Phase changes of the ZrO2-12wt%Y2O3 film with Ar+ irradiation

The zirconia containing 12wt%Y₂O₃ thin films deposited by r.f. magnetron sputtering at 25℃ or 400℃, and then bombarded with Ar⁺ beam at room temperature were characterized with XRD before and after Ar⁺ bombardment. It is found that a series of phases formation and transformation happened, among them the mostimportant event is that T' phase appeared after Ar⁺ irradiation andthe content of the T' phase increased with the increase of Ar⁺ iondoses from 5×10¹⁵ to 6×10¹⁶ ions cm^-2.     

Sheet Resistance and Gas-Sensing Properties of Tin Oxide ThinFilms by Plasma Enhanced Chemical Vapor Deposition＊

Tin oxide (SnO2) thin films are prepared at different temperatures by plasmaenhanced chemical vapor deposition (PECVD). The structural characterizations of the films are investigated by various analysis techniques. X-ray diffraction patterns (XRD) show that the phase of SnO2 films are different at different deposition temperatures. The sheet resistance of the films decreases with increase of deposition temperature. X-ray photoelectron spectroscopy (XPS) shows that the SnO2 thin film is non-stoichiometric. The sheet resistance increases with increase in oxygen flow. Sb-doped SnO2 thin films are more sensitive to alcohol than carbon monoxide, and its maximum sensitivity is about 220％.     

Structural and Electrical Properties of Sulfur-Doped Diamond Thin Films

We report our observations on the higher carrier mobility and higher conductivity of sulfur-doped n-type diamond thin films synthesized by the hot filament chemical vapor deposi- tion （HFCVD）. The structural and electrical characterizations of the films are measured by X-ray diffraction （XRD）, Raman spectroscopy, scanning electron microscope （SEM）, energy dispersion X-ray spectra （EDX）, and Hall effect measurements. It is found that the sulfur atoms are in- corporated into the polycrystalline diamond films. The n-type conductivity of the films increases with the H2S concentration, and a conductivity of the films as high as 1.82 ~-l.cm-1 is achieved. The results show that the sulfur atom plays an important role in the structural and electrical properties of sulfur-doped diamond thin films.     

Ions Bombardment in Thin Films and Surface Processing

Ions bombardment is very important in thin films and surface processing.The ion energy and ion flux are two improtant parameters in ion bombardment.The ion current density mainly dependent on the plasma density gives the number of energetic ions bombarding the substrate.The self-bias voltage in plasma sheath accelerates plasma ions towards the substrate.RF discharge can increase plasma density and RF bias can also provide the insulator substrate with a plasma sheath.In order to choose and control ion energy,ion density,the angle of incidence,and ion species,ion beam sources are used.New types of electrodeless ion sources(RF,MW,ECR-MW) have been introduced in detail,In the last,the effects of ion bombardment on thin films and surface processing are presented.     

Thermodynamic Characteristics of Dusty Plasma Studied by Using Molecular Dynamics Simulation

Thermodynamic properties of a Debye-Yukawa system of particles are explored by using molecular dynamics simulation in the canonical ensemble.The excess free energy f of the Debye-Yukawa system is calculated by using two different approaches for the liquid phase,and the energy is obtained in a coupling parameter range of 0≤Γ≤100 and a wide range of the screening parameter κ.Simulation measurements for excess internal energy and pressure of the system over dimensionless parameters (κ,Γ) are also presented and compared with previous theoretical and simulated results.A Γ-expansion-fitting approach for the liquid phase is introduced with the expansion coefficients,which are functions of the screening parameter κ.The fitting coefficients are obtained by directly comparing them with the simulation measurements with a relative deviation of 1% or less.It is shown that the computational results provide a relatively simple method to calculate the excess internal energy and free energy in certain cases,which depend strongly on.     

