Synthesis of CuInS2 Nanocubes by a Wet Chemical Process

Cube‐shaped CuInS₂ nanoparticles were successfully prepared through a simple low‐temperature solution route. Mercaptoacetic acid was used as capping agent. The product was characterized by means of X‐ray diffraction (XRD), energy dispersive analysis of X‐rays (EDAX), transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL). The CuInS₂ nanocubes obtained were of a chalcopyrite structure. The EDAX analysis shows that as‐synthesized CuInS₂ nanocubes were slightly Cu‐rich and nearly stoichiometric.     

Pulsed-Spray Radiofrequency Plasma Enhanced Chemical Vapor Deposition of CuInS2 Thin Films

Thin films of CuInS₂ were grown on various substrates at a temperature of 523 K from two metal-organic precursors using radiofrequency plasma enhanced chemical vapor deposition (PECVD). Two precursor molecules, with different solubility properties, were dissolved in appropriate solvents and sprayed into the plasma region in the PECVD chamber. The resulting films were examined for atomic composition, growth rate, crystalline orientation, and uniformity. Films made from each precursor differed in thickness, atomic composition, and crystallinity. The uniformity of the film was fairly good from near the edge to the center of the substrate, and evidence for a chalcopyrite-like structure was found in several samples deposited from one of the precursor molecules.     

Growth of CuInS2 Nanotubes from Cu2S-CuInS2 Heterostructures as a Potential Photovoltaic Material

Chemically synthesized nanostructures possess well-defined domains with an interconnected network, which helps the carriers to bypass the other material in the solar cell while moving to their respective electrodes. In this work, CuInS₂ films constituting CuInS₂ nanotubes and nanoparticles were fabricated using a hot-injection chemical technique, followed by sulfurization. Structural and microstructural investigations reveal Cu₂S nanoparticle formation at an early stage of growth of nanotubes, serving as possible catalyst sites for the subsequent anisotropic growth of the heterostructured hexagons. The crossover takes place over a number of intermediate stages. This sharing of the heterostructure by the hexagonal Cu₂S and chalcopyrite CuInS₂ minimizes the lattice distortion. The Cu₂S- CuInS₂ interface in the heterostructure acts as the nucleation center for CuInS₂ nanotubes. Optical absorption and Raman spectroscopy studies reveal better optical properties for CuInS₂ nanoparticles as compared to CuInS₂ nanotubes. Compared to all other nanostructures, nanowires or nanotubes tend to provide single-crystalline nanograins for direct characterization. These nanoparticles, especially the nanotubes, can be used to form an interconnected network structure of p- and n-type materials in bulk heterojunctions providing the key to improve solar cell efficiencies.     

Formation of Anatase Nanocrystals in Sol-Gel Derived TiO2-SiO2 Thin Films with Hot Water Treatment

We have successfully prepared transparent and porous anatase nanocrystals-dispersed films by treating the sol-gel derived TiO₂-SiO₂ films containing poly(ethylene glycol), PEG, with hot water. This process was done at temperatures lower than 100°C under atmospheric pressure, and thus anatase nanocrystals-dispersed films can be formed on various kinds of substrates including organic polymers with poor heat resistance. The changes in structure and composition of the TiO₂-SiO₂ gel films with hot water treatment were related to the formation process of anatase nanocrystals in the TiO₂-SiO₂ gel films with hot water treatment. The formation of anatase nanocrystals was found to proceed to hydrolysis of Si–O–Ti bonds and dissolution of SiO₂ component. In addition, porous film structure formed by leaching of PEG with hot water treatment led to homogenous dispersion of anatase nonocrystals in the films.     

