氢化锆表面多元复合膜层制备和研究

采用尿素高温分解产生的氧化性气氛在氢化锆表面制备多元复合膜层。利用XRD、SEM、EDS、XPS、AES等分析测试手段对氢化锆表面膜层的相结构、截面形貌、元素成分及价态进行性能表征。物相分析结果表明膜层主要有氧化锆相和Zr N相,且氧化锆相由单斜相(m-ZrO_2)和四方相(t-ZrO_2)组成。扫描电镜形貌分析表明原位生长氧化物膜层致密,膜层与氢化锆基体结合紧密。俄歇电子能谱结果表明膜层由C、N、O、Zr元素组成,并具有明显的分层现象,膜层由外向内分为富(C/N)层及富O层,随膜层表面溅射时间增加,O、Zr元素相对含量明显增加,C、N元素相对含量明显降低。X射线光电子能谱分析表明多元复合膜层存在Zr-O、Zr-C、Zr-N-O、Zr-N、O-H等键。     

氢化锆表面Cr-C-O氢渗透阻挡层XPS分析

在空间堆中,氢化锆作为慢化剂的工作温度为650～750℃,在此温度范围内,H/Zr原子数之比大于1.8的氢化锆中的氢很容易析出.通过X射线光电子能谱(XPS)研究了电镀法制备的氢化锆表面氢渗透阻挡层的化学态,对镀层进行了深度(100、200、300nm)刻蚀分析和镀层原子的定量分析.结果表明,镀层中含有C、O、Cr和Zr,进行氢渗透试验后(700℃保温)的试样镀层的C-H键数量有明显增加,而O-H键的数量变化不大.由此可以说明,氢渗透受阻的原因是氢在渗透过程中被镀层中的C优先捕获生成C-H键.     

氢化锆表面原位氧化法制备氢渗透阻挡层的研究

采用原位氧化法在氢化锆表面制备了氢渗透阻挡层，分析了工艺参数对氧化层生长的影响，借助XRD，XPS，SEM等分析测试手段对氧化层的物相组成和截面形貌进行分析，并对氧化层的阻氢效果进行检测。结果表明，氧化层的质量增量随氧化温度的升高而增大，在氧分压为0．1MPa，550℃恒温氧化2h的工艺条件下，在氢化锆表面制得了厚度为50～60um的氧化层；该氧化层主要为Baddeleyite结构的ZrO2；氧化层中含有O，Zr，C等元素并存在O-H键；氧化层均匀、致密，具有一定的阻氢作用。     

CO2反应法制备氢化锆表面氢渗透阻挡层的研究

氢化锆因具备诸多作为反应堆中子慢化材料的优点,有着良好的应用前景.在空间堆中,慢化剂的工作温度范围为650～750℃,而在此温度下,H/Zr原子比大于1.8的氢化锆中的氢很容易析出.利用ZrH2和CO2、P反应在氢化锆表面制备氢渗透阻挡层,并借助SEM、XPS和XRD对膜层进行截面形貌观察和物相分析.XRD分析表明氢化锆表面生成了baddeleyite 结构的氧化锆.XPS分析表明膜层中含有Zr、C、O、P等元素;窄谱分析还发现膜中生成了C-H键和O-H基团(可能O-H又和锆形成Zr-OH键).C-H键和O-H基团的存在可能是阻挡氢析出的原因.     

碳和氧在氢渗透阻挡层中的作用

为了了解氢渗透阻挡层的阻氢机理,在氢化锆表面电镀Cr-C后,再对镀层进行热处理(400℃),最后把试样在700℃的真空中保温10h.用EDS法对没有进行热处理的镀层的成分进行分析,再用X射线光电子能谱(XPS)研究氢渗透阻挡层不同深度处的化学态,并对阻挡层原子进行定量分析.结果发现:未热处理的镀层主要含有C和Cr,阻挡层中含有C、O、Cr和Zr,进行氢渗透试验(700℃保温)后的阻挡层中C-H和O-H含量都增加,前者更明显.由此可说明H因破坏C、O原来的成键方式而被C、O捕捉,C对氢渗透阻挡层的作用大于O的作用.     