Surface Treatment of Polypropylene Films Using Dielectric Barrier Discharge with Magnetic Field

Atmospheric pressure non-thermal plasma is of interest for industrial applications.In this study,polypropylene (PP) films are modified by a dielectric barrier discharge (DBD) with a non-uniform magnetic field in air at atmospheric pressure.The surface properties of the PP films before and after a DBD treatment are studied by using contact angle measurement,atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS).The effect of treatment time on the surface modification with and without a magnetic field is investigated.It is found that the hydrophilic improvement depends on the treatment time and magnetic field.It is also found that surface roughness and oxygen-containing groups are introduced onto the PP film surface after the DBD treatment.Surface roughness and oxygen-containing polar functional groups of the PP films increase with the magnetic induction density.The functional groups are identified as C-O,C=O and O-C=O by using XPS analysis.It is concluded that the hydrophilic improvement of PP films treated with a magnetic field is due to a greater surface roughness and more oxygen-containing groups.     

Gamma irradiation-induced effects on the properties of TiO_2 on fluorine-doped tin oxide prepared by atomic layer deposition

The effect of gamma irradiation with different doses(25–75 kGy) on TiO_2 thin films deposited by atomic layer deposition has been studied and characterized by X-ray diffraction(XRD),photoluminescence measurements,ultraviolet–visible(UV–Vis) spectroscopy,and impedance measurements.The XRD results for the TiO_2 films indicate an enhancement of crystallization after irradiation,which can be clearly observed from the increase in the peak intensities upon increasing the gamma irradiation doses.The UV–Vis spectra demonstrate a decrease in transmittance,and the band gap of the TiO_2 thin films decreases with an increase in the gamma irradiation doses.The Nyquist plots reveal that the overall charge-transfer resistance increases upon increasing the gamma irradiation doses.The equivalent circuit,series resistance,contact resistance,and interface capacitance are measured by simulation using Z-view software.The present work demonstrates that gamma irradiation-induced defects play a major role in the modification of thestructural,electrical,and optical properties of the TiO_2 thin films.     

Observation of the Structure of Tungsten Films Prepared by MOCVD

The tungsten films with ultra microstructure on CuCrZr alloy and China Low Activation Martensitic(CLAM) steel have been prepared by metal organic chemical vapor deposition(MOCVD).The films were produced by pyrolysing the tungsten hexacarbonyl at air or argon atmosphere.When formed at or below 400 C,they were poorly crystalized and the films showed low quality in thickness,density,bonding performance etc.While above this temperature,the properties of tungsten films have been improved,all the films consist of tungsten in the β-W.And β-W can change into α-W after heat treatment.As in other variations of pyrolysis,oxygen and carbon were observed.When filled with argon,the oxygen and carbon content would reduce apparently.Tungsten films prepared by MOCVD have stable chemical composition and microstructure.Besides,the properties of films on CuCrZr alloy are better than that on CLAM steel.     

Study of Control rod worth in the TMSR

Control rod is a primary control part of emergency control and power regulation in nuclear reactor. The main application of it is to control fast change of the reactivity. The theoretical analysis for the worth of control rod is necessary in the stage of design. Based on design requirements, some results are calculated. Firstly, control rod worth with different density of neutron absorber is calculated by MCNP here. Secondly, the study of integral and differential control rod worth is presented in this paper while the control rod is inserted into reactor core and total worth of three rods with different positions are also calculated. Finally, the effect of the axial and radial neutron flux in reactor core which is caused by the control rods is simulated. The simulation results of the control rods meet design requirements for TMSR.     

CEMS AND COUPLING EFFECT OF INTERLAYERS IN MULTILAYERED FeSi/Si AMORPHOUS FILMS

Multilayered FeSi/Si amorphous films with fixed FeSi layer thickness and different Si layer thicknesses have been studied by conversion electron Mossbauer spectroscopy at room temperature. The results showed that with decreasing the Si layer thickness, the hyperfine field of samples increased and the thickness of interface dead layers arisen from the atomic interdiffusion effect decreased. These are due to the coupling effect between the magnetic layers. When the Si layers are thinner than 0.88 nm, the direction of the magnetization is out of the film plane.     

