Investigation of bonded hydrogen defects in nanocrystalline diamond films grown with nitrogen/methane/hydrogen plasma at high power conditions

In this work, we investigate the influence of some growth parameters such as high microwave power ranging from 3.0 to 4.0 kW and N2 additive on the incorporation of bonded hydrogen defects in nanocrystalline diamond (NCD) films grown through a small amount of pure N2 addition into conventional 4% CH4/H2 plasma using a 5 kW microwave plasma CVD system. Incorporation form and content of hydrogen point defects in the NCD films produced with pure N2 addition was analyzed by employing Fourier-transform infrared (FTIR) spectroscopy for the first time. A large amount of hydrogen related defects was detected in all the produced NCD films with N2 additive ranging from 29 to 87 µm thick with grain size from 47 nm to 31 nm. Furthermore, a specific new H related sharp absorption peak appears in all the NCD films grown with pure N2/CH4/H2 plasma at high powers and becomes stronger at powers higher than 3.0 kW and is even stronger than the 2920 cm−1 peak, which is commonly found in CVD diamond films. Based on these experimental findings, the role of high power and pure nitrogen addition on the growth of NCD films including hydrogen defect formation is analyzed and discussed

Magnetic phase diagram in Eu1−x_{1-x}Lax_xFe2_2As2_2 single crystals

We have systematically measured resistivity, susceptibility and specific heat under different magnetic fields (H) in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals. It is found that a metamagnetic transition from A-type antiferromagnetism to ferromagnetism occurs at a critical field for magnetic sublattice of $Eu^{2+}$. The jump of specific heat is suppressed and shifts to low temperature with increasing H up to the critical value, then shifts to high temperature with further increasing H. Such behavior supports the metamagnetic transition. Detailed H-T phase diagrams for x=0 and 0.15 crystals are given, and possible magnetic structure is proposed. Magnetoresistance measurements indicate that there exists a strong coupling between local moment of $Eu^{2+}$ and charge in Fe-As layer. These results are very significant to understand the underlying physics of FeAs superconductors.Comment: 5 pages, 4 figure

Characterization of starch synthetic genes and starch granule during seeds development between synthetic hexaploid wheat and its parents

To study the development of starch granules in polyploid wheats, we investigated the expression of starch synthetic genes between the synthetic hexaploid wheat SHW-L1, its parents T. turgidum AS2255 and diploid Ae. tauschii AS60. The synthetic hexaploid wheat SHW-L1 showed significantly higher starch content and grain weight than its parents. Scanning electron microscopy (SEM) showed that SHW-L1 rapidly developed starch granules than AS2255 and AS60. The amount of B-type granule in AS60 was less than that in SHW-L1 and AS2255. RT-qPCR result showed that the starch synthetic genes AGPLSU1, AGPLSU2, AGPSSU1, AGPSSU2, GBSSI, SSIII, PHO1 and PHO2 expressed at earlier stages with larger quantity in SHW-L1 than in its parents during wheat grain development. The expression of the above mentioned genes in AS60 was slower than in SHW-L1 and AS2255. The expression pattern of starch synthase genes was also associated with the grain weight and starch content in all three genotypes. The results suggested that the synthetic hexaploid wheat inherited the pattern of starch granule development and starch synthase gene expression from tetraploid parent. The results suggest that tetraploid wheat could plays more important role for starch quality improvement in hexaploid wheat

Partial Wave Analysis of J/ψ→γ(K+K−π+π−)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

BES data on $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $\Gamma = 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ component peaking at 2.55 GeV. The non-$K^*\bar K^*$ contribution is close to phase space; it peaks at 2.6 GeV and is very different from $K^{*}\bar{K^{*}}$.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

Body-centered-cubic Ni and its magnetic properties

The body-centered-cubic (bec) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bec Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52 \uc2\ub1 0.08 \uce\ubcB/atom. The cubic magneto-crystalline anisotropy of bec Ni is determined to be +4.0 \uc3\u97 105 ergs \uc2\ub7 cm-3, as opposed to -5.7 \uc3\u97 10 4 ergs \uc2\ub7 cm-3 for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bec Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation

Relationship Between the Thermodynamic Parameters, Structure, and Anticorrosion Properties of Al-Zr-Ni-Fe-Y Alloys

The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y alloys are presented. To reduce the number of experiments, a thermodynamic approach was applied in which the entropy and Gibbs free energy of representative alloys were optimized. The low glass-forming ability of Al-Zr-Ni-Fe-Y alloy systems was related to the crystallization of the Al3Zr phase from the melt. The structural analysis showed that phases containing Ni and Fe, such as Al19Ni5Y3, Al10Fe2Y, and Al23Ni6Y4, played a key role in the formation of amorphous alloys. According to this, the simultaneous addition of Ni/Fe and Y is important to prevent the crystallization of Al-based alloys in the melt. The formation of an amorphous phase in Al80Zr5Ni5Fe5Y5 alloys and the complete amorphization of Al85Ni5Fe5Y5 alloys were responsible for the high corrosion resistance compared with fully crystalline alloys. Moreover, the addition of Y had a significant impact on the anticorrosion properties. The XPS results showed that the alloys tended to form a passive Al2O3 and Y2O3 layer on the surface