Dielectric and Piezoelectric Properties of Sodium Bismuth Titanate Ceramics with KCe Substitution

The piezoelectric properties of the (KCe)-substituted sodium bismuth titanate (Na_0.5Bi_4.5Ti₄O₁₅, NBT) piezoelectric ceramics are investigated. The piezoelectric properties of NBT ceramics are significantly enhanced by (KCe) substitution. The Curie temperature Tc, and piezoelectric coefficient d₃₃ for the (KCe)-substituted NBT are found to be 663ºC, and 27pC/N, respectively. Dielectric and annealing spectroscopy resent that the (KCe) co-substituted NBT piezoelectric ceramics possess stable piezoelectric properties.     

Photoelectron Spectroscopy of Nickel, Palladium, and Platinum Oxide Anions

The 364-nm negative ion photoelectron spectra of XO and OXO molecules (X=Ni, Pd, and Pt) are reported. The spectra yield the electron affinities (EAs): EA(NiO)=1.455±0.005 eV; EA(PdO)=1.672±0.005 eV; EA(PtO)=2.172±0.005 eV; EA(ONiO)=3.043±0.005 eV; EA(OPdO)=3.086±0.005 eV; EA(OPtO)=2.677±0.005 eV. In addition, for the diatomics, transitions from the anion X?²Π_3/2 and X?′²Π_1/2 states into neutral X?³Σ⁻, ³Π, and for NiO and PdO, ¹Π, are assigned. Several states have been reassigned from those in the existing literature. Anion ²Π_3/2-²Π_1/2 spin-orbit splittings are measured, as are neutral ³Π₂-³Π₁ spin-orbit splittings: the XO ³Π ₂-³Π₁ splittings increase from 405±30 cm⁻¹ (NiO) to 805±30 cm⁻¹ (PdO) to 3580±40 cm⁻¹ (PtO). A bond length shortening of 0.03±0.01 Å is measured upon electron detachment from NiO⁻, resulting in an anion bond length of 1.66±0.01 Å. The bond length does not change upon electron detachment from PdO⁻ using 3.4-eV photons. The Pt-O bond length decreases by 0.035±0.010 Å in the ³Π₁←²Π_3/2 transition. The spectrum of OPtO displays a significantly more extended vibrational progression than those of ONiO or OPdO, and the O-Pt bond length is found to decrease by 0.07±0.01 Å upon electron detachment. The spectra support the view that the Ni-O bond is largely ionic, the Pd-O bond is somewhat less so, and the Pt-O bond displays a substantial covalent character.     

Raman Investigation of Sodium Titanate Nanotubes under Hydrostatic Pressures up to 26.9GPa

High pressure behavior of sodium titanate nanotubes （Na2Ti2O5） is investigated by Raman spectroscopy in a diamond anvil cell （DAC） at room temperature. The two pressure-induced irreversible phase transitions are observed under the given pressure. One occurs at about 4.2 GPa accompanied with a new Raman peak emerging at 834 cm-1 which results from the lattice distortion of the Ti-O network in titanate nanotubes. It can be can be assigned to Ti-O lattice vibrations within lepidocrocite-type （H0.7Ti1.825V0.175O4＆#12539;H2O）TiO6 octahedral host layers with V being vacancy. The structure of the nanotubes transforms to orthorhombic lepidocrocite structure. Another amorphous phase transition occurs at 16.7 GPa. This phase transition is induced by the collapse of titanate nanotubes. All the Raman bands shift toward higher wavenumbers with a pressure dependence ranging from 1.58-5.6 cm-1/GPa.     

氦原子注入缺陷性纳米碳管的机理

采用经典分子动力学方法和TLHT势模型,研究了He注入不同管壁缺陷的单壁纳米碳管（SWNCT）的动力学过程,发现对应不同入射能量,He有4种典型的运动模式。管壁缺陷的尺寸对He在SWNCT中的吸附存储行为有很大影响。 Based on the classical molecular processes of He atom into SWCNT with wall dynamics method and TLHT potential model, the injection defects of different radius are studied. The calculated results indicate that there are four typical moving patterns of He atom with different injective energy and the size of wall defects make a great difference to the absorption and storage behavior of He into SWNT.     

