One-step Solid-state Reaction Research Articles

Electrochemical performance of LiVPO4F/C synthesized by different methods

LiVPO4F/C samples were synthesized by one-step solid-state reaction and two-step solid-state reaction methods, respectively. The X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance tests were adopted to characterize the properties of LiVPO4F/C. XRD results show that the LiVPO4F/C samples prepared by one-step solid-state reaction method have the same triclinic structure (space group as that synthesized by conventional two-step solid-state reaction. SEM image exhibits that the particle size of LiVPO4F/C prepared by one-step solid-state reaction method is smaller than that of the sample synthesized by two-step solid-state reaction. The improved electrochemical properties of the LiVPO4F/C are attributed to the depressed grain size and enhanced electrical conductivity produced via one-step solid-state reaction method using oxalic acid as both reduction agent and carbon sources. AC impedance measurements also show that the LiVPO4F/C synthesized by one-step solid-state reaction route significantly decreases the charge-transfer resistance.

Superconducting and thermoelectric properties of new layered superconductor Bi4O4S3

Polycrystalline sample of the new layered superconductor Bi4O4S3 is successfully synthesized by solid-state reaction method by using Bi, S and Bi2O3 powders with one-step solid state reaction. The superconducting transition temperature (Tconset=4.5K), the zero resistance transition temperature (Tc0=4.07K) and the diamagnetic transition temperature (4.02K at H=10 Oe) were confirmed by electrical transport and magnetic measurements. Also, our results indicate a typical type II-superconductor behavior and the charge carriers are mainly electron-type. In addition, a large thermoelectric effect was observed with a dimensionless thermoelectric figure of merit (ZT) of about 0.03 at 300K.

Facile synthesis of CdS nanoparticles photocatalyst with high performance

A simple one-step solid-state reaction has been introduced to synthesize CdS nanoparticles. The as-prepared CdS product was characterized by X-ray powder diffraction (XRD), BET surface area measurement, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), particle size distribution (PSD) and UV–vis absorption spectrum. The experiment results reveal that the CdS product was composed of nanoparticles about 60nm in diameter, of which specific surface area is 78.02m2/g. The photocatalysis results indicate that the CdS nanoparticles exhibit excellent photocatalytic activity for the degradation of rhodamine B under UV irradiation. Nearly 95% of rhodamine B was degraded after 60min of irradiation, higher than that of P25, which is due to the large specific surface area and mesoporous structure.

Preparation and electrochemical properties of homogeneous carbon-coated LiFe0.9Mn0.1PO4 as cathode material for lithium-ion batteries

Homogeneous carbon-coated LiFe0.9Mn0.1PO4 cathode material was synthesized by one-step solid-state reaction using glucose as carbon source. Powder X-ray diffractometry (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic measurements were employed to characterize the samples. Mn-doping and carbon co-modification did not affect the olivine structure of LiFePO4, but improved its kinetics in terms of capacity delivery, polarization and rate capability. When compared with the undoped LiFePO4/C, the LiFe0.9Mn0.1PO4/C sample presented good size distribution - around 100-200 nm - and better electrochemical performance. At current rates of 0.1, 1.0, 3.0 and 10.0 C (C = 170 mA g-1), the LiFe0.9Mn0.1PO4/C electrode delivered discharge capacities of 154.1, 138.8, 120.0 and 94.0 mA h g-1, respectively. Results obtained by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that the polarization and charge transfer resistance of the sample were greatly decreased by Mn-doping.

Volatile Single-Source Molecular Precursor for the Lithium Ion Battery Cathode

The first single-source molecular precursor for a lithium-manganese cathode material is reported. Heterometallic β-diketonate LiMn(2)(thd)(5) (1, thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) was obtained in high yield by simple one-step solid-state reactions employing commercially available reagents. Substantial scale-up preparation of 1 was achieved using a solution approach. The crystal structure of the precursor contains discrete Li:Mn = 1:2 trinuclear molecules held together by bridging diketonate ligands. The complex is relatively stable in open air, highly volatile, and soluble in all common solvents. It was confirmed to retain its heterometallic structure in solutions of non-coordinating solvents. The heterometallic diketonate 1 was shown to exhibit clean, low-temperature decomposition in air/oxygen that results in nanosized particles of spinel-type oxide LiMn(2)O(4), one of the leading cathode materials for lithium ion batteries.

