金属氢化物力学性能的第一性原理研究

采用第一性原理方法详细研究了氟化钙结构的多种金属氢化物MH₂ (M= La, Nd, Gd, Tb, Y, Dy, Ho, Er, Lu, Sc, Ti, Zr, Hf)的力学性质(弹性常数、体弹模量、剪切模量、杨氏模量).计算结果表明, MH₂ (M= La, Nd, Gd, Tb, Y, Dy, Ho, Er, Lu, Sc)在低温下具有稳定的氟化钙结构,其抵抗体积形变, 切应变和拉伸(或压缩)形变的能力从LaH₂, NdH₂, GdH₂, TbH₂, YH₂, DyH₂, HoH₂, ErH₂, LuH₂到ScH₂逐次递增, 而MH₂ (M= Ti, Zr, Hf)在低温下的氟化钙结构不稳定.通过对两种稳定的氢化物(TbH₂, ErH₂) 和两种不稳定的氢化物(TiH₂, HfH₂)的电子态密度以及差分电荷密度进行对比, 发现它们的稳定性与金属和氢之间的相互作用有密切关系.     

锆吸氘和氚的动力学同位素效应

应用反应速率分析方法,在高真空金属系统上测定了锆在恒容体系和450～630 ℃范围内吸收氘和氚的p-t曲线。由p-t曲线可知,在同一温度下,锆吸氚的速率低于锆吸氘的速率;而随着温度的升高,由于解吸逆反应的影响,锆吸氚(氘)的反应速率降低。根据p-t曲线计算了吸气反应在不同温度的速率常数,得到锆吸氘和氚的表观活化能分别为(-25.9±0.7)和(-16.8±0.8)kJ·mol^-1。从活化能数据可以看出     

放射性洗涤废水的SDBS光催化降解研究

光催化氧化是处理含表面活性剂放射性洗涤废水的新途径。本文采用臭氧/纳米二氧化钛光催化的方法,对十二烷基苯磺酸钠(SDBS)进行降解研究,考察了SDBS溶液初始浓度、溶液pH、光照时间、臭氧通入量、反应温度等因素对其降解效果的影响。并添加裂片核素~(90)Sr~(2+)和~(137)Cs~+,评价本方法对含SDBS的放射性洗涤废水的降解效果。结果表明,采用臭氧/纳米二氧化钛光催化系统对于300mg·L~(-1)的SDBS溶液进行降解,30分钟SDBS的去除率可达99. 95%,且放射性核素~(90)Sr~(2+)、~(137)Cs~+的同时存在对O_3/纳米TiO_2光催化降解SDBS的性能几乎不影响; FT-IR测试结果表明不同浓度的SDBS的去除率,皆与反应时间正相关关系。     

铒、钪膜中离子注入氦的热解析行为

采用热解析法初步研究了铒、钪膜中离子注入氦的热解析行为。研究结果表明:同种元素铒中离子注入氦的热释放峰位相同,但膜的致密性将影响氦的释放量,结构疏松的膜中存在的孔洞是氦的快速释放通道;在相同注入剂量和能量条件下,铒、钪膜中注入氦的热释放峰位不同,这可能与氦在铒、钪膜中的深度分布及膜的致密性有关,利用质子增强背散射法测量出能量为60 keV的4He+在铒、钪膜中的注入深度分别为210,308 nm。     

氢同位素转动跃迁拉曼频移的理论计算

激光拉曼光谱作为一种非侵入式的物质结构和成分分析的测试手段特别适合于核工业中含氚放射性同位素气体的定性和定量分析。将经典物理学方法和量子力学理论相结合,采用非刚性转子校正模型,计算获得了H2、HD、HT、D2、DT、T26种氢同位素气体分子的转动跃迁拉曼频移,为氢同位素气体拉曼光谱谱峰的辨识提供理论数据。通过实验测定H2和D2的转动拉曼光谱,得到这2种分子的转动拉曼图谱和拉曼频移,并将测定结果与计算结果进行比较,验证了理论计算方法的可行性和正确性。     

二项指数法修正静态热解析系统压力测量误差

热解析技术是目前研究热解析动力学，决定吸附热、表面反应阶数、吸附状态数和晶面吸附分子浓度的最广泛使用的技术。热解析系统样品室程序升温导致系统内气体温度不均匀，必然引起材料解析出气体压力测量的误差。采用二项指数法对这一误差进行了修正。     

Microstructure and hardening effect of pure tungsten and ZrO2 strengthened tungsten under carbon ion irradiation at 700℃

Microstructure evolution and hardening effect of pure tungsten and W-1.5%ZrO₂ alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 ℃ with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The W-1.5%ZrO₂ alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO₂ phase improves the sink strength for irradiation defects. It is confirmed that the W-1.5%ZrO₂ alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO₂ into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials.     

六角相ErAx (A=H,He)体系弹性性质的第一性原理研究

本文采用第一性原理研究了六角相ErA_x (A=H, He)的弹性性质, 其中x=0, 0.0313, 0.125, 0.25, 分别讨论了体系中不同浓度的氢和氦对体系弹性性质的影响. 计算结果表明, 六角相铒-氢体系晶体的弹性常数、体弹模量、剪切模量、杨氏模量基本上随着晶体中氢的浓度增加而增加, 然而, 铒-氦体系的弹性常数、体弹模量、剪切模量和杨氏模量几乎随着氦浓度的增加而降低. 从电荷转移方面分析了氢和氦与Er的相互作用, 发现六角相ErH_x的弹性性质随H浓度的变化机理与ErHe_x随He浓度的变化机理不同. 关键词： 第一性原理 弹性性质 x')" href="#">六角相ErH_x x')" href="#">六角相ErHe_x     

Fabrication processing effects on microstructure and morphology of erbium film

The effects of substrate temperature on the microstructure and the morphology of erbium film are systematically investigated by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). All the erbium films are grown by the electron-beam vapor deposition (EBVD). A novel preparation method for observing the cross-section morphology of the erbium film is developed. The films deposited at 200 ℃ have (002) preferred orientation, and the films deposited at 450 ℃ have mixed (100) and (101) texture, which are due to the different growth mechanisms of surface energy minimization and recrystallization, respectively. The peak positions and the full widths at half maximum (FWHMs) of erbium diffraction lines (100), (002), and (101) shift towards higher angles and decrease with the increasing substrate temperature in a largely uniform manner, respectively. Also, the lattice constants decrease with the increasing temperature. The transition in the film stresses can be used to interpret the changes in peak positions, FWHMs, and lattice constants. The stress is compressive for the as-growth films, and is counteracted by the tensile stress formed during the process of temperature cooling down to room temperature. The tensile stress mainly originates from the difference in the coefficients of thermal expansion of substrate--film couple.     

Ti-Hf合金的结构和吸氘热力学性质

采用磁悬浮法制备了4种TiHfx,(x=0.13,0.26,0.52,1.03)二元合金。利用X射线衍射技术对纯钛、纯铪和4种成分Ti-Hf二元合金吸氘前后的物相结构、晶胞参数和吸氘特性进行了研究。Ti-Hf合金吸氘前均为六方密堆结构,饱和吸氘后形成较单一的面心四方ε相氘化物。随Hf含量增加,Ti-Hf合金及其ε相氘化物的晶胞参数均呈增大趋势。压强-组成等温线显示,Hf含量增加将导致氘化物室温平衡压升高,Ti-Hf合金热力学性质趋近于H-Hf体系,Hf对Ti-Hf合金氘化物热力学性质起主导作用。Hf掺杂显著降低了Ti吸氘的体膨胀,从而有望缓解由于体胀导致的氢脆现象。