Superacid Univalent Metal Phosphites (MH2PO3)2· H3PO3 (M = Rb,Tl(I)) and MH2PO3· H3PO3(M = K,Cs): Synthesis and Structure

By reacting the K, Rb, Cs, or Tl carbonates with excess phosphoric acid, crystals of superacid phosphites, namely, (RbH₂PO₃)₂· H₃PO₃(I), (TlH₂PO₃)₂· H₃PO₃(II), KH₂PO₃· H₃PO₃(III), -CsH₂PO₃· H₃PO₃(IV), and -CsH₂PO₃· H₃PO₃(V), were synthesized. Their structures were determined by single-crystal X-ray diffraction analysis at 150 K. Crystals I: triclinic system, space group , a= 7.713(2) Å, b= 8.679(3) Å, c= 9.235(3) Å, = 79.36(3)°, = 67.60(2)°, = 88.13(3)°, R ₁= 0.0252; crystals II: triclinic system, space group , a= 7.690(3) Å, b= 8.494(3) Å, c= 9.292(4) Å, = 79.48(3)°, = 66.72(3)°, = 85.45(3)°, R ₁= 0.0485; crystals III: monoclinic system, space group P2₁/c, a= 8.726(3) Å, b= 12.182(4) Å, c= 6.354(2) Å, = 104.14(3)°, R ₁= 0.0241; crystals IV: orthorhombic system, space group P2₁2₁2₁, a= 6.033(1) Å, b= 6.444(1) Å, c= 18.345(4) Å, R ₁= 0.0172; crystals Vare monoclinic, space group C2/c, a= 9.990(3) Å, b= 12.197(4) Å, c= 6.866(2) Å. = 118.14(3)°, R ₁= 0.0181. The hydrogen bonding systems form corrugated bands (Iand II), bent layers (III), individual tubes with rectangular cross sections (V), or a three-dimensional framework (IV). A comparative analysis of the crystal structures of acid phosphites with different compositions was performed.     

Phase equilibria in the system Rb3PO4–Ba3(PO4)2

The system Rb₃PO₄–Ba₃(PO₄)₂ was investigated by thermoanalytical methods, X-ray powder diffraction, ICP, and FT-IR. On the basis of the obtained results its phase diagram was proposed. For this system with one intermediate compound, BaRbPO₄, we found that this compound melts congruently at 1700 °C, exhibits a polymorphic transition at 1195 °C and is high-temperature unstable. Also, the intermediate compound was subject to gradual decomposes to Ba₃(PO₄)₂ (the solid phase) and vaporization (with conversion of phosphorus and rubidium oxides into vapor phase). We also found that Rb₃PO₄ melts congruently at 1450 °C and shows a polymorphic transition at 1040 °C. Regarding Ba₃(PO₄)₂, we have confirmed that it melts congruently at 1605 °C and exhibits a polymorphic transition at 1360 °C.     

LiNd(PO3)4晶体的热分析研究

对LiNd(PO₃)₄晶体分别在N₂气和空气下进行了TG和DTA热分析研究,给出TG和DTA曲线,讨论了LNP晶体在N₂气和空气下不同的热分解机理.得到分解产物分别为Nd₄(P₂O₇)₃和NdP₂O₇.     

Ce(ph3PO)(DBM)2(NO3)2的合成与鉴定

β-二酮络合物已获得广泛而深入的研究,Ce(Ⅳ)的β-二酮类络合物的研究也有报导^[1-3].但是,关于Ce(Ⅳ)的β-二酮与其它混合配体络合物的研究至今未见报导.我们以(NH₄)₂Ce(NO₃)₆为起始物质,经由双-(三苯基氧化膦)硝酸铈(Ⅳ)中间络合物在混合溶剂中与DBM反应制得该化合物.通过紫外、红外光谱以及¹HNMR谱等研究,对该络合物的性质进行了讨论.     