Excellent stability of spinel LiMn2O4-based composites for lithium ion batteries

Spinel LiMn2O4-based composites with cation (Li+)/anion (F−) co-doping and Li2MnO3 thin surface coating are synthesized by one-step solid-state reaction. The composites modified with body-doping and surface-coating exhibits excellent cycling performance and high rate capability. The LF04 sample tested at 1 C rate exhibits only 1.2% capacity loss after 1000 cycles at room temperature; and when cycling at 55 °C, the composite still shows 94.3% capacity retention after 100 cycles. As the charge–discharge rate increases to 7 C, the as-prepared LiMn2O4-based composites deliver more than 95.5% capacity retention after 300 cycles at room temperature and exhibit an average value of coulombic efficiency more than 99.6%. The improved cycling performance of the composites is ascribed to double doping in the spinel structure and the coating on the surface of the spinel particles. The ionic doping could eliminate the problems with cooperative Jahn–Teller distortion and suppress Li+-ion order at 0.5 Li; and the inborn Li2MnO3 coating containing only Mn4+ ions, could prevent the disproportionation of Mn3+ on the surface.

One-Step Synthesis of Asphalt Based Li3V2(PO4)3/C Nanocomposites as Cathode Materials for Lithium-Ion Batteries

A new kind of cathode materials, Li3V2(PO4)3/C nanocomposites, has been prepared via one-step solid-state reaction using ultra low-cost asphalt as both reduction agents and carbon sources. The asphalt is contained 60.37% of fixed carbon and 0.18% of other impurity.It is purchased from Zhen jiang Xin Guang Metallurgical Subsidiary Material Plant. Structural analysis shows that the obtained Li3V2(PO4)3/C nanocomposites contain abundant Li3V2(PO4)3 nanorods and micro/nano particles encapsulate with carbon shells. The Li3V2(PO4)3/C nanocomposites achieve enhanced dischargeability, reversibility, and cycleability. Electrochemical tests show that the Li3V2(PO4)3/C nanocomposite has initial discharge capacities of 170 mAhg-1 at 0.1C in the voltage range of 3.0 to 4.8 V. The improved electrochemical properties of the Li3V2(PO4)3/C nanocomposites are attributed to the presence of Li3V2(PO4)3/C nanorods and the electronically conductive carbon shell. This one-step solid state reaction using low-cost asphalt as carbon sources is feasible for the preparation of the Li3V2(PO4)3/C nanocomposites which can offer favorable properties for commercial applications.

Carbon coated Na 3V 2(PO 4) 3 as novel electrode material for sodium ion batteries

A Na 3V 2(PO 4) 3 sample coated uniformly with a layer of 6 nm carbon has been successfully synthesized by a one-step solid state reaction. This material shows two flat voltage plateaus at 3.4 V vs. Na +/Na and 1.63 V vs. Na +/Na in a nonaqueous sodium cell. When the Na 3V 2(PO 4) 3/C sample is tested as a cathode in a voltage range of 2.7–3.8 V vs. Na +/Na, its initial charge and discharge capacities are 98.6 and 93 mAh/g. The capacity retention of 99% can be achieved after 10 cycles. The electrode shows good cycle performance and moderate rate performance. When it is tested as an anode in a voltage range of 1.0–3.0 V vs. Na +/Na, the initial reversible capacity is 66.3 mAh/g and the capacity of 59 mAh/g can be maintained after 50 cycles. These preliminary results indicate that Na 3V 2(PO 4) 3/C is a new promising material for sodium ion batteries.

