Cu掺杂ZnO薄膜的制备及其光谱特性

采用溶胶-凝胶法在铟锡氧化物(ITO)导电玻璃基底上制备了不同掺杂浓度的Cu∶ ZnO薄膜.采用X射线衍射仪和扫描电子显微镜分析了薄膜样品的晶相结构和形貌,用荧光光谱仪测量了薄膜样品的光致发光谱.结果表明:Cu∶ ZnO薄膜均为六角纤锌矿结构,呈c轴择优取向,且因压应力的存在使其晶格常数略小于未掺杂薄膜样品的晶格常数;低温和高温退火处理的薄膜样品的光致发光谱(PL)中分别观察到414 nm、438 nm的蓝光双发射峰和510 nm左右的绿光发射峰.蓝光发射峰与样品中的Vzn和Zni有关,而绿光发射峰与样品中的Vo -Zni有关.     

Al2O3衬底上生长ZnO薄膜的结构和光学特性

用脉冲激光沉积法在Al2O3(0001)衬底上沉积了ZnO薄膜.衬底温度分别为300℃、400℃、500℃、600℃和700℃.利用X射线衍射(XRD)和光致发光谱(PL)对薄膜的结构和光学性能进行研究.X射线衍射的结果表明在不同温度下生长的ZnO薄膜均具有高度c轴择优取向,衬底温度400℃时,膜的应力较小质量较高.ZnO薄膜有很强的紫外发光峰,紫外发光峰的强度与衬底温度密切相关,并发现当衬底温度从300℃增到400℃时,紫外发射峰出现6nm的蓝移.     

溶胶-凝胶法制备ZnO薄膜及其微结构特性研究

采用溶胶-凝胶法(Sol-Gel)制备氧化锌(ZnO)薄膜,研究镀膜层数和退火温度对ZnO薄膜晶体结构、光谱性质及表面形貌的影响.X射线衍射谱测试表明,退火温度为600℃、镀膜层数为10层时制备样品的晶粒尺寸最大,结晶度最好.紫外-可见透过谱发现,样品退火后其透过率曲线变得陡直,光学带隙随退火温度升高而逐渐减小.光致发光谱测试显示,ZnO薄膜的发光谱包含388 nm和394 nm附近的两个主要发光峰,分别对应于本征发射和缺陷发射,其强度随退火温度升高呈现相反的变化.原子力显微照片则显示了随退火温度的升高制备样品表面晶粒的分布趋于均匀而致密.     

不同Ag光照时间对ZnO纳米花荧光增强的影响

采用水浴结合光照法,在Si(100)衬底上制备了Ag/ZnO纳米花结构,研究了不同Ag光照时间对ZnO发光性质的影响.通过X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光谱(PL)对Ag/ZnO纳米花的结构、形貌和光学性能进行了研究.研究表明,由水浴法制得的ZnO纳米花结构长度约1.0 μm,直径为200nm左右;不同光照时间的Ag掺杂后Ag/ZnO纳米花的衍射峰强度都增强,当光照时间为5min时,出现了Ag3O4的衍射峰.当光照时间为5 min时,Ag/ZnO纳米花结构具有最强的可见发射强度.     

煅烧和除碳温度对氮化硼晶须的影响

以三聚氰胺和硼酸为原料通过水浴加热合成晶须前驱体,然后经高温烧结成功制备出BN晶须.扫描电镜显示制备的BN晶须为针状结构,其直径和长径比分别为2～3 μm和40～100.通过X射线衍射分析,制备的BN晶须为六方晶相,晶格参数为a=0.2524 nm和c=0.6592 nm.红外光谱图谱表明在1383 cm-1和 812 cm-1处存在两个明显的B-N特征吸收带.晶须的烧成制度以及除碳温度对晶须形貌和性能的影响研究结果表明,当烧成温度为1700 ℃、除碳温度为600 ℃时可制备出形貌良好和结晶度高的氮化硼晶须.     

