Solvothermal synthesis of In(OH)3 nanorods and their conversion to In2O3

In this work, we demonstrate that monodisperse indium hydroxide (In(OH)₃) nanorods constructed with parallel wire-like subunits have been fabricated via a acrylamide-assisted synthesis route without any template. NH₃ from the hydrolysis of acrylamide acts as the OH⁻ provider. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TG). A detailed mechanism has been proposed on the basis of time-dependent experimental results. Furthermore, by annealing In(OH)₃ precursors at 500 °C for 3 h in air, In₂O₃ samples were obtained with the designed morphology.     

Self-assembled 3D flower-like NaY(MoO4)2:Eu microarchitectures: Hydrothermal synthesis, formation mechanism and luminescence properties

Self-assembled 3D flower-like NaY(MoO₄)₂:Eu³⁺ microarchitectures were successfully synthesized by a glycine-assisted hydrothermal method at 180 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM) were employed to characterize the as-obtained products. It was found that morphology modulation could be easily realized by changing the time of hydrothermal reaction system. 3D flower-like NaY(MoO₄)₂:Eu³⁺ microarchitectures were formed with 72 h reaction time. The formation mechanism for flower-like architecture was proposed on the basis of a series of time-dependent experiments. The NaY(MoO₄)₂:Eu³⁺ powders obtained can be effectively excited by 396 nm light, and exhibit strong red emission around 615 nm, attributed to the Eu³⁺⁵D₀ → ⁷F₂ transition. An investigation on the photoluminescence (PL) properties of NaY(MoO₄)₂:Eu³⁺ obtained revealed that the luminescence properties were correlated with the morphology and size.     

A simple route to synthesis of BaCO3 nanostructures in water/ethylene glycol mixed solvents

Barium carbonate (BaCO₃) nanostructures with different morphologies were synthesized using Ba(NO₃)₂ and (NH₄)₂CO₃ in the water/ethylene glycol (EG) mixed solvents by oil bath heating at 80 °C for 30 min. The molar ratio of water to EG had an effect on the morphology of BaCO₃. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM).     

Synthesis of GaN nanorods by ammoniating Ga2O3 films on TiO2 (rutile) layer deposited on Si(111) substrates

GaN nanorods have been synthesized by ammoniating Ga₂O₃ films on a TiO₂ middle layer deposited on Si(111) substrates. The products were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformed infrared spectra (FTIR) and high-resolution transmission electron microscopy (HRTEM). The XRD analysis indicates that the crystallization of GaN film fabricated on TiO₂ middle layer is rather excellent. The FTIR, SEM and HRTEM demonstrate that these nanorods are hexagonal GaN and possess a rough morphology with a diameter ranging from 200 nm to 500 nm and a length less than 10 μm, the growth mechanism of crystalline GaN nanorods is discussed briefly.     

A facile hydrothermal route to spinel CoCo2O4 nanotubes and porous nanostructures without assisted surfactants and templates

Spinel CoCo₂O₄ nanotubes and porous nanostructures have been synthesized by a novel hydrothermal method from Co(NO₃)₂·6H₂O in mixtures of ammonia and cyclohexane at 220 °C. The morphology and phase of CoCo₂O₄ can be controlled by adjusting the experimental parameters that include the Co²⁺ concentration and the volume ratio of ammonia to cyclohexane. X-ray diffraction and transmission electron microscopy analyses were used to characterize the products. The formation mechanisms of CoCo₂O₄ nanostructures is proposed in detail. The electrochemical properties of the as-prepared samples have been investigated.     

Hydrothermal synthesis and characterization of monodisperse α-Fe2O3 nanoparticles

Monodisperse α-Fe₂O₃ nanoparticles have been successfully prepared by hydrothermal synthetic route using FeCl₃, CH₃COONa as reagents and reacted at 200 °C for 12 h. The morphology and structure of products were characterized by powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the α-Fe₂O₃ nanoparticles were single-crystalline hexagonal structure and average diameters were about 80 nm. Magnetic properties have been detected by a vibrating sample magnetometer at room temperature. The nanoparticles exhibited a ferromagnetic behavior with the coercive force (Hc), saturation magnetization (Ms) and remanent magnetization (Mr) was 185.28 Oe and 0.494 emu/g, 0.077 emu/g.     

