A phase-matchable nonlinear optical crystal 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole: Synthesis,crystal growth and characterization

In this paper, we report the synthesis, growth and characterization of a new organic NLO single crystal of 4-amino-5-mercapto-3-[1-(4-isobutylphenyl)ethyl]-1,2,4-triazole (AMIT). The title compound is synthesized and single crystals were grown by the slow evaporation technique at room temperature. The grown crystal was characterized by powder XRD, FTIR, UV-Vis. and microhardness studies. The thermal analysis of the crystal was carried out by TGA, DTAand DSC. FromDSC, the melting point of the crystal is found to be 168°C. The scanning electron microscopy (SEM) provides information about the surface morphology of the crystal. The SHG efficiency has been estimated as 0.3 times that of KDP using Kurtz powder method and is found to be a phase-matchable NLO crystal.     

Thermal, optical, mechanical and dielectric properties of nonlinear optical crystal 4-methoxy benzaldehyde-N-methyl 4-stilbazolium tosylate

We have grown organic nonlinear optical 4-methoxy benzaldehyde-N-methyl-4-stilbazolium tosylate (MBST) crystals by slow evaporation technique. The grown crystals were analyzed by powder XRD, FTIR, NMR, UV, Thermal, mechanical and dielectric measurements. Lattice parameters and crystallinity of the crystal is confirmed by the XRD studies. The FTIR and NMR studies give the details about the various functional groups present. In order to study the optical quality of the crystal, the UV-vis absorption spectrum was recorded and cut-off wavelength was determined. Melting point of the crystal is found from the differential scanning calorimetry. The powder SHG studies were done with the Kurtz powder technique and the NLO efficiency is 17.2 times greater than that of urea. The surface of the grown crystal was analyzed with etching. Laser damage threshold studies have been carried out for the crystal using a Q-switched Nd:YAG laser of 10 ns pulses.     

GeS2-Ga2S3-CdS透明表面微晶玻璃的二阶非线性光学效应

采用热诱导法制备了GeS2-Ga2S3-CdS硫系微晶玻璃,X射线衍射(XRD)、透射光谱、扫描电子显微镜(SEM)测试结果表明,获得了含CdGa2S4微晶的透明表面微晶玻璃。采用Maker条纹法研究了微晶玻璃的二次谐波(SHG)效应,结果表明玻璃中的CdGa2S4微晶诱导了二次谐波效应的产生。CdGa2S4微晶在玻璃表面择优生长时,破坏玻璃的各向同性,可获得两个包络的Maker条纹,且入射角在±(35°~50°)左右时,二次谐波的相对强度出现最大值,二阶非线性强度最大可为α-石英单晶的8倍;CdGa2S4微晶在玻璃表面无择优生长时,由于玻璃表面较大的CdGa2S4晶粒的散射作用,只能获得一个包络的Maker条纹,即入射角为0°时,二次谐波的相对强度出现最大值。     

Influence of 60Co gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol crystals

In this article, effect of gamma irradiation on the structural and optical properties of 2-aminopyridinium 4-nitrophenolate 4-nitrophenol (2AP4N) has been reported. The grown crystals of 2AP4N were exposed to ⁶⁰Co gamma rays with a dose of 50 kGy and 100 kGy. The radiation-induced effects were analyzed using X-ray diffraction, FT-IR, UV–visible, photoluminescence techniques. The refractive index was determined using a long arm spectrometer. The structural properties of the pristine and irradiated crystals were studied using powder XRD. The peak intensity decrease after irradiation may be attributed to the formation of point defects. The UV visible study reveals that the energy gap has decreased after irradiation and then has increased for the higher dose. The intensity variation in the PL spectra is due to colour center mechanism. The SHG efficiency of 2AP4N crystals was found to be unaffected by gamma irradiation.     

A compact autocorrelator for the wavelength range between 4 and 10 μm

A compact autocorrelator suitable for the measurement of the optical pulse length of the infrared free electron laser (IR-FEL) at the S-DALINAC is described. It allows to investigate the energy transfer process from the electrons into the laser light within the undulator of the FEL. The autocorrelator utilizes the second harmonic generation (SHG) and it provides the possibility of a background-free measurement at wavelengths between 4 and 10 μm. Simulations for three different crystals used for SHG show that the largest efficiency for SHG and the best temporal resolution is achieved with a ZnGeP₂ crystal at a length of 2 mm. A test experiment at the free electron laser for infrared experiments confirmed the expected high efficiency of about 7.5% of SHG for the ZnGeP₂ crystal as well as the easy handling and fast adjustment of the system.     

