溶胶—凝胶法制备SiO2基片Er^3＋：Al2O3光学薄膜

用溶胶—凝胶法在SiO2基片上提拉制备了掺Er^3 ：Al2O3光学薄膜。采用扫描电子显微镜、原子力显微镜、差热—热重分析仪、X射线衍射仪研究了掺Er^3 ：Al2O3光学薄膜的肜貌和结构特性。在900℃烧结后，SiO2基片上提拉15次形成厚度8μm掺摩尔比0．01Er^3 的面心立方结构γ-Al2O3薄膜具有明显(110)择优取向，掺摩尔比0．01Er^3 对γ—Al2O3的品体结构和结晶生长过程木产生显著影响。薄膜具有均匀多孔结构，平均粒径为30～100nm，平均孔径为50～100nm，表面起伏度为10～20nm。掺摩尔比0．01Er^3 ：rAl2O3薄膜，获得了中心波长为1．534μm(半峰全宽为36nm)的光敛发光谱。     

Thermodynamical Phase Equilibrium of Iron Nitrides at Low Temperatures

The presence of α-Fe(N),γ‘-Fe4N and ε-Fe2N1-x phases and the phase equilibrium between αFe(N) and γ′-Fe4N,and γ′-Fe4N and ε-Fe2N1-x have been studied at low temperatures below 350℃ ,according to the binary Fe-N phase diagram calculated using the sublattice-compound energy model,The α-Fe(N),γ′-Fe4N and ε-Fe2N1-x phases would be thermodynamically stable at the low temperatures.Thermodynamic phase equilibrium of the iron nitrides is supproted by the experimental results,explaining the phase formation and its stability in the Fe-N system at low temperatures.     

Green and red up-conversion emissions and thermometric application of Er^3＋-doped silicate glass

The green and red up-conversion emissions centred at about 534, 549 and 663 nm of wavelength, corresponding respectively to the ^2H11/2 → ^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 → ^4I15/2 transitions of Er^3＋ ions, have been observed for the Er^3＋-doped silicate glass excited by a 978 nm semiconductor laser beam. Excitation power dependent behaviour of the up-conversion emission intensity indicates that a two-photon absorption up-conversion process is responsible for the green and red up-conversion emissions. The temperature dependence of the green up-conversion emissions is also studied in a temperature range of 296-673 K, which shows that Er^3＋-doped silicate glass can be used as a sensor in high-temperature measurement.     

镱铒共掺Al2O3光波导放大器的净增益特性

将中频磁控溅射方法沉积制备的镱铒共掺Al2O3薄膜刻蚀成矩形截面、直线通道的光波导放大器.测量了净增益与抽运功率的关系，结果表明：净增益随抽运功率近似线性增加，阈值抽运功率为18 mW；抽运功率为68 mW时，长2.24 cm 的光波导放大器净增益为8.44 dB.数值模拟结果显示，相同抽运功率下的净增益为10.6 dB.     

Er3+掺杂SiO2复合的Al2O3粉末结构及光致发光特性

采用溶胶-凝胶(sol-gel)工艺制备0.1 mol% Er3+掺杂Al2O3体系和SiO2-Al2O3复合体系粉末. 实验结果表明:5 mol%的SiO2复合加入Al2O3抑制γ→θ和θ→α相转变. 掺0.1 mol%Er3+:Al2O3体系粉末,900℃烧结,在1.47-1.63 μm波段内光致发光(PL)谱为中心波长1.53 μm、半高宽56 nm的单一宽峰,1000-1200℃烧结,劈裂为多峰PL谱. 掺0.1 mol%Er3+:SiO2-Al2O3复合体系粉末,在高达1200℃烧结,仍保持中心波长1.53 μm的单一宽峰PL谱,由于-OH更完全的脱除,PL强度较900℃烧结Al2O3体系,SiO2-Al2O3复合体系均提高1个数量级.     

