Low-temperature Solid-state Reaction Research Articles

Luminescence properties of chlorine and oxygen co-doped ZnS nanoparticles synthesized by a solid-state reaction

Cl− and O2− co-doped ZnS nanoparticles were synthesized using a low temperature solid-state reaction method. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and ultraviolet–visible spectroscopy were used to characterize their crystal structure, chemical state, diameter, surface states, and photoluminescence (PL) properties. The effects of Cl− and O2− doping concentration on the crystal structure, the crystallite size, and luminescence properties of ZnS nanoparticles were investigated. The results indicated that the ZnS:Cl, O nanoparticles had a cubic blende structure, and an average crystallite size of about 4.28–5.08nm. It was found that the PL intensity of the Cl− and O2− co-doped ZnS nanoparticles remarkably increased with the increase of Cl− and O2− doping concentration. The emission intensity of the 7mol% Cl− and 4mol% O2− co-doped ZnS nanoparticles was about 4 (10) times stronger than the ZnS doped with Cl− (O2−) nanoparticles. Mechanism for the enhanced luminescence of Cl− and O2− co-doped ZnS nanoparticles was discussed. This work suggests that the low temperature solid-state reaction method can be used to synthesize Cl− and O2− co-doped ZnS nanoparticles with strong PL properties.

Effects of highly crumpled graphene nanosheets on the electrochemical performances of pseudocapacitor electrode materials

Highly crumpled graphene nanosheets (GS) with a BET surface area as high as 722.1 m2g−1 is prepared by a thermal exfoliation method. A systematical investigation is performed on the electrochemical performances of porous Ni2P/GS nanocomposite synthesized by the low temperature solid state reaction method. It is shown that Ni2P nanoparticles anchor on graphene sheets producing a porous structure and GS have beneficial effects on the electrochemical properties of Ni2P nanoparticles when investigated as pseudocapacitor materials. The novel Ni2P/GS composite electrode exhibits a superior specific capacitance of 1912 F g−1 and 888 F g−1 at current densities of 5 and 50mAcm−2, respectively. The specific capacitance decreases to 1473 F g−1 after 2500 cycles, suggesting its excellent cycling stability. It is confirmed that the GS with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during cycling, thus, leading to enhancement of the electrochemical properties of the Ni2P electrode.

Structural, optical and photoconductivity study of ZnS nanoparticles synthesized by a low temperature solid state reaction method

In the present work, ZnS nanoparticles have been synthesized by a simple solid state reaction method at different temperatures. X-ray diffraction patterns show that the synthesized ZnS nanoparticles have a zinc blende structure of ZnS. SEM micrographs show formation of spherical nanoparticles of ZnS. UV–vis spectra show blue-shifting in an absorption edge corresponding to all the synthesized ZnS nanoparticles as compared to their bulk counterparts. FTIR study is performed to determine the absorbance and nature of bonds present in synthesized samples. Photoconductivity properties have been investigated by varying voltage and as a function of time. Photocurrent varies linearly for all the synthesized samples. Rise and decay exhibit negative photoconductivity in samples synthesized at lower temperatures.

Low Temperature Synthesis and Characterization of Cu2ZnSnS4 (CZTS) Nanoparticle by Solution Based Solid State Reaction Method

Cu2ZnSnS4 (CZTS) has emerged as a potential candidate in optoelectronic devices due to its non-toxicity, low cost and abundance of its constituents in earth's crust. Conventional CZTS synthesized techniques are either energy intensive or use toxic chemical. A modified, low temperature solid state reaction route for synthesis of CZTS nanoparticles using metal acetates, thiourea and SnCl2 is demonstrated. Synthesis of stoichiometric amount of these precursors at 250°C for 1h is sufficient to form single phase. Synthesised powder was characterized by means of X-ray diffraction (XRD), Raman spectroscopy and Transmission Electron Microscopy (TEM) and UV–visible (UV–vis) absorption spectrumm. Band gap of as prepared CZTS was found to be around 1.45eV, which is appropriate for use as absorber layer in a thin film solar cell.

Effect of solid-state synthesized alumina properties on the structure and catalytic performance of NiMo catalyst in hydrodesulfurization

In this paper, a precursor ammonium aluminum carbonate hydroxide (AACH) was synthesized by a low-temperature solid-state reaction, then alumina labeled as Al2O3-AC was obtained by the calcination of AACH, and finally, catalyst labeled as NiMo/Al2O3-AC supported on Al2O3-AC was prepared using the method of incipient wetness impregnation. The properties of both support and catalyst were investigated by a series of characterization methods. The results indicated that Al2O3-AC had unique bimodal porous structure, high acid content and five-fold coordinated aluminum (AlO5) on the surface. Moreover, NiMo/Al2O3-AC exhibited uniform dispersion of active components, higher Brőnsted acid sites concentration and weaker metal-support interaction. Encouraged by those excellent properties of Al2O3-AC and NiMo/Al2O3-AC, the catalyst NiMo/Al2O3-AC was evaluated in the hydrodesulfurization (HDS) of dibenzothiophene (DBT), showing high conversion ratio of DBT.

