Morphology-controlling synthesis of ZnS through a hydrothermal/solvthermal method

Different morphologies of ZnS have been synthesized by a solvothermal process, through the reaction of Zn(CH₃COO)₂·2H₂O and SC(NH₂)₂ in different mixed solvents, changing the density of the surfactant (C₁₂H₂₅SO₃Na). The samples were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX) techniques. The results show that the as-prepared ZnS have different morphologies, such as lamellar ZnS, smooth microspheres, roughen microspheres, plate-like ZnS and so on. So far, to our knowledge, lamellar ZnS have not been synthesized by solvothermal route before.     

Synthesis of CuInS2 quantum dots on TiO2 porous films by solvothermal method for absorption layer of solar cells

Copper indium disulfide (CuInS₂) nano-particles have been synthesized by solvothermal method for absorption layer of solar cells. The CuInS₂ nano-particles can be adsorbed in pores of TiO₂ porous films. The effects of heat-treatment on crystalline structures and sizes of the CuInS₂ nano-particles were investigated. Crystalline structures and sizes were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM) investigations. Surface morphologies and optical properties were studied by field-emission scanning electron microscope (FESEM) and UV–vis spectra when CuInS₂ were absorbed on TiO₂ films.The results show that the CuInS₂ quantum dots (size is smaller than 10 nm) can be synthesized by solvothermal method at 150 °C. CuInS₂ particles sizes increase with the rise of reaction temperature and time. The CuInS₂ quantum dots can be adsorbed on TiO₂ films well and high-absorptive anodic electrode of solar cells can be prepared. Blue shift of absorption edge was observed as the sizes of CuInS₂ quantum dots decreased.     

An innovative process for synthesis of superfine nanostructured Li2TiO3 tritium breeder ceramic pebbles via TBOT hydrolysis – solvothermal method

In this paper, a method combining hydrolysis of tetrabutyl orthotitanate (TBOT) and solvothermal reaction was first used to fabricate nanostructured Li₂TiO₃ tritium breeder ceramic pebbles. Initially, superfine nanostructured Li₂TiO₃ powders were synthesized with average particle size of about 10?nm, according to TEM. The surface area of precursor particles synthesized via this method was found to be 115.85?m²/g by BET analysis, which is much larger than that of the product obtained using traditional methods. The results showed that precursor particles had high sintering activity. XRD pattern revealed that the phase transition temperature for monoclinic phase Li₂TiO₃ prepared by this method was nearly 450?°C, which was the lowest phase transition temperature reported among all wet chemical methods to date. Subsequently, investigation of ceramic sintering demonstrated that Li₂TiO₃ ceramic pebbles with desired nano-crystalline sizes (27.98 ~ 55.03?nm) were obtained by sintering at 500 ~ 600?°C for 4?h. The possible mechanisms were proposed based on the reaction processes of TBOT hydrolysis, solvothermal reaction and sintering.     

Synthesis of hexagonal pyramidal columnar hematite particles by a two-step solution route and their characterization

Hexagonal pyramidal columnar hematite (α-Fe₂O₃) particles have been synthesized by a hydrolysis method using iron sheets and nitric acid of mildly acidic pH at 90 °C. The morphologies and structures of the resulting products have been characterized by transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), and Fourier-transform IR spectroscopy (FTIR). An aggregation growth mechanism is proposed to rationalize the formation of α-Fe₂O₃. The influence of pH on the structure and morphology of the as-prepared α-Fe₂O₃ has been investigated. Additionally, magnetic investigations have shown that the hexagonal pyramidal columnar α-Fe₂O₃ exhibited weak ferromagnetism at room temperature.     

Synthesis of nanometer sized Bi<Subscript>2</Subscript>WO<Subscript>6</Subscript>s by a hydrothermal method and their conductivities

Nanometer-sized bismuth tungsten oxides, Bi₂WO₆s, were successfully synthesized by hydrothermal treatment at 200 °C for 24 hr, and their morphologies and crystallite sizes were influenced by adjusting the conditions to pH 4, 7, and 9. TEM images revealed that the particles were sheet-shaped and the crystallite sizes ranged from 7–120 nm. The samples absorbed in the visible range at about 380–400 nm. The lowest conductivity, 1.0×10⁶ ohm/square, was observed for Bi₂WO₆ prepared at pH 4 with a 150 nm film thickness. As the annealing temperature for Bi₂WO₆ prepared at pH 7 was increased, the conductivity decreased due of formation of larger particles by coagulation and sintering at high temperatures. Conductivity appears to improve with increasing film thickness up to 1,500 nm.     

