超细层状材料A2La2Ti3O10(A=Na,K) 的低温合成及表征

Ultrafine A₂La₂Ti₃O₁₀ (A=K, Na) powders with laminar structure were successfully synthesized by citric acid sol-gel method using ANO₃(A=K, Na)、La(NO₃)₃、Ti(OBu)₄ and citric acid as starting precursors. The crystalline phase of A₂La₂Ti₃O₁₀ can be obtained by thermal decomposition of citrate complex precursors at a relatively low temperature of 800 ℃ (600 ℃ for A=Na), about 300 ℃(500 ℃ for A=Na) lower than that of conventional solid state reaction process. The properties of the citrate precursors and the calcined powders were characterized by Infrared spectroscopy (IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal-gravimetric-differential thermal analysis (TG-DTA), inductively coupled plasma (ICP) and Brunauer-Emmett-Teller (BET) techniques. Results show that the average size of A₂La₂Ti₃O₁₀ powders obtained by citric acid sol-gel route was reduced to 200 nm×250 nm and the specific surface area was up to 19 m²·g^-1. At the same time, the product was with more regular morphological characteristics. The synthesis process and the formation of A₂La₂Ti₃O₁₀ were also discussed. The obtained A₂La₂Ti₃O₁₀ was found to be transformed from A₂La₂Ti₃O_9.5 during the formation process.     

Al掺杂La10(SiO4)6O3的制备及其导电性能

以溶胶-凝胶法在850℃制备了Al掺杂La10(SiO4)6O3,即La10(SiO4)6-x(AlO4)xO3-0.5x(x=0,0.5,1.0,1.5和2.0),通过TG-DTA、XRD、IR和SEM表征,所得产品为磷灰石相。以电化学阻抗谱研究了其导电性能,发现决定电导率大小的因素有两种,一是间隙氧的数量,二是晶胞的大小,两种因素的综合作用,使得Al掺杂0.5时La10(SiO4)5.5(AlO4)0.5O2.75的电导率最大,在700℃时其电导率达到1.88×10-2S·cm-1。氧分压对电导率的研究表明,其主要的电荷载体是O2-离子。     

(Zn，M)TiO3(M=Co，Ni，Co0.5Ni0.5)固溶体的溶胶-凝胶法合成

通过改进的溶胶-凝胶工艺在低温(800 ℃)下合成了基于钛酸锌(ZnTiO₃)体系的(Zn_1-xCo_x)TiO₃、(Zn_1-xNi_x)TiO₃和[Zn_1-x(Co_0.5Ni_0.5)_x]TiO₃陶瓷固溶体。采用X射线衍射分析(XRD)和差示扫描量热法(DSC)等测量技术对产物进行了物相和热稳定性分析。XRD结果表明，获得单一六方相(Zn_1-xCo_x)TiO₃、(Zn_1-xNi_x)TiO₃和[Zn_1-x(Co_0.5Ni_0.5)_x]TiO₃时各自的固溶稳定区间为0.5 ≤ x ≤ 1.0, 0.9 ≤ x ≤ 1.0和0.8 ≤ x ≤ 1.0。与此同时，热分析结果证实，伴随钛酸锌基陶瓷体系掺杂钴量的增加，其六方相的热稳定性提高，且效果比掺杂镍更加显著。     

Li4Ti5O12-聚苯胺复合材料的合成与表征

以醋酸锂和钛酸四丁酯为原料，以乙醇为溶剂，采用溶胶-凝胶法制备Li₄Ti₅O₁₂;以苯胺、过硫酸铵为原料，以盐酸为溶剂，采用原位聚合法合成Li₄Ti₅O₁₂-聚苯胺复合材料。采用X-射线衍射、红外光谱和电化学测试等对复合材料进行了表征。结果表明，聚苯胺的加入明显提高了Li₄Ti₅O₁₂的电子导电性能，Li₄Ti₅O₁₂-PAn复合材料具有比Li₄Ti₅O₁₂更好的高倍率性能和循环稳定性。0.1C和2.0C放电时Li₄Ti₅O₁₂-PAn的放电容量达到了191.3和148.9 mAh·g^-1，经80次循环后二者平均每次循环容量衰减率分别为0.13%和0.61%。     

