电化学沉积Mn掺杂纳米ZnO的结构和光学性质的研究

在Si衬底上用电化学沉积方法制备了Mn掺杂ZnO纳米晶X射线衍射（XRD）的研究表明,Mn离子取代Zn离子进入到 ZnO晶格中。场发射扫描电子显微镜（SEM）图像显示,ZnO纳米晶形貌的是柱状的。从光致发光谱可以看出,由于掺杂效应导致了可见发射带扩大, PL谱从122.8k到302.2k范围的拟合结果表明,Mn掺杂导致的激子结合能的降低。     

ZnO纳米晶的控制合成与表征

在苯乙烯-丙烯酸(酯)共聚物(PSA)乳胶粒上包覆1层碱式碳酸锌,形成PSA/Zn2(OH)2CO3核壳结构微球,以此核壳微球为前驱物,采用不同的焙烧方式制备出不同形貌的ZnO纳米晶.所得ZnO纳米晶的结构和形貌用XRD、TEM和SEM等技术进行了表征.     

掺杂对纳米氧化铁晶化相的影响

用X射线衍射、透射电镜和穆斯堡尔谱对由掺杂了不同比例Sb的溶胶—凝胶系统制备得的α-Fe_2O_3纳米晶的晶粒度和精细结构进行了研究。结果显示,未掺杂时由Fe(OH)_3非品相干凝胶晶化而得的α-Fe_2O_3相晶粒较大;掺Sb后,干凝胶晶化时一部分Sb参与形成FeSbO_4 晶相,另外的Sb原子进入α-Fe_2O_3晶相中,形成间隙式固溶体。系统中掺杂量增多,固溶于α-Fe_2O_3晶相中的Sb浓度相应也增大,它们很可能在晶粒的表面相对富集,形成扩散势垒,起抑制晶粒长大的作用。在高温下热处理时,固溶体中的杂质原子脱溶析出,晶粒快速长大。     

Y2O2S：Tb纳米晶的能量传递过程的研究

研究了Y2O2S：Tb纳米晶的发光性质和能量传递过程，根据浓度猝灭曲线分析了纳米Y2O2S中引起^5D3和^5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子^5D3-^7F3跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短，根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合，得到理论和试验一致的结果。     

ZnO掺杂纳米CeO2的共沸蒸馏法合成

采用化学共沉淀法结合正丁醇共沸蒸馏处理前驱体合成了ZnO掺杂纳米CeO2颗粒,通过XRD,DSC/TG,IR,TEM,原子吸收光谱以及紫外透过率分析等方法对其结构和性能进行了表征;并根据XRD线宽法,由Scherrer公式计算其晶粒尺寸,研究了共沸蒸馏、ZnO掺杂、以及焙烧温度和时间对CeO2纳米晶粒尺寸的影响.结果表明正丁醇共沸蒸馏法能有效脱除前驱体凝胶中的水分,防止干燥和焙烧过程中硬团聚的形成,从而得到粒径更小、分布更均匀、分散性更好的纳米CeO2颗粒;2 mol%～10 mol%掺杂ZnO能与纳米CeO2形成固溶体,且掺入量增加引起纳米CeO2晶粒有所增大;随焙烧温度提高,ZnO掺杂纳米CeO2晶粒显著长大,而高温下随焙烧时间延长,其晶格进一步趋于完整,晶粒尺寸增加;纳米CeO2具有良好的可见光透过和紫外光吸收能力,ZnO掺杂不会影响纳米CeO2的紫外遮蔽效果.     

ZnO掺杂纳米CeO2的共沸蒸馏法合成

采用化学共沉淀法结合正丁醇共沸蒸馏处理前驱体合成了ZnO掺杂纳米CeO2颗粒,通过XRD,DSC/TG,IR,TEM,原子吸收光谱以及紫外透过率分析等方法对其结构和性能进行了表征;并根据XRD线宽法,由Scherrer公式计算其晶粒尺寸,研究了共沸蒸馏、ZnO掺杂、以及焙烧温度和时间对CeO2纳米晶粒尺寸的影响.结果表明:正丁醇共沸蒸馏法能有效脱除前驱体凝胶中的水分,防止干燥和焙烧过程中硬团聚的形成,从而得到粒径更小、分布更均匀、分散性更好的纳米CeO2颗粒;2 mol%～10 mol%掺杂ZnO能与纳米CeO2形成固溶体,且掺入量增加引起纳米CeO2晶粒有所增大;随焙烧温度提高,ZnO掺杂纳米CeO2晶粒显著长大,而高温下随焙烧时间延长,其晶格进一步趋于完整,晶粒尺寸增加;纳米CeO2具有良好的可见光透过和紫外光吸收能力,ZnO掺杂不会影响纳米CeO2的紫外遮蔽效果.     