Hierarchical brain-coral-like structure (3D) vs rod-like structure (1D): Effect on electromagnetic wave loss features of SrFe12O19 and CoFe2O4

Morphological configuration plays a vital role in regulating the absorption performance of magnetic materials. Herein, a novel challenge is discussed on electromagnetic loss features of two hard and soft magnetic materials with hierarchical brain-coral like structure and rod-like structure. In this study, pure SrFe₁₂O₁₉ (Sr) as hard magnetic component and CoFe₂O₄ (Co) as soft magnetic component with two distinct morphologies were successfully synthesized by facile hydrothermal and solvothermal methods. In the first approach, electromagnetic loss features of rod and brain-coral-like particles were investigated, and in second approach -according to the obtained results-microwave absorption performance of a mixture of hard/soft magnetic components with hierarchical structure were evaluated. The minimal reflection loss (RL) for brain-coral-like particles of individual Sr and Co samples were −17.6 dB (at 18.8 GHz with 9 mm thickness) and −31.2 dB (at 8.1 GHz with 10 mm thickness), respectively, which show far better performance than rod-like structure. Remarkably, the composite of Sr and Co micro-particles with hierarchical structure exhibited strong RL value of −38 dB with 2.6 GHz effective absorption bandwidth at the thickness of 2.5 mm, with a filling ratio of 40 wt%. According to the results, it is founded that the electromagnetic loss features are crucially boosted via hierarchical configuration of magnetic materials. Increment in complex permittivity and permeability, accounting for the formation of cross-linked networks in the hierarchical structure, promoted the interfacial polarization phenomena with different relaxation times and appearance of multi resonance peaks.     

Preparation of Iron Sulfide Nanomaterials from Iron(II) Thiosemicarbazone Complexes and Their Application in Photodegradation of Methylene Blue

Iron sulfide nanomaterials were prepared by the solvothermal decomposition of two single source precursors i.e. [FeCl₂(cinnamtscz)₂] (1) (cinnamtscz?=?cinnamaldehyde thiosemicarbazone) and [FeCl₂(benztscz)₂] (2) (benztscz?=?benzaldehyde thiosemicarbazone) at different temperatures of 230 and 300 °C in the presence of oleylamine. Powder X-ray diffractometry shows the formation of the pyrrhotite phase at both reaction temperatures. The solvothermal decomposition of [FeCl₂(cinnamtscz)₂] and [FeCl₂(benztscz)₂] at 230 °C produced iron sulfide nanoparticles in the form of spheres. When the temperature was increased to 300 °C, particles in the form of hexagons and nanorods were obtained. Furthermore, the photocatalytic activities of all the four iron sulfide nanomaterials were tested for the degradation of methylene blue under visible light irradiation. Amongst all the materials, nanospheres of iron sulfide obtained by the solvothermal decomposition of [FeCl₂(benztscz)₂] at 230 °C showed the highest photocatalytic efficiency (88.40%).     

Synthesis and growth mechanism of donut-like lead titanate particles by hydrothermal method

Tetragonal perovskite structure PbTiO₃ donut-like particles have been synthesized by a hydrothermal method in strong alkaline environment using lead nitrate (Pb(NO₃)₂) as the lead source and TiCl₄ as the titanium source. The as-prepared particles were characterized by X-ray powder diffraction (XRD) and scanning electron microscope (SEM), and it was indicated that the phase composition and particles shapes were influenced by the reaction temperature and reaction time. Based on the morphologies and phase evolutions as a function of reaction temperature or reaction time, a mechanism for the growth of the donut-like PbTiO₃ particles was proposed to involve nucleation, agglomeration, phase in situ conversion, dissolution, and recrystallization. The spherical particles were formed by primary nucleation of PbTi_0.8O_2.6 followed by agglomeration into platelets. Then, the platelet PbTi_0.8O_2.6 particles in situ converted into Pb₂Ti₂O₆ particles. Under the effects of temperature, pressure (autogenous pressure), and high solution pH value, the platelet Pb₂Ti₂O₆ particles dissolved from its center of surface and recrystallized to form PbTiO₃ nano-particles which adhered to its edges. Finally, the monocrystal donut-like PbTiO₃ particles were formed as the dissolution of Pb₂Ti₂O₆ particles completed.     

