Microwave direct synthesis and thermoelectric properties of Mg_(2)Si by solid-state reaction

In order to reduce the oxidation and volatilization caused by Mg element in the traditional methods for synthesizing Mg2Si compounds,Mg2Si thermoelectric materials were prepared by solid state reaction and microwave radiation techniques.Structure and phase composition of the materials were investigated by X-ray diffraction.The electrical conductivity,Seebeck coefficient and thermal conductivity were measured as a function of temperature from 300 to 700 K.It is found that high purity Mg2Si powders can be obtained with excessive content of 8% Mg from the stoichiometric Mg2Si at 853 K and 2.5 kW for 30 min.A maximum dimensionless figure of merit,ZT,of about 0.13 was obtained for Mg2Si at 600 K.

Preparation of nano-sized cerium and titanium pyrophosphates via solid-state reaction at room temperature

Nano-sized cerium-titanium pyrophosphates Ce1-xTixP2O7 （with x = 0, 0.2, 0.5, 0.7, 0.9, and 1.0） were obtained by grinding a mixture of Ce（SO4）2·4H2O, Ti（SO4）2, and Na4P2O7·10H2O in the presence of surfactant PEG-400 at room temperature, washing the mixture with water to remove soluble inorganic salts, and drying at 100℃. The products and their calcined samples were characterized using ultraviolet-visible spectroscopy （UV-vis）, thermogravimetry and differential thermal analyses （TG/DTA）, X-ray powder diffraction （XRD）, and transmission electron microscopy （TEM）. The results show that nano-sized Ce1-xTixP2O7 behave as an excellent UV-shielding material. Thereinto, the CeP2O7 has the most excellent UV-shielding effect, and the amorphous state of Ce0.8Ti0.2P2O7 can keep at a higher temperature than CeP2O7. Therefore, the stabilization of the amorphous state of the cerium pyrophosphates was carded out by doping titanium. This stabilization is a significant improvement, which enables to apply these amorphous pyrophosphates not only to cosmetics and paints, but also plastics and films.

Electrochemical properties of spinel LiMn_2O_4 and LiAl_(0.1)Mn_(1.9)O_(3.9)F_(0.1) synthesized by solid-state reaction

Two types of spinel cathode powders, LiMn2O4 and LiAl0.1Mn1.9O3.9F0.1, were synthesized by solid-state reaction, X-ray diffraction （XRD） patterns of the prepared samples were identified as the spinel structure with a space group of Fd 3^- m. The cubic lattice parameter was determined from least-squares fitting of the XRD data. The LiAl0.1Mn1.9O3.9F0.1 sample showed a little lower initial capacity, but better cycling performance than the LiMn2O4 sample at both room temperature and an elevated temperature. The Vanderbilt method was used to test the electrochemical conductivity of the LiMn2O4 samples. The electrochemical impedance spectroscopy （EIS） method was employed to investigate the electrochemical properties of these spinel LiMn2O4 samples.

Synthesis and electrochemical performance of 5V spinel LiNi_(0.5)Mn_(1.5)O_4 prepared by solid-state reaction

Spinel compound LiNi0.5Mn1.5O4 with high capacity and high rate capability was synthesized by solid-state reaction. At first, MnCl2·4H2O and NiCl2·6H2O were reacted with (NH4)2C2O4·H2O to produce a precursor via a low-temperature solid-state route, then the precursor was reacted with Li2CO3 to synthesize LiNi0.5Mn1.5O4. The effects of calcination temperature and time on the physical properties and electrochemical performance of the products were investigated. Samples were characterized by thermal gravimetric analysis(TGA), scanning electron microscopy(SEM), X-ray diffractometry(XRD), charge-discharge tests and cyclic voltammetry measurements. Scanning electron microscopy(SEM) image shows that as calcination temperature and time increase, the crystallinity of the samples is improved, and their grain sizes are obviously increased. It is found that LiNi0.5Mn1.5O4 calcined at 800 ℃ for 6 h exhibits a typical cubic spinel structure with a space group of Fd3m. Electrochemical tests demonstrate that the sample obtained possesses high capacity and excellent rate capability. When being discharged at a rate as high as 5C after 30 cycles, the as-prepared LiNi0.5Mn1.5O4 powders can still deliver a capacity of 101 mA·h/g, which shows to be a potential cathode material for high power batteries.