Li3V2(PO4)3电极过程及其锂离子脱嵌动力学研究(Ⅰ)

采用溶胶凝胶法合成了Nasicon化合物Li3V2(PO4)3,采用X射线衍射(XRD)对产品进行了物相分析.采用充放电测试,循环伏安(CV)研究了化合物的电化学性能和锂离子的脱嵌过程,计算出Li+在固相中的扩散系数(10-8 cm2·s-1);采用交流阻抗测试(EIS)研究了Li3V2(PO4)3的电极过程;对两种类型的阻抗图谱提出不同等效电路模型并对结果进行了拟合;研究了Li3V2(PO4)3电极过程动力学以及新鲜电极界面在充放电过程中的变化特性.     

SYNTHESES AND SPECTROSCOPIC PROPERTIES OF LANTHANIDE COMPLEXES, Ln(acac)_3(Ph_3PO)_3

A series of new complexes of formula Ln(acac)_s(Ph_3PO)_3 (where Ln~(3+)=Nd~(3+), Sm~(3+), Eu~(3+), Tb~(3+), Ho~(3+)) have been prepared and characterized. The coordination of two ligands with lanthanide ions are studied by IR spectra, ~1H, ~(13)C, ~(31)P-NMR and metal-ligand charge tranafer tranaition is also discussed via electronic adaorption and luminescence spectroscopy.     

可见光响应的Co3(PO4)2/Ag3PO4纳米复合光催化剂的制备及表征

采用简单的化学偏聚法合成出Ag3PO4纳米颗粒、磷酸钴(Co3(PO4)2,CoP)纳米片以及它们两者的纳米复合结构(CoP/Ag3PO4),同时还比较了它们的可见光催化活性.采用场发射扫描电镜(FESEM)、X射线衍射(XRD)、紫外-可见(UV-Vis)吸收光谱以及光致发光谱等手段对其形貌、结构、光学以及可见光催化性能等进行表征.结果表明,CoP/Ag3PO4复合纳米结构的可见光降解甲基橙(MO)的速率和循环稳定性均明显优于其它两种物质.这表明CoP应该起着共催化剂的作用,它能够抑制光生电子与空穴之间的复合,并且提供大量高活性的光生空穴.此外,我们还发现CoP/Ag3PO4降解另一种阳离子型染料——罗丹明B(RhB)的能力则远不如纯Ag3PO4,这可能是与光催化剂的表面性质发生改变有关,造成更低的RhB吸附能力.本文提供了一种廉价制备高效可见光催化剂的新方法.     

可见光响应的CO3(PO4)2/Ag3PO4纳米复合光催化剂的制备及表征

采用简单的化学偏聚法合成出Ag3PO4纳米颗粒、磷酸钴(Co3(PO4)2,CoP)纳米片以及它们两者的纳米复合结构(CoP/Ag3PO4),同时还比较了它们的可见光催化活性.采用场发射扫描电镜(FESEM)、X射线衍射(XRD)、紫外-可见(UV-Vis)吸收光谱以及光致发光谱等手段对其形貌、结构、光学以及可见光催化性能等进行表征.结果表明,CoP/Ag3PO4复合纳米结构的可见光降解甲基橙(MO)的速率和循环稳定性均明显优于其它两种物质.这表明CoP应该起着共催化剂的作用,它能够抑制光生电子与空穴之间的复合,并且提供大量高活性的光生空穴.此外,我们还发现CoP/Ag3PO4降解另一种阳离子型染料——罗丹明B(RhB)的能力则远不如纯Ag3PO4,这可能是与光催化剂的表面性质发生改变有关,造成更低的RhB吸附能力.本文提供了一种廉价制备高效可见光催化剂的新方法.     

LiTi2(PO4)3的Na/Li离子交换特征

锂离子传导材料LiTi₂(PO₄)₃能在LiCl水溶液中高选择性地与Na⁺进行离子交换. 研究了NaCl 溶液中LiTi₂(PO₄)₃上的Na/Li离子交换反应, 实验结果表明, 升高温度能显著提高LiTi₂(PO₄)₃上的Na/Li交换反应速率, 其离子交换动力学规律可近似由JMAK(Johnson-Mehl-Aurami-Kalmogorav)方程描述. 对LiTi₂(PO₄)₃在水和NaCl溶液中的溶解行为的研究结果表明, 升高温度能加快其在水中的溶解速率, pH值过大或过小及离子交换都会加剧LiTi₂(PO₄)₃的溶解.     