Facile synthesis of ZnO nanocrystals via a solid state reaction for high performance plastic dye-sensitized solar cells

We report the facile synthesis of ZnO nanocrystals via a one-step solid state reaction at room temperature and their application as the photoanode in plastic dye-sensitized solar cells (DSCs). ZnO nanoparticles were prepared utilizing zinc acetate dihydrate and sodium hydroxide with a short grinding time and without a sintering process. The as-prepared samples with the polycrystalline hexagonal wurtzite structure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The obtained ZnO nanoparticles exhibited high crystallinity even without a high temperature sintering treatment during the preparation process. The effects of compression post-treatment on the photovoltaic performance of DSCs were also investigated using intensity modulated photocurrent spectroscopy (IMPS), incident photo-to-current conversion efficiency (IPCE), and electrochemical impedance spectroscopy (EIS). The results indicate that the improvement of power conversion efficiency after compression post-treatment of ZnO photoelectrode can be attributed to its high photoelectron collection efficiency and effective electron transport. Under the optimized conditions, a full plastic D149-sensitized ZnO solar cell measured under illumination of 100 mW·cm−2 (AM 1.5G) presents an energy conversion efficiency of 3.76% with open-circuit voltage of 0.688 V, short-circuit current density of 8.55 mA·cm−2, and fill factor of 0.64. These results demonstrate that the one-step solid state reaction is a convenient and effective method for the synthesis of ZnO nanocrystals for use in plastic DSCs. Open image in new window

The Role of MgCl<sub>2</sub> in Preparation of SnO<sub>2</sub>, MgSnO<sub>3</sub> and Mg<sub>2</sub>SnO<sub>4</sub> Nanopowders

Tin oxide (SnO2) ,MgSnO3and Mg2SnO4nanocrystals have been synthesized by one-step solid-state reactions. in the first step, The powder of SnCl4.5H2O was mixed with MgCl2and Mg(OH)2with weight ratio of Sn to Mg (1:1), (2:1) And (1:2) in an air atmosphere at room, and annealing temperature in this work were 200°C, 400°C ,600°C , 800°C and 1000°C . XRD patterns show the SnO2, MgSnO3and Mg2SnO4particle size of synthesized powders by MgCl2were 3 nm, 4nm and 27 nm respectively. In fact the excess amount of Mg role of crystallite growth inhibitor in SnO2. this method is a simple ,inexpensive ,efficient and economic preparation for SnO2, MgSnO3and Mg2SnO4nanoparticles with adjustable grain sizes in the range of 3-44nm in high yield. This article shows the role of mass MgCl2in producing of SnO2nanoparticles.

Kinetic Analysis of One-Step Solid-State Reaction for Li4Ti5O12/C

The kinetics of one-step solid-state reaction of Li(4)Ti(5)O(12)/C in a dynamic nitrogen atmosphere was first studied by means of thermogravimetric-differential thermal analysis technique at five different heating rates. According to the double equal-double steps method, the Li(4)Ti(5)O(12)/C solid-state reaction mechanism could be properly described as the Jander equation, which was a three-dimensional diffusion with spherical symmetry, and the reaction mechanism functions were listed as follows: f(α) = (3)/(2)(1 - α)(2/3)[1 - (1 - α)(1/3)](-1), G(α) = [1 - (1 - α)(1/3)](2). In FWO method, average activation energy, frequency factor, and reaction order were 284.40 kJ mol(-1), 2.51 × 10(18) min(-1), and 1.01, respectively. However, the corresponding values in FRL method were 271.70 kJ mol(-1), 1.00 × 10(17) min(-1), and 0.96, respectively. Moreover, the values of enthalpy of activation, Gibbs free energy of activation, and entropy of activation at the peak temperature were 272.06 kJ mol(-1), 240.16 kJ mol(-1), and 44.24 J mol(-1) K(-1), respectively.

One-step Solid-state Reaction for the Synthesis of Hexagonal or Rhombohedral Boron Nitride Nanoplates in Autoclaves

Abstract Crystalline hexagonal boron nitride (h-BN) hexagonal nanoplates were synthesized by the reaction of B2O3, NH4F, and metallic Na at 700 °C. The edge sizes of the hexagonal nanoplates are 400 nm, and the average thickness is 100 nm. As the reaction temperature was set at 500 °C, rhombohedral boron nitride (r-BN) triangular nanoplates nearly 200 nm across and about 20 nm thick were obtained. TGA analysis results reveal that thermal stability of h-BN hexagonal nanoplates was better than that of r-BN triangular nanoplates in air.