An Efficient Approach to Produce Clean Diesel Fuel: Development of Catalysts With Ultra-High Hydrogenation Performance

The sulfur specification for diesel fuel has been tightened exponentially over the years. To help resolve this question, the authors aimed to develop a novel unsupported Ni-Mo sulfide catalyst with ultra-high hydrogenation performance, for the production of clean diesel fuel. This catalyst was prepared directly with ammonium tetrathiomolybdate and basic nickel carbonate as the catalyst precursors through the low-temperature solid-state surface reaction. XRD and HRTEM characterization results indicate that the stacking number of MoS2 layers is very high in the unsupported Ni-Mo sulfide. The evaluation results of model compound (dibenzothiophene) and FCC diesel fuel demonstrate that the unsupported Ni-Mo sulfide catalyst has excellent hydrodesulfurization activity and ultra-high hydrogenation performance, which can be attributed to the high stacking number of MoS2 layers.

Low temperature solid state synthesis and characterisation of lauric acid/SiO2 phase change energy storage materials

Lauric acid/silicon dioxide composite phase change energy storage materials were prepared by low temperature solid state reaction using lauric acid as phase change component and sodium silicate as matrix. The structure, morphology and thermal performance of the composite were characterised by X-ray diffraction (XRD), environmental scanning electron microscopy (ESEM), Fourier transform infrared spectrometer (FT-IR) and differential scanning calorimetry (DSC). The test results show that lauric acid materials are effectively imbedded into the net of silicon dioxide by low temperature solid state reaction. The latent heat and melting temperature of the composite are 98·94 J g−1 and 58·6°C respectively. Furthermore, the thermal conductivity of composite phase change materials is improved by using silicon dioxide as matrix material.

Synthesis of SnO2 functionalized amorphous carbon nanotube for efficient electron field emission application

Amorphous carbon nanotubes (aCNTs) were synthesized by a very simple low-temperature solid state reaction. The walls of the as prepared aCNTs were decorated with chemically synthesized SnO2 nanoparticle both by in situ and ex situ process. All the samples were characterized by X-ray diffraction, field emission scanning electron microscope, high resolution transmission electron microscope, X-ray photoelectron spectroscopy. It is observed that when functionalization of SnO2 particles onto aCNTs wall was performed by in situ process it results a uniform coating, whereas ex situ treatment gives discrete attachment of SnO2 onto aCNTs wall. The field emission properties of as synthesized and modified sample were carried out in the laboratory made high vacuum field emission set up. Result of field emission has been compared with pure aCNTs and pure SnO2. It has been found that attachment of SnO2 nanostructure can effectively enhance the field electron emission of the aCNTs with lowering the turn on field from 6.57 to 2.15V/μm. The enhancement of field emission characteristic is believed to be due to the enhanced roughness of the coated aCNTs wall as well as lower work function of outer SnO2 material.

Synthesis and characterization of SrFe12O19 nanoparticles produced by a low-temperature solid-state reaction method

Ultra-fine nanoparticles of strontium hexaferrite, SrFe12O19, have been synthesized by low-temperature solid-state reaction method without ball-milling process. The effects of the preparing conditions of samples such as calcination temperature, Fe3+/Sr2 and Na1+/Sr2+ mole ratio on the phase composition, particle size and shape and magnetic properties of the calcined samples have been investigated by differential thermal analysis, X-ray diffraction, field emission scanning electronic microscopy, and vibrating sample magnetometery. The X-ray diffraction patterns showed the formation of SrFe12O19 single phase at temperatures as low as 750° C. Fine particles with particle size around 30–100 nm obtained at 750° C with Fe3+/Sr2 mole ratio of 10. The magnetic measurements and structural analysis showed that particles were single domain and exhibited better magnetic properties than those obtained by the ceramic method.

