FORMATION OF HEXAGONAL Co_(2—3)C IN Co BY CARBON ION IMPLANTATION

Co thin films were subjected to 50 keV carbon ion implantation.At the dose of 2.5× 10^(17)/cm^2,a hexagonal Co-carbide phase was observed for the first time.The lattice con- stants from electron diffraction are a=0.2685 nm and c=0.4335 nm.The phase does not dis- appear until the dose of 9×10^(17)/cm^2.Auger spectra showed that the stoichiometry was Co_(2-3)C.The behavior of the ferromagnetic carbides along the descending sequence of Ni-Fe-Co by Fermi energy of solids was interpreted.Furthermore,based on the kinetic con- dition of phase transformation and the band theory of solids,a possible explanation about the difference of the results of ion-metallurgy and thermal metallurgy was proposed.

Synthesis of Poly[(3-octanoylpyrrole-2,5-diyl)-p-(N,N-dimethylamino)benzylidene] and Its Properties by Nitrogen Ion Implantation

A novel soluble π-conjugated polymer, poly[(3-octanoylpyrrole-2,5-diyl)-p-(N,N-dimethylamino)benzylidene](POPDMABE), was synthesized firstly by the condensation of 3-octanoylpyrrole with para-dimethylaminobenzaldehyde. The chemical structure of the polymer was characterized by FTIR and 1H NMR spectrometries. The polymer is a potential nonlinear optical(NLO) material. According to the function of optical forbidden band gap(E_g) and photon energy(hν), the optical forbidden band gaps of the polymer before and after ion implantation were calculated. The resonant third-order nonlinear optical properties of POPDMABE before and after ion implantation were also studied by using the degenerate four-wave mixing(DFWM) technique at 532 nm. When the energy is 25 keV and the dose is 2.2×10 17 ions/cm 2, the {polymer′s} optical forbidden band gap is about 1.63 eV which is smaller than that of the non-implanted sample(1.98 eV) and the resonant third-order NLO susceptibility of POPDMABE is about 4.3×10 -7 esu, 1 order of magnitude higher than that of the non-implanted sample(4.1×10 -8 esu). The results show that nitrogen ion implantation is an effective method to improve the resonant third-order NLO property of the polymer.

Spectral Properties and Sensitization of Ce^(3+) and Eu^(2+) Codoped Calcium Zinc Chlorosilicate

The Ce^3+ and Eu^2+ ions codoped calcium zinc chlorosilicate Ca_8Zn(SiO_4)_4Cl_2 phosphors have been synthesized for the first time. The diffuse reflection, excitation and emission spectra of Ca_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ have been measured at room temperature. The luminescence sensitizaiton of Eu^2+ by Ce^3+ inCa_8Zn(SiO_4)_4Cl_2∶Ce^3+, Eu^2+ has been expounded under the excitation of ultraviolet light and the efficient nonradiative energy transfer from Ce^3+ to Eu^2+ in this system is confirmed.

A New High Efficiency Green Luminescent Material──the System Al_2O_3-B_2O_3 Containing Ce^(3+) and Tb^(3+) Ions

To obtain high efficiency luminescent materials, the system Al2O3-B2O3 containing Ce3+ andTb3+ ions with variation of B2O3-content, has been prepared by Al2O3, H3BO3, CeO2 and Tb4O7 underreducing atmosphere at 1250i . It is notable that the brightness of the sample with appropriatecomposition is similar to that of commercial phosphorous containing Ce3+ and Tb3+, indicating that a newhigh efficency green luminescent material was obtained with appropriate B2O3-content.

INVESTIGATION OF SURFACE DAMAGE OF LiNbO_3 IMPLANTED BY Ti ION

In this paper, damages and annealing effects of X,Y and Z cut LiNbO-3 implanted by 350keV high energy Ti (1.5 x 1017 / cm2) are studied. The surface damages of X,Y cut plates are nearly amorphous, but the surface damage of Z cut does not reach saturation. Radiation damage is mainly due to Nb moving atoms and Ti atoms occupy the interstitial sites. By annealing the sample at 1000℃, most damage is removed from the boundary between implanted layer and LiNbO3 base to surface.