Controlled-surfactant-directed solvothermal synthesis of γ-Al2O3 nanorods through a boehmite precursor route

Ceramic one-dimensional particles are fascinating nanomaterials for sustainable future industries. Nanorods of γ-Al₂O₃ with single crystallinity and 10 nm diameter regime were newly developed through solvothermal procedure between AlCl₃·6H₂O, NaOH, and sodium dodecylbenzene sulfonate at 200 °C for 24 h. Controlling the pH values, reaction time, temperature, and effect of surfactant during the solvothermal reaction was studied to control the morphology and structure of nanorods. The solvothermal procedure for preparing γ-AlOOH nanorods followed lamellar growth, assembly, and ripening routes. The γ-AlOOH nanorods were converted to γ-Al₂O₃ through calcination reaction at 500 °C for 3 h. The produced γ-Al₂O₃ nanorods were 10 nm average width, 100–200 nm average length, and exposed with [101] orientation and a linear structure. FTIR, HRTEM, FESEM, XRD, and X-ray photoelectron spectroscopy methods were used for characterizing the prepared nanomaterials. New features and applied fields are predictable for the designed γ-AlOOH and γ-Al₂O₃ nanorods.     

The Influence of the Temperature on the Optical Absorption Properties and Morphologies of WO<Subscript>3</Subscript> Nanorods Synthesized by the Hydrothermal Method

Crystalline WO₃ nanorods of less than 100 nm in diameter have been successfully synthesized at 240 °C for 48 h at pH 1.5 by the hydrothermal method with sodium tungstate as a tungsten source and potassium sulphate as a subsidiary salt. The morphologies and structures of WO₃ rods were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected-area electron diffraction (SAED). SEM analysis confirms that the slenderness ratio of the WO₃ rods is enlarged with the increase of the reaction temperature at pH 1.5. SAED analysis shows that the synthesized WO₃ nanorods are crystalline. Ultraviolet–visible (UV-VIS) absorption spectroscopy shows that absorbent power of UV light for WO₃ nanorods enhances with an increase of the slenderness ratio.     

Synthesis,morphology, and upconversion luminescence of Tm3 +/Yb3 + codoped bulk and submicro-rod CaSc2O4 phosphors

CaSc₂O₄: Tm^3 +/Yb^3 + submicro-rods were synthesized using the mild solvothermal and annealing technique. The temperature of formed pure phase is as low as 600 °C. The synthesized submicro-rods are uniform in size and shape. The size of rod is only small with 35 nm in width and 200 nm in length, which favors the application in biological assays and medical image. Furthermore, samples prepared exhibit the stronger upconversion luminescence than that of obtained by conventional solid state reaction method under 980 nm excitation. The near infrared emission around 800 nm is enhanced twofold closely. CaSc₂O₄ phosphor synthesized through the solvothermal and annealing method is a promising submicron upconversion material. The solvothermal and annealing technique is a suitable method for preparing CaSc₂O₄ sample with rod-like morphology.     

Precipitation and Growth Mechanism of Diverse Sr5(PO4)3F Particles

Strontium fluorapatite particles with tunable morphologies and geometries were successfully synthesized via a precipitation system by adjusting the pH value and temperature. Several analysis techniques were used to investigate and characterize the particles. The surface energy was calculated using first‐principle calculations based on density functional theory. Capsule‐like nanosized primary grains with axial growth directions parallel to the c‐axis were synthesized at higher pH values, resulting from the difference in surface energy for the different planes of the Sr₅(PO₄)₃F lattice. Bundle‐like clusters were obtained at a pH value of ~7, which was attributed to a combination of the difference in surface energy and the phenomenon of heterogeneous nucleation occurring at low degrees of supersaturation. The study determined the approaches necessary to manufacture Sr₅(PO₄)₃F powders with specific characteristics for different applications.     

