Hydrothermal Synthesis and Phase‐, Morphology‐Evolution Mechanism of Lead Titanate Nanostructures Assisted with Tetramethylammonium Hydroxide

Lead titanate nanostructures with different phases and morphologies, layered hexagonal PbTiO₂(CO₃)_0.3‐ (NO₃)_0.35(OH) nanosheets, pyrochlore Pb₂Ti₂O₆ nanodendites, pre‐perovskite PbTiO₃ nanofibres and perovskite PbTiO₃ nanoplates, have been synthesized via a conventional hydrothermal route assisted with different concentrations of tetramethylammonium hydroxide (TMAH). X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high‐resolution TEM (HRTEM) were employed to characterize the phase, morphology and growth behavior of the synthesized samples. The results reveal that at low TMAH concentration the obtained samples are mainly of PbTiO₂(CO₃)_0.3(NO₃)_0.35(OH) nanosheets. With the TMAH concentration increasing, the obtained samples change to pyrochlore Pb₂Ti₂O₆ nanodendites, pre‐perovskite PbTiO₃ nanofibres and perovskite PbTiO₃ nanoplates in turn. With the basis of the experimental results, the phase‐ and morphology‐evolution mechanism of the lead titanate nanostructures is discussed by combining the analysis of the lattice structure feature and the properties of TMAH.     

页岩储层各向异性对水平井坍塌压力的影响

为揭示层理页岩强度各向异性对水平井井壁坍塌压力的影响规律,对取自四川盆地龙马溪组页岩钻井不同层理角度的岩芯,通过岩芯观测、偏光显微镜、扫描电镜试验分别从宏观和微观角度研究了页岩层理特征,并基于单轴抗压强度研究了页岩强度各向异性特征.层理结构发育导致页岩呈现出显著的各向异性特征,粗略地将页岩视为各向同性体及简单采用Mohr-Coulomb准则作为破坏判据,使得预测的维持井壁稳定的坍塌压力不能满足安全钻井的需要.该文在研究层理地层岩石力学特性的基础上,采用横观各向同性地层井周应力分析模型,研究了弹性模量及地应力各向异性比对井周应力的影响;并结合考虑中间主应力的Mogi-Coulomb判据,分析了井壁坍塌压力对弹性模量E和Poisson(泊松)比ν各向异性比值变化的敏感性.实例分析结果表明:弹性模量和水平地应力各向异性比值的变化会对井周应力产生较大影响;Poisson比各向异性对井壁坍塌压力没有明显影响,而弹性模量比值的变化对井壁坍塌压力影响较大;横观各向同性地层中井壁坍塌压力与储层水平和垂直方向的硬脆性强弱关系有关,弹性力学参数各向异性既有可能利于井壁稳定,也可能更易导致井壁的剪切破坏;在实际工程中应根据储层岩石水平和垂直方向的硬脆性强弱关系,确定安全钻井液密度窗口.该结果对现场施工具有很好的指导意义.     

Hydrothermal Synthesis,Crystal Structure,Thermal Stability and Photophysical Property of a Novel Zinc Complex with Mixed Ligands

A novel metal-organic coordination complex [Zn(CHIP)(AIC)]n(1, CHIP = 2-(4-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, AIC = 5-amino-isophthalic acid) has been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric(TG) analysis, infrared spectrum(IR) and single-crystal X-ray diffraction. Complex 1 crystallizes in monoclinic, space group C2/c with a = 18.259(5), b = 17.191(4), c = 16.371(4) A, V = 4717(2) A3,C27H-116 ClN 5O4Zn, Mr = 575.29, Dc = 1.620 g/cm3, μ(Mo Kα) = 1.202 mm, F(000) = 2335, Z = 8, the final R = 0.032 and w R = 0.074 for 4723 observed reflections(I 2σ(I)). Single-crystal X-ray diffraction reveals that 1 exhibits one-dimensional(1D) double chains, which are linked by H-bond intersections into a 2D structure. TG analysis shows clear weight loss due to the decomposition of different ligands. The luminescent properties for the ligand and complex 1 were also studied.     

Hydrothermal Synthesis,Structure, and Optical Properties of Two Nanosized Ln26@CO3 (Ln=Dy and Tb) Cluster‐Based Lanthanide–Transition‐Metal–Organic Frameworks (Ln MOFs)

Two Ln₂₆@CO₃ (Ln=Dy and Tb) cluster‐based lanthanide–transition‐metal–organic frameworks (Ln MOFs) formulated as [Dy₂₆Cu₃(Nic)₂₄(CH₃COO)₈(CO₃)₁₁(OH)₂₆(H₂O)₁₄]Cl ? 3 H₂O ( 1 ; HNic=nicotinic acid) and [Tb₂₆NaAg₃(Nic)₂₇(CH₃COO)₆(CO₃)₁₁(OH)₂₆Cl(H₂O)₁₅] ? 7.5 H₂O ( 2 ) have been successfully synthesized by hydrothermal methods and characterized by IR, thermogravimetric analysis (TGA), elemental analysis, and single X‐ray diffraction. Compound 1 crystallizes in the monoclinic space group Cc with a=35.775(12) Å, b=33.346(11) Å, c=24.424(8) Å, β=93.993(5)°, V=29065(16) ų, whereas 2 crystallizes in the triclinic space group P with a=20.4929(19) Å, b=24.671(2) Å, c=29.727(3) Å, α=81.9990(10)°, β=88.0830(10)°, γ=89.9940(10)°, V=14875(2) ų. Structural analysis indicates the framework of 1 is a 3D perovskite‐like structure constructed out of CO₃@Dy₂₆ building units and Cu⁺ centers by means of nicotinic acid ligand bridging. In 2 , however, nanosized CO₃@Tb₂₆ units and [Ag₃Cl]²⁺ centers are connected by Nic^? bridges to give rise to a 2D structure. It is worth mentioning that this kind of 4d–4f cluster‐based MOF is quite rare as most of the reported analogous compounds are 3d–4f ones. Additionally, the solid‐state emission spectra of pure compound 2 at room temperature suggest an efficient energy transfer from the ligand Nic^? to Tb³⁺ ions, which we called the “antenna effect”. Compound 2 shows a good two‐photon absorption (TPA) with a TPA coefficient of 0.06947 cm GM^?1 (1 GM=10^?50 cm⁴ s photon^?1), which indicates that compound 2 might be a good choice for third‐order nonlinear optical materials.     