三元掺杂改性锂离子电池正极材料Li3V2(PO4)3

以柠檬酸为螯合剂和还原剂, NH₄VO₃为钒源,通过溶胶-凝胶法制备了锂离子电池正极材料Li₃V₂(PO₄)₃及其三元掺杂体系Li_2.85Na_0.15V_1.9Al_0.1(PO₄)_2.9F_0.1.分别采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、能量损失谱(EELS)、拉曼(Raman)光谱、扫描电子显微镜(SEM)、X射线能谱(EDS)、恒流充放电、循环伏安(CV)和交流阻抗谱(EIS)等技术对材料的微观结构、颗粒形貌和电化学性能进行分析.结果表明:在残余碳包覆的基础上, Na、Al、F三元掺杂有利于稳定Li₃V₂(PO₄)₃的晶体结构,进一步减少颗粒团聚和提升材料导电特性,促进第三个锂离子的脱出和嵌入,从而显著改善Li₃V₂(PO₄)₃的实用电化学性能.未经掺杂的Li₃V₂(PO₄)₃原粉在1/9C、1C和6C倍率下的可逆比容量分别为141、119和98 mAh·g^-1,而三元掺杂改性材料在1/9C、1C、8C和14C倍率下的比容量分别为172、139、119和115 mAh·g^-1.在1C倍率下循环300圈后,掺杂体系的比容量依然高达118 mAh·g^-1,比原粉高出32.6%.值得注意的是,这种三元掺杂还使Li₃V₂(PO₄)₃的多平台放电曲线近似转变为一条斜线,显示出可能不同的储锂机制.     

Compound formation,crystal chemistry,and phase equilibria in the system Li3PO4Zn3(PO4)2

The system Li₃PO₄Zn₃(PO₄)₂ contains several new phases and solid solution series, some of which are interconvertible by high-temperature, composition-dependent, phase transitions. Crystal data are given for two of the new phases, α- and β-Li₄Zn(PO₄)₂. The β form appears to be structurally related to γ-Li₃PO₄, but with some cation disorder. The α form is ordered and appears to be structurally related to Li₂Zn₃(SiO₄)₂. The equilibrium phase diagram for this system has been determined.     

NaSn2(PO4)3的水热合成与结构性能研究

应用水热合成技术制备了具有NASICON型结构的NaSn₂(PO₄)₃离子导体.研究了其结构与电导性能.结果表明,水热合成制备NaSn₂(PO₄)₃离子导体化合物,是一条新的途径,它比传统的高温固相反应方法更加方便有效,尤其容易获得较纯的物相及单晶,并且水热晶化产物与固相反应产物具有相同的结构和性能.     

CRYSTAL STRUCTURE OF TRIS(2-THENOYLTRIFLUOROACETONATO)BIS(TRIPHENYLPHOSPHINE OXIDE)EUROPIUM(Ⅲ), Eu(TTA)_3.(Ph_3PO)_2

<正> C60H42O8F9S3P2Eu,Mr=1372.07 triclinic, space group Pl,a = 11.191(1), b = 12.121(2), c = 23.529(3) A,α=80.08(1),β=76.51(1),γ=70.46(1)°,V=2909.3(6)A3, Dm(flotation in CCl4/BrCH2CH2Br) = 1.566, Dx(Z=2) = 1.562 g cm-3,λ(MoKα) =0.71073 A,μ=13.16 cm-1, F(OOO)=1376, T =295 °K, final RF=0.033 for 9104 observed reflections with |Fσ|>3σ(|Fσ|).The compound is isostructural with the known neodymium(Ⅲ) complex. The metal atom in the monomeric molecule is coordinated dodecahedrally by the eight 0 atoms of the surrounding ligands with Eu-0 bond distances in the range 2.361(2)-2.457(3) A.     

