Synthesis of Mesoporous Chromium Aluminophosphate (CrAlPO) via Solid State Reaction at Low Temperature

Mesoporous chromium aluminophosphate （CrAIPO） was successfully synthesized via solid state reaction （SSR） route at low temperature in the presence of a cationic surfactant cetyltrimethyl ammonium bromide （CTAB） and inorganic sources such as A1C13 · 6H20, CrCI3 · 6H20 and NaH2PO4 · 2H20. Characterizations by means of powder X-ray diffraction （XRD）, N2 adsorption- desorption, high resolution transmission electron microscopy （HR-TEM）, scanning electron micrography （SEM）, energy dispersion spectroscopy （EDS）, thermo-gravimetry （TG）, Fourier transform infrared spectroscopy （FT-IR）, and ultraviolet visible light spectroscopy （UV-Vis） were carried out to understand both the pore characteristics and electron transition route of these obtained materials. The experimental results show that the meso-CrA1PO materials with various Cr/A1 molar ratios possess a mesostructure and a specific surface area of 193 to 310 m2/g corresponding to an average pore size of 5.5 to 2.2 rim, respectively. The maxium content of Cr in meso-CrA1PO materials synthesized via SSR route can achieve 16.7wt%, being significantly higher than that of the meso-CrA1PO prepared via a conventional sol-gel route. Meanwhile, the formation mechanism of the meso-CrA1PO was also proposed.

Preparing Nano-ZnS by Solid State Reaction at Room Temperature

ZnS nanoparticles were prepared by using solid-state reaction method at room temperature in agate mortar for the first time. The average particle size was about 20nm. This reaction is affected by the structure of reactant, crystal water and defects.

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.

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.

Microstructural evolution of NiFe_2O_4-10NiO powder prepared by high temperature solid state reaction

The NiFe2O4-10NiO powder for inert anode of aluminium electrolysis was prepared by high temperature solid state reaction. The microstructural evolution from the raw materials NiO and Fe2O3 to the NiFe2O4-10NiO powder was studied by SEM. The results show that the domain structure making up of the agglomerate particles of Fe2O3 remains after high temperature solid state reaction, and the diffusion of Ni2+ into Fe2O3 structure is the control step of the reaction process. A microstructure with compact structure and fine grain inside the particle results from the sintering of NiFe2O4-10NiO powder.

Salt-assisted Low Temperature Solid State Synthesis of High Surface Area CoFe_2O_4 Nanoparticles

A novel salt-assisted low temperature solid state method using CoCl2.6H2O, FeCl3.6H2O and NaOH as precursor and using NaCI as a dispersant to synthesize high surface area CoFe2O4 nanoparticles, has been investigated. The effects of the molar ratio of added salt and calcination temperature on the characteristics of the products were investigated by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, vibrating sample magnetometer （VSM） and Brunauer, Emmett and Teller （BET） surface area analysis. Results showed that the introduction of leachable inert inorganic salt as a hard agglomeration inhibitor in the mixture precursor led to the formation of high dispersive CoFe2O4 nanoparticles; and the increase in specific surface area from 28.28 to 73.97 m^2/g, and the saturation magnetization is 84.6 emu/g.

Solid-state synthesis of Sr-and Co-doped LaMnO_3 perovskites

The synthesis process for La 1- x Sr x Mn 1- y Co y O 3- δ ( x = 0.2, 0.3; y = 0.2, 0.8, designated as LSMC below) perovskite oxides prepared by solid state reaction was investigated using DSC/TG, XRD, EPMA and particle size analysis methods. It was found that LSMCs were all of single phase and the synthesis process might be divided into three stages: the decomposition of reactants, the formation of LaMn(Co)O 3 based oxides, and the formation of LSMC solid solution. Typical average and the peak value of particle size, and the specific surface area are 14.65?μm, 16.4?μm and 1.38?m 2/mL, respectively, for mixed reactants and are 23.81?μm, 32.11?μm and 0.5?m 2/mL, respectively, for powder synthesized at 1?200?℃ for 8?h in air.

Fabrication and characterization of SmO_(0.7)F_(0.2)FeAs bulk with a transition temperature of 56.5 K

The superconductivity of iron-based superconductor SmO 0.7 F 0.2 FeAs was investigated. The SmO 0.7 F 0.2 FeAs sample was prepared by the two-step solid-state reaction method. The onset resistivity transition temperature is as high as 56.5 K. X-ray diffraction （XRD） results show that the lattice parameters a and c are 0.39261 and 0.84751 nm, respectively. Furthermore, the global J c was more than 2.3 × 10 5 A/cm 2 at T = 10 K and H = 9 T, which was calculated by the formula of J c = 20ΔM/[a（1-a/（3b））]. The upper critical fields, H c2 ≈ 256 T （T = 0 K）, was determined according to the Werthamer-Helfand-Hohenberg formula, indicating that the SmO 0.7 F 0.2 FeAs was a superconductor with a very promising application.