不同溶剂和Al掺杂对微波辅助合成ZnO纳米颗粒性能的影响

利用Zn(NO3)2作为Zn源,AlCl3为Al源,以水和乙二醇为溶剂,采用微波辅助合成法制备了一系列ZnO纳米颗粒.用X射线衍射仪和扫描电子显微镜对其相结构及形貌进行了表征和分析,结果表明,得到的纳米颗粒均为纯的ZnO纤锌矿结构,但溶剂种类对纳米颗粒形貌影响较大.水溶剂和乙二醇溶剂微波辅助合成法制备的ZnO纳米颗粒禁带宽度分别为2.85 eV和3.12 eV,掺Al后的禁带宽度缩减到2.78 eV和3.10 eV.ZnO纳米颗粒在450 nm和560 nm左右处有由于氧空位引起的较强蓝绿光发射,掺Al的ZnO光致发光峰只在560 nm左右处出现.     

在钛酸锶衬底上外延生长ZnO薄膜及其性能研究

用脉冲激光淀积法(PLD)在(111)面SrTiO3衬底上外延生长ZnO单晶薄膜.样品分别在衬底温度为350℃、500℃、600℃下外延生长.X射线衍射(XRD)的结果表明,所得的ZnO单晶薄膜结晶性能好,只出现(002)和(004)两个衍射峰,(002)峰的半高宽度(FWHM)为0.23°.在荧光光谱中我们只观察到来源于带边激子跃迁的强UV发射,并且随着生长温度的升高,紫外峰的强度逐渐增强.样品的SEM图像表明所得ZnO薄膜表面平整,晶粒均匀.衬底温度为600℃时,所得到的ZnO薄膜结构完整,晶粒尺寸最大,均匀;而且紫外发射最强.     

CdS量子点敏化ZnO薄膜的制备及其性能研究

本文以Zn(CH3COO)2·2H2O、CdCl2和硫脲的水溶液分别为前驱体,采用超声喷雾热解法在ITO导电玻璃上成功的制备了CdS量子点敏化ZnO薄膜(ZnO∶ CdS).通过扫描电镜(SEM),X射线衍射(XRD),光致发光(PL)谱和吸收光谱对CdS量子点敏化ZnO薄膜形貌,结构和光学性能进行了研究.SEM图表明CdS量子点已成功沉积到ZnO薄膜上,量子点呈颗粒状,直径约71 nm.XRD结果显示,除观察到原有的ZnO特征峰外,在2θ=30.3°处有一明显的特征峰,对应着CdS的(111)晶面.PL谱图表明在325 nm的光激发下,CdS量子点敏化ZnO薄膜在400 nm处有一较强的紫外发射峰,在500～700 nm处有一个较宽的黄绿发射带.吸收光谱表明,CdS量子点敏化后ZnO薄膜在可见光区的吸收边为586 nm.     

声化学法制备ZnS: Mn纳米晶及其光学性能

以无水氯化锌,四水氯化锰以及硫代乙酰胺为原料,采用声化学法成功制备了锰掺杂的ZnS(ZnS: Mn)纳米晶.采用透射电子显微镜镜(TEM)、X射线能谱仪(EDS)、X射线粉末衍射(XRD)和光致发光谱(PL)对所制得的纳米进行了表征.结果表明:所制备ZnS: Mn为立方闪锌矿结构,纳米粒子的形貌接近于球形.平均晶粒尺寸为10 nm左右.PL光谱分析表明:所制备试样有两个主要的发射峰,分别位于在480 nm和570 nm左右,后者与体材料ZnS: Mn相比发生了明显蓝移,但仍表现为橙黄色发光.Mn2+掺杂浓度对ZnS: Mn的光致发光性能有显著影响,原料中Zn: Mn: S(物质的量比)为3: 1: 4,Mn2+掺杂浓度为2.64 at;时,光致发光光谱发射峰强度达到最大值.     