Synthesis, Characterization and Magnetoresistance Studies of Tl0.5Pb0.5Sr1.6Ba0.4CaCu2−x Ru x O7−δ Superconductor

Bulk superconducting samples of type Tl0.5Pb0.5Sr1.6Ba0.4CaCu2−xRuxO7−δ, (Tl,Pb)/Sr-1212, with 0.0≤x≤0.525 were synthesized by the conventional one-step solid-state reaction technique via a short time, using SrO2 instead of SrCO3. X-ray powder diffraction XRD, scanning electron microscope SEM and the electrical resistivity measurements at different applied dc magnetic fields (0.0–4.4 kG) were performed in order to investigate the effect of Ru4+ ions substitution on (Tl,Pb)/Sr-1212 phase. Enhancement of the phase formation, the superconducting transition temperature Tc and the hole carriers concentration P was observed up to x=0.075, and they decreased for further increase in x. The magnetoresistance data of these samples were analyzed within the thermally activated flux creep TAFC model and the Ambegaokar and Halperin AH theory. The derived flux pinning energy U, the critical current density Jc(0) and the upper critical magnetic field Bc2(0) enhanced up to x=0.075, beyond which they decreased for further increase in Ru-content. The coherence length at 0 K ζ(0) decreased up to x=0.075 and increased with x>0.075. In addition, we reported a comparison between the effect of Ru substitution on the physical properties for Gd-123, (Bi,Pb)-2223 and (Tl,Pb)/Sr-1212 phases.

EPR Studies of Tl0.5Pb0.5Sr1.6Ba0.4CaCu2−x Ru x O7−δ Superconductor

Bulk superconducting samples of type Tl0.5Pb0.5Sr1.6Ba0.4CaCu2−xRuxO7−δ, (Tl, Pb)/Sr-1212, with 0.0 ≤ x ≤ 0.525 were prepared by the conventional one-step solid-state reaction technique. The prepared samples were investigated using X-ray powder diffraction, electrical resistivity and electron paramagnetic resonance (EPR) measurements. Enhancement of the phase formation, superconducting transition temperature Tc and hole carriers concentration P was observed up to x = 0.075. For x > 0.075, a reverse trend was observed. EPR spectra were measured at different temperatures (120–290 K) for all prepared samples. The number of spins N participating in the resonance and the paramagnetic susceptibility χ were calculated as a function of both Ru-content and temperature. N and χ increased as the Ru-content increased. A linear relationship between logN and 1/T was established, from which the activation energy Ea was calculated as a function of the Ru-content. The temperature dependence of χ was fitted according to Curie–Weiss type of magnetic behavior. Curie constant C, Curie temperature θ, the effective magnetic moment μ and the electronic specific heat γ were estimated as a function of the Ru-content.

Effects of carbon source and carbon content on electrochemical performances of Li4Ti5O12/C prepared by one-step solid-state reaction

Li4Ti5O12/C composites were synthesized by one-step solid-state reaction method using four commonly used organic compounds or organic polymers as carbon source, i.e., polyacrylate acid (PAA), citric acid (CA), maleic acid (MA) and polyvinyl alcohol (PVA). The physical characteristics of Li4Ti5O12/C composites were investigated by X-ray diffraction, electron microscopy, Raman spectroscopy, particle size distribution and thermogravimetry-derivative thermogravimetry techniques. Their electrochemical properties were characterized by cyclic voltammograms, electrochemical impedance spectra, constant current charge–discharge and rate charge–discharge. These analyses indicated that the carbon source and carbon content have a great effect on the physical and electrochemical performances of Li4Ti5O12/C composites. An ideal carbon source and appropriate carbon content effectively improved the electrical contact between the Li4Ti5O12 particles, which enhanced the discharge capacity and rate capability of Li4Ti5O12/C composites. PAA was the best carbon source for the synthesis of Li4Ti5O12/C composites. When the carbon content was 3.49wt.% (LiOH·H2O/PAA molar ratio of 1), as-prepared Li4Ti5O12/C showed the maximum discharge capacity. At 0.2C, initial capacity of the optimized sample was 168.6mAhg−1 with capacity loss of 2.8% after 50 cycles. At 8 and 10C, it showed discharge capacities of 143.5 and 132.7mAhg−1, with capacity loss of 8.7 and 9.9% after 50 cycles, respectively.

