单根锑掺杂ZnO微米线热电发电机的制备及热电性能

采用化学气相沉积(CVD)方法,在无催化剂的条件下,生长出了锑掺杂的超长、大尺寸ZnO微米线。测试表明微米线的平均长度可达1~2.5 cm,微米线中锑元素的含量约为3.1%(n/n)。此外,将挑选出的单根锑掺杂ZnO微米线以银浆为电极制作成热电发电机,并研究了微米线长度和微米线直径对器件输出性能的影响。研究表明当器件两电极之间的温差为20 K且两电极间微米线的长度为1.6 cm时,器件能够输出的最大电压和最大输出功率分别约为36 m V和10.8 n W,微米线的赛贝克系数约为-1.80 m V·K-1。此外,热电器件的输出电压随着微米线长度的增加而增大,随微米线直径的增加而减小。     

含氟绿光铱配合物的设计、合成及其高效磷光电致发光器件

以2-(3-(2',4'-二氟苯基)苯基)吡啶(Hdfbppy)为环金属C^N配体,乙酰丙酮(Hacac)为辅助配体,设计合成了一种绿色磷光铱配合物(Ir(dfbppy)₂(acac));研究了此配合物的光物理性质及其电致发光器件性能。室温下,配合物Ir(dfbppy)₂(acac)的二氯甲烷溶液的最大发射波长为520nm,量子效率为71%,寿命为381ns。将此配合物掺杂在4,4'-N,N'-二咔唑基二联苯(CBP)中,作为发光层制备了有机发光二极管器件。结果显示,该器件在7.2V电压下呈现的最大亮度为68324cd·m^-2,最大电流效率约为53cd·A^-1,最大功率效率为37lm·W^-1,色坐标为(0.33,0.62)。     

M2+(M=Cu、Cd、Ag、Fe)掺杂氧化锌纳米粉晶的抗菌性能

采用柠檬酸溶胶-凝胶法制备了ZnO及M²⁺掺杂ZnO纳米粉晶(M=Cu、Cd、Ag、Fe),用现代测试技术表征了样品的组成、结构和形貌,以大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphylococcus aureus)和白色念珠菌(Candida albicans)为测试菌株,用抑菌圈、最小抑菌浓度和最小杀菌浓度等方法研究了样品在日光照射下的抗菌活性。结果表明,与母体ZnO相比,Cu、Ag、Cd掺杂样品的抗菌性能明显地增强,这可能是由于掺杂金属离子置换Zn²⁺生成了晶格缺陷和电荷缺陷,阻止了光生电子和光生空穴对的复合从而增强了光催化活性和抗菌活性。     

盐酸和磺基水杨酸复合掺杂聚苯胺的热电性能

以苯胺为单体, 过硫酸铵为氧化剂, 采用化学氧化聚合法在盐酸和磺基水杨酸混合溶液中制备了导电聚苯胺。通过XRD、SEM、FTIR等分析手段, 对所得产物的结构进行研究, 并探讨在相同聚合条件下, 不同的磺基水杨酸和盐酸的物质的量浓度比(c_SSA:c_HCl)对聚苯胺热电性能的影响。结果显示, 混合酸掺杂聚苯胺的电导率随c_SSA:c_HCl的增加而增大, 但Seebeck系数的变化趋势却与之相反。当c_SSA:c_HCl=0.25:1时, 掺杂态聚苯胺的功率因子在175℃时达到最大值为0.46 μW·m^-1·K^-2,分别是相同条件下HCl和SSA掺杂聚苯胺的1.7和1.9倍。这表明适当配比的有机酸与无机酸混合掺杂比单一酸掺杂更有利于聚苯胺热电性能的提高。     

二氧化钛多孔纳米片在染料敏化太阳电池中的应用

运用连续吸附反应法和化学腐蚀-沉积法,用ZnO/FTO（氟掺杂氧化锡）多孔纳米片为模板,制备了TiO₂/FTO多孔纳米片。研究了吸附次数对形貌、光散射性能和染料敏化太阳电池性能的影响。最佳吸附次数为30,由此得到的太阳能电池的效率、短路电流密度J_sc、开路电压V_oc和填充因子FF分别为：5.57%、9.26mA·cm^-2、0.835V和72.04%。这个效率略高于P₂₅（5.32%）,但远高于ZnO（2.41%）。     