Li3V2(PO4)3/C和Li2.5Na0.5V2(PO4)3/C的结构和电化学性能的比较研究

采用溶胶-凝胶法合成了锂离子正极材料Li3V2(PO4)3/C(LVP/C)及Li2.5Na0.5V2(PO4)3/C,并用XRD、循环伏安及交流阻抗等方法,研究了大量Na+掺杂对材料结构和电化学性能影响。结果表明,大量钠离子的掺杂会使LVP结构由单斜向菱方转变。掺杂化合物Li2.5Na0.5V2(PO4)3/C在0.5 C充电1 C放电时,首次放电容量为118 mAh.g-1,50次循环后容量保持率为92.4%,并发现与单斜LVP存在多个放电平台不同,Li2.5Na0.5V2(PO4)3/C仅在3.7 V处有一个放电平台。     

ALa9(SiO4)6O2.5(A=Ca，Sr，Ba)的合成及其电性能

利用溶胶-凝胶法在850 ℃合成了硅酸盐氧基磷灰石ALa₉(SiO₄)₆O_2.5(A=Ca、Sr和Ba),经XRD表征所得产品为磷灰石相。以电化学阻抗谱研究了ALa₉(SiO₄)₆O_2.5的导电性能,发现A的原子半径越大,体系的电导率越高,活化能却减小。在700 ℃时BaLa₉(SiO₄)     

二价与四价金属离子等摩尔共掺杂的锂离子电池正极材料LiMn1.9Mg0.05Ti0.05O4的制备与表征

以氢氧化锂、乙酸锰、硝酸镁和钛酸丁酯为原料, 以柠檬酸为螯合剂, 采用溶胶-凝胶法制备了二价镁离子与四价钛离子等摩尔共掺杂的尖晶石型锂离子电池正极材料LiMn_1.9Mg_0.05Ti_0.05O₄. 采用热重分析(TGA), X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM)和电化学性能测试(包括循环伏安(CV)和电化学交流阻抗谱(EIS)测试)对所得样品的结构、形貌及电化学性能进行了表征. 结果表明: 780℃下煅烧12 h 得到了颗粒均匀细小的尖晶石型结构的LiMn_1.9Mg_0.05Ti_0.05O₄材料, 该材料具有良好的电化学性能, 在室温下以0.5C倍率充放电, 在4.35-3.30 V电位范围内放电比容量达到126.8 mAh·g^-1, 循环50 次后放电比容量仍为118.5mAh·g^-1, 容量保持率为93.5%. 在55℃高温下循环30次后的放电比容量为111.9 mAh·g^-1, 容量保持率达到91.9%, 远远高于未掺杂的LiMn₂O₄的容量保存率. 二价镁离子与四价钛离子等摩尔共掺杂LiMn₂O₄, 改善了尖晶石锰酸锂的电子导电和离子导电性能, 使其倍率性能和高温性能都得到了明显的提高.     

无机-有机杂化钼磷酸盐化合物(NH3CH2CH2NH3)2Mo5O15(HPO4)2的合成与表征

0引言 钼磷酸盐由于具有丰富的晶体结构特点和化学特性使得这种材料在催化、离子交换剂和材料科学等领域有着更加广阔的应用前景[1～3].     

一种新型多孔道配位聚合物[La(C8H6NO2)3]n的合成及晶体结构表征

A novel porous coordination polymer [La(C₈H₆NO₂)₃]_n was synthesized by hydrothermal reaction of flexible ligands 3-(3-pyridyl)acrylate and La(NO₃)₃·6H₂O. The structure was characterized by elemental analysis， IR spectroscopy and X-ray single crystal diffraction. X-ray single crystal analysis reveals the structure consists of [La(C₈H₆NO₂)₃]_n. It crystallizes in monoclinic crystal system with space group P2(1)/c. Crystallographic date: a=0. 7889(3)nm， b=2.5916(9)nm， c=1.1489(4)nm， α=90.00°， β=95.219(6)°， γ=90.00°， V=2.3393(15)nm³， Z=4， D_c=1.656g·cm^-3， μ=1.871mm^-1， F(000)=1152， R₁=0.0328， wR₂=0.0522. CCDC: 211700.     