Synthesis RMn2O5 (R = Gd and Sm) nano- and microstructures by a simple hydrothermal method

Single-phase RMn₂O₅ (R = Gd and Sm) nano- and microstructures have been successfully synthesized via a simple hydrothermal process at 250 °C for 24 h using NaOH as mineralizer. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selective area electron diffraction patterns (SAED) were used to characterize the as-synthesized GdMn₂O₅ and SmMn₂O₅ samples. The effect of NaOH concentration and the molar ratio of Mn²⁺/Mn⁷⁺ on the morphology and size of the final products was studied, and a possible formation mechanism of RMn₂O₅ (R = Gd and Sm) nanoplates and nanorods under hydrothermal conditions was proposed.     

Hydrothermal-polyol route to synthesis of β-Ni(OH)2 and NiO in mixed solvents of 1,4-butanediol and water

The β-Ni(OH)₂ with flower-like morphology assembled from nanosheets has been successfully synthesized by a hydrothermal-polyol method from Ni(CH₃COO)₂·4H₂O in mixed solvents of 1,4-butanediol and water at 200 °C for 24 h. The NiO with similar morphology was obtained by a simple thermal decomposition of the precursor (β-Ni(OH)₂) at 400 °C for 3 h in air. The products were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), thermogravimetric analysis (TG) and differential scanning calorimetric analysis (DSC). We expect that this hydrothermal-polyol method may be extended to the preparation of nanostructures of other kinds of metal oxides.     

Hydrothermal synthesis of single-crystal BaTiO3 dendrites

In this paper, we report a simple hydrothermal method without any surfactants, for the first time, to synthesize single-crystal BaTiO₃ dendrites. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM). The KOH concentration was found to be vital to the final formation of BaTiO₃ dendrites. An obvious morphology evolution from sphere-like shape to dendrite was observed when KOH concentration was decreased from 1 M to 0.1 M. It is rational to expect that dendritic structures of other perovskite oxides may also be synthesized by this simple method.     

Hydrothermal synthesis of single-crystalline Bi2Te3 nanoplates

Novel Bi₂Te₃ nanoplates with about 0.2-1 μm in diagonal and 100 nm in thickness have been facilely synthesized via hydrothermal routes in the presence of polyvinylpyrrolidone (PVP). Various techniques such as X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform infrared spectrometry (FT-IR) have been used to characterize the obtained products. The results show that the existence of PVP is vital to the formation of the plate-like morphology. Other factors, such as the reaction temperature and the different surfactants also have influence on the morphology of the final products to some extent.     

Synthesis of worm-like Ag2S nanocrystals in W/O reverse microemulsion

High-aspect-ratio of worm-like Ag₂S nanocrystal with length up to several micrometers and a diameter of 25-50 nm has been successfully prepared by a Triton X-100/cyclohexane/hexanol/water W/O reverse microemulsion in the presence of TAA (Thioacetamide) as a sulfur source and EDTA (ethylene diamine tetraacetic acid) as a chelating ligand. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance absorption spectra. The results indicate that the morphology and size of Ag₂S nanocrystal can be readily controlled by modulating the mole ratio of Ag⁺ to EDTA, the molar ratio of water to surfactant (ω₀), and the aging time.     

Synthesis of (K, Na)NbO3 particles by high temperature mixing method under hydrothermal conditions

In order to prepare the pure (K, Na)NbO₃(KNN) particles with higher crystallinity, the high temperature mixing method (HTMM) under hydrothermal conditions was carried out in this work. The obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). The results indicate that the KNN particles size decrease gradually with the increase of mineralization concentration in the starting solution. The ratio of K⁺/(K⁺ + Na⁺) in the starting solution has a great effect on the phase of the products, and several phases coexist in the product when the ratio of K⁺/(K⁺ + Na⁺) in the starting solution is 0.7.     

A facile approach to synthesize silver nanorods capped with sodium tripolyphosphate

Silver nanorods have been successfully synthesized via a facile route using sodium tripolyphosphate (Na₅P₃O₁₀) as the capping agent. Silver nitrate and glucose served as the Ag⁺ source and green reducing agent in aqueous solution, respectively. The products were characterized by X-ray powder diffraction (XRD), UV–visible spectroscopy (UV–vis), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The results showed that the obtained silver nanorods are highly crystallized with an average diameter of 30 nm and lengths up to 400 nm. The linear structure of the capping agent and slow reaction rate are considered to be key factors in the control of particle morphology. The possible formation mechanism has been discussed based on the experimental results.     