Effect of Co substitution and magnetic field on the morphologies and magnetic properties of CeO2 nanoparticles

Pure and Co-doped CeO₂ nanoparticles were synthesized successfully by the solvothermal method. The effect of Co substitution and external magnetic field on the morphologies and magnetic properties of nanoparticles was investigated. Results showed that synthesized Co-doped CeO₂ had the face-centered cubic structure and no other impurities existed in the samples with the increase of Co concentration from 5 to 75?wt%. The increasing Co concentration made the morphologies of Co-doped CeO₂ nanoparticles vary from the hollow sphere, solid sphere to rod-like shape. The applied external magnetic field of 5T decreased the nanoparticle size effectively including the diameter of hollow sphere with low Co concentration and rod-like particles with high Co concentration. Moreover, the wall thickness of hollow sphere particles was also decreased from 35?nm to 18?nm for pure CeO₂. The Co-doped CeO₂ nanoparticles showed the weak ferromagnetic behavior. With the increase of Co concentration, the saturation magnetization (M_s) value increased first and then decreased. The Co-doped CeO₂ with 30?wt% showed the highest value of 3.65?×?10^?2 emu/g (M_s). The M_s value of Co-doped CeO₂ prepared in 5T showed an increasing trend with the Co concentration. The highest value (M_s) reached 4.21?×?10^?2 emu/g for doped CeO₂ with 75?wt% Co.     

Solvothermal Conversion of Nanofiber to Nanorod‐Like Mesoporous γ‐Al2O3 Powders,and Study Their Adsorption Efficiency for Congo Red

Mesoporous γ‐Al₂O₃ powders with nanofiber and nanorod‐like structures were synthesized using boehmite sols in the presence of triblock copolymer, P123 in ethanol by solvothermal process at different temparatures (100°C–165°C) followed by calcination at 400°C–1000°C. The powders were characterized by low‐ and wide‐angle X‐ray diffraction (XRD), N₂ adsorption–desorption, and transmission electron microscopy (TEM). The adsorption efficiency of the powders with Congo red (CR) was studied by UV–vis spectroscopy. The γ‐Al₂O₃ phase became stable up to 1000°C. The nanorods obtained at 165°C had narrower pore size distribution (PSD) than nanofibers synthesized at 100°C, the former showed higher CR adsorption efficiency. The stepwise growth mechanism of nanofibers to nanorods conversion with increase in solvothermal temperatures was illustrated.     

Controlled synthesis of copper nano/microstructures using ascorbic acid in aqueous CTAB solution

This paper describes a low-temperature green chemical synthesis of various morphologies of copper nano/microstructures. These syntheses achieved high yields in aqueous solution using ascorbic acid as a reductant and the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a capping agent. The resulting copper particles were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and UV-Vis. absorption spectroscopy techniques. From the SEM analysis, it was found that different morphologies of copper particles, including submicron polyhedrons, micrometer rods, spherical nanoparticles, and nanowires were obtained by varying factors such as the molar ratio of reactants (ascorbic acid and CuSO₄·5H₂O), pH, reaction time, and temperature. Increasing the molar ratio of ascorbic acid to precursor salt and increasing the pH led to a decrease in the size of copper particles formed. At short reaction times, spherical copper nanoparticles with an average diameter of 90 nm are obtained. When the reaction time was prolonged, the nanoparticles transformed into nanowires with diameters in the range of 100-250 nm, and lengths of up to 6-8 μm. When the reaction temperature was decreased, Cu mixed with Cu₂O particles were obtained instead of Cu particles. The resultant copper particles were confirmed by EDX and XRD to be pure Cu, with face-centred cubic (fcc) structures.     

Tunable emission and applications of Ln3+ doped NaGd(WO4)2 nanocrystals via a facile solvothermal process

Double tungstate crystal has outstanding capabilities of gain media for the application in mode-locked ultrafast lasers. Among them, NaGd(WO₄)₂:Ln³⁺ is widely using in laser, pH sensing or lighting devices. However, general synthetic methods require high temperature, long reaction time or adjustment of solution pH, which is seriously hinder their related applications. Here, we synthesized NaGd(WO₄)₂:Ln³⁺ nanocrystals through a solvothermal strategy. The synthesis was designed to avoid the solvent effect of water. Our nanoparticles with a rod shape and average size is ∼3.8 × 46.3 nm. Furthermore, Terbium and Europium ions co-doped in a single NaGd(WO₄)₂ host has been obtained, energy migration from Terbium ions to Europium ions also implemented. A series of emission colours (from green to white) were obtained. At last, a distinguished performance NaGd(WO₄)₂:0.03Tb,0.03Eu based UV-LED equipment was realized. Their adjustable emissions, convenient preparation method and special morphology reveal that NaGd(WO₄)₂:Ln³⁺ is a potential candidate for solid-state lasers and UV-LEDs applications.     