高质量Cu2ZnSnS4纳米晶的合成及其自组装行为的研究

本文以简单的无机盐,包括醋酸铜、醋酸锌、四氯化锡为原料,以硬脂酸和硬脂胺作为保护剂,以二苯醚作为溶剂,采用高温热注射的方法,合成出了高质量的具有自组装行为的Cu₂ZnSnS₄纳米晶,并详细研究了酸和胺对于纳米晶形貌的影响。研究结果表明,随着硬脂酸用量的增加,Cu₂ZnSnS₄纳米晶的尺寸逐渐变大,并且呈现出具有多个棱角的复杂结构。此方法制备的Cu₂ZnSnS₄纳米晶对于紫外和可见光区均有很强的吸收,是构筑高效、低耗的薄膜太阳能电池的理想材料。     

掺杂对棒状纳米SrFe_(12)O_(19)形貌和性能的影响

以FeCl2为原料,利用化学沉淀法制备了针状纳米α-FeOOH中间体,并通过柠檬酸法在针状纳米α-FeOOH表面包裹锶的柠檬酸配合物,煅烧后形成的棒状纳米SrFe12O19并分别在共沉淀和溶胶-凝胶2个不同过程中对纳米SrFe12O19进行镧掺杂。采用XRD,TEM和振动样品磁强计(VSM)对SrFe12O19及掺杂锶铁氧体的结构、形貌及磁性能进行了表征。结果表明:沉淀法和柠檬酸法相结合后制得的针状前驱体于900℃煅烧后可制得平均直径为40nm,长径比为15～20的棒状纳米SrFe12O19。在沉淀过程中对前驱体进行掺杂后制得的SrLaxFe12-xO19较同温度时在溶胶-凝胶过程中进行掺杂制得样品的长径比有所增加,进而使得SrLaxFe12-xO19的各向异性变大,磁性能增加,且在沉淀过程中掺杂镧后,样品的矫顽力和饱和磁化强度达到最大值时,x值明显大于溶胶-凝胶过程中进行掺杂制得的棒状SrLaxFe12-xO19。利用共沉淀法掺杂后,当x=0.15时制备的样品的矫顽力最大为6179.1Oe,此时样品的饱和磁化强度和剩余磁化强度分别65.7和38.4emu·g-1。当x=0.2时制备的样品的饱和磁化强度达到最大值为67.3emu·g-1,样品的矫顽力为5852.7Oe。     

Effect of SnO2 Nanocrystals on the Emission of Eu3+ Ions in Silica Matrix

Silica xerogels containing Eu³⁺ ions and SnO₂ nanocrystals were prepared in the sol‐gel process, and characterized by x‐ray diffraction (XRD) and photoluminescence spectra. Under the excitation at 393 nm, characteristic emission of Eu³⁺ ions at 614 nm was enhanced with increasing amount of SnO₂ nanocrystals. Moreover, when the Eu³⁺/SnO₂ co‐doped samples were excited at 345 nm, corresponding to the sideband of SnO₂ nanocrystals, the emission of Eu³⁺ ions at 614 nm was clearly observed, while no emission of Eu³⁺ ions for the Eu³⁺‐doped sample. It may be ascribed to the energy transfer from SnO₂ conduction band to Eu³⁺ conduction band. Further experimental results suggest that the energy transfer may be achieved through surface transition state.     

Ta2O5 Nanocrystals Strengthened Mechanical,Magnetic, and Radiation Shielding Properties of Heavy Metal Oxide Glass

In this study, for the first time, diamagnetic 5d⁰ Ta⁵⁺ ions and Ta₂O₅ nanocrystals were utilized to enhance the structural, mechanical, magnetic, and radiation shielding of heavy metal oxide glasses. Transparent Ta₂O₅ nanocrystal-doped heavy metal oxide glasses were obtained, and the embedded Ta₂O₅ nanocrystals had sizes ranging from 20 to 30 nm. The structural analysis of the Ta₂O₅ nanocrystal displays the transformation from hexagonal to orthorhombic Ta₂O₅. Structures of doped glasses were studied through X-ray diffraction and infrared and Raman spectra, which reveal that Ta₂O₅ exists in highly doped glass as TaO₆ octahedral units, acting as a network modifier. Ta⁵⁺ ions strengthened the network connectivity of 1–5% Ta₂O₅-doped glasses, but Ta⁵⁺ acted as a network modifier in a 10% doped sample and changed the frame coordination units of the glass. All Ta₂O₅-doped glasses exhibited improved Vicker’s hardness, magnetization (9.53 × 10⁻⁶ emu/mol), and radiation shielding behaviors (RPE% = 96–98.8%, MAC = 32.012 cm²/g, MFP = 5.02 cm, HVL = 0.0035–3.322 cm, and Z_eff = 30.5) due to the increase in density and polarizability of the Ta₂O₅ nanocrystals.     