溶剂热法制备ATO纳米球及其性能研究

以五水四氯化锡和三氯化锑为主要原料,以乙二醇为溶剂,采用溶剂热法合成了锑掺杂氧化锡(ATO)纳米球。用X射线衍射仪和透射电子显微镜对合成的ATO纳米球进行结构表征,用紫外可见分光光度计和低阻抗表面阻抗仪研究其光电性能。结果表明：所合成的ATO均为四方晶型结构,由粒径为5~10 nm的ATO纳米晶聚集成直径为80~120 nm的纳米球,且分散性良好。Sb³⁺掺杂量对ATO纳米球的光、电性能有很大影响,随着Sb³⁺掺杂量的增加其可见光透过率和电导率都呈现先增大后减小的变化关系。在n_Sb/n_Sn比为9∶100时其光电性能达到最佳。     

纳米氧化锌的低温热容和热力学性质

用扫描电子显微镜(SEM)测定了纳米氧化锌试样的粒径, SEM结果表明ZnO试样平均粒径为30 nm. 在83～350 K温区, 用精密低温绝热量热计测定了ZnO的等压摩尔热容, 拟合出其等压摩尔热容与热力学温度的函数关系式: C_p＝－3.249＋0.2400T－3.413×10^－4T ²＋4.485×10^－7T ³. 根据热容与热力学函数关系, 计算了以298.15 K为基准的纳米ZnO的热力学函数, 并与粗晶ZnO和18 nm ZnO热容文献报导值进行了比较, 从能量角度分析了不同粒径ZnO热容曲线差别产生的原因.     

Bi4-xEuxTi3-yMyO12（M=Fe，Co，Ni）纳米颗粒的制备及光学和磁学性能

三层结构的Aurivillius相的Bi_4-xEu_xTi_3-yM_yO₁₂（x=0~0.6;M=Fe/Co/Ni,y=0.01,0.02,0.04,0.06,0.08,0.10）纳米颗粒,是通过共沉淀法和后续的高温煅烧处理所制备的。利用XRD,SEM,PL,Raman,PPMS等方法对样品进行表征,研究了不同掺杂浓度下的产物的物相、形貌和性能等。实验结果表明,通过掺杂,发现纳米颗粒的粒径变小,形貌更均一,分散性也更好。通过对掺杂离子浓度的优化,发现Eu³⁺离子的掺杂浓度为x=0.4时,发光强度是最强的。此外,对Ti位进行了磁性离子（Fe³⁺,Co³⁺和Ni²⁺）的掺杂,实验结果发现随着掺杂的磁性离子浓度的减少,发光强度是逐渐增强,而且产物具有很好的铁磁性。     

LiBa0.95-yBO3:0.05Tb3+,yBi3+荧光粉的制备及荧光性质

以硼酸和碳酸盐为原料,用高温固相法制备了可被（近）紫外光（369、254 nm）有效激发的Tb³⁺单掺杂LiBa_1-xBO₃：xTb³⁺（物质的量分数x=0.02、0.03、0.04、0.05、0.06、0.07）及Bi³⁺和Tb³⁺共掺杂LiBa_0.95-yBO₃：0.05Tb³⁺,yBi³⁺（物质的量分数y=0.02、0.03、0.04、0.05、0.06、0.07）的2个系列荧光粉,产物的结构和形貌分别用粉末X射线衍射（PXRD）和扫描电子显微镜进行表征。PXRD测定结果表明2个系列的产物均为纯相LiBaBO₃。通过对第一系列产物荧光光谱的测定,筛选出发光强度最好的产物,据此确定铽离子的最佳掺杂量;在此基础上制备出铋离子掺杂量不同的第二系列荧光粉。荧光光谱测定的实验结果表明,Tb³⁺/Bi³⁺共掺杂的荧光粉的发光强度好于Tb³⁺单掺杂的荧光粉,这说明Bi³⁺对Tb³⁺有敏化作用;而且随着Bi³⁺掺杂量的增加,产物的荧光强度表现出先增加后减小的趋势,当Bi³⁺的掺杂量y=0.03时,产物的荧光强度达到最大。Bi³⁺和Tb³⁺之间存在偶极-四极相互作用而进行能量传递。系列荧光粉的CIE坐标显示其发光颜色在一定程度上呈现出由绿色光到白光的渐变趋势。     