水热法制备的Li4-3xEux(MoO4)2微晶及其发光性能

采用水热法制备了Li_4-3xEu_{x(MoO4)2系列红色荧光粉.通过X射线衍射(XRD)、扫描电镜(SEM )和荧光分析(FL)对产物的微结构、形貌和发光性能进行表征分析.XRD分析表明,制备的Li4-3xEux(MoO4)2微晶均为白钨矿四方结构.SEM结果显示:随着x的增大,Li4-3xEux(MoO4)2微晶的晶粒尺寸相应减小,在0.2~0.5 μm之间变化.荧光分析结果表明:源于Eu³⁺的⁵D0→⁷F2和⁵D0→⁷F1电荷转移的592 nm和614 nm的特征发射峰显现明显,后者的发射强度远远大于前者.随着x的增大,样品中Eu³⁺的两个特征发射峰的强度先增大后减小,在x=1.0时达到最大.}     

非线性光学晶体4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲基苯磺酸盐的制备与性能研究

采用籽晶法制备了大体积高质量的4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲基苯磺酸盐(DAST)晶体，对制备条件进行了优化，对DAST晶体X射线衍射谱图中的主要峰进行了指标化.另外，还对所制备的DAST晶体的透光性、热稳定性进行了研究， 并对265℃的焙烧产物进行了X射线衍射 (XRD)和傅里叶变换红外光谱(FT-IR)测试，证明了260℃是DAST晶体的熔化相变温度， 说明采用熔融法制备DAST晶体是可行的；同时还对DAST晶体的热失重过程进行了初步探讨. 关键词： 4-(4-二甲基氨基苯乙烯基)甲基吡啶对甲基苯磺酸盐 晶体生长 X射线衍射 热稳定性     

NiFe_2O_4纳米粉末的制备及磁性研究

以硝酸铁、硝酸镍以及柠檬酸为原料,采用凝胶-热分解法制备了N iFe2O4纳米粉末。利用X射线衍射确定了粉体的相结构、比表面积和晶格常数,扫描电子显微镜(SEM)观察了颗粒的形貌,振动样品磁强计(VSM)测量样品的磁性能。结果表明:所制备的样品均为尖晶石结构,颗粒粒径为36nm~68nm,且颗粒的粒径随着热处理温度的升高而增大,样品的比饱和磁化强度最大可达54.63 emu/g。同时,文章也对反应的动力学原理进行了研究,得出N iFe2O4纳米颗粒形成的活化能为15.8kJ/mol。     

4-硝基-4′-氨基偶氮苯的光学性质研究

采用紫外可见吸收和二次谐波产生技术研究了“推-拉”型偶氮苯分子Langmuir-Blodgett(LB)膜的光谱和二阶非线性光学特性.4-硝基-4′-氨基偶氮苯(NAA)分子能制成很好的LB多层膜,在稀溶液中以单体的反式异构体形式存在,在膜中主要以J-聚集体的形式存在,LB膜的紫外可见吸收谱的吸收峰较之溶液的发生了52 nm的红移.NAALB膜的二阶非线性极化率χ(2)为19.59×10－8 esu,一阶超极化率β值较大,约为1.974×10－29 esu.其光学二阶非线性起源于电偶极子机制.     

Investigation on intracavity second-harmonic generation of a new Li-doped GdCa4O(BO3)3 crystal

Efficient intracavity second-harmonic generation (SHG) has been realized in a new Li-doped GdCa₄O(BO₃)₃ (GdCOB) crystal. 2.55 W CW SHG output power was obtained with an optical conversion efficiency of 19.6%, while the effective intracavity SHG efficiency was determined to be 44%. Compared to that of undoped GdCOB crystal, the effective SHG efficiency of the Li-doped GdCOB crystal was found to increase by 12.5%.     