原子吸收光谱法测定粉煤灰中氧化钾、氧化钠

采用火焰原子吸收光谱法测定粉煤灰中氧化钾、氧化钠含量。采用氢氟酸-高氯酸混合酸分解样品,以氯化锶消除其他元素的干扰。本方法操作简便、再现性好、灵敏度高,适用于粉煤灰中氧化钾、氧化钠含量的测定。     

Synthesis,Structural and Optical Studies of Barium Strontium Titanate Borosilicate Glasses Doped with Ferric Oxide

Various barium strontium titanate borosilicate glasses were prepared by a rapid melt-quench technique. Spectroscopic studies have been carried out on investigated glasses for their structural information. Infrared and Raman spectroscopic studies showed that these glasses are formed by glass-forming network of borate and silicate as well as network modifiers in the form of cations of alkaline earth atoms. The borate and silicate networks are modified by barium, strontium, titanium, and iron cations in glass matrix. The network of triborate unit is modified in tetraborate unit by adding ferric oxide in a glassy matrix. The optical studies are performed by ultraviolet-visible spectroscopy and it confirms that the band gap decreases with increase in the concentration of ferric oxide.     

IPTO薄膜制备及其在有机光电器件中的应用

新型IPTO(Pr Ti O3掺杂In2O3)薄膜的可见光透过率及导电性可与商业化的ITO薄膜媲美。采用双源电子束设备制备了一种新型的IPTO透明导电薄膜,通过开尔文探针法测试,其功函数为5.14 e V。为验证新型IPTO透明导电阳极对有机电致发光器件性能的影响,将IPTO替代商业化ITO作为阳极制备了有机电致发光器件。基于IPTO阳极的器件的亮度最大值为85 140 cd/m2,外量子效率最大值为3.16%,分别为以ITO为阳极的器件的3倍及1.13倍。这种性能的改善是由于IPTO具有较小的表面粗糙度及较高的功函数,可以降低阳极的注入势垒,有利于电荷向有机层注入,改善了器件内的空穴及电子的注入平衡。     

A Mode-Locked Soliton Erbium-Doped Fiber Laser with a Single-Walled Carbon Nanotube Poly-Ethylene Oxide Film Saturable Absorber

We present a simple, compact and low-cost mode-locked erbium-doped fiber laser （EDFL） using single-wMled carbon nanotubes （SWCNTs） embedded in a poly-ethylene oxide （PEO） thin film as a passive saturable absorber. The film is fabricated by using a prepared homogeneous SWCNT solution, which is mixed with a diluted PEO solution and cast onto a glass Petri dish to form, by evaporation, a thin film. The 50 μm-thick film is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate self-started stable soliton pulses operating at 1560.8nm. The soliton pulse starts to lase at a pump power threshold of 12.3mW with a repetition rate of 11.21MHz, a pulse width of 1.02ps, an average output power of 0.65 mW and a pulse energy of 57.98pJ.     

化学计量的氧化钠团簇阳离子结构的离子迁移质谱法研究

本文通过离子迁移质谱法研究了氧化钠团簇阳离子(Na_nO_m⁺,n≤11)的稳定结构. 质谱结果表明化学计量组成Na(Na₂O)_(n-1)/2⁺ (n=3、5、7、9和11)系列是稳定的,并且NaO(Na₂O)_(n-1)/2⁺ (n=5、7、9和11)系列作为二级稳定系列. 为了获得这些团簇离子的结构,通过离子迁移率测量实验测定离子和氦缓冲气体之间的碰撞截面. 同时计算了这些组合物优化结构的理论碰撞截面. 结果表明,Na(Na₂O)_(n-1)/2⁺和NaO(Na₂O)_(n-1)/2⁺的结构除了n=9之外,其它具有相似结构框架. Na(Na₂O)_(n-1)/2⁺所有的化合键位于钠和氧之间. 另一方面,NaO(Na₂O)_(n-1)/2⁺中除了Na-O键之外,还存在一个O-O氧键,表明NaO(Na₂O)_(n-1)/2⁺具有过氧化物离子(O₂^2-)作为Na(Na₂O)_(n-1)/2⁺的氧化物离子(O^2-) 的替代物. Na(Na₂O)_(n-1)/2⁺和NaO(Na₂O)_(n-1)/2⁺两种稳定系列都是闭壳组合物. 这些闭壳特征对氧化钠簇阳离子的稳定性具有强烈影响.     

Oxygen Diffusion into Multiwalled Carbon Nanotube Doped Polystrene Latex Films Using Fluorescence Technique

This study examines the oxygen diffusion into polystyrene (PS) latex/multiwalled carbon nanotube (MWNT) nanocomposite films (PS/MWNT) consisting of various amounts of MWNT via steady state fluorescence technique (SSF). PS/MWNT films were prepared from the mixture of MWNT and pyrene (P)-labeled PS latexes at various compositions at room temperature. These films were then annealed at 170 °C above glass transition (T_g) temperature of PS. Fluorescence quenching measurements were performed for each film separately to evaluate the effect of MWNT content on oxygen diffusion. The Stern-Volmer equation for fluorescence quenching is combined with Fick’s law for diffusion to derive the mathematical expressions. Diffusion coefficients (D) were produced and found to be increased from 1.1?×?10^?12 to 41?×?10^?12 cm²s^?1 with increasing MWNT content. This increase was explained via the existence of large amounts of pores in composite films which facilitate oxygen penetration into the structure.     

