纳米Ce_(1-x)(Fe_(0.5)La_(0.5)x)O_(2-δ)固溶体的水热合成及光谱分析

采用水热方法合成Ce1-x(Fe0.5La0.5)xO2-δ固溶体。利用X射线衍射技术(X-ray diffraction tech-nique,XRD)表征样品的相结构,并对固溶体的晶胞参数进行拟合,通过紫外可见漫反射光谱(UV-Vis dif-fraction spectrum)及拉曼光谱(Raman spectrum)表征其电子跃迁性能及由于双离子掺杂所引起的一系列掺杂效应。XRD结果表明,Ce1-x(Fe0.5La0.5)xO2-δ固溶体为CeO2立方萤石结构,当掺杂量增加到x=0.30时出现了微弱的Fe2O3杂相衍射峰;讨论了两种离子在晶格中不同的取代位置。晶胞参数随着掺杂量的增大而逐渐增大,当掺杂量达到x=0.18后保持基本不变。紫外漫反射光谱表明,随着掺杂量的增大,固溶体的带隙吸收边红移,即能隙逐渐减小,Fe离子在CeO2晶格中表现为+3价。Raman光谱F2g振动峰位逐渐向低波数方向移动,同时振动峰逐渐宽化,进一步证明了掺杂离子的影响效应。     

溶胶凝胶法制备Ce_xPd_(1-x)O_(2-δ)纳米晶的结构表征及紫外拉曼光谱研究

通过溶胶凝胶法合成了Ce_xPd_(1-x)O_(2-δ)(x=1,0.7,0.5,0.3)系列纳米晶,X射线衍射(XRD)结果显示所得晶体为立方相。X射线光电子能谱(XPS)测试结果显示Pd的价态有Pd~(4+),Pd~(2+)及Pd0,其中Pd4+的出现说明形成了固溶体结构。结合高分辨透射电镜(HRTEM)、XRD和Raman光谱数据,发现掺杂物的物相中含有PdO。HRTEM谱图显示CeO_2表面分布有Pd单质,说明形成固溶体后高温导致晶格中的Pd析出。对系列化合物分别进行可见光拉曼谱(λ_(ex)=532nm)和紫外光拉曼谱(λ_(ex)=325nm)测试,并采用归一化法对比PdO的峰面积及CeO_2的峰面积,发现紫外光谱下CeO_2的F2g峰得到增强,同时还在593cm-1,1170cm-1,1750cm-1处出现三个峰,分别归为CeO_2本征纵向光学吸收LO(longitudinal optic),2LO和3LO,该现象由于共振拉曼效应导致的。结合紫外拉曼光谱,对不同比例Pd掺杂的CeO_2纳米晶中的氧缺位进行了量化研究。结果表明,随着Pd掺杂量的提高,氧缺位浓度逐渐增加,这与XPS测试结果的趋势基本一致。     

GdBa_2Cu_(3-x)Fe_xO_(7-δ)超导体系结构相变及拉曼谱特征

采用固态反应法制备了GdBa2Cu3-xFexO7-δ(x=0.00-0.30)系列样品,利用X射线衍射、拉曼光谱以及电测量技术对体系的晶体结构、拉曼散射谱特征以及电输运特性进行了系统研究。结果表明,当Fe掺杂量在x=0.05-0.10区间时,体系的晶体结构发生了从正交相到四方相的转变。通过对拉曼光谱中典型振动模的指认及振动模随Fe掺杂量的变化规律,得到了拉曼谱随体系正交-四方结构相变的变化特征:对于具有正交相的x=0.00-0.05样品,拉曼谱具有五个与正交相结构相对应的特征峰;而对于具有四方相的x=0.10-0.30样品,随Fe掺杂量增加,振动模强度变弱,且典型振动模发生了不同程度的展宽或频移。电输运测量表明,随Fe掺杂量的增加,超导临界温度Tc降低,正常态电阻率增加且发生了金属-半导体相变。     

