Metalorganic Chemical Vapor Deposition of GaNAs Alloy Using Dimethylhydrazine as Nitrogen Precursor

GaNAs alloy is grown by metalorganic chemical vapor deposition (MOCVD) using dimethylhydrazine (DMHy) as the nitrogen precursor.High resolution X ray diffraction (HRXRD) and secondary ion mass spectro metry (SIMS) are combined in determining the nitrogen contents in the samples.Room temperature photoluminescence (RTPL) measurement is also used in characterizing.The influence of different Ga precursors on GaNAs quality is investigated.Samples grown with triethylgallium (TEGa) have better qualities and less impurity contamination than those with trimethylgallium (TMGa).Nitrogen content of 5 688% is achieved with TEGa.The peak wavelength in RTPL measurement is measured to be 1278 5nm.

Magnetic properties and heavy metal contents of automobile emission particulates

Measurements of the magnetic properties and total contents of Cu, Cd, Pb and Fe in 30 automobile emission particulate samples indicated the presence of magnetic particles in them. The values of frequency dependent susceptibility （Xfd） showed the absence of superparamagnetic （SP） grains in the samples. The IRM20mT （isothermal remanent magnetization at 20 mT） being linearly proportional to SIRM （saturation isothermal remanent magnetization） （R^2=0.901）, suggested that ferrimagnetic minerals were responsible for the magnetic properties of automobile emission particulates. The average contents of Cu, Cd, Pb and Fe in automobile emission particulates were 95.83, 22.14, 30.58 and 34727.31 mg/kg, respectively. Significant positive correlations exist between the magnetic parameters and the contents ofPb, Cu and Fe. The magnetic parameters of automobile emission particulates reflecting concentration of magnetic particles increased linearly with increase of Pb and Cu content, showed that the magnetic measurement could be used as a preliminary index for detection of Pb and Cu pollution.

Preliminary comparison of trace metals in coastal aerosols between Qingdao and Liverpool

Aerosol samples were collected at two coastal suburban stations, Qingdao （China） in 1995-1996 and Liverpool （U.K.） in 1995, respectively. The samples were analyzed to determine the concentrations of trace metals （Cr, Zn, Cu, Co, Ni, Pb, V, and Cd） as well as A1, Fe and Mn. Data were examined to understand the difference of trace metals in aerosols between coastal zones downwind the developing area （near the Yellow Sea） and developed region （near the Irish Sea）. The results show that most elements at Qingdao have levels 4-5 times higher than those at Liverpool, particularly for the crust-dominated elements （e.g. Al, Fe and Mn）. Moreover, the aerosol composition at Qingdao is higher in spring than in summer, underlying the influence of westerlies and local emissions in combination, whereas seasonal change of aerosol composition is not significant at Liverpool. The enrichment factors for the crustal source elements （EFcrust） at Liverpool are much higher than those at Qingdao. The contributions from the pollutant source （Rp） for some trace metals like Cu, Pb, Zn and Cd are 〉90% at Qingdao and Liverpool, suggesting overwhelming anthropogenic contributions to these metals. The contributions from crustal source （Re） for trace metals tend to increase with higher aerosol levels and Al concentration at Qingdao, indicating a good correlation between the crust-dominated component and the air mass. At Liverpool, the Rc values for trace metals are positively correlated with Al concentrations instead of with aerosol mass, suggesting that Al in aerosols represents the crustal component even though the aerosols come from different sources.

A microporous lanthanide metal-organic framework containing channels:Synthesis,structure,gas adsorption and magnetic properties

Under solvothermal condition,the reaction of furan-2,5-dicaboxylate(H2FDA) and glycol with Gd(NO3)3.6H2O gave microporous lanthanide metal-organic framework(MOF),{[Gd(FDA)1.5(glycol)].1.5H2O}}n(1).This compound was characterized by single crystal X-ray diffraction,infrared spectroscopy,elemental analysis,thermogravimetry analysis,and powder X-ray diffraction.The Gd(III) ions were connected by carboxylic group of FDA2-to give 1D chains,which were further linked by FDA2-,forming a 3D porous framework with 3D channels.Gas adsorption properties with N2,H2 and CO_(2) of the compound were studied.Magnetic studies show that there are weak ferromagnetic interactions transmitted by μ1,3 carboxylic group between the Gd(III) ions.

MOCVD derived double-sided YBa_2Cu_3O_(7-δ) films on Y_2O_3 /YSZ/CeO_2 buffered textured metal substrates

We have successfully employed metal-organic chemical vapor deposition （MOCVD） technique to simultaneously deposit double-sided YBa2Cu3O7-δ （YBCO） films on both sides of YzO3/yttria-stabilized zirconia （YSZ）/CeO2 （YYC） buffered biaxially textured Ni-5 at.% W substrates, which is of great prospect to cut the production cost of YBCO coated conductors. X-ray diffraction analysis revealed that both sides of YBCO film were purely c-axis oriented and highly textured. The co-scan of （005） YBCO and Ф-scan of （103） YBCO yielded full width at half maximum （FWHM） values of 4.9° and 6.6° for one side of double-sided YBCO film, respectively, as well as 4.4° and 6.4° for the other side. The current transportation measurements performed on such double-sided 500 nm-thickness YBCO films showed the self-field critical current density （Jc） at 77 K of 0.6 MA/cm^2 and 1.2 MA/cm^2, respectively. Further research is in the process of exploring new solution to improve the Jc in practice.