NAGAOKA Akira

写真a

Affiliation

Engineering educational research section Research & Development Center for Sustanable Energy and Environmental Engineering

Title

Associate Professor

External Link

Degree 【 display / non-display

  • 博士(工学) ( 2014.3   宮崎大学 )

Research Areas 【 display / non-display

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electric and electronic materials

  • Nanotechnology/Materials / Energy chemistry

Education 【 display / non-display

  • University of Miyazaki

    2011.4 - 2014.3

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    Country:Japan

  • University of Miyazaki   Graduate School, Division of Engineering

    2009.4 - 2011.3

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    Country:Japan

  • University of Miyazaki   Faculty of Engineering

    2005.4 - 2009.3

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    Country:Japan

External Career 【 display / non-display

  • 東京工業大学フロンティア材料科学研究所   共同研究員

    2017.4

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    Country:Japan

  • 九州大学応用力学研究所   共同研究員

    2017.4

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    Country:Japan

  • Kyoto University

    2017.4 - 2018.10

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    Country:Japan

  • University of Utah   日本学術振興会海外特別研究員

    2015.4 - 2017.3

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    Country:United States

  • Kyoto University

    2014.4 - 2015.3

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    Country:Japan

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Professional Memberships 【 display / non-display

  • JSAP: Japan Society of Applied Physics

  • IEEE

  • Professional Group of Multinary Compounds and Solar Cells

  • Thermoelectrics Society of Japan

  • Division of Crystals Science and Technology

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Papers 【 display / non-display

  • Physicochemical insights into semiconductor properties of a semitransparent tantalum nitride photoanode for solar water splitting

    Higashi T., Nishiyama H., Pihosh Y., Wakishima K., Kawase Y., Sasaki Y., Nagaoka A., Yoshino K., Takanabe K., Domen K.

    Physical chemistry chemical physics : PCCP   25 ( 30 )   20737 - 20748   2023.8

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Physical chemistry chemical physics : PCCP  

    The self-conductivity of tantalum nitride (Ta3N5) thin film-based semitransparent photoanodes was found to promote the current originating from the photoelectrochemical oxygen evolution reaction (PEC OER) without a conducting substrate. With surface modification by the NiFeOx-electrocatalyst, an optimized Ta3N5 thin film fabricated directly on a transparent insulating quartz substrate generated a photocurrent density of ∼5.9 ± 0.1 mA cm-2 at 1.23 V vs. the reversible hydrogen electrode under simulated AM 1.5G solar illumination. The correlation between the PEC OER performance of NiFeOx-modified Ta3N5 photoanodes and the electrical properties of Ta3N5 thin films was investigated based on the Hall effect measurements. By changing the nitridation conditions, these properties can be tuned so that the higher the Hall mobility (0.2 to 1.7 cm2 V-1 s-1) and the lower the carrier concentration (1020 to 1019 cm-3). The surface chemical states of Ta3N5 thin films were investigated using X-ray photoelectron spectroscopy as a means of evaluating surface oxygen impurities and nitrogen vacancies, which may correlate with the PEC OER performance and the electrical properties of the material.

    DOI: 10.1039/d3cp02563b

    Scopus

  • 3D Solar Irradiance Model for Non-Uniform Shading Environments Using Shading (Aperture) Matrix Enhanced by Local Coordinate System Reviewed

    Araki K., Ota Y., Nagaoka A., Nishioka K.

    Energies   16 ( 11 )   4414   2023.6

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Energies  

    Building-integrated photovoltaics (BIPVs) and vehicle-integrated photovoltaics (VIPVs) receive solar irradiance through non-uniform shading objects. Standard scalar calculations cannot accurately determine the solar irradiance of BIPV and VIPV systems. This study proposes a matrix model using an aperture matrix to accurately calculate the horizontal and vertical planes affected by non-uniform shading objects. This can be extended to the solar irradiance on a VIPV by applying a local coordinate system. The 3D model is validated by a simultaneous measurement of five orientations (roof and four sides, front, left, tail, and right) of solar irradiance on a car body. An accumulated logistic function can approximate the shading probability. Furthermore, the combined use of the 3D solar irradiance model is effective in assessing the energy performance of solar electric vehicles in various zones, including buildings, residential areas, and open spaces. Unlike standard solar energy systems, the energy yield of a VIPV is affected by the shading environment. This, in turn, is affected mainly by the location of vehicle travel or parking in the city rather than by the climate zones of the city.

    DOI: 10.3390/en16114414

    Scopus

  • Direct Observation of Group-V Dopant Substitutional Defects in CdTe Single Crystals Reviewed International coauthorship

    Nagaoka A., Kimura K., Ang A.K.R., Takabayashi Y., Yoshino K., Sun Q., Dou B., Wei S.H., Hayashi K., Nishioka K.