液相Y、Nb共掺杂BaTiO_3基PTC陶瓷的制备与性能

本文以Ba(OH)2.8H2O、Sr(OH)2.8H2O、TiCl4、NbCl5、YCl3和Mn(Ac)2为原料,采用室温研磨、低温固态反应合成了一系列的纳米钛酸钡基PTCR陶瓷粉,首先实现了Y和Nb双施主以离子的形式共掺杂。采用XRD,TEM对样品进行了表征。研究表明,产品为立方晶系的完全互溶取代固溶体。粒子基本成球形,分布均匀,粒径大约60 nm。通过优化Y和Nb的掺杂量,使材料的室温电阻得到了进一步降低,并提高了材料的升阻比。当Y、Nb和Mn的用量分别为0.2 mol%、0.18 mol%和0.04 mol%时,加入定量的AST烧结助剂,控制最高烧结温度为1310℃,制备出了室温电阻17.6Ω,正温度系数为18.6%/℃,升阻比为6.5×104的性能优异的PTCR电阻材料。另外还就烧结条件对材料PTC性能的影响进行了讨论。

Preparation and gas sensing properties for acetone of amorphous Ag modified NiFe_2O_4 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.

Bi掺杂BaTiO_3基PTC陶瓷的制备、微结构和电性能

采用液相掺杂及低温固相反应法制备了Bi掺杂BaTiO3纳米晶体,然后经烧结制得了Bi掺杂BaTiO3基PTC陶瓷。分析了所制Bi掺杂BaTiO3晶体的物相、晶粒大小及微结构,研究了烧结条件对所制PTC陶瓷电性能的影响。结果表明:Bi掺杂BaTiO3晶体在常温下为立方晶系,颗粒基本呈球形且大小均匀,粒径约为60 nm;在烧结温度为1 330℃、保温时间为20 min条件下所制PTC陶瓷性能最佳:室温电阻为26.29,升阻比为3.585×104。

无铅高居里点BaTiO_3-Bi_(0.5)K_(0.5)TiO_3陶瓷的制备及其PTC性能的研究

采用固相反应法制备了(1-x)BaTiO3-xBi0.5K0.5TiO3(BT-BKT,x=0,0.1和0.2),对陶瓷样品进行X射线衍射、扫描电镜、介电常数-温度及电阻率-温度测试分析,研究了掺杂BKT对该系统陶瓷相组成、显微结构和电性能的影响。结果表明:BaTiO3陶瓷的晶格参数c轴值随着BKT含量的增加基本不变,而a轴值有所减小。BT-BKT陶瓷的居里温度(Tc)随着BKT的加入向高温移动,当x=0.1和0.2时,Tc分别提高至170℃和185℃左右;但室温电阻率随着BKT含量的增加明显增大。

基于LTCC技术的BaTiO_3-NiCuZn复合材料的研制

采用高纯度原材料,严格控制主配方和生产工艺,由固相反应法制备出高性能的低温烧结NiCuZn铁氧体材料,然后再与高介电钙钛矿(BaTiO3)混合低温烧结制得一类新型介电-铁磁复合材料。固定助溶剂Bi2O3比例2%,研究了铁电-铁磁含量对复合材料的电容、电感双性的影响,并将材料在生产线进行流延测试,表明流延效果良好。这种材料解决了介电与铁磁材料层低温共烧兼容的问题。

La和Y掺杂对BaTiO_3基PTC陶瓷性能的影响

采用低温固相反应法(800℃)合成了一系列纳米掺杂BaTiO3基PTC瓷粉。经XRD分析,产品为立方晶系的完全互溶取代固溶体。分别研究了La和Y双施主掺杂以及烧结条件对材料PTC性能的影响,实验表明,以La和Y进行双施主掺杂可使材料的室温电阻进一步降低,升阻比提高。通过合理地调整双施主的相对含量,优化烧结制度,制备出了室温电阻为14.25?,升阻比达3.7×104的PTCR材料。

NaTi_2(PO_4)_3纳米晶的室温固相合成及表征

以Ti(SO4)2和Na3PO4.12H2O为原料,在表面活性剂聚乙二醇(PEG)-400的存在下,进行固相反应,然后将混合物在60℃下保温4 h,接着用水洗去混合物中的可溶性无机盐并于100℃下干燥,即得纳米晶NaTi2(PO4)3的前驱体,将前驱体煅烧可得NaTi2(PO4)3纳米晶。前驱体和它的煅烧产物通过TG/DTA,IR,XRD和UV-vis表征。结果表明,500℃下煅烧2 h得到的产物为无定形结构,700℃下煅烧2 h得到具有高结晶度的斜方NaTi2-(PO4)3[空间群R-3c(167)],其平均一次粒径为47 nm。前驱体及煅烧产物均具有强的紫外吸收能力。

