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Shota Hayashida, Masamitsu Takahashi, Hiroshi Deguchi, Hiroaki Tsuchiya, Koushu Hanaki, Masato Yamashita, Shinji Fujimoto, Structure of Corrosion Product Formed on Carbon Steel Covered with NiSO4-Added Resin Coating under Sulfuric Acid Mist Environment Containing Chloride, Materials Transactions, 2021, Volume 62, Issue 6, Pages 781-787, Released on J-STAGE May 25, 2021, Advance online publication May 14, 2021, Online ISSN 1347-5320, Print ISSN 1345-9678, https://doi.org/10.2320/matertrans.C-M2021819., Corrosion resistance of carbon steel covered with resin coating containing nickel sulfate has been evaluated under chloride and sulfuric acid mist environment. The structure of corrosion products formed on steel surface was investigated by XRD and XAFS analyses using synchrotron radiation. Nickel sulfate promoted the formation of goethite and akaganeite. It was considered that this akaganeite was not tetragonal β-FeOOH but monoclinic akaganeite containing nickel.

Advanced synchrotron radiation (SR) has been recognized as a premier research tool for developments of science and technology as well as for core industrial applications. Large-scale SR facilities around the world are constantly evolving, providing super brilliant and super directive X-rays. Consequently, a new range of applications in the nano-disciplines has been created. Since 2012, we have been pursuing a low emittance 3 GeV synchrotron radiation facility project: SLiT-J (Synchrotron Light in Tohoku, Japan). After extended deliberations, the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan decided to initiate construction of the new 3 GeV facility on the campus of Tohoku University. The construction and operation of the facility will be carried out by a new organization. It is a combined public–private regional partnership, in which the partners are the National Institute of Quantum Radiological Science & Technology (QST), Tohoku University, Miyagi Prefecture, Sendai-City; the Tohoku Economic Federation; and the Photon Science Innovation Center. Funding comes from private sector investments, local governments, and MEXT through QST.

The structural dynamics of an iodide layer adsorbed on Au(111) were investigated using X-ray photon correlation spectroscopy (XPCS), electrochemical scanning tunneling microscopy (STM), and time-resolved Xray diffraction. At the adsorption equilibrium of iodide at a constant electrode potential, the STM images captured at regular intervals show the migration of atomic vacancy sites in the ordered adsorbed iodide layer. The results indicate that reversible adsorption/desorption and site conversion continuously occur at the equilibrium state. Although the transitions occur at various time scales according to the STM images, the time decay of the autocorrelation function at the specular position is estimated to be 127 s according to the XPCS measurement. The dynamics observed using XPCS suggest that the vertical relaxation of the surface layers is associated with the adsorption of iodide.

塩化物を含む硫酸ミスト環境において，NiSO4含有樹脂を被覆した炭素鋼の耐食性を評価した．形成した腐食生成物の構造を解明するため，放射光を用いたXRDおよびXAFS解析を実施した．NiSO4により，ゲーサイトおよびアカガネアイトの形成が促進された．このアカガネアイトは正方晶系のβ-FeOOHではなく，Niを含有した単斜晶系のアカガネアイトであると考えられる．, Corrosion resistance of carbon steel covered with resin coating containing nickel sulfate has been evaluated under chloride and sulfuric acid mist environment. The structure of corrosion products formed on steel surface was investigated by XRD and XAFS analyses using synchrotron radiation. Nickel sulfate promoted the formation of goethite and akaganeite. It was considered that this akaganeite was not tetragonal β-FeOOH but monoclinic akaganeite containing nickel.

量子科学技術研究開発機構では、文科省のナノテクノロジープラットフォーム事業を受託して、大型放射光施設SPring-8に設置している専用装置の外部利用者の支援を行っている。そのうちの表面X線回折計、ダイヤモンドアンビルセル回折計、高温高圧プレス装置の3つについて、装置の概要と代表的研究例を紹介する。

Using in situ synchrotron X-ray reciprocal space mapping, this study investigates the evolution of lattice deformations in the InGaAs/GaAs(111)A structure with or without a thin InAs layer grown by molecular beam epitaxy. During the initial growth phase, InGaAs directly grown on GaAs(111)A showed an anomalous lattice shrinkage along the c-axis, with no change in the indium composition. Conversely, the InGaAs grown on InAs/GaAs(111)A showed no initial lattice distortion, but a variable indium composition. The evolution of the diffraction peak broadening was also monitored. The results confirmed that the thin InAs layer effectively improved the crystal quality during the initial growth of InGaAs.

