Effects of Distribution of Induced Defects on Positron Diffusion

The effects of distribution of induced defects on the positron diffusion was studied by using the point-source diffusion model and 6 function method.

Femtosecond laser induced defects in various silica glasses

The mechanism of near infrared (IR) focused femtosecond (fs) laser induced defects in silica glasses produced by different methods is systematically investigated through measurements of absorption, fluorescence, and electronic spin resonance (ESR) spectra. The influence of impurities and hydroxyl groups on defects is discussed. The results show that ES silica glasses containing high OH and few defects are much stable under fs laser irradiation. It is also verified that Si E_δ~′center formation has no direct relation with chloride ions.

The Progress on Abnormal Development Mechanism

What summarized in this paper is the progress in recent years' in the causdive mechanism on study of developmental toxicants as chemical teratogenesis in three aspects.(1) It is about the phenomena and the possible reason of chemical teratogenesis in the preimplantation period. These research results are contrary to the past traditional concepts. (2) Due to using much more molecular biology methods, it can be observed more dead foetus phenomena before birth, which cannot be done previously and are of great value for reference. (3) When analyzing the genetic reason of chemical abnormal, a new research idea may be showed, i.e. the developmental abnormal due to chemical teratogenesis is induced with association of more relative genes and their expression abnormal. 13 references are involved in.

Low Temperature Plasma CVD Grown Graphene by Microwave Surface-Wave Plasma CVD Using Camphor Precursor

Hydrocarbon precursor such as methane has been widely used to grow graphene films and the methods of growing quality graphene films are dominated by thermal CVD （chemical vapor deposition） system. Graphene films grown by plasma process are generally highly defective which in turns degrade the quality of the films. Here, using a green precursor, camphor we demonstrate a simple and economical method to get high-quality graphene film on copper substrate by micro wave surface-wave plasma CVD at relatively low temperature 550℃. Graphene film grown using camphor shows superior quality than that of the film grown using methane. Results revealed that camphor precursor is a good alternative to hydrocarbon precursors for graphene research.

Effects of Oxygen Concentration in Monocrystalline Silicon on Reverse Leakage Current of PIN Rectifier Diodes

The effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diodes were studied.We fabricated the PIN rectifier diodes with different initial oxygen concentrations,and analyzed the electrical properties,anisotropic preferred etching by means of optical microscopy,Fourier transform infrared spectroscopy and transmission electron microscopy.It is pointed out that the reverse leakage current increases exponentially with the increasing initial oxygen concentration.Furtherly,we researched and analyzed the mechanism of the effects of initial oxygen concentration on the reverse leakage current of PIN rectifier diode.It is shown that the oxygen precipitations present in an "S" curve with increasing initial oxygen concentration after high temperature diffusion.The main reason is that the nucleation and growth of oxygen precipitation at high temperature induce bulk oxidation-induced defects (B-OSF),which are mainly dislocations,and a small amount of rod stacking faults.The density of B-OSF increases with the increasing initial oxygen concentration.The existence of B-OSF has great effects on the reverse leakage current of PIN rectifier diode.

TEM Foil Preparation from Irradiated Metallic Materials： A Practical Approach

This paper focuses on work related to post irradiation examination of 300-series austenitic stainless steel taken from reactor vessel internals of PWR. High neutron irradiation dose in NNP＇s leads to a degradation of microstructure of the material in a nano-metric scale. Hence, it is important to characterize the irradiated materials to understand the physical basis of the degradation mechanisms. Microstructural characterization of neutron-irradiated materials by TEM requires enhanced sample preparation methodologies, which commonly needs general improvements regarding particular experiment to be performed. In this study, the authors have developed methodology specialized in 1 mm TEM thin foil preparation from a deformed shank of a broken miniaturized tensile specimen. TEM foil size in current studies is smaller than standard because of the small shank diameter and high radioactivity of the studied material. The reduction of the TEM foil radioactivity to minimum is crucial to perform EDX chemical analysis and to increase the EDX detector lifetime. This paper describes whole process from bulk sample handling, including remote-controlled material cutting in shielded hot-cells and disc polishing in glow-boxes, up to the final procedure of electrolytic-polishing of electron transparent 1 mm TEM foils. Eventually, results of TEM microanalysis of radiation-induced defects were present.

Structure-activity relationship of defective electrocatalysts for nitrogen fixation

Ammonia(NH_(3)), as an important chemical substance and clean energy carrier, plays an indispensable role in industrial and agricultural production. The electrocatalytic synthesis of NH+3 under mild conditions has attracted worldwide attention in the energy field due to its environmental friendliness and cost efficiency,but unsatisfactory NH_(3) yields and Faradaic efficiencies are restricting its development. The introduction of defect has been demonstrated as a feasible way to overcome the disadvantages of electrochemistry, as it can regulate the electronic structure and modulate coordination environment of electrocatalysts, which further create active sites and enhance nitrogen adsorption. In this regard, it is necessary to understand the effects of various types of defects on electrocatalysts based on the latest progress in the defect engineering for nitrogen reduction reaction(NRR). In this review, the concept, classifications, and characterization of defects as well as the approaches to create them in electrocatalysts are firstly discussed.Then, certain types of defects(vacancy, dopant, amorphism, edge/corner, and porousness) affecting the performances of various electrocatalysts are further described. Finally, the summary and challenges of electrocatalytic ammonia synthesis are proposed to design advanced electrocatalysts with high efficiency.

Role of oxygen defects in inducing the blue photoluminescence of zinc oxide films deposited by magnetron sputtering

A number of zinc oxide（Zn O） films are deposited on silicon substrates using the magnetron sputtering method.After undergoing thermal treatment under different conditions, those films exhibit hexagonal wurtzite structures and different photoluminescent characteristics. Besides the notable ultraviolet emission, which is related to the free exciton effect, a distinct blue fluorescence around 475 nm is found in some special samples.The blue photoluminescence emission of the Zn O film is believed to be caused by oxygen vacancies.