Y_2O_2S∶Tb纳米晶的能量传递过程的研究

研究了Y2O2S∶Tb纳米晶的发光性质和能量传递过程,根据浓度猝灭曲线分析了纳米Y2O2S中引起5D3和5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子的5D3-7F5跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短,根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合,得到理论和试验一致的结果。     

Mn掺杂ZnO基纳米纤维的制备与表征

有效地制备出均一单相的Mn掺杂ZnO基纳米纤维是构建微型自旋电子器件的前提和基础。采用静电纺丝法制备了5种不同浓度的Mn掺杂ZnO纳米纤维。通过调节控制纺丝过程中的工作电压,可以有效控制前驱体纤维的形貌和直径分布。在适当的热处理条件下,XRD图谱表征该5种掺杂浓度的纤维均呈现良好的六方纤锌矿结构。光致发光谱显示该纤维在400~1000nm的波长范围内出现了2个发光峰,且均随着Mn掺杂的进入而发生蓝移现象。     

有机纳米颗粒复合Co掺杂ZnO热电性能研究

有机-无机纳米结两端有机材料的离散轨道能级与无机半导体的连续能带差异减小时,使得纳米结界面具有选择性散射不同能量载流子的特征,有利于提高赛贝克系数和热电性能。本文利用溶胶-凝胶法合成了具有有机-无机纳米结结构的聚对苯撑(PPP)纳米复合Zn_1-xCo_xO材料。研究结果表明,较高电导率和赛贝克系数使Zn_0.925Co_0.075O/9 wt% PPP呈现较大的功率因子。另外,有机-无机纳米界面上的界面散射大大降低了热导率。因而,合成的纳米复合材料最大ZT值达到0.22,是Zn_0.925Co_0.075O基体材料的5倍。这一实验结果表明纳米结效应是提高块体热电材料热电性能的有效途径。     

Eu3 掺杂纳米ZnO的制备和发光特性研究

用固相反应法制备ZnO:Eu3 纳米粉末,研究其发光特性.观察到从基质ZnO到Eu3 的能量传递现象.研究表明,不论是ZnO基质的激子激发还是Eu3 的高能态激发,随着Eu3 浓度从0.1 mol%增加到1 mol%,Eu3 的发射增强.在基质激子的激发下,ZnO:Eu3 纳米粉末产生了很强的Eu3 红色特征发射而没有ZnO的宽带发光.结果表明,ZnO:Eu3 纳米粉末的XRD谱中不存在可观测到的Eu2O3杂相,激发光谱中出现ZnO的带间激发与纯Eu2O3的激发光谱不同,这几方面说明了Eu3 进入了ZnO的晶格中.     

氧化锌纳米棒束的制备、表征及性质研究

以水合醋酸锌和水合肼为反应物,在不使用任何表面活性剂的条件下,采用一种简单温和的液相法制备了氧化锌纳米棒束.利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和高分辨透射电子显微镜(HRTEM)对所得产物的结构和形貌进行了表征,利用荧光光谱仪对产物的室温发光性质进行了测试.测试结果证明所得产物为定向排列的纳米棒自组装而成的尺寸均匀、结晶良好的氧化锌纳米棒束,单根纳米棒的直径20～30 nm,其相结构为六方纤锌矿氧化锌.所得产物在紫外区381 nm处具有一个尖锐的发光峰,在400～600 nm的可见光区域的发光被显著减弱,显示了优良的发光性质.     

Er_2O_3掺杂对ZnO压敏电阻性能的影响

研究了Er_2O_3掺杂对ZnO压敏电阻微观结构和电性能的影响.实验发现,在ZnO压敏电阻中加入Er_2O_3不仅可以提高压敏电压V1mA,同时还可改善非线性系数和漏电流特性.但过量的Er_2O_3将会使压敏电阻的耐大电流冲击特性劣化.微观结构和XRD图谱分析表明,Er_2O_3以一种化合物的形式存在于晶界,阻碍了晶界的运动,使材料烧结后具有较小的晶粒尺寸,并且粒径分布比较均匀.当Er_2O_3的添加量为0.8 mol%时,样品的压敏电压V1mA约为360 V/mm,非线性系数α达到86,并且在8/20 μs的耐大电流冲击能力的试验中,样品耐受冲击电流的峰值大于1.6 kA/cm~2.     

Y和Zr掺杂对CeFeB合金微观结构和磁性能的影响

研究了Y和Zr掺杂对CeFeB合金相组成、磁性能和温度稳定性的影响。结果表明,CeYFeB合金由2:14:1主相和少量α-Fe相组成。Y掺杂可有效提高合金的矫顽力、剩磁和最大磁能积。同时由于Y₂Fe₁₄B相优异的磁性能与高温稳定性,其温度稳定性也得到明显改善,掺杂后合金的剩磁和矫顽力温度系数分别为-0.32%/K和-0.41%/K,与纯CeFeB合金相比分别提高了38.5%和40.6%。Y和Zr共掺杂后,由于增加的磁晶各向异性场和晶粒尺寸细化所产生的联合效应,合金的矫顽力、剩磁和最大磁能积大幅度提高,分别比纯CeFeB合金提高了30.9%、58.1%和204.8%。     