Synthesis and Characterization of Conducting PANI/PNA Blend Polymer Doped with ZrO2 and CdO Nanocrystals

Composites of ZrO₂ and CdO nanocrystals with conducting polyaniline/p-nitroaniline blended in different ratios have been prepared and investigated by UV-vis spectrophotometer, luminescence spectrophotometer and structural characterization of copolymer was studied by FTIR method. A decrease in nanocrystals photoluminescence (PL) has been observed with the increase in the concentration of PANI/PNA in the composites. A phenomenon of quenching is observed in the nanocrystals by luminescence.     

Synthesis of CuInS2@CdS Core‐Shell Nanocrystals

CuInS₂@CdS core‐shell nanocrystals were prepared in a wet chemical process. Transmission electron microscope (TEM), x‐ray energy dispersive spectroscopy (EDAX), x‐ray diffraction (XRD), absorption, and photoluminescence (PL) spectra were used to confirm the formation of the CuInS₂@CdS core‐shell structure. The growth of CdS shell not only increased the PL intensity, but also restrained the transformation of CuInS₂ from nanoparticles to nanorods after annealing, which was attributed to an effective chemical passivation of the CuInS₂ core by the CdS shell.     

具有18电子结构的Mg2CoH5纳米晶制备及其储氢性能研究

本文研究了Mg2CoH5纳米晶的制备及其储氢性能。在室温和氩气气氛下,以MgH2和纳米Co为原料,采用球磨法制备了Mg2CoH5纳米晶。对所制备Mg2CoH5的组成、结构和形貌进行了表征,并且对Mg2CoH5的储氢性能进行了研究。实验结果表明,通过该种方法制备了纯度较高(产物纯度为79%)的四方结构Mg2CoH5纳米晶,其形貌呈球形且分布较均匀,最频粒径为80 nm。制备的Mg2CoH5纳米晶具有较低的活化能和较好的吸放氢动力学性能,其放氢的脱附焓和脱附熵分别为-115.0 kJ.mol-1H2和-193.6.1 J.mol-1.K-1H2。再氢化时,在543 K时仅7 min内其吸氢量就达到1.5wt%。     

Formation and Crystallization Behavior of Gels in the Na2O-SiO2-TiO2-ZrO2 System

SiO₂-TiO₂-ZrO₂ and 5Na₂O·95(SiO₂ + TiO₂ + ZrO₂) gels were synthesized and role of Na₂O in gel formation and crystallization behavior of gels were studied. From Si(OC₂H₅)₄, Ti(iso-OC₃H₇)₄, Zr(n-OC₃H₇)₄ and NaOCH₃ solutions in EtOH without H₂O, transparent and opaque gels were obtained. Opaque bulk gels, rich in TiO₂ or ZrO₂ composition in Na₂O containing SiO₂-TiO₂-ZrO₂ system, contain agglomerated spherical particles of diameter small <10 m, in contrast with opaque gels having large particles <30 m in alkali-free SiO₂-TiO₂-ZrO₂ system. Crystallization temperature (Tc) was measured by DTA on dried gels. Compared with the alkali-free SiO₂-TiO₂-ZrO₂ gels, 5 mol% Na₂O containing gels gave lower Tc in SiO₂ rich compositions and higher in TiO₂ rich or ZrO₂ rich compositions.     