阶跃掺杂Er∶Al2O3光波导放大器增益特性数值模拟

构建了纵向阶跃非均匀掺杂的掺铒Al2O3光波导放大器理论模型，利用有限元法、速率方程和传输方程，数值模拟了放大器的净增益特性.计算结果表明：阶跃掺杂掺铒Al2O3光波导放大器提高了抽运效率，净增益和信号光输出功率比优化后的均匀掺杂光波导放大器分别提高了9.2%和90.5%，长度却缩短了16.9%.     

γN相/Si3N4陶瓷球摩擦副在干摩擦条件下的磨损机制转变图

采用等离子体源渗氮技术在AISI 316奥氏体不锈钢表面制备γN相层.研究了γ_N相层/Si_3N_4陶瓷球摩擦副在球-盘式磨损仪、载荷2~8 N、滑动速度0.15~0.22 m/s干摩擦条件下的磨损行为,基于详细的磨痕表面和磨屑显微分析,通过响应面分析法建立γ_N相层在此状态下的磨损机制转变图.结果表明:γ_N相层在低载荷下的磨损机制主要是氧化磨损;而在较高载荷下的磨损机制主要是塑性变形和磨粒磨损.     

氧等离子体改性聚乙烯表面的疏水性过回复机制

用200 W射频容性耦合氧等离子体处理低密度聚乙烯(LDPE)表面1 min,研究了老化温度及时间对LDPE表面成分、形貌和润湿性的影响.扫描电子显微镜结果表明,等离子体改性LDPE表面出现纳米凸点织构,在60和90℃老化24 h后纳米凸点织构特征基本保持稳定.X射线光电子能谱分析表明,等离子体改性LDPE表面经60℃老化24 h后,C—C含量由76.9%增至83.0%,C—O,C O和O—C O含量分别由16.4%,2.2%和4.5%降至13.1%,1.9%和2.0%.经90℃老化24 h后,C—C含量较60℃老化表面增至84.1%,C—O含量分别降至10.1%,C O和O—C O含量分别增至3.1%和2.7%.等离子体改性LDPE表面接触角由97.2°降至42.3°,经60℃老化24 h后接触角增至95.9°,经90℃老化24 h后接触角增至104.2°,等离子体改性LDPE表面发生"疏水性过回复".根据含有粗糙因子的接触角随时间演变模型,得到了具有纳米凸点织构LDPE表面在不同老化温度下的可移动极性基团所占面积分数(fpm)、固定极性基团所占面积分数(fpim)和特征时间常数(τ)3个成分重构参数,解释了"疏水性过回复"现象.     

Research on ZrO2 Thermal Barrier Coatings Modified by High-Intensity Pulsed Ion Beam

We report a modification method for ZrO2 thermal barrier coatings （TBCs） by high-intensity pulsed ion beam （HIPIB） irradiation. Based on the temporal and spatial distribution models of the ion beam density detected by Faraday cup in the chamber and the ions accelerating voltage, the energy deposition of the beam ions in ZrO2 is calculated by Monte Carlo method. Taking this time-dependent nonlinear deposited energy as the source term of two-dimensional thermal conduction equation, we obtain the temporal and spatial ablation process of ZrO2 thermal barrier coatings during a pulse time. The top-layer TBC material in thickness of about 0.2 μm is ablated by vaporization and the coating in thickness of 1 μm is melted after one shot at the ion current density of 200 A/cm^2. This calculation is in reasonable agreement with those measured by HIPIB irradiation experiments. The melted top coat becoming a dense modification layer due to HIPIB irradiation seals the gaps among ZrO2 crystal dusters, and hence barrels the direct tunnel of oxygen.     

阶跃掺杂Er∶Al2O3光波导放大器增益特性数值模拟

构建了纵向阶跃非均匀掺杂的掺铒Al2O3光波导放大器理论模型,利用有限元法、速率方程和传输方程,数值模拟了放大器的净增益特性.计算结果表明:阶跃掺杂掺铒Al2O3光波导放大器提高了抽运效率,净增益和信号光输出功率比优化后的均匀掺杂光波导放大器分别提高了9.2%和90.5%,长度却缩短了16.9%.