Strontium ferrite powders prepared from oily cold rolling mill sludge by solid-state reaction method

Oily cold rolling mill （CRM） sludge is one of the pollutants emitted by iron and steel plants. Recycling oily CRM sludge can not only reduce pollution but also bring social and environmental benefits. In this study, using oily CRM sludge as sources of iron oxide, the strontium ferrite powders were synthesized in multiple steps including vacuum distillation, magnetic separation, oxidizing roasting, and solidstate reaction. The optimal technological conditions of vacuum distillation and oxidizing roasting were studied carefully. To consider the effects of Fe203/ SrCO3 tool ratio, calcination temperature, milling time and calcination time on magnetic properties of prepared strontium ferrite powders, the orthogonal experimental method was adopted. The maximum saturation magneti- zation （62.6 mA-m2.g-1） of the synthesized strontium ferrite powders was achieved at the Fe203/SrCO3 mol ratio of 6, 5 h milling time, 1250 ~C calcination temperature, and 1 h calcination time. Strontium ferrite powders syn- thesis method not only provides a cheap, high quality raw material for the production of strontium ferrite powders, but also effectively prevents the environmental pollution.

Effects of Solid-State Reaction Synthesis Processing Parameters on Thermoelectric Properties of Mg_2Si

The Mg_(2)Si-matrix thermoelectric material was synthesized by low temperature solid-state reaction.This paper studies the effects of holding time and reaction temperature on the particle size and the properties of the material,and also studies effects of doping elemental Sb,Te and their doping seqence on the properties of the material.The result shows that excessively high temperature and elongated holding time of solid-state reaction are harmful,there is a range of particle size to ensure optimum properties and the doping sequence of Sb or Te without influencing the properties.

Preparation of NH_4ZrH(PO_4)_2·H_2O via solid-state reaction at low heat and its catalytic performance in the synthesis of butyl acetate

Nanocrystalline NH4ZrH（PO4）2·H2O was obtained by grinding ZrOC12·8H2O and （NH4）2HPO4 in the presence of surfactant PEG-400 via solid-state reaction at room temperature. The product NH4ZrH（PO4）2·H2O and its product of thermal decomposition were characterized using thermogravimetry and differential thermal analyses （TG/DTA）, Fourier transform infrared spectroscopy （FT-IR）, X-ray powder diffraction （XRD）, and transmission electron microscopy （TEM）. Nanocrystalline NHaZrH（PO4）2·H2O with an average particle size of 17 nm was obtained when the product was kept at80℃ for 3 h. Its crystalline framework was stable at temperatures below 250℃. In addition, the catalytic performance of NH4ZrH（PO4）2·H2O in the synthesis of butyl acetate was investigated. The results show that NH4ZrH（PO4）2·H2O behaved as an excellent heterogeneous catalyst in the synthesis of butyl acetate.

Preparation of new sunscreen materials Ce_(1-x)Zn_xO_(2-x) via solid-state reaction at room temperature and study on their properties

Superfine cerium-zinc oxides Ce1-xZnxO2-x with x = 0, 0.1, 0.3, 0.5, and 1.0 were obtained by grinding Ce（SO4）2·4H2O, ZnSO4·7H2O and NH4HCO3 under the condition of surfactant PEG-400 being present at room temperature, washing the mixture with water to remove soluble inorganic salts, drying at 80°C, and calcining.The precursor and its calcined samples were characterized using thermogravimetry and differential thermal analyses（TG/DTA）, UV-vis absorption spectroscopy, X-ray powder diffraction（XRD）, and scanning electron microscopy（SEM）.The results showed that superfine Ce1-xZnxO2-x behaved as an excellent UV-shielding material.The ZnO-doped CeO2 can facilitate the formation of crystalline state CeO2.The catalytic ability of products used in air oxidation of castor oil was investigated.The results showed that the catalytic abilities of products decreased with increasing zinc amount.

