Inclusions in large diamond single crystals at different temperatures of synthesis

The inclusions in large diamond single crystals have effects on its ultimate performance, which restricts its industrial applications to a great extent. Therefore, it is necessary to study the inclusions systematically. In this paper, large diamond single crystals with different content values of inclusions are synthesized along the(100) surface by the temperature gradient method(TGM) under 5.6 GPa at different temperatures. With the synthetic temperature changing from 1200?C to 1270?C,the shapes of diamonds change from plate to low tower, to high tower, even to steeple. From the microscopic photographs of the diamond samples, it can be observed that with the shapes of the samples changing at different temperatures, the content values of inclusions in diamonds become zero, a little, much and most, correspondingly. Consequently, with the temperature growing from low to high, the content values of inclusions in crystals increase. The origin of inclusions is explained by the difference in growth rate between diamond crystal and its surface. The content values of inclusions in diamond samples are quantitatively calculated by testing the densities of diamond samples. And the composition and inclusion content are analyzed by energy dispersive spectroscopy(EDS) and x-ray diffraction(XRD). From contrasting scanning electron microscopy(SEM) photographs, it can be found that the more the inclusions in diamond, the more imperfect the diamond surface is.

Effect of FeS doping on large diamond synthesis in FeNi-C system

The large single-crystal diamond with FeS doping along the （111） face is synthesized from the FeNi-C system by the temperature gradient method （TGM） under high-pressure and high-temperature （HPHT）. the effects of different FeS additive content on the shape, color, and quality of diamond are investigated. It is found that the （111） face of diamond is dominated and the （100） face of diamond disappears gradually with the increase of the FeS content. At the same time, the color of the diamond crystal changes from light yellow to gray-green and even gray-yellow. The stripes and pits corrosion on the diamond surface are observed to turn worse. The effects of FeS doping on the shape and surface morphology of diamond crystal are explained by the number of hang bonds in different surfaces of diamond. It can be shown from the test results of the Fourier transform infrared （FTIR） spectrum that there exists an S element in the obtained diamond. The N element content values in different additive amounts of diamond are calculated. The XPS spectrum results demonstrate that our obtained diamond contains S elements that exist in S-C and S-C-O forms in a diamond lattice. This work contributes to the further understanding and research of FeS-doped large single-crystal diamond characterization.

Synthesis and Characteristics of Type Ib Diamond Doped with NiS as an Additive

Large diamond single crystals doped with NiS are synthesized under high pressure and high temperature. It is found that the effects on the surface and shape of the synthesized diamond crystals are gradually enhanced by increasing the NiS additive amount. It is noted that the synthesis temperature is necessarily raised to 1280℃ to realize the diamond growth when the additive amount reaches 3.5% in the synthesis system. The results of Fourier transform infrared spectroscopy(FTIR) demonstrate that S is incorporated into the diamond lattice and exists in the form of C–S bond. Based on the FTIR results, it is found that N concentration in diamond is significantly increased, which are ascribed to the NiS additive. The analysis of x-ray photoelectron spectroscopy shows that S is present in states of C–S, S–O and C–S–O bonds. The relative concentration of S compared to C continuously increases in the synthesized diamonds as the amount of additive NiS increases. Additionally,the electrical properties can be used to characterize the obtained diamond crystals and the results show that diamonds doped with NiS crystals behave as n-type semiconductors.

Tetracycline removal by a magnetic heterojunction Cu_(2)O/CoFe_(2)O_(4) activating peroxymonosulfate

The electron transfer mechanism in the process of peroxymonosulfate(PMS)activation using heterojunction catalyst was controversial.In this work,magnetic heterojunction Cu_(2)O/CoFe_(2)O_(4)(CC)was first synthesized to activate PMS.An innovative reaction mechanism based on built-in electric field-driven electron migration from Cu2O to CoFe2O4 and effective magnetic moment of CC for enhancing PMS activation was proposed.Meanwhile,the CC/PMS system was used for efficient removal of antibiotic tetracycline(TC).Under optimal conditions,98.0%TC could be removed using CC/PMS catalytic system after only 30 min.The catalytic activity was higher than that of Cu_(2)O/PMS and CoFe_(2)O_(4)/PMS.Meanwhile,the impact of solution pH on TC removal was insignificant,suggesting the pH-insensitive PMS activation ability of CC.Besides,the coexisting inorganic ions in the environment,such as HCO_(3)-,H_(2)PO4-,NO_(3)-,Cl-and humic acid(HA)as representative of natural organic matter,did not inhibit TC removal in CC/PMS system.Furthermore,CC/PMS system exhibited excellent reusability with more than94.0%TC removal after the 5th reuse.Electron paramagnetic resonance(EPR)tests and quenching experiments showed that O_(2)·-and 1O_(2) played vital roles in TC removal.The intermediate products and corresponding toxicity assessment revealed that this catalytic system could reduce TC toxicity.This work provided new insights into the PMS activation mechanism using heterogeneous magnetic catalysts,including transition metal oxide.

A novel method to detect bacterial resistance to disinfectants

In clinical practice,the important hygienic prevention of bacterial pathogen spread is disinfection of potentially contaminated area.Benzalkonium bromide and chlorhexidine acetate are commonly used disinfectants with a broad spectrum of antimicrobial effect.It is vital to inhibit the spread of pathogen in hospital.However,a large number of pathogens with the decreased antiseptic susceptibility have been isolated from clinical samples which showed an increased minimal inhibitory concentration(MIC)against those antiseptics.These resistant pathogens are the major causes for nosocomial crossinfections in hospital.The present study demonstrated the utility of Oxford plate assay system in determining the potential disinfectant resistance of bacteria.The microbiological assay is based on the inhibitory effect of tested disinfectants upon the strains of Staphylococcus aureus and Escherichia coli.Statistical analysis of the bioassay results indicated the linear correlation(r=-0.87-0.99,P<0.01)between the diameter of growth inhibition zone and the log dosage of the tested disinfectants.Moreover,comparison of inhibitory efficacy of benzalkonium bromide upon 29 S.aureus strains isolated from clinical samples by both Oxford plate method and broth dilution method showed that the diameter of growth inhibition zone has significantly negative correlation with the minimal inhibitory concentration(MIC)(r=-0.574,P<0.001).These results suggest that the Oxford plate is a simple and time-saving method in detecting potential clinical disinfectant resistance and its usefulness for routine surveillance of pathogenic resistance to disinfectants warrants further investigation.

Experimental investigation of migration and solidification of molten salt leaking through tank cracks

Molten salt is often used for heat transfer and thermal energy storage in concentrated solar power.Molten salt leakage and migration is a significant issue in its application.Molten salt migration and solidification in thermal porous foundation materials through cracks are experimentally investigated.The impact of factors,including crack length and width,operation temperature,and leakage mass of molten salt,are studied through an experimental device modeling the leakage of the actual molten salt storage tank.Experimental results show that the crack width and length slightly affect the migration depth,but directly affect the shape of the agglomeration of solidified salt and porous foundation material.The most important factor affecting the migration depth of molten salt leaking through cracks is the tank operating temperature.The molten salt migration depth when the operating temperature is 500℃ is 95.8% higher than that with an operating temperature of 300℃.As the leakage molten salt mass reached 400 g,the average migration width increased by 23.6%,but the migration depth only increased by 5.2%.It is found that the foundation material temperatures after leakage accidents increase with an increase in the mass of leaked molten salt.