Na_2SiO_3溶液体系ZrH_(1.8)表面微弧氧化陶瓷层的研究

在Na2Si O3+Na OH+Na2EDTA体系下,采用恒压模式对氢化锆进行微弧氧化处理获得Zr O2陶瓷层。通过扫描电镜(SEM)、X射线衍射(XRD)仪、电子能谱(EDS)仪,分析了陶瓷层的表面形貌、截面形貌、相结构及陶瓷层的元素分布。结果表明:在硅酸盐体系中,通过恒压模式在Zr H1.8表面制得膜厚约为45m的Zr O2陶瓷膜,膜层分为过渡层、致密层和疏松层。EDS结果表明:微弧氧化陶瓷层中除基体元素Zr及溶液元素O外,未发现Si、Na等溶液元素的出现,说明Si O2-3、Na+等没有参与反应;在硅酸盐体系中Zr H1.8表面微弧氧化陶瓷层主要由M-Zr O2、T-Zr O2及C-Zr O2构成,M-Zr O2约90%。     

恒压模式下电源频率对ZrH_(1.8)表面微弧氧化陶瓷层的影响

在磷酸盐体系下,采用恒压模式对氢化锆(Zr H1.8)进行微弧氧化。考察了电源频率对氧化膜的厚度、相结构、截面形貌以及阻氢性能的影响。利用扫描电镜(SEM)、X射线衍射(XRD)、膜层测厚仪分析了氧化膜的表面形貌、截面形貌、相结构及膜层厚度。通过真空脱氢实验评估膜层的阻氢性能。结果表明:随着电源频率的增加,Zr H1.8表面微弧氧化膜层厚度由约50μm仅减小至约45μm;电源频率的增加能有效提高膜层的致密性;电源频率的改变对于膜层的相结构没有明显影响,膜层主要由单斜相氧化锆(M-Zr O2)和四方相氧化锆(T-Zr O1.88)构成,其中单斜相占80%以上;电源频率的增加有助于提高氧化膜的阻氢效果,当电源频率增加到300 Hz时,氧化膜的氢渗透降低因子PRF值高达10.8。     

Na_5P_3O_(10)体系氢化锆表面微弧氧化陶瓷层组织与阻氢性能的研究

在Na_5P_3O_(10)+NaOH+Na_2EDTA体系下,采用恒压模式对氢化锆进行微弧氧化处理获得连续、致密且裂纹、孔洞等缺陷较少的ZrO_2陶瓷层。通过扫描电镜(SEM)、X射线衍射(XRD)及能谱(EDS)仪,分析了陶瓷层的表面形貌、截面形貌、相结构及元素分布。通过真空脱氢实验及XRD分析对陶瓷层的阻氢性能进行评价。结果表明:氢化锆表面ZrO_2陶瓷膜厚度约为78μm,陶瓷层由过渡层、致密层和疏松层构成;ZrH_(1.8)表面微弧氧化陶瓷层主要由M-ZrO_2、T-ZrO_2及C-ZrO_2构成,主要为M-ZrO_2,约90%;微弧氧化陶瓷层氢渗透降低因子(PRF)高达11.7,具有优越的阻氢效果。     

氢化锆表面阻氢渗透层在高温二氧化碳气氛中的腐蚀

使用24h、48h、120h的CO2气固反应法在氢化锆表面生成具有阻氢渗透性能的致密氧化膜,然后将3种试样在含50.662kPa的CO2气氛中700℃保温72h,结果试样都出现表面起皮,局部粉化甚至断裂.SEM分析表明,致密氧化锆膜在高温下要与CO2反应生成非保护性的氧化层,并产生相变应力加速阻氢渗透层的腐蚀.3种试样在700℃相同CO2气氛中保温400h后都完全反应成白色氧化锆粉末.     