Characteristics of La_0.7Sr_0.3MnO₃Films Modified by Aluminum Ions Implantation and Post-Implantation Annealing

The magnetron sputtered La0.7Sr0.3MnO3 films were implanted with different doses (5 ′ 1015 ions×cm?2 and 5 ′ 1016 ions×cm-2) of Al ions at different negative pulsed voltages (30 kV and 50 kV) by plasma based ion implantation and then annealed at 973 K for 1 h in air. The microstructure, surface morphologies, surface roughness, metal-insulator transition and room temperature emittance properties of the post-implantation annealed films were investigated and compared with those of the La0.7Sr0.3MnO3 film annealed at 973 K for 1 h in air. The results indicate that the post- implantation annealed films show single perovskite phase and obvious (100) preferred orientation growth. The Mn-O bond length, surface roughness and metal-insulator transition temperature (TMI) of the films can be effectively adjusted by changing implantation voltage or implantation dose of Al ions. However, the change of implantation parameters just has a small effect on room temperature emittance of the films. Compared with the annealed film, the post-implantation annealed films have shorter Mn-O bond length and lower room temperature emittance. The TMI of the films implanted at low voltage is lower than that of the annealed film, which mainly results from the degradation of oxidization during annealing process and the part displacement of Mn3+-O2+- Mn4+ double exchange channels by Al3+-O2?-Mn4+. The post-implanted annealed film implanted at 50 kV/5 ′ 1016 ions×cm-2 has a higher TMI than the annealed film, which is 247 K. The increase of TMI of the film implanted with high dose of Al ions at high voltage can be attributed to the improvement of microstructure.

Effects of Ce^(3+) on Chloroplast Senescence of Spinach under Light

The effects of Ce^3 ＋ on the chloroplast senescence of spinach under light were studied. The results show that when the chloroplasts are illuminated for 1, 5 and 10 min with 500 μmol·cm^-2· min^-1 light intensity, the oxygen evolution rate is rapidly increased. When the chloroplasts are treated for 20, 30 and 40 min with 500 μmol·cm^-2·min^-1 light intensity, the oxygen evolution rate is gradually decreased. While spinach is treated with 16μmol·L^-1 Ce^3＋ , the rate of oxygen evolution of chloroplasts in different illumination time （1,5, 10, 20, 30, 40 min） is higher than that of control, and when illumination time is over 10 min, the reduction of the oxygen evolution rate is lower than that of control. It suggests that Ce^3＋ treatment can protect chloroplasts from aging for long time illumination. The mechanism research results indicate that Ce^3＋ treatment can significantly decrease accumulation of active oxygen free radicals such as O2^- and H2O2, and reduce the level of malondialdehyde （MDA）, and maintain stability of membrane structure of chloroplast under light. It is shown that the redox took place between cerium and free radicals, which are eliminated in a large number, leading to protect the membrane fiom peroxidating.

Guiding properties of proton-implanted Nd^(3+)-doped phosphate glass waveguides

We report on the fabrication and properties of an optical waveguide in Nd^3＋-doped phosphate glass. The planar waveguide was obtained by 550-ke V proton implantation with a dose of 8.0×10^16 ions/cm^2. The proton–glass interaction was simulated by the stopping and range of ions in matter（SRIM software）. The characteristics of the waveguide including the refractive index profile and the near-field intensity distribution were studied by the reflectivity calculation method and the end-face coupling technique. The optical waveguide demonstrated multi-mode behavior at the wavelength of 632.8 nm.The propagation features of the proton-implanted Nd^（3＋）-doped phosphate glass waveguide shows its potential to operate as an integrated photonic device.

Effect of Chemical Doping and Ion Implantation on Cond uctivity of Poly(p-phenylene vinylene) Derivatives

The surface conductivity of poly [2-methoxy-5-(3 '-methyl)butoxy]-p-phenylene vinylene (PMOMBOPV) films doped with FeCl3 and H2 SO4 by chemical method and implanted by N+ ions was studied and the comparison of environmental stability of conductive behavior was also investigated. The energy and dose of N+ions were in the rang 15～35 kev and 3. 8× 1015 ～9. 6× 1016 ions/cm2, respectively. The conductivity of PMOMBOPV film was enhanced remarkably with the increases of the energy and dose of N+ ions. For example, the conductivity of PMOMBOPV film was 3.2 × 10-2 S/cm when ion implantation was performed with an energy of 35 kev at a dose of 9. 6 × 1016 ions/cm2 , which was almost seven orders of magnitude higher than that of film unimplanted. The environmental stability of conductive behavior for ionimplanted film was much better than that of chemical doped films. Moreover, the conductive activation energy of ion-implanted films was measured to be about 0.17 eV.