Luminescence enhancement of zincblende ZnS:Cl − nanoparticles synthesized by a low temperature solid state reaction method

Abstract Cl − -doped ZnS (ZnS:Cl − ) nanoparticles with strong blue emission were synthesized using a facile low temperature solid state reaction method. X-ray powder diffraction, scanning electron microscopy, UV–vis absorption, and X-ray photoelectron spectroscopy were used to characterize their crystal structures, microstructural characteristics, and chemical compositions, respectively. The ZnS:Cl − nanoparticles were quasi-spherical in shape and had a cubic zincblende crystal structure. Cl − doping was found to lead to a reduction in the crystallite size of the ZnS:Cl − nanoparticles. It showed that Cl − doping remarkably enhanced the luminescence properties of the ZnS:Cl − nanoparticles, and an optimal Cl − doping condition was determined. Post annealing was found to further improve the luminescence properties of the ZnS:Cl − nanoparticles. The effect of post annealing temperature on the luminescence properties of the ZnS:Cl − nanoparticles was systematically studied and discussed.

Strong blue luminescence of O2−-doped ZnS nanoparticles synthesized by a low temperature solid state reaction method

O2−-doped ZnS(ZnS:O) nanoparticles with strong blue emission were successfully synthesized using a facile low temperature solid state reaction method. X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize their crystal structures, sizes, morphologies, and photoluminescence. The ZnS:O nanoparticles were quasi-spherical particles with a cubic zincblende crystal structure, and their average crystallite diameter was about 8.35–13.50nm. Dependence of the photoluminescence properties of the ZnS:O nanoparticles on the Zn/O ratio in the source materials was studied, and an optimal O2− doping condition was found to be Zn/O=10:5.3. The ZnS:O (Zn/O=10:5.3) nanoparticles exhibited strong blue emission with an intensity 9 times higher than the undoped nanoparticles.

Na0.5K0.5NbO3 and 0.9Na0.5K0.5NbO3–0.1Bi0.5Na0.5TiO3 nanocrystalline powders synthesized by low-temperature solid-state reaction

Nanocrystalline powders of K0.5Na0.5NbO3 (KNN) and 0.9Na0.5K0.5NbO3–0.1Bi0.5Na0.5TiO3 (KNN–BNT) have been prepared using a low-temperature solid-state reaction. Phase development of the powders incurred during various calcination temperatures was examined by X-ray diffraction (XRD). Crystallite size and particle morphology of KNN powders were examined by XRD and transmission electron microscopy, respectively. Perovskite phase was formed at the temperature as low as 500°C, and the average crystallite size of KNN powders depended on calcination temperature. In addition, the crystalline structure of KNN powders tended to change from tetragonal symmetry to orthorhombic symmetry with increase in crystallite size. Similar results were obtained in KNN–BNT system. The developed method is well suited for the mass production of niobate nanocrystalline powders due to its simplicity and low cost.

Thin copper phosphide films as conversion anode for lithium-ion battery applications

Air stable copper phosphide of thicknesses (0.2, 0.4μm) was synthesized over copper plates (of 10mm diameter) by hybrid electrochemical deposition and low temperature solid-state reaction. Stoichiometric amount of red phosphorus (P) were sprayed over electrodeposited copper and followed by annealing at 250°C under inert gas atmosphere for different durations (5h, 7h and 12h). During this process, phosphorus particles diffuse by excavating into the copper deposits, producing holes, where the Cu3P crystallites nucleate and lead to conglomeration of several agglomerates and hence resulted in non-homogeneous morphology. A small extend of Cu3P oxidation occurs over the film's top surface. X-ray diffraction (XRD) patterns confirm that the layer to be pure Cu3P. Scanning electron microscopy (FEG-SEM) reveals a porous microstructure consisting of agglomerated particles with ∼10μm size. The as-prepared carbon-free Cu3P electrodes exhibited significantly improved capacity retention and rate capability characteristics over 40 cycles when electrochemically tested against lithium at constant 20μA/cm2 rendering it as possible negative electrode for high energy density lithium-ion battery (LiB) applications.

Fabrication and Characterization of CuInSe2Thin Film Applicable for a Solar Energy Light Absorption Material via a Low Temperature Solid State Reaction

The chalcopyrite CuInSe2thin film synthesized via a low temperature solid state reaction from CuSe and InSe powders was investigated using X-ray diffractomy (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), and UV-vis absorption spectroscopy. CuSe and InSe phases react and directly transform into CuInSe2without the occurrence of any intermediate phase. The morphology of the newly formed CuInSe2crystalline was close to that of the CuSe reactant particle based on the TEM results, which indicate that the solid state reaction kinetics may be dominated by the In3+ions diffusion. The CuInSe2thin film prepared from the solid state reaction did not use the selenide process; its band gap might reach 1.06 eV, which is competent and suitable to be used for a thin film solar cell light absorption layer.