Effects due to multiple scattering of fission fragments in layers of fissioning material

Computer simulation with the SRIM program is used to investigate the passage of fragments from ²³⁵U fission by thermal neutrons through 50–400 μg/cm² thick uranium layers. The calculations are performed in the two-fragment approximation: light ⁹⁷Mo and heavy ¹³⁹Ba. The energy spectra of the fission fragments emanating from the layer are calculated and the effects due to multiple scattering of the fragments in thin layers are estimated. __________ Translated from Atomnaya énergiya, Vol. 100, No. 1, pp. 57–63, January, 2005.     

Atomic mobility in energetic cluster deposition

This paper tries to outline the influence of atomic mobility on the initial fabrication of thin films formed by LECBD. Based on our recent studies on low-energy cluster beam deposition (LECBD) by molecular dynamics simulation, two examples, the deposition of small carbon clusters on Si and diamond surfaces and AI clusters on Ni substrate, were mainly discussed. The impact energy of the cluster ranges from 0.1 eV to 100 eV. In the former case,the mobility and the lateral migration of surface atoms, especially the recoil atoms, are enhanced with increasing the impact energy, which promote the film to be smoother and denser. For the latter case, the transverse kinetic energy of cluster atoms, caused mainly by the collision between moving cluster atoms, dominates the lateral spread of cluster atoms on the surface, which is contributive to layer-by-layer growth of thin films. Our result is consistent with the experimental observations that the film structure is strongly dependent on the impact energy. In addition, it elucidates that the atomic mobility takes a leading role in the structure characteristic of films formed by LECBD.     

Atomic layer deposition of copper thin film and feasibility of deposition on inner walls of waveguides

Copper thin films were deposited by plasma-enhanced atomic layer deposition at low temperature, using copper(I)-N,N′-di-sec-butylacetamidinate as a precursor and hydrogen as a reductive gas. The influence of temperature, plasma power, mode of plasma, and pulse time, on the deposition rate of copper thin film, the purity of the film and the step coverage were studied.The feasibility of copper film deposition on the inner wall of a carbon fibre reinforced plastic waveguide with high aspect ratio was also studied. The morphology and composition of the thin film were studied by atomic force microscopy and x-ray photoelectron spectroscopy,respectively. The square resistance of the thin film was also tested by a four-probe technique. On the basis of on-line diagnosis, a growth mechanism of copper thin film was put forward, and it was considered that surface functional group played an important role in the process of nucleation and in determining the properties of thin films. A high density of plasma and high free-radical content were helpful for the deposition of copper thin films.     

Intense Yellow Photoluminescence from Silicon Oxynitride Films Prepared by Dual Ion Beam Sputtering

In this work, results on the study of the structure and photoluminescence (PL) properties of SiOxNy thin films are presented. The films were deposited at room temperature using a dual-ion-beam co-sputtering system. The XRD and TEM results show that the deposited films have an amorphous structure. In the XPS result, we find N 1 s spectra consist of one symmetric single peak at 397.8 eV, indicating that the nitrogen atoms are mainly bonded to silicon. It is in agreement to the result of FTIR. In SiOxNy films, an intense single PL peak at 590 nm is observed. Furthermore, with the increase of the N content in the SiOxNy films, the intensity of the PL peak at 590 nm increases a lot. The PL peak of 590 nm is suggested to originate from N-related defects.     

Investigation of combined degrader for proton facility based on BDSIM/FLUKA Monte Carlo methods

The significant advantage of proton therapy over other particle-based techniques is in the unique physical characteristics of the Bragg peak. It can achieve a highly conformal dose distribution and maximize the probability of tumor control by varying the irradiation energy. Most proton facilities use cyclotrons for fixed energy beam extraction and are equipped with degrader and collimator systems for energy modulation and emittance suppression.However, interactions between charged particles and ...     