低束流Nd^(3+)注入硅基薄膜结构及光致发光的研究

采用金属蒸气真空弧离子源（MEVVA）制备了掺Nd3+硅基薄膜材料。用扫描电镜和X射线衍射观测了表面形貌及物相结构随注入条件、退火温度的变化,样品经1000°C退火处理形成NdSi相钕硅化合物。测试了样品的光致荧光谱,在254nm（～5.0eV）光激发下获得了紫蓝光区（410～430nm）和红光区（746nm）荧光发射,随着退火温度的升高,荧光强度增大。746nm红光光谱显示了Nd3+特征光发射跃迁（4F7/2,4S3/2→4I9/2）,讨论了注入层结构与荧光发射的相关性。

N^+离子注入α-Al_2O_3的表面结构及摩擦性能

利用Ｘ射线衍射、光电子能谱、电镜、Ｒａｍａｎ光谱等现代测试手段分析了Ｎ＋注入α－Ａｌ２Ｏ３前后材料表面的相组成、原子组成及显微结构，对离子注入改性Ａｌ２Ｏ３表面的摩擦、磨损行为进行了研究。结果表明１×１０１７Ｎ＋／ｃｍ２离子注入Ａｌ２Ｏ３后，Ｃ在Ａｌ２Ｏ３表面上的污染所形成较牢固的膜和注入增加的表面硬度，使Ａｌ２Ｏ３的润滑性能有明显的改善。同时，Ｎ＋注入Ａｌ２Ｏ３后产生的表面压应力使陶瓷表面裂纹变短、变细、变圆等，提高了陶瓷的磨损性能。

C^+离子注入对Al_2O_3单晶表面韧性的影响

对Ｃ＋注入α－Ａｌ２Ｏ３单晶样品的表面残余应力、显微硬度、断裂韧性和注入层破坏临界负荷等力学性能的变化进行了研究．结果表明：Ｃ＋离子注入Ａｌ２Ｏ３单晶时，表面层的破碎临界负荷增大．在１×１０１７Ｃ＋／ｃｍ２时表面产生的残余压缩应力达到最大，而更高剂量的注入使表面层产生非晶化，降低了表面的残余压缩应力．在５×１０１７Ｃ＋／ｃｍ２注入剂量时，由于表面残余压缩应力和表面非晶化的协同效应使注入层具有较高的表面韧性和表面层耐破碎临界负荷．

离子注入改性聚[2-甲氧基-5-(3’-甲基)丁氧基]对苯乙炔微观结构与性能

采用低能氮正离子(N+)对π共轭高分子聚[2甲氧基5(3’甲基)丁氧基]对苯乙炔(MMB PPV)薄膜进行离子注入改性,注入剂量为9.6×1016ions/cm2,能量为30keV。利用红外光谱、紫外可见吸收光谱、X射线衍射、透射电镜及热失重等手段对离子注入改性MMB PPV薄膜的微观结构及热学性能进行研究。红外光谱显示,注入后分子侧链烷氧取代基的C H振动峰强度减弱,同时在3442、1622cm-1等处出现了N H键的振动峰;薄膜的紫外可见吸收光谱向长波方向移动,且在可见光区范围内的吸收强度增加;离子注入使聚合物分子链排列更加规整,取向度明显增大,结晶性能大大改善;经过离子注入后,聚合物材料的初始分解温度由未注入时的245.64℃提高至280.52℃,分子的热稳定性能显著增强。

电化学腐蚀对Si：Er^（3＋）材料中Er^（3＋）发光的影响

利用离子注入技术在硅片表面制备了不同Ｅｒ３＋注入剂量的Ｓｉ：Ｅｒ３＋样品，研究了电化学过程对Ｓｉ：Ｅｒ３＋样品中Ｅｒ３＋发光的影响．样品低温红外光致发光实验证明：电化学过程同样在Ｓｉ：Ｅｒ３＋样品的硅基质晶体中引入了大量的深能级局域态，且这些局域态较难用退火方式进行控制．值得注意的是电化学过程同时使Ｓｉ：Ｅｒ３＋样品中Ｅｒ３＋的１．５４μｍ光致发光效率提高很多，同时谱峰增宽，伴线更丰富．