Dy3+，Eu3+共掺的LiGd(MoO4)2单一相荧光粉的合成、发光及能量传递

采用溶胶-凝胶法制备了LiGd(MoO_4)_2∶Dy~(3+),Eu~(3+)系列荧光粉。用X射线衍射仪(XRD)、场发射扫描电镜(FESEM)、荧光光谱仪等对所得样品的结构、形貌和发光性能进行了表征,并研究了其能量传递机理。结果表明:白钨矿结构的Li Gd(Mo O_4)_2∶Dy~(3+),Eu~(3+)荧光粉的形貌为不规则颗粒,其粒径为1.8μm。在354 nm近紫外光激发下,该荧光粉显示出Dy~(3+)的特征黄、蓝光发射和Eu~(3+)的特征红光发射。计算Dy~(3+)和Eu~(3+)的临界距离为1.383 nm,Dy~(3+)→Eu~(3+)之间能量传递机理为偶极-四极相互作用。通过调节Dy~(3+)、Eu~(3+)的掺杂浓度,荧光粉可实现暖白光发射。此外,详细研究了稀土离子(Dy~(3+),Eu~(3+))的掺杂浓度与荧光粉的色温值之间的关系。     

Synthesis and characterization of sodium titanates Na2Ti3O7 and Na2Ti6O13

Na₂Ti₃O₇ and Na₂Ti₆O₁₃ were synthesized by sol-gel method in order to obtain pure phases. Different heat-treatments were applied on powders and pellets of these materials. The effects were studied by XRD, dilatometry, TGA-DTA, SEM and electrochemical impedance spectroscopy. Pure Na₂Ti₃O₇ was obtained at 973 K. Sintering at 1373 K caused a partial decomposition into Na₂Ti₆O₁₃. The Na₂Ti₃O₇ powder sintered at 1273 K showed polygonal microstructure. Na₂Ti₃O₇ pellets sintered at 1323 K for 10 h exhibited large structures. This latter microstructure decreased the electrical conductivity of Na₂Ti₃O₇. Pure Na₂Ti₆O₁₃ was obtained at 873 K. Sintering at 1073 K caused a partial decomposition into TiO₂ (rutile). Na₂Ti₆O₁₃ pellets sintered at 1323 K for 10 h exhibited common shrinkage behavior. This shrinkage process increased the electrical conductivity of this material. The presence of TiO₂ resulted in a oxygen partial pressure dependence of the electrical conductivity.     

Synthesis and spectroscopic characterization of P-doped Na4Si4

Na₄Si₄ is a Zintl salt composed of Na⁺ cations and tetrahedral anions and is a unique solid-state precursor to clathrate structures and nanomaterials. In order to provide opportunities for the synthesis of complex materials, phosphorus was explored as a possible substituent for silicon. Phosphorus doped sodium silicides Na₄Si_4−xP_x (x≤0.04) were prepared by reaction of Na with the mechanically alloyed Si_4−x:P_x (x=0.04, 0.08, 0.12) mixture in a sealed Nb tube at 650 °C for 3 days. Energy dispersive X-ray spectroscopy confirms the presence of P in all products. Powder X-ray diffraction patterns are consistent with the retention of the Na₄Si₄ crystal structure. As the amount of P increases, a new peak in the diffraction pattern that can be assigned to black phosphorus is apparent above the background. Raman and solid-state NMR provide information on phosphorus substitution in the Na₄Si₄ structure. Raman spectroscopy shows a shift of the most intense band assigned to the ν₁ (A₁) mode from 486.4 to 484.0 cm⁻¹ with increasing P, consistent with P replacement of Si. Differential nuclear spin-lattice relaxation for the Si sites determined via ²⁹Si solid-state NMR provides direct evidence for Si-P bonding in the (Si_1−xP_x)⁴⁻ tetrahedron. The ²³Na NMR shows additional Na…P interactions and the ³¹P NMR shows two P sites, consistent with P presence in both of the crystallographic sites in the (Si₄)⁴⁻ tetrahedron.     

