Preparation of Ta Thin Films by RF Sputtering Method

Ta thin films are prepared by sputtering under various conditions. Ar gas pressure during sputtering is in the range of l×10⁻³～1×10⁻² torr. Either α―Ta(b. C. C.) similar tO a bulk or β―Ta (tetragonal) obtained only on a film is deposited. It appears that α―Ta is formed in a contaminative atomosPhere, while β―Ta is formed in a clean atomosphere. The α or β Ta phase Of the sputtered films is determined by X―ray diffraction pattern or by measuring the specific resistivity. The α―Ta films show the main peak of the (110) plane parallel to the glass substrate and the β―Ta films show the main peak of the(200) plane parallel to the glass substrate. The X―ray oscillation Photographs also show that both the α―Ta and the β―Ta have fibre structures. Specific resistivities of the α―Ta and the β―Ta are 50～100 μΩ―cm and 180 ～230 μΩ-cm, respectively

The Electrical Characteristics of Anodic Oxidized Ta₂O₅ Films

The dielectric constant, the dielectric　loss, the breakdown voltage and the current at high electric fields of Ta₂O₅ 1ayers have been measured using Ta-Ta₂O₅-Au devices with various thicknesses. The Ta₂O₅ layer is prepared by anodizing sputtered Ta films. The rate of anodic oxidation is about 16-18Å/V. The Ta-Ta₂O₅-Au devices with the Ta₂O₅ layers more than 1500Å thick are electrically stable and show the dielectric constants of 20-25, which are slightly smaIIer than those of bulk (25-27). The current at high electric fields depends strongly upon temperature and therefore is considered to be the Schottky current. The breakdown electric field is about 5x10⁶V/cm. A few of the Ta-Ta₂O₅-Au devices studied show the remarkable rectifying characteristics, which may be due to the n― i―p junction of the Ta₂O₅ 1ayer

Effectiveness of Oxidation-Reduction Potential and pH as Monitoring and Control Parameters for Nitrogen Removal in Swine Wastewater Treatment by Sequencing Batch Reactors

Two bench-scale sequencing batch reactors (SBRs) were operated in a fixed hydraulic retention time study to investigate the effectiveness of oxidation-reduction potential (ORP), pH and dissolved oxygen as parameters for indicating denitrification followed by nitrification in SBRs for swine wastewater treatment. The ORP and pH profiles were monitored and evaluated under different denitrification and nitrification conditions with and without a supplemental carbon source. With a low C/N ratio, and using a suitable C/N ratio adjustment control, ORP and pH could be used as monitoring and control parameters in both the anoxic and oxic phases for practical swine wastewater treatment. High-level accumulation of nitrate was observed without any C/N ratio adjustment. In this case, ORP and pH were not useful for monitoring denitrification followed by nitrification in SBRs. According to our research, with regard to N removal, it would be better to use pH as a parameter during the oxic phase and ORP as a parameter during the anoxic phase. Using a suitable adjustment of a C/N ratio in the influent by adding swine slurry, a high total nitrogen removal efficiency of up to 95.5% was reached. It was found that, in this case, the use of ORP and pH as parameters for real-time control processes was possible in swine wastewater treatment

Pollution of Polyaromatic Hydrocarbons in the Airborne Particles in the Developing Countries in Asia Region

Joint Research on Environmental Science and Technology for the Eart

Angle-resolved photoemission study of MX-chain compound [Ni(chxn)2_2Br]Br2_2

We report on the results of angle-resolved photoemission experiments on a quasi-one-dimensional $MX$-chain compound [Ni(chxn)$_2$Br]Br$_2$ (chxn = 1$R$,2$R$-cyclohexanediamine), a one-dimensional Heisenberg system with $S=1/2$ and $J \sim 3600$ K, which shows a gigantic non-linear optical effect. A "band" having about 500 meV energy dispersion is found in the first half of the Brillouin zone $(0\le kb/\pi <1/2)$, but disappears at $kb / \pi \sim 1/2$. Two dispersive features, expected from the spin-charge separation, as have been observed in other quasi-one-dimensional systems like Sr$_2$CuO$_3$, are not detected. These characteristic features are well reproduced by the $d$-$p$ chain model calculations with a small charge-transfer energy $\Delta$ compared with that of one-dimensional Cu-O based compounds. We propose that this smaller $\Delta$ is the origin of the absence of clear spin- and charge-separation in the photoemission spectra and strong non-linear optical effect in [Ni(chxn)$_2$Br]Br$_2$.Comment: 4 pages, 3 figure

Spin frustration in antiperovskite systems: (TTF˙+or TSF˙+)3[(Mo6X14)2−Y−]

Two novel antiperovskite charge-transfer (CT) solids composed of a tetraselenafulvalene radical cation (TSF˙+), a dianionic molybdenum cluster unit [Mo6X14]2−, and a halogen anion (Y−) (X, Y = Cl, Br) were prepared by electrocrystallization. Their crystal structures and magnetic properties with regard to spin frustration are discussed together with those of isostructural tetrathiafulvalene (TTF) CT solids previously reported. Both TSF and TTF salts have an apex sharing distorted octahedral spin lattice with a rhombohedral R[3 with combining macron] space group. The calculated overlap integrals based on the crystal structures and insulating nature of the TSF salts indicate that they are Mott insulators. Their spin susceptibilities obeyed the Curie–Weiss law and exhibited an antiferromagnetic ordering at lower temperatures for the TSF salts (Néel temperature, TN = 3.0 K for X = Y = Cl and 5.5 K for X = Y = Br) than the TTF salts. The Curie–Weiss temperatures (|ΘCW| ∼ 1.6–6.3 K) for the TSF salts are lower than those of the TTF salts. For the TSF salts, spin-flop behavior was detected at 3.2 T for X = Y = Cl and 1.5 T for X = Y = Br at 1.9 K. Due to both the distortion of the octahedral geometry of the spin lattice and the anisotropic molecular orientation, the geometrical spin frustrations in TSF and TTF systems are weakened