一种新型的硼酸盐晶体BiB_3O_6的二阶非线性光学行为的理论计算(英文)

利用化学键的观点 ,研究了一种新型硼酸盐晶体BiB3O6 的二阶非线性光学行为。计算结果表明 :该晶体确实具有很好的倍频性能。但是 ,它的性能还达不到目前实验报道的数值。从该晶体的结构特征出发 ,作者分析了所得出的结果 ,期待对该晶体性能做进一步测定。     

无机硼酸盐体系的二阶非线性光学晶体材料

总结了无机硼酸盐二阶非线性光学晶体材料的结构特征，即无中心对称性和阴离子基团的π共轭类芳香性结构；讨论了阴离子基团理论处理实际体系时遇到的困难及其假设中的不尽合理之处。以BBO（低温相偏硼酸钡β-BaB2O4）和LBO（三硼酸或LiB3O5）晶体为例，从含组态作用的INDO/S记结合态求和方法计算得到的结果分析后表明，BBO和LBO的价带具有相同的原子轨道组成，导带的底部，在BBO中主要是Ba原子轨道的贡献；在LBO中主要是（B3O5）-基团的贡献。前者对二阶极化率的贡献主要来自环外O原子的2p轨道到Ba原子的电荷转移，而后者的贡献则主要来自[B－O]阴离子基团内的电荷转移．计算得到的BBO和LBO的价带和导带间的电子跃迁能分别是6.28eV和7.26eV，相当好地接近于紫外吸收边的测量值6．43eV和7.78eV，最大的二阶非线性极化系数Xyyy（7．18X10-9esu）和Xzyy（2.38X10－9esu）相当接近实验测量值d22（5．30X10－9esu）和d32（2．79X10－9esu）。     

化学键观点在寻找新型非线性光学晶体材料中的应用

从晶体组成化学键的角度出发 ,研究和探讨了化学键观点在寻找新型非线性光学晶体材料工作中的应用     

晶体非线性光学效应的微观理论

1961年,Franken发现倍频效应,产生了非线性光学。二十年来,人们做了大量工作,取得了很大进展。例如,借助于混频、参量振荡和受激喇曼等非线性过程,可以扩展相干辐射的波长范围,并在一定波长范围内实现了连续或准连续可调谐,使非线性光学的研究成果得到最直接应用。同时,非线性光学揭示了普通光     

非线性光学有机晶体材料的研究进展

随着科技的进步和时代的发展,光电子技术将是21世纪的核心技术之一.对于光电子技术的发展,非线性光学材料,尤其是非线性光学晶体是不可缺少的关键材料.本文主要从分子设计方面概述了阴阳离子二元生色团体系、纯有机分子、纳米晶体和有机金属复合物等几种主要的非线性光学有机晶体材料的研究情况,并对其各自的特点做了简单的说明.     

有机和金属有机非线性光学晶体材料

非线性光学材料是激光技术的重要物质基础之一,是高技术研究的一个组成部分。二十多年来,非线性光学材料的研究经历了无机晶体、有机材料的阶段,现在又开始了金属有机非线性光学材料的探索。本文拟综述有机和金属有机二阶非线性光学晶体材料的研究进展,而不讨论高分子材料以及三阶非线性光学效应。鉴于刊物读者的特     

络合滴定法确定一种新型硼酸盐晶体的组成

1　引　　言ＣａＬａ2 Ｂ1 0 Ｏ1 9晶体是我们近期发现的一种具有良好光学性能的新型非线性光学材料。为了得到大尺寸、高光学均匀性的晶体 ,需要对它的组成、原料的成分及晶体生长过程中炉料成分的变化进行分析。但是 ,目前ＣａＯ Ｌａ2 Ｏ3 Ｂ2 Ｏ3三元体系中各组分含量的常量分析方法还未见报道。为此 ,我们建立了一种简便并较为准确的分析方法来测定体系中ＣａＯ、Ｌａ2 Ｏ3、Ｂ2 Ｏ3的含量 ,确认了该晶体的组成。2　实验原理先测定ＣａＯ Ｌａ2 Ｏ2 Ｂ2 Ｏ3三元体系中ＣａＯ和Ｌａ2 Ｏ3的含量 ,再根据样品总质量求出Ｂ2 Ｏ3的含量。由…     

硼酸盐倍频晶体材料探索-α-LiCdBO3的合成

基于平面构型的阴离子基团可能具有大的倍频效应的观点,以固相反应法在LiBO2:CdCO3=1:1摩尔比,反应温度600～620℃,空气气氛中合成了α-LiCdBO3,α-LiCdBO3在高于620℃时开始转变成β-LiCdBO2,此β-多型体在867±5℃异元熔融而分解,考查了α-LiCdBO2的合成条件及其粉末倍频效应,测得α-LiCdBO3的SHG(Second harmonic generation)强度是ADP(NH4H2PO4)的三倍,β-LiCdBO3无倍频效应。     

一种新的有机非线性光学晶体——L-精氨酸磷酸盐

近年来,在探索新的有机非线性光学晶体的工作中,对含有给电子或受电子基团的芳香族化合物已有广泛深入的研究,并已研制出像2,4-二硝基苯丙氨酸甲酯(MAP)等具有较大倍频系数的新的非线性光学晶体。但是,由于强的共轭效应使它们大π键各能级间的距离接近而使此类晶体无法应用于紫外区。     

锂化硼氮纳米管的二阶非线性光学理论研究

基于硼氮纳米管(BNNTs), 研究了多重锂化硼氮纳米管Li_n-(n,0,l)BNNTs(n=6和8, l=2~4)的结构与非线性光学性质. 研究表明, 在Li_n-(n,0,l)BNNTs中, Li原子上的自然键轨道电荷接近+1(0.769～0.827 e), 表明Li原子上的电子转移到了硼氮纳米管上, 从而形成了多重锂盐. 同时发现, 增加管长和拓宽管径都可有效地增加体系的一阶超极化率. 更重要的是, Li_n-(n,0,l)BNNTs的紫外-可见吸收主要发生在270~290 nm附近, 且当管长增加时, Li_n-(n,0,l)BNNT的紫外-可见吸收光谱发生了蓝移, 改善了非线性与透光性之间的关系. 此外, Li_n-(n,0,l)BNNTs还具有良好的稳定性[垂直电离势(VIP)=5.85～6.0 eV].     