Y1-xCaxBaCo2O5+δ的制备和性能表征

利用固相反应法合成了层状钙钛矿钴氧化物Y_1-xCa_xBaCo₂O_5+δ(x=0,0.1,0.15,0.2)材料,系统研究了材料的氧吸附性能和电输运性质。XRD结果表明Ca²⁺掺杂的样品具有母相YBaCo₂O_5+δ层状钙钛矿结构,随着Ca²⁺掺杂量的增加,样品的晶格参数增大。TG结果显示：从室温到1 273 K,所有样品经历了两次吸氧和脱氧的过程,Ca²⁺掺杂增强了样品的氧脱附性能。在中低温下,约650 K附近,吸氧量达到最大,同时,样品发生了半导体金属转变。Ca²⁺掺杂量的增加,半导体金属转变温度增大,电导率下降。半导体金属转变与氧变化量δ有关而电导率下降与Ca²⁺掺杂引起Co³⁺离子的增加有关。     

Sb掺杂大尺寸ZnO纳米棒的制备及其特性研究

采用化学气相沉积法,在没有采用任何催化剂的条件下,在Si(100)衬底上成功制备出Sb掺杂大尺寸ZnO纳米棒,并对样品进行了结构和光学性质的表征。结果表明:纳米棒为结晶质量较好的六角纤锌矿结构,在能量色散谱(EDS)中观测到了Sb元素的存在。此外,在低温光致发光(PL)光谱中还观测到了与Sb掺杂相关的中性受主束缚激子发光峰(A0X)、自由电子到受主能级跃迁的发光峰(FA)、施主受主对(DAP)以及DAP的一级纵向光声子伴线(DAP-1LO),因此证实Sb元素作为受主杂质掺杂已进入ZnO晶格。     

Influence of Ga dopant on photoelectrochemical characteristic of Ga‐doped ZnO thin films deposited by sol–gel spin‐coating technique

In this study, Ga‐doped ZnO thin films were prepared using sol–gel technique via spin‐coating method. The effect of Ga‐doping dopant (0, 1, 2 and 3 at.%) on microstructural, optical, electrical and photoelectrochemical (PEC) characteristics have been investigated. The spin‐coating was repeated six times, and as‐obtained thin films were then annealed at 500 °C for 1 h in vacuum. After annealing, all samples revealed single phase of hexagonal ZnO polycrystalline structure with a main peak of (002) in X‐ray diffraction (XRD) pattern. Raman spectra show that the vibration strength of E₂ is highly decreased by Ga doping. Thicknesses of all samples were ~300 nm measured via scanning electron microscopy (SEM) cross‐section images and alpha‐step. The optical band gap and resistivity of samples were in the range of 3.24 to 3.28 eV and 102 to 9 Ohm cm, respectively. Resulting from PEC response, the 2 at.% Ga‐doped ZnO thin film has a better PEC performance with photocurrent density of ~0.14 mA/cm² at 0.5 V versus saturated calomel electrode (SCE) under illumination with the intensity of 100 mW/cm². This value was about seven times higher than the un‐doped film (reference sample). Observed higher photocurrent density was likely because of a suitable Ga‐doping concentration causing a lower resistivity. Copyright © 2016 John Wiley & Sons, Ltd.     

