芪类分子掺杂极化聚合膜的非线性光学性质

采用实时测量光学二次谐波产生（SHG）和吸收光谱的方法时芪类有机分子DANS（4’－N,N－dimethylamino－nitrostilbene）及一种新合成的经氰基团修饰的有机分子CNDS（α’－cyano－4’－nitro－4－N,N－dimethylaminostilbene）掺杂PMMA[poly（methylmethacrylate）]极化聚合膜的非线性光学性质进行了研究。在电晕极化条件下,由于聚合膜的电导率随温度的变化急剧增加,实验中发现两种掺杂极化聚合膜的最佳电导极化温度均低于它们的玻转温度Tg．在最佳极化条件下,从极化前和极化后的吸收光谱变化可看出CNDS的有序度较DANS的差．但实时SHG表明,CNDS／PMMA极化掺杂聚合膜的二阶非线性系数X（2）较DANS／PMMA极化聚合膜的大．结合极化前和极化后吸收峰强度的变化,我们得到CNDS分了的非线性极化率β约为140×10-30esu.在撤离极化场后,CNDS／PMMA的SHG强度的弛豫也比DANS／PMMA慢,说明CNDS是一种性能较DANS优越的制备二阶光学非线性的掺杂分子．     

Ca2B2O5的电子结构和能带结构

合成了标题化合物,在已测晶体结构的基础上,利用含组态作用的INDO/S方法计算了其他电子能带结构;利用态求和方法计算了微结构分子的线性极化率及其晶体的平均折射率。分析结果表明,价带主要由B^3^+和O^2^-离子的价轨道的贡献,导带底部主要由Ca^2^+离子轨道的贡献,从O^2^-离子到Ca^2^+离子的电荷转移对线性极化率起主要贡献。     

BaFeO3和BaCeO3钙钛矿型氧化物的储氮性能

 采用改进的溶胶－凝胶法制备了Ba－Fe－O（Ba／Fe原子比为0．5），Ba－Ce－O（Ba／Ce原子比为1）和Ba－Sn－O（Ba／Sn原子比为1）氧化物，并考察了其储氮性能．结果表明，750℃焙烧的Ba－Fe－O样品，在400℃下的NOx储存容量（NSC）最大，其次为900℃焙烧的Ba－Ce－O样品；相同温度焙烧的样品，在400℃下的NSC均大于200℃下的NSC．XRD测试结果表明，750℃焙烧的Ba－Fe－O样品的缺陷钙钛矿BaFeO3－δ可能是储存NOx的主要活性相，而Ba－Ce－O和Ba－Sn－O样品储存NOx的活性相分别为钙钛矿型BaCeO3和BaSnO3．BET测定结果表明，样品的比表面积均较小．用FT－IR分析了Ba－Fe－O样品上储存的NOx物种．讨论了NSC大小与吸收温度、NOx吸收物种及样品物相之间的关系．     

LnCu2O4(Ln=Gd,Nd)电子结构的XPS研究

用XPS测定了LnCu2O4(Ln=Gd, Nd)的内层和价层电子能谱,观察到LnCu2O4中稀土金属的3d电子结合能比相应的稀土金属简单氧化物的3d结合能低0.8～0.9 eV,而Cu的2p电子结合能比CuO的高0.4～0.5 eV,因此推断在LnCu2O4的Ln－O－Cu链中存在Cu→O→Ln电荷转移.XPS分析还表明LnCu2O4的Cu原子上有较低的电荷密度,但不存在混合价态.此外,通过比较价电子能谱,发现NdCu2O4的Ln 4f Cu 3d O 2p价带中心比GdCu2O4的价带中心向Fermi能级移近了3.4 eV,而且NdCu2O4的价带谱更窄.     

LnCu_2O_4(Ln=Gd,Nd)电子结构的XPS研究

用 XPS测定了 LnCu2O4(Ln=Gd, Nd)的内层和价层电子能谱,观察到 LnCu2O4中稀土金属的 3d电子结合能比相应的稀土金属简单氧化物的 3d结合能低 0.8～ 0.9 eV,而 Cu的 2p电子结合能比 CuO的高 0.4～ 0.5 eV,因此推断在 LnCu2O4的 Ln－ O－ Cu链中存在 Cu→ O→ Ln电荷转移 .XPS分析还表明 LnCu2O4的 Cu原子上有较低的电荷密度,但不存在混合价态 .此外,通过比较价电子能谱,发现 NdCu2O4的 Ln 4f Cu 3d O 2p价带中心比 GdCu2O4的价带中心向 Fermi能级移近了 3.4 eV,而且 NdCu2O4的价带谱更窄 .     