LaBa2Cu3-xCoxOy体系中声子振动和自旋关联的研究

我们用X射线衍射,红外光谱以及电子顺磁共振等实验手段,对LaBa2Cu3-xCoxOy (0≤x≤1.0)系列样品进行了研究.研究表明:所有样品皆为单相正交结构.对于不掺杂的样品在535cm-1和585cm-1附近有两个显著的吸收峰,分别相应于Cu(1)-O(1) 和Cu(2)-O(2) 的伸缩振动.在低掺杂区(0≤x≤0.5)535cm-1处的红外峰随x增加向低频方向移动,而585cm-1处的红外峰位置基本不变.当x＞0.5时,这两个峰逐渐宽化,最后变成单个宽峰(x=1.0).掺杂样品在657cm-1处的声子振动模随掺杂量增加向高频方向移动,该峰为Cu(1)-O(4)的伸缩振动模.本文分析了晶体结构和声子振动以及自旋关联变化的相互关系.     

银(Ⅰ)、镉(Ⅱ)4-巯基吡啶配合物的光谱研究

采用常规溶液反应蒸发法以4-巯基吡啶(简写为4-MPy)为有机配体与银、镉的硝酸盐合成了两种金属有机配合物。并利用红外、拉曼、紫外-可见光谱技术对4-MPy及合成的配位化合物进行了研究,对主要红外和拉曼谱带进行了经验归属,并进一步讨论了配体和配合物的特征吸收谱带与配合物结构间的关系。在红外光谱中,配体在1 459cm-1处的吸收峰归属为CC和CN复合振动峰,形成配合物后在两种配合物中,此吸收峰分别向高波数位移至1 464和1 464cm-1。在拉曼光谱中,两种有机配位化合物在1 004和1 008cm-1处归属为环呼吸振动峰、在1 617和1 615cm-1处归属为环伸缩振动峰、在720和720cm-1处归属为β(C—C)和ν(C—S)的复合振动峰,各自十分相似。     

基于苯溶剂化效应的多种邻苯二甲酸酯(PAEs)拉曼特征振动光谱辨识

利用密度泛函与自洽反应场理论在B3LYP/6-311G(d)水平下对16种邻苯二甲酸酯(PAEs)进行结构优化,并计算气态环境及溶剂中PAEs的拉曼光谱振动频率和去偏振度。研究显示,16种PAEs拉曼振动归属为苯环变形、酯基振动、C—C伸缩、C—H摇摆、C—H伸缩与耦合振动。其中酯基官能团出峰位置在1 700~1 780cm-1之间,拉曼峰较强,去偏振度较低(振动的对称性较强),可将酯基振动作为特征振动;但气态环境下仅12种PAEs拉曼峰之间的最小波数差大于显微拉曼光谱仪的检出限(0.2 cm-1),即利用酯基频区的去偏振度和拉曼峰不能完全辨识16种PAEs。溶剂化效应分析显示,溶剂苯对16种PAEs具有明显的溶剂化增强效应,16种PAEs拉曼峰之间最小波数差均增大到0.2 cm-1以上,且峰强增加了23%~183%,说明溶剂化效应下可利用酯基频区的去偏振度和拉曼峰辨识16种PAEs。本文的研究结果为PAEs拉曼光谱检测提供了理论依据。     

Eu(Pr)替代Ba位对EuBa2Cu3O7-δ晶体结构及其超导电性的影响

采用X射线衍射、直流输运和拉曼光谱法分别研究了Pr和Eu替代EuBa2 Cu3O7 δ的Ba位对晶体结构及其超导电性的影响。实验结果表明 ,随着Pr和Eu替代浓度的增加 ,晶体结构发生了从正交相到四方相的结构转变 ,超导临界温度Tc 迅速降低 ,拉曼光谱表明 ,随着替代含量的增加 ,Cu(1)—O(4 )的拉伸振动 5 0 4cm- 1 和Cu(2 )—O(2 ,3)反相弯曲的振动模 30 4cm- 1 系统地向高波数移动。     