MOCVD法在(220)CaF2衬底上生长ZnO薄膜及其性能研究

采用金属有机化学汽相沉积(MOCVD)法在(220)CaF2衬底上外延生长ZnO薄膜.利用X射线衍射(XRD)、紫外-可见光谱和光致发光谱(PL)对ZnO薄膜的结构和光学性能进行了分析.XRD结果表明,所制备的ZnO薄膜结晶性能良好,具有高度的(002)的择优取向,002衍射峰的半高宽(FMHM)为0.115°.所制备的ZnO薄膜透明,透过率超过85;.在常温的(He-Cd激光器)PL谱中,只有378.5 nm的带边发射.用同步辐射光源测试的真空紫外光谱中,在低温20K时,出现218 nm、368 nm、418 nm、554 nm发光峰,其中368 nm峰强度随着温度的升高强度逐渐下降,到常温时几乎消失.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

X-ray analysis of sideroxol from <Emphasis Type="Italic">Sideritis leptoclada</Emphasis>

Sideroxol (1), a kaurane diterpene which has the ent-7α,18-dihydroxy-15β,16β-epoxykaurane structure (MW = 320.47, C₂₀H₃₂O₃) was obtained from the acetone extract of Sideritis leptoclada plant as well as from some other Sideritis species. It crystallizes in the orthorhombic space group P2₁, 2₁, 2₁ with a = 10.967(3), b = 24.555(5), c = 6.372(4) Å, Dc = 1.240 g cm⁻³, Z = 4, and refines to R = 0.065 for 721 independent reflections. The skeleton consists of three fused six-membered rings and a five-membered ring with fused epoxide. The six membered rings exhibited slightly distorted chair conformation. In addition to sideroxol, two kaurane and five kaurene diterpenes were isolated from the hexane and acetone extracts of the studied plant.     

Photoluminescence characteristics of Mg- and Si-doped GaN thin films grown by MOCVD technique

We have studied the optical, structural and surface morphology of doped and undoped GaN thin films. The p- and n-type thin films have been successfully prepared by low-pressure MOCVD technique by doping with Mg and Si, respectively. The different carrier concentrations were obtained in the GaN thin films by varying dopant concentrations. Photoluminescence (PL) studies were carried to find the defect levels in the doped and undoped GaN thin films at low temperature. In the undoped GaN thin films, a low intensity and broad yellow band peak was observed. The donor–acceptor pair (DAP) emission and its phonon replicas were observed in both the Si or Mg lightly doped GaN thin films. The dominance of the blue and the yellow emissions increased in the PL spectra, as the carrier concentration was increased. The XRD and SEM analyses were employed to study the structural and surface morphology of the films, respectively. Both the doped and the undoped films exhibited hexagonal structure and polycrystalline nature. Mg-doped GaN thin films showed columnar structure whereas Si-doped films exhibited spherical shape grains.     

New zeotype borophosphates with chiral tetrahedral topology: (H)0.5M1.25(H2O)1.5[BP2O8]·H2O (M = Co(II) and Mn(II))

Two new isostructural open‐framework zeotype transition metal borophosphate compounds, (H)_0.5M_1.25(H₂O)_1.5[BP₂O₈]·H₂O (M = Co(II) and Mn(II)) were synthesized by mild hydrothermal method. The structure of compounds were characterized by single‐crystal X‐ray diffraction which have ordered, alternating, vertex‐sharing BO₄, PO₄, and (MO₄)OM(H₂O)₂ groups with hexagonal, P 6₁ 2 2 (No 178) space group and unit cell parameters for Co a = 9.4960(6) Å, c = 15.6230(13) Å, for Mn a = 9.6547(12) Å, c = 15.791(3) Å, Z = 1 for both of them. TGA/DTA analysis, IR spectroscopy were used for characterization. Magnetic susceptibility measurements for both of the compound indicate strong antiferromagnetic interaction between metal centers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Solubility of Ag2O into the Na2O–B2O3–Al2O3 system

The solubility of Ag₂O was measured for the Na₂O–B₂O₃ and Na₂O–B₂O₃–Al₂O₃ system with the rotating crucible method and static method, respectively, under air atmosphere at temperatures ranging from 1273 to 1423 K. The contamination of melts from crucibles could be avoided by the rotating crucible method, with which it became possible to measure the solubility of Ag₂O for the Na₂O–B₂O₃ system above the melting point of Ag for the first time. It was found that the addition of Na₂O decreases the solubility of Ag₂O while the addition of Al₂O₃ had little effect on the solubility. The effect of Na₂O and Al₂O₃ on the solubility of Ag₂O is expressed by interaction coefficients and is analyzed in terms of the basicity of melts. The solubility of Ag₂O in Na₂O–B₂O₃–Al₂O₃ melts increased with increased temperature. This phenomena was explained by a small enthalpy change in oxidation of silver.     