锂离子电池正极材料LiFePO4的密度泛函研究

采用密度泛函(B3LYP)方法计算锂离子电池正极材料LiFePO4/FePO4,净电荷和共价键级的计算结果都表明磷氧原子间作用力最强,锂氧原子间作用力最弱,有利于Li离子在晶格中的自由移动.以Li/LiFePO4锂离子电池的平均电压为3.2 V,和实验值3.4 V基本一致.态密度分析表明FePO4和LiFePO4都是典型的半导体,O原子轨道主要贡献总态密度靠费米能级价带一侧,Fe原子轨道主要贡献总态密度靠费米能级导带一侧.     

混合价化合物的研究(Ⅱ)─—电化学及现场光谱电化学方法研究非质子介质中Dawson结构杂多阴离子[HAs_2Mo_(18)O_(62)]~(n-)的电还原性质

以电化学和现场紫外－可见－近红外及现场FTIR光谱电化学方法对Dawson结构杂多阴离子［HAS2Mo18O62］5－在非质子介质（CH3CN）中的电还原过程进行了研究．结果表明，该杂多阴离子在非质子介质中经历4步单电子还原反应，所产生的杂多蓝阴离子在近红外区出现宽广的价间电荷转移吸收带，而红外区Mo＝O端键及Mo—O—Mo桥键的特征吸收峰在还原后均有不同程度的红移．     

有机生色团/SiO_2-TiO_2二阶非线性光学杂化材料的研究

以分散橙－3（DO－3）与γ－缩水甘油氧与基三甲氧基硅烷（KH－560）反应 得到的功能性生色团ASD为前体，采用溶胶－凝胶（sol-gel）法使ASD与钛酸四正 丁酯在酸性条件下共水解缩合，合成了新型稳定的有机生色团/SiO_2-TiO_2杂化溶 胶，并对该溶胶体系的相图进行了研究。利用傅立叶红外（FTIR）、透射电镜（ TEM）和X射线能量色散谱仪（EDS）研究了杂化溶胶形成过程中的络合机理及溶胶 形态。由一维刚性取向气体模型计算杂化材料膜的二阶非线性光学（NLO）系数X~ (2) is 1.43 * 10~(-7) esu。差示扫描量热法（DSC）测得杂化材料的玻璃化温度 可达196 ℃；用紫外－可见光谱对杂化膜在极化前后的取向及取向稳定性进行了研 究。     

柱撑化合物Zn2Al-PW11Z的结构模型及酯化活性

杂多化合物是性能优异的酸型和氧化型或双功能催化剂[1－4]，而通式为的阴离子粘土通常具有减催化或还原催化性能[5，6]．因此，从在分子及原子水平上设计催化剂，调控催化性能观点出发，人们期望将体积较大的杂多阴离子嵌入阴离子粘土层间，合成大层间距的新型柱撑微孔材料．1988年Pinnavaia等人[7]首次报导了Zn2Al－V10O28是具有2．0nm孔径分布的中微孔材料．最近，笔者将单取代型Keggin结构杂多阴离子GeW11O39Z（H2O）6－（其中Z＝Ni2 和Cu2 ）和缺位Keggin结构的GeW11O嵌入Zn2Al－NO3层间，合成了通道高度为0．9nm的新型柱撑…     

4-取代苯亚甲基唑-5(4H)酮和9-取代苯基吖啶二阶非线性极化率

以尿素微晶作参比,用激光器测定了11个2－甲基（或苄基）－4－取代苯亚甲基恶唑－5（4H）酮和5个9－取代苯基吖啶微晶相对尿素的二阶非线性极化率值,结果表明化合物7,8和9具有较高的二阶非线性极化率值。     

Nonlinear Optical BBO Crystals: Growth, Properties and Applications

1　 INTRODUCTIONLow temperature phase barium metaborateβ- Ba B2 O4 ( BBO) as a new nonlinearoptical material was firstdiscovered in 1 979by Chen's group of the Fujian Instituteof Research on the Structure of Matter,People's Republic of China〔1〕.BBO has anumber ofexcellentpropertiessuch aslarge effective SHG coefficients,large birefrin-gence,wide transparent spectral range,high damage threshold and good machnicaland chemical properties.Particularly attractive feature is its UV t…     

First-principles electronic structure study of the monoclinic crystal bismuth triborate BiB3O6