    Journal of the American Chemical Society   145 ( 16 )   9191 - 9197   2023.4

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    Authorship:Lead author, Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of the American Chemical Society  

    Point defect chemistry strongly affects the fundamental properties of materials and has a decisive impact on device performance. The Group-V dopant is prominent acceptor species with high hole concentration in CdTe; however, its local atomic structure is still not clear owing to difficulties in definitive measurements and discrepancies between experimental observations and theoretical models. Herein, we report on direct observation of the local structure for the As dopant in CdTe single crystals by the X-ray fluorescence holography (XFH) technique, which is a powerful tool to visualize three-dimensional atomic configurations around a specific element. The XFH result shows the As substituting on both Cd (AsCd) and Te (AsTe) sites. Although AsTe has been well known as a shallow acceptor, AsCd has not attracted much attention and been discussed so far. Our results provide new insights into point defects by expanding the experimental XFH study in combination with theoretical first-principles studies in II-VI semiconductors.

    DOI: 10.1021/jacs.3c01248

    Scopus

  • Controlling the conduction type in a thermoelectric material (Cu1-xAgx)2ZnSnS4 Reviewed

    Okamoto K., Nagaoka A., Nagatomo K., Yoshino K., Ota Y., Nishioka K.

    Journal of Physics and Chemistry of Solids   171   111016 pp1 - 111016 pp5   2022.12

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    Authorship:Corresponding author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Journal of Physics and Chemistry of Solids  

    Quaternary kesterite p-type Cu2ZnSnS4 (CZTS) has the potential to be used as an environmentally friendly thermoelectric (TE) material. Conversion of p-n conduction is required for the realization of a CZTS-based TE device. Herein, we studied the growth of a polycrystalline (Cu1-xAgx)2ZnSnS4 (CAZTS) and its fundamental TE properties. An n-type CAZTS (x = 0.4) with a negative Seebeck coefficient (60–70 μV/K) can be obtained without secondary phases. The electrical conductivity decreased with increasing Ag content owing to defect compensation. The conduction mechanism of the polycrystalline CAZTS can be demonstrated through hopping conduction, thermal activation, and a potential barrier at the grain boundary.

    DOI: 10.1016/j.jpcs.2022.111016

    Scopus

  • Characterization of Cu-Bi-S Powders Synthesized by Polyol Method Reviewed

    Shirahata Y., Nagaoka A., Araki H., Kawakubo T.

    Materials Transactions   63 ( 10 )   1496 - 1500   2022.9

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Materials Transactions  

    Cu-Bi-S powders were synthesized by a polyol method at 180°C and a speed of 600 rpm for 70 min. X-ray diffraction patterns of the Cu-Bi-S powders showed that single-phase Cu3BiS3 was obtained at a thiourea concentration of 197 mmol·L-1. Microstructural analysis of the CuB-S powders revealed that the sizes of the Cu-Bi-S particles with single-phase Cu3BiS3 were 200-400 nm and their composition was Cu-poor, Bi-rich, and slightly S-poor. From the optical measurement by an ultraviolet-visible-near infrared spectroscopy, the optical bandgap of the CuB-S powder with single-phase Cu3BiS3 was estimated to be 1.24 eV. Based on the obtained results, the influences of thiourea concentration on synthesis of Cu3BiS3 were discussed.

    DOI: 10.2320/matertrans.M-M2022809

    Scopus

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Books 【 display / non-display

  • 国立大学で工学を学ぼう vol. 2

    永岡 章( Role: Contributor ,  身近な温度差を電気に換える「熱電変換」材料)

    株式会社フロムページ  2022.1 

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    Language:Japanese Book type:Scholarly book

  • Copper Zinc Tin Sulfide-Based Thin Film Solar Cells

    Akira Nagaoka and Kenji Yoshino( Role: Joint author ,  Chapter 6 Growth of CZTS single crystals)

    Wiley  2015 

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    Responsible for pages:133-148   Language:Japanese Book type:Scholarly book

  • 電子機器・部品における故障・発火原因解析と対策技術

    永岡章, 吉野賢二( Role: Joint author)

    技術情報協会  2014 

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    Responsible for pages:587-591   Language:Japanese Book type:Scholarly book

MISC 【 display / non-display

  • 廃熱を有効活用する環境調和型熱電変換デバイスの開発 Invited

    永岡 章

    月刊機能材料   ( 3月号 )   2023.3

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    Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

  • 研究室紹介 宮崎大学工学部 環境・エネルギー工学研究センター Invited

    永岡 章

    日本熱電学会誌   19 ( 2 )   82 - 83   2022.12

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    Authorship:Lead author   Language:Japanese   Publishing type:Internal/External technical report, pre-print, etc.   Publisher:日本熱電学会  

  • 無次元性能指数ZT=1.6を示す環境調和型Cu2ZnSnS4単結晶 Invited

    永岡 章

    日本熱電学会誌   18 ( 3 )   142   2022.4

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    Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)   Publisher:日本熱電学会  

  • 自動車廃熱の有効活用へ向けた環境調和型熱電変換材料の開発 Invited

    永岡 章

    月刊車載テクノロジー   ( 12月号 )   61 - 65   2021.12

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    Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

  • Doping control in a cadmium telluride photovoltaic device Invited

    NAGAOKA Akira

    Oyo Buturi   89 ( 11 )   661 - 665   2020.11

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    Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

    Control of the electronic defect populations in CdTe by the combination of group-V element doping and Cd-rich composition is the most promising current strategy for maximizing acceptor doping while preserving the high minority carrier lifetime. In this paper, we will summarize some recent results that contributed to a better understanding of the group-V doping process in CdTe. We will also review some of the topics that are important for CdTe photovoltaics.