Synthesis and Ionic Conductivity of LiZr2(VO4)x(PO4)3 – x

Russian Journal of Electrochemistry - Vanadate phosphates LiZr2(VO4)x(PO4)3 – x are synthesized by the sol-gel technique with subsequent annealing and studied using X-ray diffraction...     

Phase formation along the PO 4 3− /Zr = 1.5–2.0 section of the ZrO(NO3)2-KF-H3PO4-H2O) system

The phase composition of precipitates at 20°C along the PO ₄ ^3? /Zr = 1.5–2.0 section at KF/Zr = 1–5 (mol/mol) of the ZrO(NO₃)₂-H₃PO₄-KF-H₂O system has been investigated. Phases in these precipitates have been identified by X-ray powder diffraction, crystal-optical, chemical, and thermal analyses and by IR spectroscopy. The previously known potassium zirconates K₃ZrF₇ and K₂ZrF₆ have been revealed, and crystalline fluorophosphate zirconate K₃Zr₃F₃(HPO₄)₃(PO₄)₂ and a phosphate nitrate of unknown formula have been obtained for the first time.     

A Pseudo-Keggin Compound:Hydrothermal Synthesis and Crystal Structure of (DETAH)(DETAH3)3[V18O42(PO4)]·(PO4)·2H2O

The novel vanadophosphate (DETAH)(DETAH3)3[V18O42(PO4)]·(PO4)·2H2O has been synthesized under hydrothermal conditions and its structure was determined by single-crystal X-ray diffraction. The compound crystallizes in monoclinic, space group C2/c with a=23.857(3), b=12.9619(18), c=20.204(3) (A), β=105.692(2)°, V=6015.0(14) (A)3, Z=4, Dc=2.473 g/cm3, Mr=2239.68, F(000)=4432, R=0.0725, wR=0.1524 and GOOF=1.095. The metaloxo cluster contains a novel six-capped pesudo-Keggin structure unit which encloses a disorder PO43- guest.     

LiTi2(PO4)3/C 复合材料的制备及电化学性能

采用聚乙烯醇(PVA)辅助溶胶-凝胶法合成了具有Na+超离子导体(NASICON)结构的LiTi2(PO4)3/C复合材料.运用X射线衍射(XRD)、扫描电子显微镜(SEM)、充放电测试、循环伏安(CV)、电化学阻抗谱(EIS)等对其结构形貌和电化学性能进行表征.实验结果表明:合成的LiTi2(PO4)3/C具有良好的NASICON结构,首次放电容量为144mAh·g-1.电化学阻抗谱测试结果显示,LiTi2(PO4)3/C复合材料电极在首次嵌锂过程中分别出现了代表固体电解质相界面(SEI)膜及接触阻抗、电荷传递阻抗和相变阻抗的圆弧,并详细分析了它们的变化规律.计算了Li+在LiTi2(PO4)3中嵌入/脱出时的扩散系数,分别为2.40×10-5和1.07×10-5cm2·s-1.     

Li3Fe2(PO4)3正极材料的制备及电化学性能研究

本文以本文通过高温固相反应合成了Nasicon型的Li_3Fe_2(PO_4)_3电极材料。XRD结果显示850℃烧结得到的Li_3Fe_2(PO_4)_3结晶性最好。为了优化Li_3Fe_2(PO_4)_3电极的性能,使用行星球磨将制备得到的Li_3Fe_2(PO_4)_3与乙炔炭黑混合均匀,得到了Li_3Fe_2(PO_4)_3/C复合正极材料。扫描电镜照片显示,球磨后活性材料的颗粒尺寸明显减小,而且更加均匀。对于Fe~(3 )/Fe~(2 )的氧化还原电对,恒电流充放电测试和伏安循环法揭示Li_3Fe_2(PO_4)_3/C复合正极材料再放电过程中在2.8和2.7V具有两个电压平台。样品球磨后,与800℃和900℃烧结得到的Li_3Fe_2(PO_4)_3相比,850℃烧结得到的材料具有更好的可逆性和更高的容量保持性,而且它的比容量在初始循环以C/20的倍率放电可以达到92 mAhg~(-1)以及在结束时的循环以C/10的倍率放电还具有62 mAhg~(-1)。