STUDY ON Fe ION DISTRIBUTION IN NATURAL CHROMITE BY MOSSBAUER TECHNIQUE

Mossbauer absorption spectra in a natural chromite from Shanxi province of China were measured, covering a temperature range from 12 K to 800 K. Each spectrum at low temperature can be fitted to three doublets: the first two are attributed to tetrahedral T-site Fe ions and the third one to octahedral M-site Fe ions. Such assignment was confirmed by the detailed analyses of the temperature dependent centre shift and other parameters. As a main result, our data strongly supported the ordered distribution with Fe2+ in T-site and Fe3+ in M-site for chromite studied. No evidence for electron hopping processes was detected.     

Determination of Iron in Water Solution by Time-Resolved Femtosecond Laser-Induced Breakdown Spectroscopy

The influence of the energy of femtosecond laser pulses on the intensity of Fe I (371.99 nm) emission line and the continuous spectrum of the plasma generated on the surface of Fe3+ water solution by a Ti: sapphire laser radiation with pulse duration <45 fs and energies up to 7 mJ is determined. A calibration curve was obtained for Fe3+ concentration range from 0.5 g/L to the limit of detection in water solution, and its saturation was detected for concentrations above 0.25 g/L, which is ascribed to self-absorption. The 3σ-limit of detection obtained for Fe in water solution is 2.6 mg/L in the case of 7 mJ laser pulse energy. It is found that an increase of laser pulse energy insignificantly affects on LOD in the time-resolved LIBS and leads to a slight improvement of the limit of detection.     

脉冲Ti＋C双重离子注入抗磨损优化结构的研究

大剂量Ｔｉ＋、Ｃ＋和Ｔｉ＋＋Ｃ＋注入Ｈ１３钢可使注入层硬度和抗磨损寿命明显增加，尤以Ｔｉ＋＋Ｃ＋双注入效果最佳．实验结果表明注入的Ｔｉ和Ｃ原子浓度可分别达到２２％和４５％；超饱和Ｔｉ和Ｃ浓度形成了固溶强化；注入层中已形成弥散的硬化相，如Ｆｅ２Ｔｉ、ＴｉＣ、Ｆｅ２Ｃ和Ｆｅ５Ｃ２等，出现了弥散强化效果．注入层表面形成了一层２０ｎｍ厚的薄碳层，使之呈现出自滑润特性。     

Impact of Material Configuration Behind First Wall on Helium Formation in In-Vessel Components of Fusion Reactor

The results of neutron transport calculations of the He formation based on the JENDL gas-production cross section file are discussed for some metals and alloys, namely ²⁷A1, Ti, ⁵¹V, Cr, ⁵⁵Mn, Fe, Ni, Zr, Mo, austenitic stainless steel (Ti modified 316 SS: PCA), Ni-base alloy (Inconel 625), ferritic steel (Fe-11Cr-1Mo: HT-9), Ti-base alloy (Ti-6A1-4V) and V-base alloy (V-5Cr-5Ti). Impacts of the two shields having the steel-rich and the H₂O-rich compositions and the two blankets having the Li₂O/Be-base and the liquid Li/Be-base compositions on the He formation rate in the above-mentioned metals and alloys are discussed. The relation between the He formation rate and the fast neutron flux (14.1 MeV>E>0.1 MeV) is investigated. The decrease of He formation at any distance Δ from the first wall more than Δ_as, the distance where the shape of neutron spectrum reaches its asymptotic form, is modelled by the simple formula based on the exponential dependence, as those reported so far for the fast neutron flux and the displacement damage rate.     

Microstructure and mechanical properties of Fe alloys ion implanted with Ti and N

The microstructure resulting when Ti and N are both ion-implanted into pure Fe at room temperature has been examined with ion beam analysis, transmission electron microscopy, and electron energy loss spectroscopy. Precipitates of TiN form within the bcc Fe matrix, in contrast to the amorphous phase which forms when Ti and C are both implanted. For comparison, the microstructure resulting when N alone is implanted into Fe was also examined, and Fe₂N precipitates were observed within the Fe matrix. The surface mechanical properties of 15?5 PH steel which was implanted with both Ti and N were examined with pin-on-disc testing, and the results were interpreted in terms of the microstructures observed in Fe. The modifications produced by Ti + N implantation are the same as observed with other treatments producing hard nitrides or carbides within the iron-based matrix: reduced wear is observed, but not reduced friction.     

钙钛锆石的自蔓延高温合成与热力学分析

基于自蔓延高温合成法,采用Fe₂O₃、CrO₃和Ca(NO₃)₂为氧化剂,Ti为还原剂制备了钙钛锆石。共设计了4个体系,计算了各体系的绝热温度,测量了各体系的实际燃烧温度,并探索了Ca(NO₃)₂为氧化剂时,TiO₂与Ti摩尔比（TiO₂∶Ti）对燃烧温度的影响。结果显示,所有体系均能自持发生,但以Fe₂O₃和CrO₃为氧化剂时,产物的主要物相为烧绿石(Ca₂Ti₂O₆)、Zr₅Ti₇O₂₄、钙钛矿(CaTiO₃)及少量TiO₂,以Ca(NO₃)₂为氧化剂时,各体系的主要物相均为钙钛锆石(CaZrTi₂O₇)、CaTiO₃及少量TiO₂。同时,以Ca(NO₃)₂为氧化剂时,随TiO₂∶Ti的降低,燃烧温度和绝热温度均逐渐升高。     

MOSSBAUER POLARIMETER AND MOSSBAUER FARADAY EFFECT

A Mossbauer polarimeter consists of a gamma ray source (polarizer), transmitter (sample to be analyzed), analyzer and automatic counting system. This equipment was used to observe the Mossbauer Faraday effect in non-stoichiometric Fe3O4. Experimental results demonstrated that electronic hopping above the Verwey temperature between Fe2+- Fe3+ ions on the octahedral sites is a only localized phenomenon and the recoilless fractions of 57Fe nuclei in Fe3-vO4 (v=0.02) are 0.71 for A sites and 0.62 for B sites, respectively.     

X-ray spectroscopy of highly ionised atoms of Ti through Zn in a dense plasma

X-ray spectra for several elements have been observed from a high-temperature plasma produced in a vacuum spark using a curved-crystal spectrometer. The transition wavelengths of the He-like resonance lines for Ti through Zn are determined for the first time under careful experimental treatments. The result is compared with theoretical predictions. The transition wavelengths of the Fe He-like resonance series lines up to 1s6p–1s² and the Kβ transition energies of Ti partially M-shell-ionised ions (Ti VI–XIII) are also determined. As a result, several satellite lines are found.     

Pu(Ⅲ)-Fe(Ⅱ)-N_2H_5~+-HNO_3溶液中的光化反应

本文探索了钚的还原剂Fe(Ⅱ)和稳定剂肼的光氧化规律性,研究了各种条件对其氧化速率的影响。实验结果表明,在硝酸水溶液中,紫外光能使它们迅速而完全氧化。还研究了含有Fe(Ⅱ)、肼和HNO_3的水溶液中,Pu(Ⅲ)光氧化的规律性,测定了各种因素对Pu(Ⅲ)光氧化的影响。结果表明,紫外光照射含Pu(Ⅲ)、Fe(Ⅱ)和肼的硝酸溶液时,能使Pu(Ⅲ)迅速而完全氧化。光氧化产生的Pu(Ⅳ)经光歧化产生Pu(Ⅵ)。实验中还发现,Fe(Ⅲ)的存在对Pu(Ⅳ)的光歧化有强烈的抑制作用。