Monoclinic BiB(3)O(6) is an excellent nonlinear optical material with many advantages compared to other borate crystals. The origins of the optical effects and the chemical stability of BiB(3)O(6) are studied with gradient-corrected hybrid B3PW density functional theory within the Gaussian-orbital-based CO-LCAO scheme. Including spin-orbit coupling, the B3PW hybrid functional provides an estimate of the indirect band gap of 4.29-4.99 eV closer to the experimental value of 4.3 eV than HF, LDA, or GGA. The crystal orbital overlap population to give a detailed first-principles analysis of chemical bonding and the density of optical absorptions by convoluting the occupied density of states and the virtual density of states have been calculated. Obvious Bi-O covalent bonds have been found with different energy ranges for 6s-2p and 6p-2p interactions. The reason that [BiO(4)](5-) units are mainly responsible for the optics of BiB(3)O(6) in the long-wavelength region is due to the electronic transfer from occupied O 2p to empty Bi 6p orbitals favored by the Bi-O covalent bonds. The relativistic and correlation effects lead to fundamental differences of the band structure, chemical bonds, and optical effects for BiB(3)O(6) compared with nonrelativistic and uncorrelated calculations.     

Electronic polarizability and Judd-Ofelt parameters of Nd3+ and Er3+ ions in transparent crystallized glasses with nonlinear optical Ba2 TiSi2O8 nanocrystals

Transparent crystallized glasses consisting of nonlinear optical Ba(2)TiSi(2)O(8) nanocrystals are prepared in Eu(2)O(3)-, Nd(2)O(3)-, and Er(2)O(3)-doped 40BaO-20TiO(2)-40SiO(2) glasses by a conventional heat treatment method in order to clarify the optical properties of rare-earth (RE) ions in nanocrystals. The electronic polarizabilities of crystallized glasses are evaluated from the values of density and refractive index, and are found to decrease due to nanocrystallization, which indicates that the chemical bonding state in the crystallized glasses is more covalent compared to the precursor glasses. It is proposed from x-ray diffraction analyses and photoluminescence spectra of Eu(3+) ions that RE ions such as Nd(3+) and Eu(3+) are incorporated into Ba(2)TiSi(2)O(8) nanocrystals. The Judd-Ofelt parameters, Omega(t) (t=2, 4, and 6), of Nd(3+) and Er(3+) ions are evaluated from optical absorption spectra. It is observed that the Omega(2) parameter of Nd(3+) and Er(3+) increases largely due to nanocrystallization, suggesting that the site symmetry of Nd(3+) and Er(3+) ions in nanocrystallized glasses is largely distorted due to their incorporations into the Ba(2+) sites in Ba(2)TiSi(2)O(8) nanocrystals. The change in the Omega(4) and Omega(6) parameters due to nanocrystallization is small. It is proposed that nonlinear optical Ba(2)TiSi(2)O(8) nanocrystals including RE ions would have a high potential as active optical materials.     

Characterisation and theoretical investigation of the electronic properties and second-order nonlinearity of some three dentate salicylaldiminato Schiff base ligands

A series of asymmetric three dentate salicylaldiminato Schiff base ligands 1-4 (Scheme 1) has been synthesized and their structures, electronic properties and second order nonlinearities are investigated using the AM1 Hamiltonian SCF-MO methods. The analysis of MOs indicates that the O(2) atom could be the coordination site if the ligands were monodentate. In addition, the atomic orbitals on the O(9) atom have no contributions to the frontier MOs of the anionic form of these three dentate ligands. The Mulliken populations reveal that the coordination sites N(6) and O(9) possess different character in generation of the Schiff base complexes. The molecular first-order hyperpolarizability value of ligands was calculated using finite field method. Generally the presence of the methoxy group as third dentate play a major role in increasing the second harmonic generation (SHG) responses of three dentate ligands. Comparison of the NLO properties of two dentate with three dentate salicylaldiminine-based ligands reveals that the presence of -NO2 and -OCH3 groups as R1 and R2 substituents enhance the second-order nonlinear optic properties of these type ligands.     