Synthesis of MnO/C composites through a solid state reaction and their transformation into MnO 2 nanorods

MnO nanospheres encapsulated in carbon (MnO/C) composites were synthesized through a one-step solid state reaction between potassium permanganate and salicylic acid at 700 °C, which could be transformed into MnO 2 nanorods after being annealed in ambient atmosphere. Their formation mechanisms and electrochemical performances as anodes in Li-ion batteries (LIBs) were investigated. The first discharge capacity of MnO/C composites was 585.9 mA h g −1, while that of MnO 2 was 1269 mA h g −1, indicating their potential applications in LIBs.

One-step, solid-state reaction to ZnO nanoparticles in the presence of ionic liquid

ZnO nanoparticles have been synthesized in ionic liquids (1-butyl-3-methylimidazolium chloride, [BMIM]Cl) by one-step solid-state reaction at room temperature for short time. The structure and morphology of the products were characterized by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM), whose results indicated that the sample was spherical in morphology with diameters of 15–20 nm. The room temperature photoluminescence spectra (PL) showed strong and broad green light emission. In addition, [BMIM]Cl could be collected and reused for subsequent reactions. This method provides a facile, one-step and low-cost route for the synthesis of nanostructures of metal oxides with potential photo-catalysis.

Superconductivity induced by doping Rh in CaFe2−xRhxAs2

In this paper, we report the synthesis of iron-based superconductors CaFe2−xRhxAs2 using a one-step solid state reaction method that crystallizes in the ThCr2Si2-type structure with a space group I4/mmm. The systematic evolution of the lattice constants demonstrates that the Fe ions are successfully replaced by the Rh. By increasing the doping content of Rh, the spin–density–wave (SDW) transition in the parent compound is suppressed and superconductivity emerges. The maximum superconducting transition temperature is found at 18.5 K with a doping level of x=0.15. The temperature dependence of dc magnetization confirms superconducting transitions at around 15 K. The general phase diagram was obtained and found to be similar to the case of the Rh-doping Sr122 system. Our results explicitly demonstrate the feasibility of inducing superconductivity in Ca122 compounds by higher d-orbital electron doping; however, different Rh-doping effects between FeAs122 compounds and FeAs1111 systems still remains an open question.

Enhanced critical current properties in Ba0.6K0.4+xFe2As2 superconductor by overdoping of potassium

Phase-pure polycrystalline Ba0.6K0.4+xFe2As2 with 0≤x≤0.1 were prepared using a one-step solid-state reaction method. We found that overdoping of potassium can improve the critical current density (Jc). High-field Jc for samples with x=0.1 is three times higher than that for samples with x=0. Overdoping of K has minimal effect on the critical transition temperature (Tc). Less than 0.5 K degradations in Tc was measured for samples with x=0.1. Transmission electron microscopy (TEM) revealed high concentration of dislocations in samples with x=0.1, resulting in enhanced flux pining. Further analyses on magnetization loops for powder samples confirm that K overdoping can promote intragrain Jc. Our results indicate that slight excess of K in Ba0.6K0.4Fe2As2 superconductor is beneficial to high-field applications.

Direct solid-state synthesis and large-capacity anode operation of Li3−xFexN

A direct solid-state synthesis route to Li3−xFexN (x < 0.4) was developed and its electrochemical properties as an anode material for lithium-ion batteries were investigated. In order to stabilize the lower valence state of Fe(I) in the layered structure of Li1−xFexN against Fe(III) in the competent phase of anti-fluorite Li3FeN2, an argon flow was used during the sintering process instead of the nitrogen or ammonia typically used in the synthesis of nitride compounds. This stabilized Li3−xFexN at moderate temperatures around 600 °C without segregation of Fe metal or melting, and enabled a simple one-step solid state reaction. The largest reversible capacity of ca.700 mAh/g was obtained at x = 0.2 below 1.3 V versusLi/Li+.