Li2B4O7晶体生长及其二次谐波系数

用恰克拉斯基（Ｃｚｏｃｈｒａｌｓｋｉ）法特殊工艺生长出尺寸为Φ３０×３０ｍｍ的优质Ｌｉ２Ｂ４Ｏ７单晶，讨论了工艺参数对晶体宏观缺陷的影响。用Ｍａｋｅｒ条纹测量了晶体的二次谐波系数ｄ３１和ｄ３３，结果表明，Ｌｉ２Ｂ４Ｏ７的ｄ３３是石英晶体ｄ１１的三倍。     

纳米Zn_2SiO_4∶Mn包覆SiO_2颗粒的制备及表征

采用水热合成方法添加KOH在SiO2颗粒表面包覆Mn2+掺杂纳米Zn2SiO4,通过X射线衍射(XRD)仪、扫描电子显微镜(SEM)、能谱、光致发光(PL)光谱仪对产物的晶体结构、形貌及光学性能进行表征,并对Zn2SiO4晶体在水热反应过程中的反应机制进行了讨论。XRD测试结果表明:220℃水热条件下,添加少量KOH,反应不同时间后,可在石英砂表面生成一层Zn2SiO4;SEM照片显示所生成的Zn2SiO4为六棱柱形,并且不同反应条件下Zn2SiO4的包覆程度不同。反应产物经光致发光性能研究表明:Mn2+掺杂纳米Zn2SiO4包覆SiO2样品中显示两套光致发光谱,一套为250nm左右激发产生的522nm绿色发光带,另一套为340～410nm宽带激发的440nm蓝色发光带,前者为典型的Mn2+离子发光,后者440nm发光带则有可能来源于基体SiO2的氧空位缺陷。     

离子液体辅助水热法制备锡酸锌的研究

采用离子液体辅助水热法制备锡酸锌,考察了溶液pH值、水热反应时间及水热反应温度对锡酸锌晶体结构、形貌及光催化性能的影响。采用X射线衍射(XRD)确定锡酸锌的晶体结构、结晶水平及相的纯净程度;透射电子显微镜(TEM)用来分析制得的锡酸锌的形貌;通过在紫外光照射下光催化降解亚甲基蓝进行锡酸锌的光催化性能研究,结果表明:溶液pH值为9、水热反应温度为220℃、水热反应时间为32h制得的锡酸锌对亚甲基蓝有最高的光催化降解活性。对锡酸锌降解亚甲基蓝的光催化机理探究表明:锡酸锌光催化活性的差异主要归因于缺陷,缺陷往往成为电子-空穴复合中心,导致光催化活性不高;羟基自由基是光催化反应的主要活性物种。     

All-solid-state continuous-wave frequency-doubling Nd:LuVO<Subscript>4</Subscript>/GBCOB laser at 533 nm

We report an efficient intracavity second-harmonic generation (SHG) at 1066 nm in a non-linear optical crystal, GdCa₄O(BO₃)₃ (GdCOB), performed with a diode end pumped continuous-wave (CW) Nd:LuVO₄ laser. In the case of a laser with a Nd:LuVO₄ crystal frequency-doubled with a GdCOB crystal cut for type I frequency doubling. A CW SHG output power of 5.18 W has been obtained using a 10 mm long GCOB crystal. The optical conversion efficiency with respect to the incident pump power was 28.5%.     

锆英石的抗γ射线辐照能力和Rietveld结构精修

为研究放射性核素固化介质备选矿物锆英石的抗γ射线辐照结构稳定性,以澳大利亚锆英石为研究对象,通过⁶⁰Co源γ射线辐照装置对样品施以1728 kGy的γ射线辐照.利用X射线荧光光谱仪、扫描电子显微镜和X射线衍射仪对样品的元素含量、γ射线辐照前后的微观形貌及物相变化进行表征,同时利用Rietveld方法对γ射线辐照前后的样品进行了结构精修.结果表明:澳大利亚锆英石经1728 kGy剂量的γ射线辐照后未发生物相变化,射线辐照前后样品的晶胞参数仅发生了10^-4 量级的变 关键词： 锆英石 γ射线 辐照 Rietveld结构精修     