Intercalation of Platinum into a Graphene Film Formed on Molybdenum Carbide Mo2C

Technical Physics - It has been shown that platinum atoms evaporation on graphene covering molybdenum carbide Mo2C at T = 1000 K causes platinum intercalation into the graphene. In such a case, a...     

Molecular Dynamics Simulation of Strontium Titanate

The molecular dynamics method is used to simulate the thermophysical properties of SrTiO3 thermoelectric material in the temperature range 300-2200 K. The Morse-type potential functions added to the Busing-Ida type potential for interatomic interaction are used in the simulation. The interatomic potential parameters are determined by fitting to the experimental data of lattice parameters with temperature and the data reported in literature. The linear thermal expansion coefficient, heat capacity and lattice contributions to the thermal conductivity are analyzed. The results agree with the data reported in the literature.     

氧化石墨烯猝灭罗丹明6G荧光的机理研究

The fluorescence quenching of Rhodamine 6G (R6G) by graphene oxide (GO) was interrogated by R6G fluorescence measurements using a set of controlled GO samples with varied C/O ratios as the quencher.The carbonyl groups on the GO nanosheet turned to play a dominant role in quenching the R6G fluorescence.The quenching in the static regime can be described by the "sphere of action" model.The significant absorption of the R6G fluorescence by the ground-state complex formed between R6G and GO was identified to be responsible for the static quenching.This work offers helpful insights into the fluorescence quenching mechanisms in the R6G/GO system.     

纳米铂颗粒的控制生长

利用吸氢再还原法,进行逐步还原反应,合成了一系列大小的铂纳米颗粒;透射电镜和X光衍射分析表征的结果表明,铂颗粒是逐步长大的,经过32次生长,铂颗粒的平均粒径从1.8nm增加到14.1nm,平均增加步长约为0.4nm,且粒子均具较好的单分散性.     

氧化铝负载二苯基硫脲分离富集ICP-AES测定贵金属的研究

报道了氧化铝负载二苯基硫脲分离富集ICP-AES法同时测定痕量Pt,Pd,Au和Rh的新方法,研究了影响分离富集的各种条件(溶液酸度、流速、试样体积、洗脱剂的种类和体积及其共存离子的影响等)对测定上述痕量元素回收率的影响。在优化的实验条件下本方法的检出限分别为Au 0.0085,Pd 0.022,Pt 0.015和Rh 0.022μg·g~(-1),相对标准偏差小于5.0％,样品加标回收率在95％～105％之间。本方法已成功地应用于地质样品中痕量Pt,Pd,Au和Rh的测定。     

Initial Stages of Growth of Barium Zirconate Titanate and Barium Stannate Titanate Films on Single-Crystal Sapphire and Silicon Carbide

Physics of the Solid State - The initial stages of growth of barium zirconate titanate and barium stannate titanate ferroelectric films on single-crystal sapphire and silicon carbide are studied...     

Properties of Carbon Nanotube Optical Antennae

The properties of carbon nanotube as optical antennae have been studied. The equation of current distribution on a single antenna has been obtained by using conventional transmission line theories. The re-radiation lobe pattern of a single antenna and an antenna arrays have been gained by computer simulation.     

High Performance of Carbon Nanotube Refrigerators

Vapor‐compression dominates the market for refrigeration devices due to low cost and relatively high efficiency. However, the most efficient vapor refrigerants are either ozone depleting or global warming substances. Solid‐state cooling is a young field of research with promising results toward the development of new, efficient, and environment friendly technology for a new generation of refrigeration devices. One of these methods is based on the so‐called elastocaloric effect (ECE), which consists of a temperature variation of a system in response to the application of adiabatic stresses. Although most of the literature describes the study of ECE solid‐state cooling based on materials undergoing phase‐transitions, a study recently predicted that carbon nanotubes (CNTs) present ECE as large as 30 K for 3% of strain. This motivates research toward the development of nanorefrigerators. As nobody knows the efficiency of such an ECE‐based CNT nanorefrigerator, here, significantly high coefficient of performance values of 4.1 and 6.5, and extracted heat per weight as large as 40 J g^?1 are reported for a zigzag CNT nanorefrigerator operating in an Otto‐like thermodynamic cycle. This efficiency is shown to overcome that of some other ECE materials.