NaCdSb: An Orthorhombic Zintl Phase with Exceptional Intrinsic Thermoelectric Performance

Many Zintl phases are promising thermoelectric materials owning to their features like narrow band gaps, multiband behaviors, ideal charge transport tunnels, and loosely bound cations. Herein we show a new Zintl phase NaCdSb with exceptional intrinsic thermoelectric performance. Pristine NaCdSb exhibits semiconductor behaviors with an experimental hole concentration of 2.9×10¹⁸ cm⁻³ and a calculated band gap of 0.5 eV. As the temperature increases, the hole concentration rises gradually and approaches its optimal one, leading to a high power factor of 11.56 μW cm⁻¹ K⁻² at 673 K. The ultralow thermal conductivity is derived from the small phonon group velocity and short phonon lifetime, ascribed to the structural anharmonicity of Cd−Sb bonds. As a consequence, a maximum zT of 1.3 at 673 K has been achieved without any doping optimization or structural modification, demonstrating that NaCdSb is a remarkable thermoelectric compound with great potential for performance improvement.     

High performance thermoelectrics from earth-abundant materials: enhanced figure of merit in PbS by second phase nanostructures

Lead sulfide, a compound consisting of elements with high natural abundance, can be converted into an excellent thermoelectric material. We report extensive doping studies, which show that the power factor maximum for pure n-type PbS can be raised substantially to ~12 μW cm(-1) K(-2) at >723 K using 1.0 mol % PbCl(2) as the electron donor dopant. We also report that the lattice thermal conductivity of PbS can be greatly reduced by adding selected metal sulfide phases. The thermal conductivity at 723 K can be reduced by ~50%, 52%, 30%, and 42% through introduction of up to 5.0 mol % Bi(2)S(3), Sb(2)S(3), SrS, and CaS, respectively. These phases form as nanoscale precipitates in the PbS matrix, as confirmed by transmission electron microscopy (TEM), and the experimental results show that they cause huge phonon scattering. As a consequence of this nanostructuring, ZT values as high as 0.8 and 0.78 at 723 K can be obtained for nominal bulk PbS material. When processed with spark plasma sintering, PbS samples with 1.0 mol % Bi(2)S(3) dispersion phase and doped with 1.0 mol % PbCl(2) show even lower levels of lattice thermal conductivity and further enhanced ZT values of 1.1 at 923 K. The promising thermoelectric properties promote PbS as a robust alternative to PbTe and other thermoelectric materials.     

Fabrication of gold microtubes and microwires in high aspect ratio capillary arrays

In this communication, we describe the sequential deposition of materials in capillaries as a means to produce self-assembled three-dimensional gold microtubes, hollow gold microwires, and microtube and microwire arrays with unprecedented aspect ratios. The initial application of this technique is the fabrication of an array of microwires within a silica capillary array. The physical characteristics of these microwires are characterized via SEM, electrochemistry, and electrogenerated chemiluminescence emission.     

Electrodeposition of Ni and Te‐doped Cobalt Triantimonide in Citrate Solutions

Skutterudite compounds form a new class of potential candidates for thermoelectric applications. Cobalt triantimonide (CoSb₃) shows good thermoelectric properties at medium and high temperatures. Doping this system with substitution elements, for either Co or Sb or both, may result in an increase of the thermoelectric figure of merit (ZT). This work focused on the electrochemical doping and characterization of films and nanowires of Co‐Sb system in citrate solutions using gold‐coated PCTE templates. The electrodeposition was performed on gold surface that was pre‐treated electrochemically to ensure reproducible results. The electrochemical treatment acted as an annealing process for the surface, which resulted in an increase in Au(111) as demonstrated by XRD. Detailed electrochemical studies including deposition‐stripping experiments was performed in order to develop a better understanding of the co‐deposition kinetics and a better control over the composition of doped Co‐Sb system. Scanning electron microscopy (SEM/EDS) helped study the morphology and the composition of the doped and undoped Co‐Sb system. Co‐deposition of Co‐Sb showed that the amount of Co is higher in nanowires than in film or mushroom caps due to the slow Sb deposition rate dictated by slow Sb(III) complex diffusion. Doped nanowires have been also obtained. Both Ni and Te electrochemical doping of the Co‐Sb system affected the composition of the deposit but there was no effect on nanowire morphology.     