氧化锌纳米线束合成及发光性质的研究

利用水合醋酸锌粉作为锌源，十二烷基苯磺酸钠（DBS）作表面活性剂，通过改进的微乳液法，在较低温度下制备出形貌均一的ZnO纳米线束。对样品进行了XRD图谱、扫描电镜（TEM）、透射电镜（SEM）、高分辨透射电镜（HRTEM）、选区电子衍射像（SAED）和光致发光（PL）性能研究。该线束由直径约为30-50nm，长度约为1．5～2．5／μm的ZnO纳米线定向聚集组成，其中，纳米线为六方纤锌矿结构的ZnO单晶纳米线，并且沿（002）晶面生长。其激发发射光谱显示样品存在两个发射带：近紫外发射峰（386nm）和一个黄绿光的发光区，紫外半峰宽约为20nm，纳米线的尺寸和形貌对光谱峰宽和谱峰位置有一定影响。     

Optical properties of antimony-implanted ZnO epilayers

Antimony ions were implanted into ZnO films grown on c-plane sapphire by pulsed-laser deposition. Raman scattering modes of the Sb-implanted samples were found to be influenced by the implantation dose. A characteristic peak at 576 cm^− 1 was observed with an asymmetric shape due to ion damage to the lattice of the implanted ZnO films. When the implant dose was low, the height of the peak was reduced by rapid thermal annealing at 400-600 °C and the symmetry of the spectra was recovered. However, when the Sb dose exceeded 1 × 10¹⁵ cm^− 2, the peak maintained unchanged after rapid thermal annealing at temperatures up to 600 °C. A broad and low Raman peak was observed at 437 cm^− 1, which is related to the surface damage caused by the energetic ion bombarding. Photoluminescence measurement showed a decrease of the bandedge emission at 3.36 eV, a clear effect of defects induced by the implantation, and confirmed partial recovery of the crystal by rapid annealing.     

Optical properties and photocatalytic activity of Nd-doped ZnO powders

To improve the photocatalytic activity of zinc oxides, ZnO powders doped with different neodymium (Nd) concentrations were prepared via hydrothermal method. X-ray diffraction (XRD) together with X-ray photoelectron spectroscopy (XPS) patterns revealed that Nd atoms were successfully incorporated into the ZnO lattice. XRD pattern also showed some anisotropy of the powders. The photoluminescence (PL) spectrum demonstrated a strong and broad peak in the visible light region, and the intensity of visible light emission was enhanced by Nd-doping. The photocatalytic activity was evaluated by the degradation of methyl orange solution. It is shown that doping of Nd into ZnO induces an increase of the photocatalytic activity and it attains to optimum at 3% (mole fraction) doping concentration. The intense visible light emission and the enhanced photocatalytic activity were explained by the increase in electron hole pairs and induced defects like antisite oxygen O_Zn and interstitial oxygen O_i, due to the doping of Nd.     

In doped ZnO thin films

ZnO thin films were deposited by ultrasonic spray technique, zinc acetate was used as starting solution with a molarity of 0.1 M. A set of indium (In) doped ZnO (between 2 and 8 wt%) thin films were grown on glass substrate at 350 °C. The present work is focused on the influence of the doping level on the structural, optical and electrical films properties. Optical film characterization was carried by using UV-visible transmission spectroscopy, the optical gap was deduced from absorption. From X ray diffraction (XRD) analysis, we have deduced that ZnO films are formed with nanocrystalline structure with preferential (0 0 2) orientation. The grain size is increased with In doping from 28 to 37 nm. Electrical characterization was achieved using two-probes coplanar structure, the measured conductivity varies from 2.3 to 5.9 Ω cm⁻¹ when increasing the doping level. However the optical gap is reduced from 3.4 to 3.1 eV.     

Growth of ZnO Nanostructures on Metal-Filled Porous Silicons

在多孔Si上使用不同催化剂成功生长ZnO纳米结构。结果表明,Au作催化剂在Si衬底上得到末端呈六角形的ZnO纳米棒,Cu作催化剂在Si(100)和(111)分别上生长出带状和棒状纳米ZnO,Zn作催化剂在Si衬底上则获得ZnO纳米线。Zn催化制备的ZnO纳米线晶面间距为0.283nm,生长方向是[0110],具有结晶较好的六角纤锌矿晶体结构。比较了不同催化剂制备ZnO的光学性能,发现得到Zn催化制备的ZnO纳米线缺陷绿光峰最弱,因此Zn催化生长制备的纳米ZnO结构质量较好。空气中退火后,3种催化剂生长的纳米ZnO的缺陷发光峰位置不变,而强度变弱。     

Doping and annealing effects on ZnO:Cd thin films by sol-gel method

In this article, ZnO:Cd films were successfully deposited on glass substrates by a sol-gel technique. The influence of doping concentration and annealing temperature effects was carefully investigated. All films exhibited c-axis preferential orientation and optical transparency with visible transmittance >80%. The minimum room temperature resistivity of 0.0341 Ω cm was obtained with 10 at.% Cd doping under 600 °C annealing temperature. The optical band gap of ZnO:Cd film was reduced as Cd doping concentration increased, while the band gap increased with the increase of annealing temperature.