电化学引起Si：Er^（3＋）材料1．54μm发光增强

利用７７Ｋ红外光致发光实验研究了电化学过程对离子注入Ｓｉ：Ｅｒ（３＋）样品的光致发光影响．实验表明：电化学过程除在Ｓｉ：Ｅｒ（３＋）样品硅基质晶体中引入大量的深能级局域态外，还使Ｓｉ：Ｅｒ（３＋）样品中Ｅｒ（３＋）的１．５４μｍ光致发光效率明显提高，且Ｅｒ（３＋）发光峰增宽，次峰更丰富．

Investigation on n-Type(-201)β-Ga_(2)O_(3)Ohmic Contact via Si Ion Implantation

Heavy doped n-typeβ-G_(2)O_(3)(HD-G_(2)O_(3))was obtained by employing Si ion implantation technology on unintentionally dopedβ-G_(2)O_(3)single crystal substrates.To repair the G_(2)O_(3)lattice damage and activate the Si after implantation,the implanted substrates were annealed at 950℃,1000℃,and 1100℃,respectively.High-resolution X-ray diffraction and high-resolution transmission electron microscopy show that the ion-implanted layer has high lattice quality after high-temperature annealing at 1000℃.The minimum specific contact resistance is 9.2×10^(-5)Ω·cm^(2),which is attributed to the titanium oxide that is formed at the Ti/G_(2)O_(3)interface via rapid thermal annealing at 480℃.Based on these results,the lateralˇ-G_(2)O_(3)diodes were prepared,and the diodes exhibit high forward current density and low specific on-resistance.

Cu注入 PTC BaTiO_3 陶瓷的复阻抗谱研究

对传统工艺法制备的ＢａＴｉＯ３陶瓷进行了Ｃｕ元素的离子注入。在较宽的频率范围内和不同温度下对样品进行了阻抗测量，确定了样品的等效电路。根据阻抗谱分析了Ｃｕ注入ＢａＴｉＯ３多晶陶瓷的晶粒、晶界电阻与温度的关系。结果表明，选择合适的注入剂量的样品，其ＰＴＣ性能优于非注入样品。

Synthesis and fluorescence properties of cerium-KMgF_3 through a solvothermal process

Phosphor of KMgF3：Ce^3＋ is synthesized through solvothermal method at 180 ℃ and characterized by means of X-ray powder diffraction （XRD） and environment scanning electron microscopy （ESEM）. X-ray photoelectron spectroscopy （XPS） is applied to the study of the energy band structure of KMgF3：Ce^3＋ and confirms the oxygen content of the product is very low. The fluorescence spectra of the rare-earth ion-doped KMgF3 is investigated by the fluorescence spectrophotometer. In the emission spectra, there is a broadband emission with a maximum center located at 306 nm arising from d-f transition of Ce^3＋ in the host. This will be useful for ultraviolet tunable lasers.

Surface modification of ultra-high molecular weight polyethylene for joint prosthesis and sports applications

The recent progresses in the surfaee modification of ultra high molecular weight polyethylene (UHMWPE) using such advanced surface modification technologies as conventional ion implantation (CⅡ), new plasma immersion ion implantation (PⅢ) and novel active screen plasma (ASP), were all reported. Significantly improved wear resistance was achieved, which has great potential for extending the life-span of joint replacement prostheses and enhancing the performance of such sports equipment as skis and snowboards.

First-principles calculations on implanted TiO_2 by 3d transition metal ions

3d transition metal (V, Cr and Fe) ions are implanted into TiO2 by the method of metal ion implantation. The electronic band structures of TiO2 films doped 3d transition metal ions have been analyzed by ab initio band calculations based on a self-consistent full-potential linearized augmented plane-wave method within the first-principle formalism. Influence of implantation on TiO2 films is examined by the method of UV-visible spectrometry. The results of experiment and calculation show that the optical band gap of TiO2 films is narrowed by ion implantation. The calculation shows that the 3d state of V, Cr and Fe ions plays a significant role in red shift of UV-Vis absorbance spectrum.