Synthesis of europium-doped zinc oxide micro- and nanowires

Single crystalline Eu³⁺-doped wurtzite ZnO micro- and nanowires were synthesized by a chemical vapor deposition method (CVD). The nanostructures were grown by autocatalytic mechanism at walls of an alumina boat. The structure and properties of the doped ZnO is fully characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectrometry (EDX), scanning and transmission electron microscopy (SEM and TEM), and photoluminescence (PL) methods. The synthesis was carried out for 10 min giving vertically aligned nanowires with mean diameter of 50–400 nm and with length of up to several microns. The nanowires were grown along ±[0001] direction. The concentration of Eu³⁺ dopant in the synthesized nanowires was varied from 0.7 to 0.9 at %. The crystal structure and microstructures of the doped nanomaterials were discussed and compared with undoped ZnO. The photoluminescence spectra show that emission of doped samples were shifted towards orange-red region (2.02 eV) relative to undoped zinc oxide nanostructures (2.37 eV) due to Eu³⁺ intraionic transitions from ZnO/Eu.     

Enhanced β‐phase in PVDF polymer nanocomposite and its application for nanogenerator

Harvesting energy from the ambient mechanical energy by using flexible piezoelectric nanogenerator is a revolutionary step toward achieving reliable and green energy source. Polyvinylidene fluoride (PVDF), a flexible polymer, can be a potential candidate for the nanogenerator if its piezoelectric property can be enhanced. In the present work, we have shown that the polar crystalline β‐phase of PVDF, which is responsible for the piezoelectric property, can be enhanced from 48.2% to 76.1% just by adding ZnO nanorods into the PVDF matrix without any mechanical or electrical treatment. A systematic investigation of PVDF‐ZnO nanocomposite films by using X‐ray diffractometer, Fourier transform infrared spectroscopy, and polarization‐electric field loop measurements supports the enhancement of β‐phase in the flexible nanocomposite polymer films. The piezoelectric constant (d₃₃) of the PVDF‐ZnO (15 wt%) film is found to be maximum of approximately −1.17 pC/N. Nanogenerators have been fabricated by using these nanocomposite films, and the piezoresponse of PVDF is found to enhance after ZnO loading. A maximum open‐circuit voltage ~1.81 V and short‐circuit current of 0.57 μA are obtained for 15 wt% ZnO‐loaded PVDF nanocomposite film. The maximum instantaneous output power density is obtained as 0.21 μW/cm² with the load resistance of 7 MΩ, which makes it feasible for the use of energy harvesting that can be integrated to use for driving small‐scale electronic devices. This enhanced piezoresponse of the PVDF‐ZnO nanocomposite film‐based nanogenerators attributed to the enhancement of electroactive β‐phase and enhanced d₃₃ value in PVDF with the addition of ZnO nanorods.     

Sb掺杂纳米TiO2光催化剂的晶体结构与光催化性能

Nanoscale Sb doped titanium dioxide thin films photocatalyst (Ti1-xSbO2) were obtained from dip-coating sol-gel method. The influence of dopant Sb density on the crystal structure and the phase transformation of the thin films were characterized by X-ray diffraction (XRD) and Raman spectra. The results of XRD showed that as-prepared films were not only in anatase state but also in brookite. The crystalline size was estimated to be around 13.3-20 nm. Raman spectra indicated there coexisted other phases and a transformation from brookite to anatase in the samples doped with 0.2% Sb. After doping a proper amount of Sb, the crystallization rate and the content of the anatase Ti1?xSbO2 in the thin films was clearly enhanced because Sb replaced part of the Ti of TiO2 in the thin films. The anode current density (photocurrent density) and the first order reaction speed constant (k) of thin films doped with 0.2% Sb reached 42.49 1A/cm2 and 0.171 h/cm2 under 254 nm UV illumination, respectively, which is about 11 times and 2 times that of the non-doped TiO2 anode prepared by the same method respectively.