射频磁控溅射生长ZnO薄膜及性能研究

采用射频磁控溅射技术在玻璃衬底生长ZnO及ZnO∶ Al薄膜,通过改变氩氧比、衬底温度和溅射功率获得样品.用X射线衍射仪、紫外-可见分光光度计、扫描电子显微镜进行表征.结果发现:室温下40W的溅射功率1h的溅射时间,改变氩氧比获得样品.XRD图谱中无明显衍射峰出现;紫外可见光分光光度计测试结果显示400nm波长以下,透光率在90;以上.说明薄膜生长呈无定形.衬底温度高于200℃样品,XRD有明显(002)衍射峰出现,在400～ 800 nm波长范围,透光率在88;以上,衬底温度300℃时,XRD衍射峰半高宽最小,晶粒尺寸大.TEM显示:衬底300℃晶粒尺寸最大,晶体发育好.在200℃掺铝ZnO薄膜,(002)峰不明显,有(101)峰出现.     

氩氧混合气体及纯氧气氛下脉冲激光沉积法制备YBa2Cu3O7-δ超导薄膜的研究

利用脉冲激光沉积法(PLD)在保证其它实验参数不变的情况下,分别在Ar∶O2为3∶1和纯O2的气氛中,在(001) SrTiO3 (STO)基片上制备了外延的高质量YBa2Cu3O7-δ(YBCO)超导薄膜.X射线衍射表明在氩氧混合气体下制备的YBCO薄膜具有更好的结晶质量.扫描电子显微镜测量结果发现:相比于纯O2氛围下制备的YBCO样品,在氩氧混合氛围中制备的薄膜表面具有较小颗粒密度.通过四引线法获得YBCO薄膜的归一化电阻(R/R100K)随温度(T)的变化关系发现,虽然对应不同氛围制备的YBCO薄膜的零电阻转变温度均为90.0K,但是,对应氩氧混合气体的YBCO具有更小的正常态电阻.研究结果表明脉冲激光制备YBCO的过程中,引入氩气可以改善YBCO薄膜的结构和性能.     

热处理对Agx O薄膜结构及成份的影响

利用X射线衍射谱(XRD)和X射线光电子谱(XPS)研究了热处理对AgxO样品的结构及成份的影响.研究结果表明所有制备的AgxO样品基本为无定型,并且AgO和Ag2O两种成份共存;两组具有代表性的AgxO样品经过高温热处理后分别呈现了(Ag+Ag2O)和Ag2O的多晶结构,结构及成份的巨大差异与样品制备条件息息相关;AgO和Ag2O两种成份的热分解临界温度分别为200℃和300℃;热处理过程中,伴随着AgxO的热分解及体内的氧原子向样品表面的扩散过程,并且Ag2O具有相对致密的结构.     

氧化钽薄膜的结构、成份和介电性能研究

采用直流磁控反应溅射技术制备氧化钽薄膜,重点研究了溅射气体中Ar:O2比例和退火温度对样品的结构.成份和介电性能的影响.XRD、XPS和介电谱分析表明:Ar:O2比例对薄膜的结晶性能和薄膜中O/Ta原子比有较大影响,但对薄膜的介电性能没有明显的影响.900℃退火后,XRD谱中出现明显的β-Ta2O5(001)和(200)衍射峰;介电损耗谱表明介质的损耗是由微弱的电导产生的,漏电电流在损耗中占主导地位.     

ITO玻璃衬底上生长的Zn0.9Mg0.1S多晶薄膜特性研究

以ZnS和Mg粉末为原料,采用真空蒸镀技术在ITO玻璃上成功地制备了宽禁带三元化合物Zn0.9Mg0.1S多晶薄膜.原子力显微镜和X射线衍射研究表明:薄膜生长形貌和结晶性能良好,为择优取向的立方闪锌矿结构,晶粒直径约20nm,薄膜的X射线衍射峰较之ZnS的衍射峰向大角度方向移动了0.46°;室温下的拉曼谱峰相对于ZnS的拉曼谱峰出现蓝移,且347.67cm-1谱峰比较强;光致发光谱显示,Zn0.9Mg0.1S薄膜在410nm处有一个较强的发光峰.良好的结晶质量和发光特性为开发多功能材料和器件提供了可能性.     

氩氧比对磁控溅射ZnO薄膜的压电响应与极化特性的影响

保持总的工作气压不变,在不同氩氧比条件下,采用射频磁控溅射法在铝电极层上制备了ZnO薄膜.用X射线衍射(XRD)、原子力显微镜(AFM)和压电响应力显微镜(PFM)分析了ZnO薄膜的择优取向、表面形貌和压电响应,并通过垂直PFM(VPFM)和水平PFM(LPFM)相位图研究了ZnO晶粒的极化特性.结果表明,氩氧比对ZnO薄膜的晶体结构和压电特性有显著影响,其中在氩氧比1∶1的条件下制备的ZnO薄膜具有最大的VPFM振幅和最佳的极化取向一致性.     

氧氩比及基底温度对脉冲磁控溅射Cu2O薄膜结构和光学性能的影响

利用脉冲磁控溅射制备技术,采用单质金属铜靶作为溅射靶,在氧气(O2)和氩气(Ar)的混合气氛下在石英玻璃基底上制备Cu2O薄膜,研究了O2和Ar流量比(O2/Ar)及基底湿度对沉积的Cu2O薄膜结构、表面形貌及光学性能的影响.结果表明:在O2/Ar为30∶80的气氛条件下,基底温度在室温(RT)和100℃时均可获得单相的Cu2O＜ 111＞薄膜;薄膜表面致密、颗粒呈球状,粗糙度的均方根(RMS)值随基底温度增加而增大;薄膜的光谱吸收范围为300～ 650 nm,紫外区吸收较强,可见光区吸收强度较弱,吸收强度随基底温度的增加而增强,光学带隙(Eg)随基底温度的增加而减小.     

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.     

化学液相沉淀法制备过氧化银及其表征

采用化学液相沉淀工艺制备了过氧化银(AgO)粉体,研究了Na2S2O8用量、反应体系的pH值、反应时间等制备工艺参数对AgO产率的影响,并采用X射线衍射仪(XRD)及扫描电子显微镜(SEM)对制备的AgO粉体进行了表征.结果表明,优选的制备工艺是将AgNO3、Na2S2O8和SDBS的质量比定为1∶4.4∶1,然后在反应体系的温度达到60℃后通过滴加NaOH溶液调整反应体系的pH值为13.00,并维持反应时间30 min.随着AgNO3与SDBS的质量比从2.5升高到20.0,AgO粉末颗粒的形貌从近似的球形转变为球状和片状结构的混合物.     

磷扩散法制备高掺磷p型ZnO薄膜的磁控溅射工艺的探索

在前期通过n+-Si衬底中的磷向沉积于其上面的ZnO薄膜的扩散制备高掺磷p型ZnO薄膜的研究基础上,探索了较有普遍应用意义的扩散法制备p型ZnO薄膜的磁控溅射工艺.结果表明,当磁控溅射的氧氩质量流量比与衬底温度满足特定的低阶指数函数的匹配关系时,所制备的ZnO薄膜为p型,而且薄膜中磷原子的深度分布是均匀的;另外,这种薄膜的厚度随着氧氩流量比的增加而减小,而薄膜中氧锌原子浓度比都大于1,比值大小与氧氩质量流量比和衬底温度有关.     

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.