Synthesis and crystal chemistry of BaNd2Ti3O10, BaNd2Ti5O14, and Nd4Ti9O24

Two new ternary compounds BaNd₂Ti₃O₁₀ (1:1:3) and BaNd₂Ti₅O₁₄ (1:1:5) have been identified in the BaONd₂O₃TiO₂ system. Single crystals of the compounds were grown and unit cell dimensions and space group symmetry were determined. BaNd₂Ti₃O₁₀ is orthorhombic with a = 3.8655 ± 0.0003, b = 28.156 ± 0.003 and c = 7.6221 ± 0.0007 Å and possible space groups are Cmcm or Cmc2. The compound melts congruently at 1640 ± 20°C. BaNd₂Ti₅O₁₄ is also orthorhombic with a = 22.346 ± 0.002, b = 12.201 ± 0.001 and c = 3.8404 ± 0.0003 Å and possible space groups are Pbam and Pba2. This compound melts congruently at 1540 ± 20°C. Single crystals of the binary compound Nd₄Ti₉O₂₄ were also grown and found to be orthorhombic with a = 35.289 ± 0.003, b = 13.991 ± 0.001, c = 14.479 ± 0.001 Å, space group Fddd.     

草酰胺桥联异三核配合物Cu(NiL)2(ClO4)2的合成、光谱表征和晶体结构(英)

A novel oxamido-bridged trinuclear complex Cu(NiL)₂(ClO₄)₂(where H₂L=2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,3-dien) has been synthesized and characterized by elemental analysis, IR spectrum, UV-Visible spectrum and single crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P2₁/n. The lattice parameters are: a=1.052 4(6) nm, b=1.182 1(6) nm, c=1.586 2(9) nm, β=91.657(9)°, and V=1.972 6(19) nm³, Z=2. The results show that the coordination geometry around copper(Ⅱ) in the title complex is hexa-coordinated octahedron. CCDC: 232608.     

新型磷酸钒孔道结构化合物(H3NCH2CH2NH3)3- [ (VO)4(PO4)2 (HPO4)4]的水热 合成及结构表征

以有机分子乙二胺作为模板剂合成了新型磷酸钒孔道化合物(H3NCH2CH2NH3)3^-[(VO)4(PO4)2(HPO4)4,并通过X射线单晶衍射实验进行了结构表征,晶体学数据为：C2/c,a=1.8505(9)nm,b=0.7089(4)nm,c=2.3304(10)nm,β=96.43(3)°,V-3.038(3)nm^3,Z=8,R=0.067,Rw^b=0.1635,该化合物具有非常独特和规整的二维孔道骨架结构,进一步的晶体化学研究表明该化合物为一新的VPO物相。     

Synthesis, structure and properties of new chain cuprates, Na3Cu2O4 and Na8Cu5O10

Na₃Cu₂O₄ and Na₈Cu₅O₁₀ were prepared via the azide/nitrate route from stoichiometric mixtures of the precursors CuO, NaN₃ and NaNO₃. Single crystals have been grown by subsequent annealing of the as prepared powders at 500 °C for 2000 h in silver crucibles, which were sealed in glass ampoules under dried Ar. According to the X-ray analysis of the crystal structures (Na₃Cu₂O₄: P2₁/n, Z=4, a=5.7046(2), b=11.0591(4), c=8.0261(3) Å, β=108.389(1)°, 2516 independent reflections, R₁(all)=0.0813, wR₂ (all)=0.1223; Na₈Cu₅O₁₀: Cm, Z=2, a=8.228(1), b=13.929(2), , β=111.718(2)°, 2949 independent reflections, R₁(all)=0.0349, wR₂ (all)=0.0850), the main feature of both crystal structures are CuO₂ chains built up from planar, edge-sharing CuO₄ squares. From the analysis of the Cu-O bond lengths, the valence states of either +2 or +3 can be unambiguously assigned to each copper atom. In Na₃Cu₂O₄ these ions alternate in the chains, in Na₈Cu₅O₁₀ the periodically repeated part consists of five atoms according to Cu^II-Cu^II-Cu^III-Cu^II-Cu^III. The magnetic susceptibilities show the dominance of antiferromagnetic interactions. At high temperatures the compounds exhibit Curie-Weiss behaviour (Na₃Cu₂O₄: , , Na₈Cu₅O₁₀: , , magnetic moments per divalent copper ion). Antiferromagmetic ordering is observed to occur in these compounds below 13 K (Na₃Cu₂O₄) and 24 K (Na₈Cu₅O₁₀).