Reactive adsorption of thiophene on Ni/ZnO adsorbent:Effect of ZnO textural structure on the desulfurization activity

To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-temperature solid-state reaction and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method.The analysis results showed that the crystalline sizes of ZnO as-synthesized as well as the BET surface areas varied obviously with the calcination temperature.The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessed a favorable textural structure as active component exhibited good activity of removing thiophene.The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converting it into ZnS in the reactive adsorption process.It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity,which may be the main reason for the different activities of the Ni/ZnO adsorbents prepared with ZnO calcined at different temperatures.

Synthesis of trans-bis(glycin- ato) copper(II) complex nanorods by room tempera- ture solid-state reaction

Trans-[Cu(glyo)2(H2O)] nanoparticles with average diameters about 20—30 nm were prepared by one- step room temperature solid-state reaction. Trans-[Cu(glyo)2] nanorods with diameters ranging from 100 to 150 nm and lengths up to several ìm were also prepared by one-step room temperature solid-state reaction in the presence of a suitable nonionic surfactant PEG400. The chemical composi- tion and structural features of the products were investigated by elemental analyses, XRD, TG, SEM and TEM, respec- tively. The mechanisms of formation were also discussed.

Synthesis and Characterization of Rare Earth Ion Doped Nano ZnO

Zinc oxide(ZnO) doped with erbium at different concentrations was synthesized by solid-state reaction method and characterized by X-ray diffraction(XRD), scanning electron microscopic(SEM), UVabsorption spectroscopy, photoluminescence(PL) study and vibrating sample magnetometer. The XRD studies exhibit the presence of wurtzite crystal structure similar to the parent compound ZnO in 1% Er^(3+)doped Zn O,suggesting that doped Er^(3+)ions sit at the regular Zn^(2+)sites. However, same studies spread over the samples with Er^(3+)content>1% reveals the occurrence of secondary phase. SEM images of 1% Er^(3+)doped ZnO show the polycrystalline nature of the synthesized sample. UV-visible absorption spectrum of Er^(3+)doped ZnO nanocrystals shows a strong absorption peak at 388 nm due to ZnO band to band transition. The PL study exhibits emission in the visible region, due to excitonic as well as defect related transitions. The magnetizationfield curve of Er^(3+)doped ZnO nanocrystals showed ferromagnetic property at room-temperature.

成型工艺和烧结温度对CaTiO_3-LaAlO_3微波介质陶瓷结构与性能的影响

采用传统固相反应法制备了CaTiO_3-LaAlO_3(CTLA)陶瓷,借助XRD、SEM和电性能测试手段,系统研究了干压、注塑两种成型工艺和烧结温度对CTLA陶瓷结构与性能的影响。结果表明,成型工艺和烧结温度不会改变CTLA陶瓷材料的主晶相,与干压成型相比,注塑成型的试样密度均匀性更好,其烧结密度、收缩率和相对介电常数略高,Q·f值下降,综合性能一般。相同成型工艺下,致密性、晶粒尺寸和相对介电常数均随烧结温度的增加而增加。烧结温度为1380℃时,干压成型试样具有最佳的性能:径向收缩率为15.02%,ε_r=44.01,Q·f(5 GHz)=41648 GHz,τ_f=1.24×10^(-6)℃^(-1)。

Synthesis,Crystal Structure,and Optical Property of Zero-dimensional Quaternary Thioborate：Ba9B3GaS15

A new zero-dimensional（0D） thioborate Ba_9B_3GaS_（15） has been discovered by conventional high-temperature solid-state reaction. The compound crystallizes in orthorhombic space group Pbca with a = 8.4759（8）,b = 22.266（2）,c = 31.426（3） ？,V = 5931（2） ？~3,Z = 8,Mr = 1819.11,Dc = 4.075 g/cm3,μ = 13.684 mm^（-1）,F（000） = 6320,S = 1.034,（Δρ）max = 5.039,（Δρ）min = –5.409 e/？~3,the final R = 0.0362 and w R = 0.1053 for 19243 observed reflections with I 〉 2σ（I）. The structure is constructed by discrete [BS_3]^（3–） trigonal planes and isolated [GaS_4]^（5–） tetrahedra with Ba^（2＋） and isolated S^（2–） filled among them. The UV-Vis-near-IR spectrum reveals a wide band gap of 3.15 eV that agrees with the electronic structure calculation.