Facile synthesis and superior supercapacitor performances of Ni2P/rGO nanoparticles

Ni2P nanoparticles grown on reduced graphene oxide (rGO) were successfully synthesized via the low-temperature solid state reaction method and investigated as electrochemical pseudocapacitor materials for potential energy storage applications. The specific capacitance of the as-prepared Ni2P/rGO is 2266 F g−1 and the Ni2P/rGO composite also exhibits superior cycling performance when they are used as the capacitor materials. The as-prepared Ni2P/rGO sample demonstrates interesting supercapacitive properties with high capacitance and good cycling performance.

A New Simple Route to ZnS Quantized Particles with Tunable Size and Shape, and Size/Shape-Dependent Optical Properties

With the features of convenience and eco-friendly, the low-temperature solid-state reaction synthesis was successfully developed as a new approach to prepare quantum-sized ZnS nanocrystals. One major achievement is that the size and shape of ZnS nanocrystals can be tuned by adjusting the surfactant and its feed. The UV-Vis absorption spectra of quasispherical and one-dimensional quantum-sized ZnS nanocrystals all showed a blue-shift from the bulk counterpart, indicating large quantum confinement effects of ZnS nanocrystals. These ZnS nanocrystals all showed well-defined excitonic emission features. Contrastive studies on photoluminescence performances indicated that the bandedge emission experienced only the size-dependent quantum confinement effect, while the trap-state emission experienced the size- and shape-dependences. So we can design a purposeful synthesis route to ZnS nanocrystals with target luminescence emission performances.

Luminescence properties of Br-doped ZnS nanoparticles synthesized by a low temperature solid-state reaction method

Br-doped ZnS nanoparticles were synthesized using a low temperature solid-state reaction method. Influence of Br doping concentration on the crystal structures, crystallite sizes, and luminescence properties of the Br-doped ZnS nanoparticles was investigated. The Br-doped ZnS nanoparticles had a cubic zincblende crystal structure, and had an average crystallite size of about 8.0–9.5 nm. Both the lattice constant and average crystallite size of the Br-doped ZnS nanoparticles decreased with Br doping concentration. It was found that the luminescence intensity of the Br-doped ZnS nanoparticles remarkably increased with Br doping concentration. The emission intensity of the 5% Br-doped ZnS nanoparticles was about 13 times stronger than the undoped ZnS nanoparticles. Mechanism for the enhanced luminescence of the Br-doped ZnS nanoparticles was discussed. This work suggests that the low temperature solid-state reaction method can be used to synthesize Br-doped ZnS nanoparticles with strong luminescence properties.

Fabrication of high-surface-area γ-alumina by thermal decomposition of AACH precursor using low-temperature solid-state reaction

In this paper, systematical investigation has been made for the new simple synthesis pathway of catalytic alumina with high surface area through thermal decomposition of ammonium aluminum carbonate hydroxide (AACH), which has been prepared by a low-temperature solid-state reaction in non-aqueous system. The results indicate that the molar ratios of NH4HCO3/Al influence crystallinities and the morphologies of AACH. Well-crystallized AACH with nanorod morphology and low-crystallized AACH with cluster structure can be obtained with different molar ratios NH4HCO3/Al. The γ-Al2O3 product with high surface area (511m2/g) can be obtained from the calcination of AACH at 500°C. Moreover, the results also indicate that crystallinities and morphologies of AACH affect their thermal decomposition behaviors. In addition, the formation of high-surface-area is possibly attributed to intracrystalline porosity of as-prepared γ-Al2O3.

Preparation and gas sensing properties for acetone of amorphous Ag modified NiFe2O4 sensor

Nickel ferrite nano-powders were prepared by microwave radiating low-temperature solid-state reaction method, and then modified with Ag by dipping method. The crystal structure and morphology of the samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of the samples were also investigated. The results reveal that the Ag, as amorphous structure, can efficiently prevent the reuniting and growing-up of nanosized NiFe2O4 grains, and 1.5% Ag modified NiFe2O4 sensor has a better sensitivity, up to 43, for acetone gas than 1.5%Ag mixed NiFe2O4 sensor prepared by low-temperature solid-state reaction, at an optimal working voltage of 4.5 V. The quick response time (1 s) and fast recovery time (∼10 s) are the main characteristics of this sensor.

Kinetic studies on low-temperature solid-state reactions in interstellar ices

Understanding the chemistry of the interstellar medium necessitates the use of gas-grain chemistry codes along with extensive databases of gas-phase and solid-phase reactions. If reaction rates have been measured for various types of gas phase reactions, no experimental kinetic studies are available for determining solid-state thermal reaction rates. We present here an experimental kinetic study of few purely thermal low-temperature solid-state reactions relevant to interstellar ice chemistry.