity and applied for Hg2+ ions detection in lake water and cosmetic, demonstrating their potential towards diverse applications.
关键词： Sulfhydryl group,Microwave hydrothermal,Nanoscale sensing,Mercury,Carbon dots (CDs),China grass carp scales (CGCS)
更新于2025-09-09 09:28:46
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Hierarchical zinc oxide nanorings with superior sensing properties
摘要： Morphology controlled hydrothermal synthesis techniques have been realised to produce hierarchical zinc oxide (ZnO) nanostructures with high surface-to-volume ratios and more exposed polar facets. Hierarchical ZnO nanorings (HNRs) were produced by growing secondary nanowires (NWs) on initial mono-morphological nanodisks (NDs). In the two steps of growth process, zinc sulphate and zinc nitrate were used as the source of zinc ions, respectively. In comparison with NWs and NDs, the grown HNRs showed more enhanced performance as gas sensors. HNRs were substantially sensitive and faster in responding to acetone. This high performance in gas sensing is due to the increased surface-to-volume ratio and small size of the NW building blocks as well as the increased proportion of (0 0 0 1) polar facets. This work represents a guide to structure induced improvement of sensing properties by controlling the morphology of nanostructures.
关键词： Nanostructures,Sensor,Zinc oxide,Nanowires,Hydrothermal synthesis
更新于2025-09-09 09:28:46
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Improved field emission from appropriately packed TiO2 nanorods: Designing the miniaturization
摘要： An improved electron field emission (FE) property from vertically aligned TiO2 nanorods (TNR) on conducting fluorine doped tin oxide coated glass substrate, prepared by hydrothermal technique, has been reported here. The TNRs having high aspect ratio with appropriate separation were prepared by optimizing the nucleation temperature. The TNR density has been optimized to cease the screening effect in closely packed nanorods. The well aligned rods have been designed so that the applied field is equally distributes on each rod to improve the electron emission. The morphology of the nanorod has been studied using scanning electron microscopy and observed FE current density-field response has been analysed within the frame work of Fowler-Nordheim modelling. Two orders of magnitude enhancement in the electric field has been observed for this kind of geometry giving improved turn on field and field enhancement factor of 0.2 V/m m and 37 thousands respectively.
关键词： Fowler-Nordheim modelling,Hydrothermal technique,Field emission,TiO2 nanorods,Field enhancement factor
更新于2025-09-09 09:28:46
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Structural Modification, Synthesis Mechanism and Properties Analysis of Li4Ti5O12 Anode Materials
摘要： Li4Ti5O12 microsphere was synthesized by hydrothermal method. The effects of amount of lithium hydroxide, hydrothermal time and sintering temperature on properties of sample were studied. The synthesis mechanism of Li4Ti5O12 microsphere was preliminary analyzed. The structural characterization was analyzed by X-ray diffraction, and the morphology was investigated by scanning electron microscopy and transmission electron microscopy. The properties of galvanostatic charge, discharge and cycle stability were also studied. The results indicated that when 2.55 mmol LiOH?H2O reacted with 0.2 g hydrolysate, the sample had pure phase, when the hydrothermal condition was 36 h and 180 oC, the structure of sample particle was intactly spherical. The volume average size of samples were between 400 nm to 600 nm. The charge and discharge voltage plateau of samples were very stable. When the sintering temperature was 700 oC, the first discharge capacity was 148.3 mAh?g-1 at 0.1 C. After 10th cycle, the discharge capacity retained at 132.5 mAh?g-1.
关键词： hydrothermal method,electrochemical property,hydrothermal condition,Lithium titanate
更新于2025-09-04 15:30:14
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Photoluminescence and Growth Mechanism of Oriented Hierarchical Fibrous-Like ZnO Nanowires
摘要： Oriented hierarchical fibrous-like ZnO nanowires with the diameter of about 30–50 nm and the length of about 15–30 um were successfully synthesized on the seed-coated Zn substrates by a simple two-step process. The morphology and structure of the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It is shown that fibrous-like ZnO nanowires with the aspect ratio of about 500～1000 present the dense reticular structure, which are grown on ZnO nanowire arrays. But beyond that, as-prepared samples are found to be good single crystalline with hexagonal wurtzite structure and preferential grow along the c-axis. A possible growth mechanism of oriented hierarchical fibrous-like ZnO nanowires is presented in detail, revealing that the synthesis of fibrous-like ZnO nanowires should be attributed to differences in the growth rate of the different crystallographic planes and the two growth ways. The photoluminescence (PL) spectra of oriented hierarchical fibrous-like ZnO nanowires grown at 240 min shows the 5 nm blue-shift and enhanced intensity property in the UV emission.
关键词： Hydrothermal Method,Fibrous-Like ZnO Nanowires,Formation Mechanism,Oriented Hierarchical,PL Property
更新于2025-09-04 15:30:14
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Moisture absorption and hydrothermal aging of phenylethynyl-terminated pyromellitic dianhydride-type asymmetric polyimide and composites
摘要： The effects of moisture on a polymerized monomeric reactant (PMR)-type polyimide (TriA X) and associated composites were investigated. Water uptake tests were performed on the polyimide at various temperatures and relative humidity levels to investigate moisture absorption behavior. Two-stage moisture absorption was observed, in which the first stage was diffusion controlled, whereas the second stage was moisture plasticization controlled. As exposure temperature increased, the equilibrium moisture content of the polyimide decreased, indicating an exothermic absorption process. The Arrhenius temperature dependence and moisture saturation as functions of temperature and humidity in the neat polymer were determined using curve fitting based on the published mathematical models. Long-term hydrothermal aging at 95°C was conducted on the neat polyimide and associated carbon fiber composites. Reversible hydrolytic reactions and a trace of irreversible hydrolysis were observed in the long-term exposure. The tensile ductility of the neat polyimide and the short-beam shear strength of the composites decreased with increasing aging time, while the tensile strength and modulus and thermal properties of the polyimide exhibited little change after 2000-h aging, demonstrating hydrothermal stability. The decrease in the ductility of the neat polymer after long-term moisture exposure was attributed to the network structure change, driven by hydrolysis and moisture plasticization.
关键词： β-relaxation,hydrothermal aging,moisture absorption,thermal properties,hydrolysis,Polyimide,composite,mechanical properties,plasticization
更新于2025-09-04 15:30:14