两个由5-硝基间苯二甲酸和双咪唑基配体构筑的锰、钴配合物的合成及晶体结构(英文)

通过水热法合成了2个新的配合物[Mn(NIPH)(mbix)]n(1)和[Co(NIPH)(mbix)(H2O)3]2n·2n H2O(2)(H2NIPH=5-硝基间苯二甲酸,mbix=1,3-双(咪唑基-1-基)苯)。并对其进行了元素分析、红外光谱、紫外光谱、热重和X-射线单晶衍射测定。这两个配合物通过氢键和π-π相互作用形成了三维超分子网状结构。     

ZnS纳米球的水热法制备及其光催化性能研究

在表面活性剂十六烷基三甲基溴化铵(CTAB)的辅助下,以乙酸锌为锌源,硫脲(NH2)2CS为硫源,使用水热法通过改变反应时间,成功制备了不同粒径的ZnS球状颗粒。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X-射线能谱,高分辨透射电子显微镜(HRTEM))、紫外可见分光光谱和光致发光谱(PL)等测试手段对样品的晶体结构、形貌、光学性质进行了分析。通过对不同粒径的ZnS纳米颗粒对亚甲基蓝的光催化降解的催化活性进行了评估。实验结果表明:在表面活性剂CTAB的作用下,随着反应时间的增加,生成的ZnS晶核生长成纳米颗粒,然后ZnS纳米颗粒将进一步发生团聚从而形成平均粒径超过500nm的ZnS纳米球,但制备的ZnS产物的晶体结构均为立方纤锌矿结构。随着ZnS粒径的增加,样品的紫外吸收峰从418nm逐渐蓝移到362nm,而PL发射峰位的峰强随着粒径的增大而增强。光催化结果显示,反应12h制备的ZnS纳米球的光催化性能最佳。     

基于四核金属单元的锌/镉配合物的合成、晶体结构及荧光性质

在水热条件下合成了2个金属配合物Zn4(Hhpa)4(phen)4(1)和{[Cd8(cnam)2(bpy)4(C2O4)6(H2O)8]·2H2O}n(2)(H2hpa=2-羟基间苯二甲酸,phen=菲咯啉,H2cnam=4-氧代-4H-吡喃-2,6-二甲酸,bpy=2,2′-联吡啶),通过元素分析、红外光谱、X-射线单晶衍射、荧光、热重分析和X-射线粉末衍射对其进行表征。配合物1为环状四核锌结构,相邻的四核锌单元通过π…π堆积作用扩展为三维超分子结构;配合物2是基于四核镉单元通过C2O42-离子和cnam2-配体连接而成的三维网状结构。在配合物1和2中Hhpa2-,cnam2-和C2O42-离子表现了丰富的配位模式。此外还研究了配合物1和2的荧光性质和热稳定性。     

具有三重螺旋链的二氯苯氧乙酸铽(Ⅲ)配位聚合物的晶体结构与荧光性质

采用水热法制备了一种新型金属配位聚合物[Tb2(2,4-D)6(2,2'-bipy)2]n(1)(2,4-D=2,4-二氯苯氧乙酸;2,2'-bipy=2,2'-联吡啶),用X-衍射单晶结构分析、红外光谱分析、荧光光谱法对产物进行了结构表征。结构分析表明,标题配合物属于单斜晶系,P2(1)/n空间群,晶胞参数a=2.792(1)nm,b=0.851(3)nm,c=3.335(1)nm,β=113.6470(1)°,V=7.2575(5)nm3,Z=4。金属离子Tb3+处于扭变的四方反棱柱构型中,金属离子之间通过配体2,4-D的羧基的桥联作用,链接成为一维三重螺旋链状配位聚合物。配合物的荧光光谱表明,配合物有望成为潜在的绿光材料。     

新型苯二甲酸和咪唑衍生物构筑的混配型镉配位聚合物的合成及其热稳定性

以硝酸镉、4-硝基邻苯二甲酸(4-NPAH2)和1,4-二咪唑二甲苯(1,4-bimb)为原料,通过水热反应合成了一个新的混配型配位聚合物{[Cd(4-NPA)(1,4-bimb)0.5]n(1)},其结构和热性能经IR,元素分析,X-射线单晶衍射及TGA表征。1属三斜晶系,P-1空间群,晶胞参数a=7.587(2),b=9.696(3),c=10.376(3),α=87.059(3)°,β=77.998(3)°,γ=89.859(3)°,V=745.6(4)3,Z=2,Dc=1.963 g·cm-3,μ=1.506mm-1,F(000)=434,R1=0.028 6,wR2=0.071 1。中心Cd(Ⅱ)与来自三个4-NPA2-配体的五个氧原子以及一个1,4-bimb分子的一个氮原子构成一个扭曲的八面体构型{Cd O5N}单元。两个相邻的八面体单元通过边共享的方式连接进而通过羧酸基团沿着a-轴方向形成一维双链结构。1,4-bimb分子采用顺式方式桥联相邻双链的Cd(Ⅱ)在ac-平面上形成zigzag层状结构。1的初始分解温度约310℃。