Selinidin: Crystal structure generated by C–H···O, C–H···π and π-π interactions

The title compound, 9,10-dihydro-8,8-dimethyl-2-oxo-2H,8H-benzo[1,2-b:3,4-b']dipyran-9-yl-2-methyl-2-butenoate, C₁₉H₂₀O₅, was isolated from the roots of Selinum vaginatum. The compound crystallizes into monoclinic space group P2 ₁ with unit cell parameters: a = 12.830(2) Å, b = 9.041(1) Å, c = 14.983(1) Å, β = 95.09(1)°, Z = 4. The crystal structure has been determined using direct methods and refined by full-matrix least-squares to a final R value of 0.0529 for 3142 observed reflections. There are two independent molecules, A and B, per asymmetric unit. In both the molecules, the coumarin nucleus is planar. However pronounced differences are observed in the conformation of dihydropyran ring which has a half-chair conformation with an 8β-9α orientation in molecule A and is intermediate between half-chair and sofa in molecule B. Differences also occur in the conformation of the 2-methylbutenoyloxy side chain at C9 due to the different geometry of C–H···π interactions in molecules A and B. Molecules A and B are connected by π–π interactions between their coumarin fragments forming dimers. The dimers interact through C–H···O and C–H···πhydrogen bonds.     

Chromene and Imidazole Based D-π-A Chemosensor Preparation and Its Anion Responsive Effects

We have designed and synthesized the colorimetric chemosensor through the reactions of 2-(4H-chromen-4-yildene)malonitrile and 4-imidazolecarboxaldehyde. Due to its well conjugated D-π-A system and the existence of NH- fragment in structure, we expected that the chemosensor can detect anion using NH- fragment in the imidazole moiety of the structure. In this regard, UV-Vis absorption spectra were measured to investigate sensing properties of the probe toward different anions in DMSO. This chemosensor can detect both fluoride and cyanide ion with absorption change in intensity. In addition, pH sensing property was also investigated upon the addition of hydroxide ion. These properties are related to the deprotonation effect. The ICT system in this molecule was also observed by the computational approach using Material Studio 4.3 package.     

电子显微分析在表征纳米晶体化学组分中的应用

纳米材料的化学组分及含量影响其光、电、声、热、磁等物理性能,电子显微分析是表征纳米晶体化学组分的重要方法之一.本文综述了X-射线能谱(EDS)、X-射线波谱(WDS)、电子能量损失谱(EELS)和选区电子衍射(SAED)等现代电子显微分析技术在表征纳米晶体化学组分、形貌、尺寸和结构等方面的应用及其研究进展,并比较了这些分析方法存在的差异,提出了其应用中存在的不足及今后的研发方向.     

Considerations on the structure and physical properties of B2O3-SiO2 and GeO2-SiO2 glasses

Data of density, refractive index and thermal expansion coefficient for B₂O₃-SiO₂ and GeO_2-SiO₂ glasses have been analyzed. The volumes of the structural units are the same found for the vitreous B₂O₃, GeO₂ and SiO₂. The volume of any structural unit is constant over the entire composition region of the glass system. The same has been found for the differential refraction and unit refraction of the structural units in these glasses. Different features are observed for the differential expansion of the structural units. There is a considerable change with composition in the differential expansion of BO₃, GeO₄ and SiO₄ units. The effect is attributed to a change in the asymmetry of vibrations with the number of Si-O-B or Si-O-Ge linkages in the matrix. The thermal expansion coefficient is mainly determined by the contribution of B₂O₃ or GeO₂ in the concerned glasses.