Two Covalent Ultraviolet Nonlinear Optical Crystals

Nonlinear optical (NLO) crystals are the vital components of laser science and technology, as they can convert lasers in common wavelengths into new wavelength bands for ultraviolet (UV), IR, and even terahertz laser output. Known UV NLO crystals mainly focus on crystals containing cations, but covalent crystals have rarely been reported. Here we report two covalent NLO crystals, B₂O₃ I and B₂O₃ II. According to the first‐principles calculations, B₂O₃ I and II have extremely short absorption edges of about 134 nm and 141 nm, large NLO coefficients of d₂₂=1.38 pm/V and d₂₄=0.702 pm/V, as well as sufficient birefringences of 0.037 and 0.031, respectively. Notably, the absorption edges are almost the shortest among NLO crystals. Meanwhile, the NLO coefficients are evidently larger than that of another well‐known covalent NLO crystal α‐SiO₂ and are comparable to those of the commercial UV NLO crystal LiBO₃ with Li⁺ cation. Furthermore, the birefringences are significantly larger than that of α‐SiO₂, which are favorable to the phase matching for both crystals. These results reveal that B₂O₃ I and B₂O₃ II are excellent candidates for UV NLO applications. In‐depth calculations are carried out to reveal the origin of excellent NLO properties. These covalent crystals provide a new direction for the research of UV NLO crystals.     

Chemical Bonding in Thermodynamically Labile Oxyanion Crystals

Crystal valence density and difference density distributions were calculated for NaNO₂, NaNO₃, KClO₃, and NaClO₄ using local density functional theory. Hybridization of the oxygen states is enhanced in compounds with lower symmetry, leading to the formation of oxygen chains in the lattice. Interaction between the oxygen and anion's central atom sublattices gives rise to electron charge maxima in the middle of the A—O bonds and to two terminal oxygen maxima. The complex character of the intraanion electron transfer and the charge transfer between the nonequivalent oxygen sublattices make these compounds susceptible to external energy effects that lead to their solidstate decomposition.     

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…     

中红外波段二阶非线性光学晶体材料研究进展

新型无机红外波段二阶非线性光学晶体材料在光电子领域有着重要的应用，对它们的探索是当前非线性光学材料研究领域的难点和前沿方向之一。本文将材料按组成分成三大类（即经典的ABC₂型黄铜矿结构化合物，硫属元素其他化合物和AMX₃型卤化物），分别就新材料探索、已知材料的单晶生长等综述了近10余年来中红外波段二阶非线性光学晶体材料的研究进展。     

Optical Waveguiding Organic Single Crystals Exhibiting Physical and Chemical Bending Features

Bendable (elastic and plastic) organic single crystals have been widely studied as emerging flexible materials with highly ordered packing structures. However, even though manifold bendable organic crystals have been recently reported, most of them bend in response to only one stimulus. Herein, we report an organic single crystal of (Z)‐4‐(1‐cyano‐2‐(4‐(dimethylamino)phenyl)vinyl)benzonitrile, which bends under external stress (physical process) and also hydrochloric acid atmosphere (chemical process). This observation indicates that a single organic crystal, whose structure has been optimized simultaneously at both the molecular and supramolecular levels, may display multiple crystal‐bending modes. Furthermore, the crystals exhibit bright orange‐yellow emission and can serve as an active low‐loss optical waveguide in both the straight and the bent state, which indicates a potential optical application.     

Inclusion Crystals of Cedrol and Phenol-type of Compounds for Second-Order Nonlinear Optical Application

This present paper reports that the cedrol and phenol-type of inclusion crystals exhibit SHG effect. These inclusion crystals with noncentrosymmetrical structure possess lower cutoff wavelength(290-380 nm) and higher reflection rate (300-1200 nm), and show a great promising application prospect.     

Hybridization: A Chemical Bonding Nature of Atoms

Both the bonding mode and geometry can serve as the chemical bonding nature of central cation, which is essentially determined by the atomic orbital‐hybridization. In this work, we focus on the possible chemical bonding scheme of central cations on the basis of a quantitative analysis of electron domain of an atom. Starting from the hybridization of outer atomic orbitals that are occupied by valence electrons, we studied the possible orbital hybridization scheme of atoms in the periodic table and the corresponding coordination number as well as possible molecular geometries. According to distinct hybrid orbital sets, the chemical bonding of central cations can be classified into three typical types, resulting in the cations with a variety of coordination numbers ranging from 2 to 16. Owing to different hybridization modes, the highest coordination number of cations in IA and IIA groups is larger than that in IB‐VIIIB groups, and the coordination number of lanthanide elements is most abundant. We also selected NaNO₃ , Fe(NO₃ )₃•9H₂O , Zn(NO₃ )₂•6H₂O , Y(NO₃ )₃•3H₂O , and La(NO₃ )₃•6H₂O as examples to confirm the direct relationship between chemical bonding characteristics and orbital hybrid set by IR spectra. The present study opens the door to reveal the chemical bonding nature of atoms on the basis of hybridization and will provide theoretical guides in structural design at an atomic level.