光电子能谱研究锌镀层硫代酰胺彩色配合物膜

用光电子能谱（XPS和AES）研究了配合物膜层的组成、结构和性能,以及在金属表面的成键特征和波谱变化。结果表明,多数硫代酰胺化合物分子中的硫代酰胺基团在参与配位反应时发生了去质子化,N,S均发生了配位,另有部分硫代酰胺基团未去质子化,直接与Zn^2＋。配位。从配合物膜的AES深度剥蚀曲线的组成恒定区求得膜层由Zn,N,C,S和O元素组成,膜层的厚度在60～200nm之间。     

铌表面初始氧化行为的EELS和AES研究

利用电子能量损失谱(EELS)和俄歇电子能谱(AES)研究室温下铌的初始氧化过程，研究表明：清洁表面铌的EELS的实验值与理论值较为符合；随着氧化程度的加剧，其体等离子体(BP)、表面等离子体(SP)以及价带间跃迁所造成的电子能量损失峰发生了明显的偏移和强弱的变化，也解释了Nb→NbO→NbO2的初始氧化过程；另外，铌在潮湿空气里氧化1周，在其表面只生成很薄一层的Nb2O5氧化层。     

A Study of Zn-Co Alloy Electrodeposits by Auger Spectroscopy and XPS

AES and XPS techniques have been used to analyse thin Zn-Co films obtained by electrodeposition at different potentials and to characterise the interface between the substrate and the deposits. Measurement of depth profiles of the thin films has been carried out by Auger spectroscopy to determine the homogeneity of the deposit and to explore the influence of the substrate on the alloy composition. It was found that the composition of the thin film is affected by the deposition potential as well as by the substrate.

XPS has been used to determine the chemical states of Zn and Co at the surface, in the bulk and at the interface with the substrate. The results showed that zinc occurs as zinc oxide and zinc metal at the surface, however in the bulk and at the interface only zinc and cobalt metals have been detected. The analyses do not provide evidence for the inclusion of zinc hydroxide in the deposit by precipitation during the deposition process. This may be significant in considering the mechanism of deposition.     

Photosensitivity and optical performance of hydrogenated amorphous carbon films processed by picosecond laser beams

In this work we investigate the photosensitivity of hydrogenated amorphous Carbon films (a-C:H) and the changes in their structural features and optical properties, when they are exposed to picosecond laser beams of various wavelengths (Nd:YAG, 1st harmonic, λ = 1064 nm and 4th harmonic, λ = 266 nm). The different light-matter interactions, which take place for the various laser wavelengths, are considered and discussed. The main findings include the formation of SiC at the a-C:H film/Si interface and the film graphitization, when the 1064 nm and 266 nm beams, respectively, are used. Finally we managed to vary locally the refractive index in the range of 1.60-1.95 (20% variations) by laser processing, a fact that is very important for various applications in photonics.     

Preparation and characterization of gelatin mediated silver nanoparticles by laser ablation

We successfully prepared colloidal silver nanoparticles (Ag-NPs) using a nanosecond pulsed Nd:YAG laser, λ = 532 nm, with laser fluence of approximately about 0.6 J/pulse, in an aqueous gelatin solution. The size and optical absorption properties of samples were studied as a function of the laser repetition rates. The results from the UV-vis spectroscopy demonstrated that the mean diameter of Ag-NPs increase with the laser repetition rate increases. The Ag-NPs have mean diameters ranging from approximately 9 nm to 15 nm. Compared with other preparation methods, this work is clean, rapid, and simple to use.     

自悬浮定向流法制备纳米Cu粉的微结构和性能表征

采用自悬浮定向流法制备纳米Cu粉：用透射电镜、X射线衍射、紫外-可见光吸收光谱、差示扫描量热-热重法和X射线光电子能谱分析对纳米Cu微晶的形貌、粒度、结构和性能进行研究。研究结果表明：在体积分数为10％He和90％Ar混合气流中和在时气流中制备的纳米Cu粒子形貌呈球形，平均粒度分别约为45和60nM；在590nm左右有1个很强的吸收峰；纳米Cu粒子表面Cu和O元素的摩尔比为94．88：5．12，有少量氧化亚铜和氧化铜的混合物存在，但在其表面未发现Ar和N。     