Synthesis of Nano-sized Barium Titanate Powder by Solid-state Reaction between Barium Carbonate and Titania

Size control of BaTiO3 in solid-state reaction between BaCO3 and TiO2 was demonstrated by varying the size of TiO2 and milling conditions of BaCO3. The smaller TiO2 particles had higher surface area, resulting in faster initial reaction. The mechanically milled BaCO3 particles accelerated the diffusion process and decreased the calcinations temperature. It can be deduced from the results that the size control is possible and nano-sized BaTiO3 particles with about 60 nm can be synthesized by using the conventional solid-state reaction between BaCO3 and TiO2.

Effect of Lithium Nitrate on the Structure and Property of α-Al2O3 Platelets Prepared via Solid-state Reaction

The α-Al_2O_3 platelets were prepared via solid-state reactions and the effect of the amount of lithium nitrate additive on the property of the platelets was investigated. The ICP results indicated that the high temperature calcination process resulted in a large loss of lithium species because of volatilization, but there was still a small amount of residual lithium species in the α-Al_2O_3 platelets. The SEM micrographs showed that lithium nitrate led to decrease in the thickness of α-Al_2O_3 platelets and irregular morphology of aggregates. Pore structures results exhibited that addition of lithium nitrate led to decrease in the pore size and increase in the specific surface area of aggregates of α-Al_2O_3 platelets. The XRD and IR patterns suggested that the residual lithium and aluminum oxide formed LiAl_5O_8. The existence of LiAl_5O_8 was the basic reason for the changed performance of α-Al_2O_3 platelets.

Preparation of transparent yttrium aluminum garnet ceramics by relatively low temperature solid-state reaction

A new preparation method for a highly sinterable Y 2O 3 powder was developed, using the mixture of the powder with Al 2O 3 powder, a transparent yttrium aluminum garnet(YAG) ceramic was prepared at relatively low temperature by a solid state reaction method. Yttrium nitrate was used as a mother salt, and aqueous ammonia was used as a precipitant reagent, the fine and dendritic precursor crystalline was prepared by adding 0.5% ammonium sulfate into the precipitation reaction system. The highly pure and low agglomerated Y 2O 3 powders were obtained by calcinating the precursor at 1 100 ℃, the primary particles are spherical and 60 nm in diameter. The mixture of Y 2O 3 and Al 2O 3 powders was calcinated, and the resulting mixture compact pressed in mold could be sintered to transparency under vacuum at 1 700 ℃. The sintered transparent YAG polycrystalline exhibits a homogeneous microstructure and its transmittance reaches 45% in the visible light region and 70% in the near infrared wavelength region.

Modulation of Electronic States in Bimetallic-doped Nitrogen-Carbon Based Nanoparticles for Enhanced Oxygen Reduction Kinetics

Controlling the local electronic structure of active ingredients to improve the adsorption desorption characteristics of oxygen-containing intermediates over the electrochemical liquid-solid interfaces is a critical challenge in the field of oxygen reduction reaction(ORR)catalysis.Here,we offer a simple approach for modulating the electronic states of metal nanocrystals by bimetal co-doping into carbon-nitrogen substrate,allowing us to modulate the electronic structure of catalytic active centers.To test our strategy,we designed a typical bimetallic nanoparticle catalyst(Fe-Co NP/NC)to flexibly alter the reaction kinetics of ORR.Our results from synchrotron Xray absorption spectroscopy and X-ray photoelectron spectroscopy showed that the co-doping of iron and cobalt could optimize the intrinsic charge distribution of Fe-Co NP/NC catalyst,promoting the oxygen reduction kinetics and ultimately achieving remarkable ORR activity.Consequently,the carefully designed Fe-Co NP/NC exhibits an ultra-high kinetic current density at the operating voltage(71.94 mA/cm^(2)at 0.80 V),and the half-wave potential achieves 0.915 V,which is obviously better than that of the corresponding controls including Fe NP/NC,Co NP/NC.Our findings provide a unique perspective for optimizing the electronic structure of active centers to achieve higher ORR catalytic activity and faster kinetics.

