A novel polymeric adsorbent for hexavalent chromium (Cr(VI)) ions was developed by photografting 2-(dimethylamino)ethyl methacrylate (DMAEMA) to a polyethylene (PE) mesh substrate. The DMAEMA-grafted PE (PE-g-PDMAEMA) meshes obtained were quaternized with iodoalkanes of different alkyl chain lengths. The grafting of DMAEMA and subsequent quaternization of dimethylamino groups were characterized by the FT-IR measurements. The Cr(VI) ion adsorption capacity at pH 3.0 and 30°C had the maximum value at the grafted amount of 2.6 mmol/g and the adsorption behavior obeyed the mechanism of the pseudo-second order kinetic model and well expressed by Langmuir isotherm. This can suggest that the adsorption occurs through an electrostatic interaction between protonated dimethylamino groups and hydrochromate ions. Cr(VI) ions were successfully desorbed in eluents such as NaOH, NaCl, and NH4Cl. When the PE-g-PDAMEMA meshes were quaternized with the iodoalkanes, the adsorption capacity increased and the maximum adsorption ratio was obtained for the PE-g-PDMAEMA mesh quaternized with iodoheptane. This value was about 1.83 times higher than the original PE-g-PDAMEMA mesh. The results obtained in this study emphasize that the PE-g-PDMAEMA meshes and their quaternized products can be applied as an adsorbent for Cr(VI) ions.
Ferroelectric microrod films with a pitch size of 5 μm for micropillar-type multiferroic composite devices were fabricated by reactive ion etching (RIE) using epitaxial c-axis-oriented (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT) thin films. The effects of the etching time, the presence of a 155-nm-thick sacrificial Pt layer and the thickness of this layer on the microstructure of the microrod films were examined. It was found that the use of the Pt layer during the RIE process allowed higher dimensional accuracy and straightness of the final microrod films.
We measured electric conductivity of YbFe2O4 poly crystal under Ar (488 nm, 2.54 eV) and He-Ne (632.8 nm, 1.96 eV) lasers. In order to discuss only photoconductive effect, sample temperature was measured during the electric measurement. The electric conductivity increases exponentially with increase of Ar laser intensity in isothermal process, despite that electric conductivity increases proportionately to light intensity in general semiconductor. This abnormal photoconductivity implies exponential increase of number of electric carrier by melt of charge order.
This study aims to develop a new film structure wherein CoPt can exhibit higher perpendicular magnetic anisotropy with samples having a magnetic layer/intermediate layer/underlayer/seed layer/substrate with AZO(Al-doped ZnO) in the intermediate layer and noble metals, such as Ru, Au, and Ag, in the underlayer. X-ray diffraction (XRD) measurements were used to investigate the effects of crystal structure on the perpendicular magnetic properties of CoPt. CoPt with a c-axis-oriented hcp structure exhibited high perpendicular magnetic anisotropy. Introducing a stacking fault into the c-axis-oriented hcp structure changed it into a (111)-axis-oriented fcc structure, reducing the vertical magnetic anisotropy. Herein, we can measure the (110) and (100) diffraction peaks of the c-axis-oriented CoPt, i.e., DL and DH, using in-plane XRD. For (111) axis-oriented fcc metal, we can detect DH but not DL. We investigated the degree of stacking faults by obtaining IL/IH, which is the ratio of the peak intensity IL and IH of DL and DH, respectively. Consequently, we observed that the insertion of an intermediate AZO layer improves the crystallinity of samples containing fcc Au and Ag metal in the underlayer and decreases the crystallinity of samples containing hcp Ru metal.
The synthesis of dibenzothiophene derivative, i.e., 2,8-bis(trimethylsilyl)dibenzothiophene (3a) and dibenzothiophene-based poly(tetramethylsilarylenesiloxane) derivative (P1) was attained. In addition, 2,8-bis(trimethylsilyl)dibenzothiophene-5,5’-dioxide (3aO) and oxidized dibenzothiophene-based poly(tetramethylsilarylenesiloxane) derivative (P1O) were obtained by oxidation reaction of 3a and P1, respectively. The glass transition temperature was raised by the oxidation of the dibenzothiophene-based poly(tetramethylsilarylenesiloxane) derivative. The introduction of alkylsilyl groups onto dibenzothiophene derivatives induced no remarkable red shifts in the absorption as well as fluorescence spectra; however, the red shifts in the fluorescence spectra were observed by oxidation of dibenzothiophene derivatives.
For cuprate superconductors, the Cu valency is a determining factor of the superconducting transition temperature (Tc). The Cu valence (v) of the superconductor YBa2Cu3Oy (YBCO) has been calculated from oxygen content (y) by the charge neutralization rule. The conventional methods for measuring the oxygen content are iodometry and coulometry. Recently, we developed a novel oxygen measuring method for La2-xSrxCuO4 that uses a dissolved oxygen sensor (the DO method). In this study, we examine whether the oxygen content of YBa2Cu3Oy can be determined by the DO method. The y value obtained by the DO method was compared with that obtained by the iodometric method. In addition, we developed a new correction method by applying the diffusion equation. After correction, the errors of v and y fit within 0.026 and 0.039, respectively. We found that DO method is effective for measuring the oxygen content of YBCO after correction.
To elucidate the effect of Pb substitution on the modulation structure of the Bi2212 phase, we prepared Pb-free Bi2Sr1.8(Ca1-xYx)Cu2Oy and Pb-substituted Bi1.6Pb0.4Sr1.8(Ca1-xYx)Cu2Oy. For both the Pb-free and Pb-substituted Bi-2212 phases, the modulation wave number σ increased with increasing oxygen content y. This tendency is explained by the excess oxygen that is inserted into the BiO layer and leads to the formation of the modulation structure. For the Pb-free Bi2212 phase, σ increased with increasing O-Cu-O length l. This tendency is explained by the lattice mismatch that exists between the O-Bi-O and O-Cu-O layers. In contrast, for the Pb-substituted Bi2212 phase, σ changed only slightly with increasing l, revealing that the relaxation mechanism for lattice mismatch in the Pb-substituted Bi2212 phase is different from that of the Pb-free Bi2212 phase. A possible mechanism for relaxation of lattice mismatch is the change in Pb valence. As the Pb valence increases from 2+ to 4+, the ionic radius of Pb decreases, suggesting that l decreases and the mismatch between the O-Cu-O and Bi(Pb)O lengths decreases.
The dynamics of crystallization in barium borate glasses is reported. The glasses of 50BaO-50B2O3 and 48BaO-48B2O3-4TiO2 were investigated. β-phase BaB2O4 microcrystals were formed by the heat treatment. The Time-Temperature-Transformation diagrams of these two glasses were obtained. It was found that 48BaO-48B2O3-4TiO2 glass was more stable than 50BaO-50B2O3 glass. The obtained diagram will be useful for the development and practical fabrication of the crystallized barium borate glasses.