Low temperature synthesis and photoluminescent properties of CaMoO4:Eu red phosphor with uniform micro-assemblies

Scheelite-type Eu³⁺-doped CaMoO₄ red phosphor with uniform micro-assemblies has been successfully synthesized via a facile hydrothermal method at 120 °C for 10 h. The Eu³⁺-doped CaMoO₄ microstructures were assembled by small nanostructures and the morphology of materials was found to be manipulated by dropping different alkalis into the stock solution for the first time. The structure, morphology, and luminescent property were characterized and investigated by techniques of X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL). The luminescent investigations confirmed that the Eu³⁺ ions have been effectively doped into CaMoO₄ nanostructures. The successfully achieved Eu³⁺-doped CaMoO₄ nanostructures will be potential in technological applications on near UV chip-based white light emitting diode (WLED).     

Synthesis of single-crystalline silver sulfide nanowires by diffusion in porous anodic aluminium oxide template

Highly ordered single-crystalline silver sulfide (Ag₂S) nanowires have been successfully achieved directly using silver nitrate and thioacetamide (TAA) as the reactants, by diffusion in the channels of anodic aluminium oxide (AAO) membrane. The products have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The results of the research show that the as-prepared Ag₂S nanowires are monodisperse with sizes of about 50 nm in diameter, closely corresponding to the pore size of the AAO membrane. Furthermore, its photoluminescence properties and the growth mechanism 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.     

Microwave synthesis and characterization of ZnO with various morphologies

ZnO micro- and nanostructures with a variety of morphologies have been synthesized using Zn(NO₃)₂·6H₂O and pyridine by a microwave-assisted aqueous solution method at 90 °C for 10 min. The pyridine has a significant influence on the morphology of ZnO. Various morphologies of ZnO (hexagonal columns, linked hexagonal needles, hollow structures, and hexagonal nanorings) were obtained by adjusting the concentration of pyridine. The effect of the type of other alkaline additive (aniline and triethanolamine) on the morphology of ZnO was also investigated. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM).     

Synthesis,characterization and formation mechanism of monodispersed Gd<Subscript>2</Subscript>O<Subscript>2</Subscript>S:Eu<Superscript>3+</Superscript> nanocrystals

Monodispersed Gd₂O₂S:Eu³⁺ nanostructures with tunable morphologies have been selectively fabricated by solvothermal method in the presence of stable inorganic precursors avoiding metalorganic precursors. The size and morphology of the products were controlled successfully by adjusting the reaction conditions. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS). The corresponding UV absorption and photoluminescence excitation spectra show a significant blue-shift confirming the quantum confinement effect. A possible growth mechanism for the formation of monodispersed Gd₂O₂S:Eu³⁺ nanocrystals has been proposed. The luminescence mechanism and the size dependence of their fluorescence properties are also discussed.     

Microwave synthesis of SrCO3 one-dimensional nanostructures assembled from nanocrystals using ethylenediamine additive

One-dimensional SrCO₃ nanostructures assembled from nanocrystals have been successfully synthesized by a microwave-assisted aqueous solution method at 90 °C using Sr(NO₃)₂, (NH₄)₂CO₃ and ethylenediamine (C₂H₈N₂). Our experiments show that the microwave heating time plays an important role in the size and morphology of SrCO₃. A rational mechanism based on the oriented attachment self-assembly is proposed for the formation of SrCO₃ nanostructures. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). This method is simple, fast, low-cost and suitable for large-scale production of SrCO₃ nanostructures with different morphologies. We expect that this method may be extended to the preparation of nanostructures of other kinds of carbonates.     

Synthesis and characterisation of SnO2 nano-single crystals as anode materials for lithium-ion batteries

Rutile structure SnO₂ nano-single crystals have been synthesized using tin (IV) chloride as precursor by the modified hydrothermal method. Controllable morphology and size of SnO₂ could be obtained by adjusting the concentration of the hydrochloric acid. The SnO₂ nanoparticles were characterised by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and electrochemical methods. The SnO₂ nanoparticles as anode materials in lithium-ion batteries exhibit high lithium storage capacities. The reversible capacities are more than 630 mA h g^− 1.