InGaN(窒化インジウムガリウム)/GaN(窒化ガリウム)多重量子井戸構造は、緑、黄色領域の発光デバイスとして期待されているが、高In組成のInGaNはGaNとの格子不整合が大きく、転位が発生しやすい[1]。そこで、転位の発生を抑制するために、ナノワイヤ構造が注目されている[2][3]。InGaN/GaN多重量子井戸ナノワイヤからの発光にはInGaN層の歪みやIn組成の均一性、積層数が深く関係しており、InGaN/GaN多重量子井戸の積層数、成長温度の最適化が必要である。そこで、本研究はInGaN層の歪み、In組成の均一性の積層数依存性、成長温度依存性を評価するために、20周期InGaN/GaN多重量子井戸ナノワイヤ成長中の放射光その場X線回折を適用した。, 第2回結晶工学×ISYSE合同研究会

IoT（Internet of Things）の普及とともに無線通信用の高周波デバイスやLED・レーザなどの光デバイス、そして各種センサーの高性能化、高機能化も求められている。特に窒化ガリウム（GaN）に代表される窒化物半導体は従来のシリコン（Si）やガリウムヒ素（GaAs）を凌駕する優れた物性値を有しており、IoT関連材料の主役として期待されている。ただし、窒化物半導体にはSiやGaAsにはない特異な歪みや欠陥、表面界面構造など結晶成長の基礎にかかわる多くの謎が取り残されたままであり、デバイス性能の飛躍的な向上のためにも、これら結晶成長メカニズムの理解と制御が急務となっている。我々は結晶成長の様子をライブ観察できる放射光その場X線回折を、微細構造解析プラットフォームを通して外部研究機関に提供し、窒化物半導体のさまざまな結晶成長メカニズムの解明に取り組んでいる。本講演では、放射光その場X線回折を用いて、IoT関連材料の構造解析を行った最近の研究例を紹介する。, 日本顕微鏡学会第７５回学術講演会

窒化ガリウム（GaN）成長中の表面構造を定量的に捉えることは、エピタキシャル成長の基礎学理を理解する上で重要であるとともに、結晶のさらなる高品質化に向けた設計指針の構築にとっても重要である。とくに分子線エピタキシャル（MBE）成長中のGaN表面は、常に液体Gaによって覆われていることが高品質な結晶を得る条件として知られており、液体GaがGaN表面に対してランダムに吸着しているのか、それともある程度の秩序をもって吸着しているのか、きわめて興味深い。我々はこれまでに、GaN表面上にGaを照射しながらX線Crystal Truncation Rod（CTR）散乱強度をその場測定することによって、Ga極性GaN表面上の液体Ga層の構造を明らかにしている。本研究は同測定手法をN極性GaN表面に適用し、実験とシミュレーションからGaN表面上の液体Ga層の構造を定量的に決定した。, 第６６回応用物理学会春季学術講演会

In situ X-ray diffraction measurement was performed to study the precipitation mechanism of graphene from Ni catalyst with and without Ti capping layer using X-ray beam from a synchrotron radiation facility. The graphene precipitated on the surface of the catalyst in the case without the Ti capping layer while it did at the interface between the catalyst and the sapphire substrate in the case with the Ti capping layer. Each process, such as graphene nucleation and precipitation was successfully monitored even though graphene precipitated under the metal catalyst. The detailed mechanisms for both cases were discussed using the experimental results. Consequently, the crystallization of the catalyst is found to effectively suppress the precipitation at low temperature, which is useful to improve the quality of the precipitated graphene. The adjustment of the amount of the carbons is another important factor to precisely control the precipitation because graphene also precipitates after the carbons saturate the catalyst.

In-situ X-ray diffraction was used to investigate the initial stages of GaN growth on graphene-covered SiO2 substrates with or without AlN buffer layers by plasma-assisted molecular beam epitaxy. The in-plane lattice parameter of GaN remained almost constant during growth without AlN buffer layers, confirming weak interactions between GaN and graphene. On the substrate with AlN buffer layers, the GaN lattice parameter continuously changed from an AlN value to GaN value, indicating that the AlN islands act as seeds for GaN growth. Besides, GaN has preferential orientations epitaxial to graphene. Graphene can be used as a template of GaN growth on amorphous substrates.

We carry out real-time in situ synchrotron X-ray diffraction on the growth of GaN and AlN on SiC(0001) substrate by molecular beam epitaxy. At the initial growth stage of GaN/SiC or AlN/SiC heterostructure, the epitaxial overlayer develops affected by defects with the strain interaction between SiC, eventually showing characteristic lattice deformations. GaN was almost relaxed at the initial stage, showing the transition of the growth mode from 3D to 2D at around 4 nm. In contrast, AlN coherently grow on SiC(0001) at the initial stage for 13 nm concomitantly showing lattice deformation with the beneath SiC, subsequently showing gradual lattice relaxation.

金触媒GaAsナノワイヤの構造多形について、放射光その場X線回折をおこない、積層欠陥密度など結晶構造の分布に関する情報を含めて決定した。測定結果は、GaAsナノワイヤの成長を核形成理論に基づくシミュレーションに基づいて考察した。その結果、ZB上のWZ成長核、WZ上のZB成長核が形成するさいに、高いエネルギー障壁があることが明らかになった。また、成長初期に見られるZB成長からWZ成長への変化は、核形成サイトの違いが要因であることがわかった。, 特別研究プロジェクト「結晶成長の数理」第12回研究会発表

Dislocation-mediated strain relaxation during lattice-mismatched InGaAs/GaAs(001) heteroepitaxy was studied through in situ X-ray reciprocal space mapping ({{\it in situ}} RSM). At the synchrotron facility SPring-8, a hybrid system of molecular beam epitaxy and X-ray diffractometry with a two-dimensional detector enabled us to perform {{\it in situ}} RSM at high-speed and high-resolution. Using this experimental setup, the strain relaxation processes were classified into four thickness ranges with different dislocation behavior. In order to discuss this observation quantitatively, a strain relaxation model was proposed based on the Dodson-Tsao's kinetic model, and its validity was demonstrated by good agreement with the experimental residual strain. In addition to the single InGaAs layer, strain relaxation processes in multi-layer structures are discussed.