金属铀氧化的显微拉曼光谱和原子力显微镜原位研究

通过光学金相、拉曼光谱和原子力显微镜分析,原位研究金属铀在大气环境、干燥空气和饱和水汽下,20～400℃的温度范围内样品显微形貌和氧化产物的变化情况,鉴定夹杂物、不同微区的腐蚀产物.铀在大气环境条件下吸附O2、H2O和CO2反应生成二氧化铀、铀酰化合物和碳酸铀等,干燥空气中加热后首先出现活性腐蚀亮斑,逐渐积累长大发生点蚀,并由UO2转变为U3O8.在饱和水汽中缓慢升温,UO2在260～280℃转化为U3O8.     

Study of sprayed coatings and compound materials by impedance spectroscopy

The impedance spectroscopy (IS) and electrical equivalent circuit method were used to investigate both electric and structural properties of materials. The analysis of a hydroxyapatite SPS sprayed layer allowed the determination of the degree of amorphousness. The difference between impedance spectra of dry and moist samples allowed the comparison of samples in terms of their porosity. Results of measurements of barium titanate nanoceramics were presented. The content of amorphous and crystalline phases was found to be dependent on the ceramic grain size. The Curie effect was observed in the crystalline phase which proved that it preserved its ferroelectric properties in spite of nanometre-sized grains.     

The poisoning of Pd–Y alloy membranes by carbon monoxide

We have explored the poisoning mechanism of CO on Pd–Y alloy membranes by means of thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). TDS results show the total deuterium content sharply decreases and the desorption peak shifts to higher temperature with the increasing concentration of CO (from 0% to 26%) in gaseous deuterium. XPS results show that there are YO_x, carbon, carbonate and adsorbed molecular CO on Pd–Y alloy surfaces after reaction with the mixture of D₂ + 26%CO at 623 K followed by cooling to room temperature. But no carbides and PdO_x are detected.     

电化学外延生长亚稳态Co薄膜的结构和磁性表征

用循环伏安法在单晶Cu（110）上沉积了亚稳态fcc相的Co磁性薄膜，并用法拉第定律估算了薄膜的厚度约为17nm。X射线衍射结果表明薄膜具有（100）的单一取向结构，而用同样方法沉积在多晶Pt片上的Co薄膜则是六方多晶结构。用扫描电子显微镜、X射线以及同步辐射光电子能谱对薄膜的表面形貌、组成以及元素的化学态进行了表征，结果表明循环伏安法制备的薄膜平整连续，Co薄膜没有明显的氧化现象；磁性测量结果表明外延生长的薄膜具有典型的软磁特征，矫顽力约为100Oe，剩磁比约0．86。软X射线磁性圆二色实验结果计算得到Co薄膜的自旋磁矩和轨道磁矩非常接近于Co体相材料的数据。     

Structural studies on iron-tellurite glasses prepared by sol-gel method

In this study, we report structural properties of the iron-tellurite glasses obtained using the sol-gel synthesis. The samples were characterized by X-ray diffraction, FTIR, UV-vis and EPR spectroscopy. Our results indicate dominant presence of iron ions in the trivalent state and the existence some Fe²⁺ ions. The analysis of the IR spectra indicates a gradual transformation of iron ions from tetrahedral into octahedral sites when the concentration of Fe(NO₃)₃ is increased beyond 0.64 mol%. EPR studies show that the increase of Fe(NO₃)₃ content in the host matrix induces the growth of the number of effective g values. This can be explained considering that the orbitals of O²⁻ ion with a large spin-orbit interaction constant will interact with the 3d orbital of Fe³⁺ ion bonded to this O²⁻ ion, thus leading to appearance of an orbital angular momentum which contributes to the magnetic moment of Fe³⁺ ion. A strong dipolar interaction, which is more predominant in a glass with higher content of Fe(NO₃)₃, causing a localized magnetic field along the site of the Fe³⁺ ions and the increase the effective g values.