Preparation of Titanium Oxide Layer on Silica Glass Substrate with Titanium Naphthenate Precursor

Nanocrystalline TiO₂ thin films on silica glass substrates were prepared by using a naphthenic acid precursor. As-deposited thin films were heat treated at 500, 600, 700 and 800^∘C for 30 min in air. The TiO₂ thin films were analyzed by High Resolution X-ray diffraction, ultra violet—visible—near infrared spectrophotometer, field emission—scanning electron microscope and scanning probe microscope. After annealing at 600 and 700^∘C, the XRD patterns consist of only anatase peaks of TiO₂ film. Rutile(110) peak begins to appear at an annealing temperature of 800^∘C. Relative high transmittance at visible range was obtained for all films except the film annealed at 800^∘C. Optical band gap, E_g, is in the range between 3.53 and 3.78 eV except the TiO₂ film annealed at 500^∘C. The best hydrophilicity was achieved with a high-temperature annealing.     

TiO2 nanoparticles incorporated with CuInS2 clusters: preparation and photocatalytic activity for degradation of 4-nitrophenol

TiO₂ nanoparticles incorporated with CuInS₂ clusters were prepared in a solvothermal process and characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy-dispersion X-ray analysis (EDX). Compared with pure TiO₂ nanoparticles, the TiO₂ nanoparticles incorporated with CuInS₂ clusters display higher photocatalytic activity with 99.9% of degradation ratio of 4-nitrophenol after 2 h irradiation. In order to investigate the effect of the CuInS₂ clusters on the photocatalytic activity of TiO₂ nanoparticles, diffuse reflectance UV–Vis spectra (DRS), photoluminescence (PL) spectra, and photocurrent action spectra were measured. The results indicate that the enhanced photocatalytic activity is probably due to the interface between TiO₂ and CuInS₂ as a trap of the photogenerated electrons to decrease the recombination of electrons and holes.     

High Photocatalytic Activity of F-Doped TiO2 Film on Glass

The photoreactivity of sol-gel (SG)-TiO₂ films was enhanced significantly with addition of a small amount of trifluoroacetic acid (TFA) into the starting solution. The promoting effect was confirmed in two separate experiments of the methylsiloxane monolayer oxidation and the photocurrent measurements. The results of film characterization indicated that the absorption coefficient for ultraviolet light ( < 360 nm) increases due to film densification and the crystallinity is improved upon F doping. The improvement in the photoreactivity was ultimately attributed to the increase in the rate at which the photogenerated charge carriers reach the surface in the photostationary state.     

Optical and Conductivity Properties of PbS Nanocrystals in Amorphous Zirconia Sol-Gel Films

Lead sulfide (PbS) nanocrystals (NCs), embedded in amorphous zirconia sol-gel film with different PbS mole concentration (5–30%), were grown at temperature, ranging from 200°C to 350°C. The size of PbS NCs was determined by TEM and by blue shift of the absorption edge. The size increased with an increase of the synthesis temperature and PbS mole concentration. The optical and electrical properties of various sizes of PbS NCs in zirconia film are investigated utilizing absorption, photoluminescence (PL) and current-voltage measurement. The PL spectra were Stokes shifted from the corresponding absorption edge by about 0.5 eV. The latter can be associated with recombination process from surface state. The electrical properties were investigated by the deposition of the PbS NCs-zirconia films on ITO/glass substrate, followed by their coverage with gold contact. The current-voltage characteristics depend on the PbS NCs size and exhibits nonlinear nearly symmetric curve, associated with the space-charge limited current or the tunneling of carriers through the nanocrystalline film.     