Investigation of solid-state reaction by terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy(THz-TDS)was utilized to investigate the solid-state reaction between L(+)-Tartaric acid and sodium hydrogen carbonate.Solid sodium hydrogen L(+)-tartrate monohydrate was synthesized efficiently by mechanical grinding,which is particularly sustainable and environmentally benign.Distinct THz absorptions were observed for pure reactants and the proposed product.The reaction process could be clearly visualized by THz spectral patterns of the reaction mixtures at different grinding time.The observed results were further confirmed by synchrotron radiation X-ray powder diffraction(SRXRPD)and Fourier transform infrared (FT-IR)spectroscopy.The study demonstrates that THz-TDS is an effective novel tool to monitor solid-state reactions in pharmaceutical industry.

Synthesis of Copper Oxalate Nanorods by a Simple One-step Solid-state Chemical Reaction Method

Copper oxalate nanorods were successfully prepared by means of a simple one-step solid-state reaction method with the assistance of a suitable surfactant, polyethylene glycol 400. The product with uniform rod-like morphology was characterized by XRD, TEM and SEM. The formational mechanism of the rod-like structure was also preliminary discussed.

Preparation and electrochemical characteristics of Co_3(PO_4)_2-coated LiNi_(0.8)Co_(0.2)O_2 by solid-state reaction at room temperature

LiNi0.8Co0.2O2 particles were modified by Co3（PO4）2 coating. The effects of the Co3（PO4）2 coating on the structure and electrochemical properties of the LiNi0.8Co0.2O2 cathode material were investigated. The Co3（PO4）2 coating forms a thin layer on the surface of the LiNi0.8Co0.2O2 material and a solid solution by interacting with the LiNi0.8Co0.2O2 core material during calcination at 700℃ for 4 h. Charge-discharge experiment results show that the Co3（PO4）2 coating improves the cycling stability of the LiNi0.8Co0.2O2 cathode material. The capacity retention of the pristine LiNi0.8Co0.2O2 cathode after 50 cycles is 83.6%, whereas it is 91.7% in the case of the LiNi0.8Co0.2O2 cathode coated with 1 wt.% Co3（PO4）2. Storage tests of the 4.35 V charged electrode at 60℃ after a month show that the Co3（POg）2-coated sample exhibits good storage properties compared with the pristine sample.

Electronic structure and spin state regulation of vanadium nitride via a sulfur doping strategy toward flexible zinc-air batteries

Owing to the distinctive structural characteristics,vanadium nitride(VN)is highly regarded as a catalyst for oxygen reduction reaction(ORR)in zinc-air batteries(ZABs).However,VN exhibits limited intrinsic ORR activity due to the weak adsorption ability to O-containing species.Here,the S-doped VN anchored on N,S-doped multi-dimensional carbon(S-VN/Co/NS-MC)was constructed using the solvothermal and in-situ doping methods.Incorporating sulfur atoms into VN species alters the electron spin state of vanadium in the S-VN/Co/NS-MC for regulating the adsorption energy of vanadium sites to oxygen molecules.The introduced sulfur atoms polarize the V 3d_(z)^(2) electrons,shifting spin-down electrons closer to the Fermi level in the S-VN/Co/NS-MC.Consequently,the introduction of sulfur atoms into VN species enhances the adsorption energy of vanadium sites for oxygen molecules.The*OOH dissociation transitions from being unspontaneous on the VN surface to a spontaneous state on the S-doped VN surface.Then,the ORR barrier on the S-VN/Co/NS-MC surface is reduced.The S-VN/Co/NS-MC demonstrates a higher half-wave potential and limiting current density compared to the VN/Co/N-MC.The S-VN/Co/NS-MC-based liquid ZABs display a power density of 195.7 m W cm^(-2),a specific capacity of 815.7 m A h g^(-1),and a cycling stability exceeding 250 h.The S-VN/Co/NS-MC-based flexible ZABs are successfully employed to charge both a smart watch and a mobile phone.This approach holds promise for advancing the commercial utilization of VN-based catalysts in ZABs.