153Sm-EDTMP体内外的竞争结合分析

With the waters ultrahydrogel^TM 120 μm HPLC column(7.8 mm×300 mm),several experiments have been finished, including the in vitro binding assay of ¹⁵³Sm-EDTMP, ¹⁵³SmCl₃ with the Cys, BSA, mouse plasma; HPLC analysis of the urine and the extracting solution of liver homogenate after having injected the ¹⁵³Sm-EDTMP and ¹⁵³SmCl₃ 2 h; HPLC analysis of the production (¹⁵³Sm-EDTMP)radiation self-decomposition with large dose. For the HPLC analysis, the condition is the mobile phase of 0.85 mol/mL PBS (pH=7.5), flow rate of 0.5 mL/min, sampling of 15 μL. The results are following (1) The ¹⁵³SmCl₃ not only is able to bind with the mouse plasma in vitro, but also is able to be absorbed by liver in vivo; (2) ¹⁵³Sm-EDTMP is not bind with the mouse plasma, the Cys and BSA in vitro & vivo; ¹⁵³Sm-EDTMP is not found in the extracted solution of liver homogenate at n(EDTMP)∶n(Sm)≥5∶1; ¹⁵³Sm-EDTMP is not decomposed in the urine, ¹⁵³Sm-EDTMP is stable in vivo; (3) ¹⁵³Sm-EDTMP radiation self-decomposition is not detected with large dose in the term of validity (6 d), but two small degradation peaks have been found in the production solution after 60 d, the radiochemistry purity of production is always great than 98 % during the period.     

Simulation of Cascade in BCC Iron

<正>When the material is irradiated,the incident particles interact with the lattice atoms of materials,experiencing the processes of collision,defect formation and annealing,which eventually lead to the evolution of the microstructure inside the material.After the collision of incident particles and lattice atoms,primary knock-on atoms(PKA)are produced first.Then,PKA trigger a     

Ionization wave propagation and cathode sheath formation due to surface dielectric-barrier discharge sustained in pulsed mode

This work deals with the experimental study of a surface dielectric-barrier discharge, as a part of the ongoing interest in the control of plasma induced electro-fluid dynamic effects(e.g. plasma actuators). The discharge is generated using a plasma reactor consisting of a fused silica plate which is sandwiched between two printed circuit boards where the electrodes are developed. The reactor is driven by narrow high voltage square pulses of asymmetric rising(25 ns) and falling(2.5 μs) parts,whi...     

Mechanism of high growth rate for diamond-like carbon films synthesized by helicon wave plasma chemical vapor deposition

A high growth rate fabrication of diamond-like carbon(DLC)films at room temperature was achieved by helicon wave plasma chemical vapor deposition(HWP-CVD)using Ar/CH_4gas mixtures.The microstructure and morphology of the films were characterized by Raman spectroscopy and scanning electron microscopy.The diagnosis of plasma excited by a helicon wave was measured by optical emission spectroscopy and a Langmuir probe.The mechanism of high growth rate fabrication for DLC films by HWP-CVD has been discussed.The growth rate of the DLC films reaches a maximum value of 54μm h~(-1)at the CH_4flow rate of 85 sccm,which is attributed to the higher plasma density during the helicon wave plasma discharge.The CH and H_αradicals play an important role in the growth of DLC films.The results show that the H_αradicals are beneficial to the formation and stabilization of C=C bond from sp~2to sp~3.     

Experimental Investigation on Airfoil Shock Control by Plasma Aerodynamic Actuation

An experimental investigation on airfoil （NACA64-215） shock control is performed by plasma aerodynamic actuation in a supersonic tunnel （Ma -= 2）. The results of schlieren and pressure measurement show that when plasma aerodynamic actuation is applied, the position moves forward and the intensity of shock at the head of the airfoil weakens. With the increase in actuating voltage, the total pressure measured at the head of the airfoil increases, which means that the shock intensity decreases and the control effect increases. The best actuation effect is caused by upwind-direction actuation with a magnetic field, and then downwind-direction actuation with a magnetic field, while the control effect of aerodynamic actuation without a magnetic field is the most inconspicuous. The mean intensity of the normal shock at the head of the airfoil is relatively decreased by 16.33%, and the normal shock intensity is relatively reduced by 27.5% when 1000 V actuating voltage and upwind-direction actuation are applied with a magnetic field. This paper theoretically analyzes the Joule heating effect generated by DC discharge and the Lorentz force effect caused by the magnetic field. The discharge characteristics are compared for all kinds of actuation conditions to reveal the mechanism of shock control by plasma aerodynamic actuation.