A study on synthesis and properties of Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles by solvothermal method

Magnetic nanoparticles (Fe₃O₄) were synthesized by the solvothermal method using FeCl₃ · 6H₂O and ethylene glycol as a reactant. Powder X-ray diffraction, FT-IR, TEM, SEM, and VSM were used to characterize the magnetic particles. The reacting factors, such as reacting time, the concentration of iron source and surfactant, especially the effect of NaAc · 3H₂O, were studied. The results indicated that NaAc · 3H₂O plays the role not only as a dispersant but also a structure-directing agent. The synthesized Fe₃O₄ particles showed excellent magnetic property, which made them have potential for application in magnetic nanodevices and biomedicine.     

Amphiphilic chitosan/acrylic acid/thiourea based semi-interpenetrating hydrogel: Solvothermal synthesis and evaluation for controlled release of organophosphate pesticide,triazophos

The current study reports the solvothermal synthesis of amphiphilic chitosan-based semi-interpenetrating (CAT-SIPH) hydrogel for controlled release of an organophosphate pesticide, triazophos. CAT-SIPH is prepared from natural backbone polymer chitosan (CS) and monomer, acrylic acid (AA) employing initiator (K₂S₂O₈), and cross-linker, thiourea (CSN₂H₄) using solvothermal technique under 7 Psi pressure in an autoclave. The polymerization reaction variables like reaction time, the volume of solvent, concentration of initiator, cross-linker, and monomer are optimized to get the best product yield in terms of percentage grafting. The optimized conditions for solvothermal polymerization reaction carried out for 60 min are solvent volume (10 ml), concentrations of acrylic acid (0.2 mol/L), K₂S₂O₈ (0.45 × 10⁻²mol/L) and thiourea (1.75 × 10⁻⁴ mol/L). The swelling behavior of CAT-SIPH hydrogel synthesized under optimized conditions is studied in the terms of swelling ratio. CAT-SIPH is characterized by Fourier transform infrared spectra (FT-IR), ^IHNMR, thermal analysis (TA), Zeta potential, and scanning electron microscopy (SEM). The potential of cross-linked hydrogel CAT-SIPH for controlled release of an organophosphate pesticide, Triazophos on to sandy loam soil is assessed. The experimental investigations proved that synthesized hydrogel can be effectively employed as a pesticide carrier for controlled release on to loamy soil as the maximum release (53%) is observed even after 25 days at pH 6 and value get lowered under acidic and basic conditions. The present investigation demonstrated the potential of chitosan-based CAT-SIPH hydrogel as a pH-responsive release vehicle for agrochemicals onto the soil matrix and offers a potential solution for the prevention of surface and groundwater contamination.     

Morphology control and growth mechanism of magnesium hydroxide nanoparticles via a simple wet precipitation method

The nanograde particles of magnesium hydroxide [Mg(OH)₂] with needle-like and disk-like morphologies were synthesized via a simple wet precipitation method. The effects of operation parameters, such as ammonia concentration, Mg²⁺ concentration, reaction temperature and ageing temperature on morphology of magnesium hydroxide nanoparticles were investigated. The samples were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractions (XRD). The influence process and growth mechanism were discussed in details.     

Controlled Synthesis of Nanostructured CuInS<Subscript>2</Subscript>: Study of Mechanism and Its Application in Low-Cost Solar Cells

Various morphologies of CuInS₂ (CIS) nanostructures were successfully synthesized by an oxalic acid (OA), H₂C₂O₄, assisted solvothermal treatment. FT-IR, XRD, scanning electron microscopy, gas-sorption measurements and diffuse transmittance spectroscopy were used to characterization of CIS nanostructures. The impact of thiourea and OA concentrations, reaction temperature and reaction time on the phase structure, morphology and optical properties are investigated. The formation process is discussed and a possible growth model is proposed. OA is found to play key role during the formation process of the CIS nanostructure. Dispersion of the final nanostructures in dimethylformamide solvent forms a viscous and stable ink which can be easily deposited onto substrates. CIS nanostructures inks were applied in a cadmium-free all solution-based CuInS₂ superstrate-type solar cell devices with Glass/FTO/TiO₂/In₂S₃/CIS/Carbon structure. All processes were vacuum- and selenization-free and were done under atmospheric condition. The optimum cell shows the short-circuit current density of 13.8 mA/cm² and the power conversion efficiency of 2.07 %, respectively. Our study outlines a general strategy for using CuInS₂ nanostructures for photovoltaic application.