离子层气相反应法(ILGAR)制备CuInS2薄膜的研究

CuInS₂ thin films have been prepared by ion layer gas reaction (ILGAR) using C₂H₅OH as solvent, CuCl and InCl₃ as reagents and H₂S gas as sulfuration source. The effects of cationic concentrations and numbers of cycle on the properties of CuInS₂ film were investigated. The chemical composition, crystalline structure, surface topography, deposited rate, optical and electronic properties of the films were characterized by X-ray diffractrometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), ultraviolet-visible spectrometry (UV-Vis) and Hall System. The results show that the crystalline of CuInS₂ thin films and the deposition rate have been improved with the increase of cationic concentration, while CuxS segregation phases appear with further increasing cationic concentration. The deposition rate is close to constant as cationic concentration is fixed. CuInS₂ thin film derived form lower cationic concentration is uniform, compact and good in adhesion to the substrates. The absorption coefficient of CuInS₂ thin films is larger than 10⁴ cm^-1, and the band gap E_g is in the range of 1.30～1.40 eV. The dark resisitivity of the thin film decreases from 50 to 10 Ω·cm and the carrier concentration ranges are over 10¹⁶ cm^-3.     

CeO2对磷酸钙玻璃固化体结构的影响

采用高温熔融冷淬法制备了xCeO₂·(100-x)CaO·100P₂O₅(x：0~12)玻璃固化体。利用XRD、Raman、FTIR和DSC等方法表征了包容CeO₂磷酸钙玻璃固化体的结构特点和析晶性能。结果表明,玻璃固化体微观结构属于偏磷酸盐玻璃。CeO₂未改变玻璃的基本结构,位于磷酸钙玻璃网络空隙中,起网络修饰作用。添加量小于6mol%时,易形成均质玻璃,在此范围内,随着CeO₂含量增加玻璃固化体的热稳定性和抗析晶能力提高,玻璃的熔化温度降低。CeO₂添加量为6mol%时,玻璃的热稳定性最好。添加量9mol%~12mol%时,CeO₂与磷酸钙玻璃基体反应生成独居石结构晶相。     

SILAR法制备化学计量CuInS2薄膜

在室温下，以不同c_Cu/c_In的CuCl₂和InCl₃混合溶液作为阳离子前驱体，Na₂S水溶液为硫源，利用连续离子层吸附反应法(SILAR)在玻璃基底上制备了CuInS₂薄膜。XRD结果表明，当c_Cu²⁺/c_In³⁺在1～1.5范围内均可形成具有黄铜矿结构的CuInS₂薄膜。SEM观察到随c_Cu²⁺/c_In³⁺的升高，薄膜表面颗粒长大并出现团簇聚集。通过XPS测定薄膜表面的化学组成证明当c_Cu²⁺/c_In³⁺=1.25时，CuInS₂薄膜接近其标准的化学计量组成。此时薄膜的吸收系数大于>10⁴ cm^-1，禁带宽度E_g为1.45 eV。     

GdF3∶Eu3+/NaGdF4∶Eu3+纳米晶的水热合成及发光性质

采用水热法,以聚乙二醇(400)为分散剂,以NaOH和HNO3溶液调节初始溶液pH值,合成GdF3∶Eu3+和NaGdF4∶Eu3+纳米晶。XRD和SEM结果表明:在酸性溶液(pH=3,5)、中性溶液(pH=7)和碱性溶液(pH=9)中,分别获得具有正交结构的GdF3∶Eu3+纳米晶,GdF3∶Eu3+和NaGdF4∶Eu3+混合晶,六方结构NaGdF4∶Eu3+棒状微米晶。根据Scherrer公式估算pH=3和pH=5时制备纳米晶的一次性粒径分别为49和28 nm。样品的发射光谱结果表明:特征发射峰来自于5D2、5D1、5D0到7FJ跃迁。在主晶相为GdF3样品中,主发射峰来自于Eu3+的5D0→7F1的磁偶极跃迁;晶相为NaGdF4样品的主发射峰来自于Eu3+的5D0→7F2电偶极跃迁。5D0→7F1和5D0→7F2跃迁发射相对强度比值显示:Eu3+在NaGdF4晶体中的格位对称性下降。激发光谱显示出Gd3+和Eu3+具有较好的能量传递。