KNb_(1-x)Mg_xO_(3-δ)的高温高压合成及输运性质研究

采用高温高压法制备了KNb1-xMgxO3 -δ(x =0 .0～ 0 .3)氧离子导电材料 ,使用XRD、TG-DTA及交流复阻抗谱对样品的结构和离子导电性进行了表征。实验结果表明 ,高压降低了合成温度 ,合成的KNb1-xMgxO3 -δ系列固溶体与其母体KNbO3 一样都为正交钙钛矿结构 ,晶胞参数随掺杂量的增加而略微增大。固溶体KNb1-xMgxO3 -δ具有离子导电特征 ,通过拟合阻抗谱数据获得了该材料晶粒电导、晶界电导和体电导率与温度的关系。样品的晶界电阻较高 ,晶界效应十分明显 ,离子跳跃传导可能在其输运机制中占据主导地位。在x =0 .1附近 ,电导率达到最大值 ,70 0℃时为 1.2× 10 - 3 S·cm- 1。     

化学计量比LiNbO_3晶体的激光显微拉曼光谱研究

对用助熔剂提拉法生长的近化学计量比LiNbO3晶体进行了激光显微拉曼光谱测试分析 ,与同成分LiNbO3晶体相比较 ,A1 (TO)与E(TO)模的谱线数目、频率基本不变 ,验证了LiNbO3晶体属置换式固溶体的结论 .738cm- 1 处拉曼振动峰 (A1 (LO)模 )的相对强度随晶体中Li2 O含量的增加发生了明显的变化 ,在两种掺杂晶体中 ,此振动峰已经消失 .根据Li空位模型 ,从占位和结构上进行了分析讨论 .在 15 2和 872cm- 1 处拉曼振动峰半高宽随晶体中Li Nb的增大而变窄 ,对二者关系进行了线性拟合 ,利用拟合公式可根据拉曼振动峰半高宽计算晶体中的Li Nb值 .     

药用植物真伪品的FT-Raman光谱法鉴别研究

首次采用近红外傅里叶变换拉曼光谱法 (NIR Raman)无损快速鉴别了药用植物肉桂、天麻及其伪(混淆 )品。结果表明 :药用植物肉桂、天麻及其伪 (混淆 )品在拉曼光谱图上有明显的差别。如肉桂在 1 60 0和 1 3 0 0cm- 1有较特征的基频振动峰 ,而肉桂的混淆品阴香 1 3 3 0cm- 1的峰较弱 ,相反的是 1 62 4和 1 5 97cm- 1的基频振动峰较强。天麻在 2 91 4cm- 1的C H振动峰与羊角天麻的 2 93 4cm- 1位移了 2 0个波数 ,另外羊角天麻在 1 60 5cm- 1有较强的拉曼基频振动峰 ,而药用天麻此处未见振动峰。凭借这些谱峰的差异可进行药材的真伪鉴别。该方法具有快速、准确、操作简单、不破坏样品 ,可直接进行鉴别的特点。     

The magnetic structure of Cs0.4 Mn0.4 Fe1.6 F6 and of Cs0.4 Ni0.4 Fe1.5 F6

The magnetic structure of the two compounds as determined by neutron diffraction is reported. Both compounds are antiferromagnetic with Néel-temperatures of 115 and 100 K respectively. Both compounds show a very pronounced diffuse scattering.     

Lithium motion in Li0.33 TiS2 and Li0.94 TiS2

We have studied the motion of lithium ions in Li_xTiS₂ (x = 0.33, 0.94) using pulsed NMR techniques. The temperature dependences of the spin lattice relaxation in the rotating frame (T_1?) suggest comparable activation energies for lithium ion diffusion for both samples, 3370 K, but an appreciably longer hopping time for the x = 0.94 sample. Low temperature values of T₂ agree with calculated and measured second moments for both materials.     