Synthesis of Ca_2ZnSi_2O_7:Eu phosphor by a modified solid-state reaction and its luminescent properties

This paper reports the detailed preparation and phosphorescence properties of Eu2+-activated Ca2ZnSi2O7 phosphors by a modified solid-state reaction.Phase-pure crystalline Ca2ZnSi2O7 is obtained at 600℃,a much lower temperature than by conventional solid-state reaction and the preparation process of Ca2ZnSi2O7 is simple.The obtained phosphors showed three emission peaks at 480,580 and 620 nm,respectively.Auxiliary activator R3+(R=Dy,Nd,Tm) would enhance their luminescent properties.

Nanoporous AlN particle production from a solid-state metathesis reaction

This paper reports that nanoporous AlN particles are synthesized from solid-state metathesis reactions using AlCl3 and Mg3N2 as reactants.The samples are characterized by x-ray diffraction （XRD）,transmission electron microscopy （TEM）,selected area electron diffraction, high-resolution transmission electron microscopy （HRTEM）,ultraviolet-visible （UV-vis） absorption spectroscopy and Raman spectroscopy.The results show that samples with walls 10 nm in thickness and pores between 10 nm and 100 nm in diameter were produced successfully from these reactions,and their band gap and vibration modes agree with those of AlN bulk crystal.

Solid-State Reaction and Vacancy-Type Defects in Bilayer Fe/Hf Studied by the Slow Positron Beam

The positron annihilation lifetimes and the Doppler broadening by slow positron beam are measured in thin Fe films with thickness 500 nm, a thin Hf film with thickness 100 nm, and the bilayer Fe (50 nm)/Hf (50 nm) on quartz glass substrate. We have analyzed the behavior in vacancy-type defects in each layer through some deposition temperatures and annealing. It is observed that the thin Fe film, the thin Hf film, and the bilayer Fe (50 nm)/Hf (50 nm) already contain many vacancy-type defects. We have investigated the change of densities of the vacancy-carbon complex and the small vacancy-cluster with carbons, through solid-state amorphization of Fe (50 nm)/Hf (50 nm) bilayer.

Study of the (Ca_1–xSr_x) RuO₃System with Nano-Crystals Prepared by the Solid-State Reaction Method

We present a study of their structure, morphology, electrical and magnetic properties on the (Ca1–xSrx) RuO3 system for x = 0.0, 0.07, 0.10, 0.15 and 1.0. The samples were prepared by the solidstate reaction method in air at ambient pressure and heat in the 700℃ - 800℃ range for 48 h. By X-ray powder diffraction (XRD), we determine a solid solution until x = 0.15. Scanning electron microscopy (SEM) indicates that the particle size is 77 - 266 nm. The resistance measurements, as a function of temperature measurements from 7 to 300 K the (Ca1–xSrx) RuO3 system for x = 0.0, 0.07, 0.10, 0.15 and 1.0 show a metallic behaviour. We can even observe that the resistance of the samples is due to the partial substitution of Sr2+ ions and Ru ion valence. Finally, the sample x = 0.07 has a magnetization applied high field to 10 K, whereas that to 300 K does not have a magnetization.