Novel mixed-valent (V/VI) triple perovskite ruthenates: observation of a complex low-temperature structural and magnetic transition

Two new mixed-valent triple perovskites, Ba(3)MRu(2)O(9) (M = Li, Na), were grown from reactive hydroxide fluxes. They crystallize in the hexagonal space group P6(3)/mmc, where Ru(V) and Ru(VI) are disordered on only one crystallographic site. Upon cooling, single crystals of Ba(3)NaRu(2)O(9) undergo a complex symmetry-breaking structural transition at ca. 225 K from room-temperature hexagonal symmetry to a low-temperature orthorhombic symmetry, space group Cmcm. Accompanying this structural transition is a rather abrupt decrease in the magnetic susceptibility at 210 K followed by a steady decrease in the susceptibility with decreasing temperature. Interestingly, the lithium analogue does not display any structural transition down to 100 K. The structural transition in Ba(3)NaRu(2)O(9) generates three crystallographically unique Ru sites in the low-temperature structure as compared to only one distinct site in the room-temperature structure. On the basis of an analysis of the Ru-Ru distances in the face-sharing bi-octahedra, the structural transition also appears to involve charge ordering of Ru(V) and Ru(VI), causing all Ru(V) to occupy one set of bi-octahedra and all Ru(VI) to occupy another set.     

Crystal growth of novel osmium-containing triple perovskites

Single crystals of two new osmium-containing triple perovskites, Ba(3)LiOs(2)O(9) and Ba(3)NaOs(2)O(9), were grown from reactive molten hydroxide fluxes in sealed silver tubes. They crystallize in the space group P6(3)/mmc with lattice parameters of a = 5.8025(1) A, c = 14.1468(4) A for Ba(3)LiOs(2)O(9) and a = 5.8858(1) A, c = 14.3451(5) A for Ba(3)NaOs(2)O(9). The magnetic susceptibility of these osmates indicates significant Os-Os coupling within the octahedra pair.     

Crystal Structure and Properties of a Sodium Terbium Borate Na2.67Tb2.11B3O9

A new nonlinear optical crystal of sodium terbium borate (Na2.67Tb2.11B3O9, Mr=573.14) was synthesized by solid reaction method. The colorless transparent single crystals were grown from the high temperature solution by employing NaBO2 as flux. The structure was determined by single-crystal X-ray diffraction method. The compound crystallizes in the orthorhombic system, space group Amm2 with a=5.0744(10), b=10.990(2), c=6.9078(14) , V=385.24(13) ·3, Dc=4.941 g/cm3, F(000)=250, Z=2, μ=9.205 mm-1, the final R=0.0253 and wR=0.0610. Its three-dimensional network structure is constructed from isolated BO33-, Na(1)O8, Na(2)O6, Na(3)O6 and Tb(1)O9 polyhedra. Variable-temperature magnetic susceptibility measurements show the compound is paramagnetic (μj=7.04 μb). The intensity of the second harmonic generation of Na2.67Tb2.11B3O9 is 2.5 times that of KDP.     

四硼酸锂单晶的非弹性光散射

四硼酸及作为表面声波装置的元素［1，2］，锂离子的超导体[3]及热致发光的剂量计［4］引起人忙越来越大的兴趣．关于它的结构已有报导【’］．Weir【司等研究了硼酸盐系列晶体的红外吸收谱．本文报导了四硼酸理在各种几何配置下的偏振拉曼光谱．分析了四配位BO4四面体和三配位     

Ba3[Ge2B7O16(OH)2](OH)(H2O) and Ba3Ge2B6O16: novel alkaline-earth borogermanates based on two types of polymeric borate units and GeO4 tetrahedra

Two new barium borogermanates with two types of novel structures, namely, Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) and Ba(3)Ge(2)B(6)O(16), have been synthesized by hydrothermal or high-temperature solid-state reactions. They represent the first examples of alkaline-earth borogermanates. Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) crystallized in a polar space group Cc. Its structure features a novel three-dimensional anionic framework composed of [B(7)O(16)(OH)(2)](13-) polyanions that are bridged by Ge atoms with one-dimensional (1D) 10-membered-ring (MR) tunnels along the b axis. The Ba(II) cations, hydroxide ions, and water molecules are located at the above tunnels. Ba(3)Ge(2)B(6)O(16) crystallizes in centrosymmetric space group P1. Its structure exhibits a thick layer composed of circular B(6)O(16) units connected by GeO(4) tetrahedra via corner sharing, forming 1D 4- and 6-MR tunnels along the c axis. Ba1 ions reside in the tunnels of the 6-MRs, whereas Ba2 ions are located at the interlayer space. Both compounds feature new types of topological structures. Second-harmonic-generation (SHG) measurements indicate that Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) displays a weak SHG response of about 0.3 times that of KH(2)PO(4). Optical, thermal stability, and ferroelectric properties as well as theoretical calculations have also been performed.