The ν3 and 2ν3 bands of SO3, SO3, SO3, and SO3

This sixth of a series of publications on the high-resolution rotation-vibration spectra of sulfur trioxide reports the results of a systematic study of the ν₃ and 2ν₃ infrared bands of the four symmetric top isotopomers ³²S¹⁶O₃, ³²S¹⁸O₃, ³⁴S¹⁶O₃, and ³⁴S¹⁸O₃. An internal coupling between the l=0(A₁^′) and l=2(E^′) levels of the 2ν₃ states was observed. This small perturbation results in a level crossing between |k−l|=9 and 12, in consequence of which the band origins of the A₁^′,l=0 “ghost” states could be determined to a high degree of accuracy. Ground and upper state rotational constants as well as vibrational anharmonicity constants are reported. The constants for the center-of-mass substituted species ³²S¹⁶O₃ and ³⁴S¹⁶O₃ vary only slightly, as do the constants for the ³²S¹⁸O₃, ³⁴S¹⁸O₃ pair. The S-O bond lengths for the vibrational ground states of the species ³²S¹⁶O₃, ³⁴S¹⁶O₃, ³²S¹⁸O₃, and ³⁴S¹⁸O₃ are, respectively, 141.981 99(1), 141.979 38(6), 141.972 78(8), and 141.969 93(8) pm, where the uncertainties, given in parentheses, are two standard deviations and refer to the last digits of the associated quantity.     

The ν9 + ν11 − ν11, ν10 + ν11 − ν11 hot band system in allene-d4

The hot band system ν₉ + ν₁₁ ? ν₁₁, ν₁₀ + ν₁₁ ? ν₁₁ in allene-d₄ was studied at a resolution near 0.010 cm^?1. About 1500 partly overlapped hot band rotational lines were assigned and fitted to a model taking into account z-Coriolis resonance between the combination levels ν₉ + ν₁₁ and ν₁₀ + ν₁₁ as well as vibrational l-type resonances within these levels. Upperstate constants have been derived from an analysis in which the constants for the ν₁₁ level were constrained. A detailed study of rotational as well as vibrational l-type doublings occurring in the KΔK = ?1 subband is presented, and the sign of vibrational l-type doubling constants for the ν₁₀ + ν₁₁ level is determined. A localized (x, y)-Coriolis resonance between ν₁₀ + ν₁₁ and ν₄(B₁) + ν₁₁ is discussed and the interaction parameter is obtained as well as some constants for ν₄ + ν₁₁.     

Wing profile measurements of the Na-doublet lines in C2H2/O2/N2, H2/O2/N2 and H2/O2/Ar frames at 1 atm

Fluorescence-excitation (wing) profiles of the Na-D doublet lines were measured over a wavelength range extending from 0.3 to 200 Å from the line center for the red D₁ and blue D₂ wings and from 0.3 to 3 Å for the red D₂ and the blue D₁ wings, respectively. The line profiles were determined with the aid of a tunable CW dye-laser as a background source by measuring the total fluorescence intensity observed on detuning the laser wavelength. The flames were premixed, laminar, shielded flames at 1 atm, with temperatures ranging from 1860 to 2270 K; N₂ and Ar served as diluent gases. The line core and near-wing profiles (i.e. the region covering 0.3<Δλ<7 Å for the outer wings and 0.3<Δλ<3 Å for the inner ones) in all of the flames studied appeared to have the same frequency dependence, regardless of the nature and concentrations of the gases used. The blue D₂-line profile followed an unexpected (-2.2) law, while the other three profiles obeyed the theoretically expected (-2) law (the dispersion profile function). The line profile in the Δλ range between the impact and quasistatic regions was found to depend on the main perturbers involved. We found that the far blue D₂- and red D₁-wings in the Ar-diluted H₂/O₂ flame obeyed the (-$\text{5}\text{4}$) and (-$\text{3}\text{2}$) laws, respectively, as predicted by the quasi-static theory for the Lennard-Jones interaction. For the N₂-diluted C₂H₂/O₂ and H₂/O₂ flames, we did not find these wing dependences in the Δλ range investigated.     

Magnetic susceptibility studies of (CH2)3(NH3)2FeCl2Br2 and (CH2)6(NH3)2FeCl2Br2

The magnetic susceptibility of the layered compounds (CH₂)₃(NH₃)₂FeCl₂Br₂ and (CH₂)₆(NH₃)₂FeCl₂Br₂ has been measured in the range 80 < T < 300 K. The results follow a Curie-Weiss behavior in the range 120 < T < 300 K but are field dependent for T < 120 K. The results are interpreted in terms of a two-dimensional antiferromagnetic interaction which is canted. A comparison with the corresponding pure chloride compounds is given.     