Growth and characterization of bis(thiourea) zinc carbonate (BTZC) a new nonlinear optical material by solution growth slow evaporation technique

A new semi-organic nonlinear optical bis(thiourea) zinc carbonate (BTZC) material has been synthesized. BTZC single crystals were grown from aqueous solution by slow evaporation method. The grown crystals were characterized by single crystal X-ray diffraction (XRD), powder XRD, FTIR, UV–visible, thermal, and second harmonic generation (SHG) analysis. Single crystal XRD study has been carried out to identify the lattice parameters. FTIR studies confirm the functional groups present in the grown crystal. Optical transmission studies have confirmed that the grown crystal is highly transparent. Thermo gravimetric and differential thermal analyses reveal the good thermal stability of the material. The SHG conversion efficiency of BTZC was determined using Kurtz powder technique and found 1.3 times more than that of KDP.     

Synthesis,spectral, thermal,optical and dielectric studies on 4-dimethylaminopyridinium picrate crystals

Single crystal of 4-dimethylaminopyridinium picrate was grown by slow evaporation solution growth method. The optical properties of the crystal were studied by using UV–vis absorption and transmittance studies. The emission spectrum indicates that the crystal shows green and red fluorescence emissions. The band gap energy of the crystal was calculated and it is found to be 2.05 eV. The thermal stability of the crystal was studied using thermogravimetry-differential thermal (TG-DTA) analyses. The thermal anomalies observed in the differential scanning calorimetry (DSC) heating and cooling cycles indicate the occurrence of a first order phase transition. FTIR spectrum was used to confirm the presence of various functional groups in the crystal. The synthesized crystal shows SHG efficiency 32 times greater than that of potassium dihydrogen phosphate (KDP). The dielectric constant and dielectric loss of the crystal decreases with increases in frequency.     

PbMoO4微晶的水热合成及光催化性能

以钼酸铵、硝酸铅为原料,采用水热法合成了纳米PbMoO₄光催化剂,并采用光还原处理对其进行表面载Ag修饰。借助X-射线粉末衍射（XRD）、扫描电镜（FE-SEM）和紫外-可见吸收光谱（UV-Vis）等测试手段对样品进行表征,并以罗丹明B为模型污染物,考察了纳米PbMoO₄光催化剂的催化活性,研究了样品的制备条件和表面载银对催化剂活性的影响。XRD分析结果表明,所得样品为四方晶系结构,且产物纯度高;样品的形貌分析和光催化活性实验结果表明,水热体系的pH值对产物的形貌和活性影响显著,且表面载银可显著提高催化剂的可见光催化活性。     

以一定重复频率工作的KTP倍频效率的演化规律

基于导带电子密度和材料的有效介电函数的表达式,推导了KTP晶体对532 nm光波的吸收系数. 对比研究了不同峰值功率密度和重复频率下KTP晶体的导带电子密度和532 nm吸收系数的演化规律,以及倍频转换效率的演化规律. 结果表明,随着导带电子密度的增加,KTP晶体532 nm吸收系数随之增加,其倍频转换效率随之减小;当基频光入射功率密度一定时,不同重复频率脉冲作用引起的导带电子密度存在积累效应,导致KTP晶体532 nm透过率及倍频转换效率均随着作用时间的增加呈指数形式变化,随着脉冲重复频率的增加其积累效果更加明显,但随着作用时间的增加,导带电子密度、吸收系数均趋于同一稳定值. 关键词： KTP晶体 灰迹 倍频转换效率     

Formation of nano-crystalline and amorphous phases on the surface of stainless steel by Nd:YAG pulsed laser irradiation

Thin surface layers consisting of nano-crystalline and amorphous phases on the surface of stainless steel have been attained under the Nd:YAG pulsed laser irradiation. The phases and microstructures were investigated by X-ray diffraction (XRD) and high resolution transmission electron microscope (HRTEM). The phase compositions of the surface determined by XRD were α-Fe (ferrite) and γ-Fe (austenite) or only γ-Fe in the near surface region on the bases of the different laser power densities. The nano-crystalline grains with sizes of 4-100 nm could result from high cooling rate and crystallization in amorphous region by homogeneous and heterogeneous nucleation. The formation of the amorphous phase was attributed to the higher cooling rates.