高品質GaInN 膜の実現は、GaN マトリックスを用いるこれまでのGaN 系発光デバイスに対し、より幅広いデバイス設計・デバイス応用を可能とする。高品質GaInN膜を実現するためには、格子緩和過程を理解し、その過程を制御することが求められる。今回は、RF-MBE 法を用いてGaN 上およびInN上にGaInN 成長を行い、その場X 線逆格子マッピング法を用いてGaInN 成長初期過程の観察を行ったので報告する。, 第78回応用物理学会秋季学術講演会

In this work, in situ synchrotron X-ray diffraction reciprocal space mapping (RSM) measurements were carried out for the radio-frequency plasma-assisted molecular beam epitaxy (RF-MBE) growth of GaInN on GaN and InN layers, which were also grown by RF-MBE on commercialized GaN/c-sapphire templates. In situ XRD RSM measurements were performed using an MBE apparatus directly coupled to an X-ray diffractometer at the beamline of the synchrotron radiation facility SPring-8. It was observed in situ that both lattice relaxation and compositional pulling occurred during the initial growth stage, reducing the strain of GaInN on GaN and InN. Different initial growth behaviors of GaInN on GaN and InN were also observed from the results of the evolution of GaInN integrated peak intensities.

This paper studies the antioxidant activity of 1,2,3,4-tetrahydroquinolines, 3,4-dihydro-2H-benzo[1,4]thiazines and 1,2,3,4-tetrahydroquinoxalines in the inhibition of the peroxidation of tetralin induced by an azo initiator. Neither 1,2,3,4- tetrahydroquinoline nor 3,4-dihydro-2H-benzo[1,4]thiazine alone acted as an antioxidant, but when they have an electron-donating group at the para position to the NH group, they act as potent antioxidants. On the other hand, 1,2,3,4- tetrahydroquinoxaline on its own showed good antioxidant activity. However, 1,2,3,4-tetrahydroquinoxalines with methyl and methoxy groups in the phenyl ring have reactivities similar to or less than that of unsubstituted 1,2,3,4-tetrahydroquinoxaline. The induction periods of 1,2,3,4-tetrahydroquinoxalines with an alkyl group or phenyl group at the 2-position were all longer than the value for the unsubstituted 1,2,3,4-tetrahydroquinoxaline, except for a compound with a t-butyl group. The oxidation of 1,2,3,4-tetrahydroquinoxalines by peroxyl radicals generated from an azo initiator in tetralin or benzene yields quinoxalines and a dimer product of quinoxalines, 6-(1,2,3,4-tetrahydroquinoxalin-1-yl)-quinoxaline.

Decarburization behavior in RH-Degasser was discussed on the basis of a comparison between simulation and operational result. In the simulation, decarburizations through Ar bubbles, CO bubbles and a free surface were considered. Furthermore, the difference in carbon concentration between the melt in the ladle and that in the vacuum vessel was also considered. As a result of the comparison, it was found that the contribution of the decarburization as CO bubbles to the total amount of decarburization is great. In order to step up the decarburization rate, increasing the circulation flow rate is effective. That is accomplished by reducing the atmospheric pressure in the vacuum vessel, injecting Ar at a deeper position, and increasing the Ar gas flow rate and the snorkel diameter. Increasing oxygen concentration is expected to be effective to promote decarburization.

We report an anomalous lattice deformation of GaN layers grown on SiC(0001) by molecular beam epitaxy. The evolution of the lattice parameters during the growth of the GaN layers was measured by in situ synchrotron X-ray diffraction. The lattice parameters in the directions parallel and normal to the surface showed significant deviation from the elastic strains expected for lattice-mismatched films on substrates up to a thickness of 10 nm. The observed lattice deformation was well explained by the incorporation of hydrostatic strains due to point defects. The results indicate that the control of point defects in the initial stage of growth is important for fabricating GaN-based optoelectronic devices.

For the reduction of non-metallic inclusions in steel, a ceramic loop filter has been developed. Void size of the filter can be adjusted widely by varying the string and loop diameters respectively. Characteristics of the loop filter, such as an inclusion removal efficiency and filter medium resistance were investigated in laboratory. From the experimental results, the mechanism of the filtration was discussed, and it was concluded that firstly the inclusion particle is entrapped onto the filter surface by the interception, secondly glued there by the attraction force based on the molten steel surface tention, and finally bonded by sintering.