The ν2, 2ν2, 3ν2, ν4, and ν2 + ν4 bands of 15NH3

The ir absorption of gaseous ¹⁵NH₃ between 510 and 3040 cm^?1 was recorded with a resolution of 0.06 cm^?1. The ν₂, 2ν₂, 3ν₂, ν₄, and ν₂ + ν₄ bands were measured and analyzed on the basis of the vibration-rotation Hamiltonian developed by V. ?pirko, J. M. R. Stone, and D. Papou?ek (J. Mol. Spectrosc.60, 159–178 (1976)). A set of effective molecular parameters for the ν₂ = 1, 2, 3 states was derived, which reproduced the transition frequencies within the accuracy of the experimental measurements. For ν₄ and ν₂ + ν₄ bands the standard deviation of the calculated spectrum is about four times larger than the measurements accuracy: a similar result was found for ν₄ in ¹⁴NH₃ by ?. Urban et al. (J. Mol. Spectrosc.79, 455–495 (1980)). This result suggests that the present treatment takes into account only the most significant part of the rovibration interaction in the doubly degenerate vibrational states of ammonia.     

Nonplanar domain walls in ferroelastic Gd2(MoO4)3 and Pb3(PO4)2

A new stable, mobile zigzag-shaped domain wall configuration has been discovered in the Gd₂(MoO₄)₃ and Pb₃(PO₄)₂ structures. Previous work on these materials had not predicted this type of domain wall. The zigzag walls have mobilities 30–40 times that of planar walls in the same material. This increased mobility can be explained as a geometrical effect.     

High-pressure Raman spectroscopic studies on orthophosphates Ba3(PO4)2 and Sr3(PO4)2

By using diamond anvil cell (DAC), high-pressure Raman spectroscopic studies of orthophosphates Ba₃(PO₄)₂ and Sr₃(PO₄)₂ were carried out up to 30.7 and 30.1 GPa, respectively. No pressure-induced phase transition was found in the studies. A methanol:ethanol:water (16:3:1) mixture was used as pressure medium in DAC, which is expected to exhibit nearly hydrostatic behavior up to about 14.4 GPa at room temperature. The behaviors of the phosphate modes in Ba₃(PO₄)₂ and Sr₃(PO₄)₂ below 14.4 GPa were quantitatively analyzed. The Raman shift of all modes increased linearly and continuously with pressure in Ba₃(PO₄)₂ and Sr₃(PO₄)₂. The pressure coefficients of the phosphate modes in Ba₃(PO₄)₂ range from 2.8179 to 3.4186 cm⁻¹ GPa⁻¹ for ν₃, 2.9609 cm⁻¹ GPa⁻¹ for ν₁, from 0.9855 to 1.8085 cm⁻¹ GPa⁻¹ for ν₄, and 1.4330 cm⁻¹ GPa⁻¹ for ν₂, and the pressure coefficients of the phosphate modes in Sr₃(PO₄)₂ range from 3.4247 to 4.3765 cm⁻¹ GPa⁻¹ for ν₃, 3.7808 cm⁻¹ GPa⁻¹ for ν₁, from 1.1005 to 1.9244 cm⁻¹ GPa⁻¹ for ν₄, and 1.5647 cm⁻¹ GPa⁻¹ for ν₂.     

正磷酸盐晶体Ba3(PO4)2和Sr3(PO4)2高温拉曼光谱研究

测量了碱土金属正磷酸盐Ba₃(PO₄)₂和Sr₃(PO₄)₂常温及高温拉曼光谱, 对拉曼振动模式进行指认, 并分析了晶体拉曼振动光谱及晶体结构在高温下的变化. 在温度升高的过程中, 拉曼振动频率向低频移动且振动峰宽度展宽, 晶体中的P-O平均键长随温度升高而变长, 但O-P-O的键角并未发生变化. 晶体在900 ℃以下无结构相变发生. 关键词： 3(PO₄)₂和Sr₃(PO₄)₂')" href="#">Ba₃(PO₄)₂和Sr₃(PO₄)₂ 高温拉曼光谱 振动模式 高温结构