    DOI: 10.11470/oubutsu.89.11_661

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Presentations 【 display / non-display

  • ケステライト化合物Cu2ZnSnS4を用いた環境調和型熱電デバイスの開発

    永岡 章,長友 克馬,岡本 晃一,吉野 賢二,西岡 賢祐

    第70回応用物理学会春季学術講演会  2023.3.16 

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    Event date: 2023.3.15 - 2023.3.18

    Language:Japanese   Presentation type:Oral presentation (general)  

  • 蛍光X線ホログラフィーによるII-VI族化合物半導体の欠陥化学の再構築

    永岡 章

    令和4年度第29回コニカミノルタ画像科学奨励賞授与式  2023.3.1 

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    Event date: 2023.3.1

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  • カーボンニュートラル達成に向けた熱エネルギー研究

    永岡 章

    経済同友会地域共創ワーキンググループ  2023.1.16 

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    Event date: 2023.1.16 - 2023.1.17

    Language:Japanese   Presentation type:Oral presentation (invited, special)  

  • デバイス化を目的としたCu2ZnSnS4の伝導型制御と伝導メカニズムの変化

    岡本 晃一, 永岡 章, 長友 克馬, 吉野 賢二, 西岡 賢祐

    2022年度多元系化合物・太陽電池研究会 年末講演会  2022.12.16 

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    Event date: 2022.12.16 - 2022.12.17

    Language:Japanese   Presentation type:Poster presentation  

  • Bi2Te3結晶の熱電特性における組成依存

    平井 優一, 永岡 章, 岡本 晃一, 長友 克馬, 吉野 賢二, 西岡 賢祐

    2022年度多元系化合物・太陽電池研究会 年末講演会  2022.12.16 

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    Event date: 2022.12.16 - 2022.12.17

    Language:Japanese   Presentation type:Poster presentation  

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Awards 【 display / non-display

  • 令和4年度 コニカミノルタ画像科学奨励賞

    2023.3   公益財団法人コニカミノルタ科学技術振興財団   蛍光X線ホログラフィーによるII-VI族化合物半導体の欠陥化学の再構築

    永岡 章

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    Award type:Award from publisher, newspaper, foundation, etc.  Country:Japan

  • 第13回半導体材料・デバイスフォーラム ポスター発表奨励賞

    2022.10   半導体デバイスフォーラム実行委員会  

    岡本 晃一,永岡 章,重枝 祐輔,吉野 賢二,西岡 賢祐

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

  • 第13回半導体材料・デバイスフォーラム 口頭発表奨励賞

    2022.10   半導体デバイスフォーラム実行委員会  

    長友 克馬,永岡 章,岡本 晃一,西岡 賢祐

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

  • 2021年講演奨励賞

    2021.12   多元系化合物・太陽電池研究会   高い熱電性能指数ZTを示すカルコパイライト 化合物ZnSnSb2

    重枝 佑輔, 永岡 章, 吉野 賢二, 西岡 賢祐

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    Award type:Award from Japanese society, conference, symposium, etc. 

  • 第12回半導体材料・デバイスフォーラム 口頭発表奨励賞

    2021.12   半導体デバイスフォーラム実行委員会  

    岡本 晃一,永岡 章,重枝 佑輔,吉野 賢二,西岡 賢祐

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    Award type:Award from Japanese society, conference, symposium, etc.  Country:Japan

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Grant-in-Aid for Scientific Research 【 display / non-display

  • IoT用独立型電源のための環境調和型多元系熱電材料の無次元性能指数向上

    Grant number:20K15221  2020.04 - 2024.03

    独立行政法人日本学術振興会  科学研究費補助金  若手研究

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    Authorship:Principal investigator 

  • 高品質ケステライト化合物バルク単結晶を用いた高効率太陽電池デバイスの創製

    2017.04 - 2020.03

    科学研究費補助金  特別研究員奨励費

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  • 高効率太陽電池のためのケステライト化合物単結晶成長と電気特性を中心とした物性評価

    2015.04 - 2017.03

    科学研究費補助金  特別研究員奨励費

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    Authorship:Principal investigator 

  • 高効率太陽電池のための新規多元系材料の単結晶成長と基礎物性の解析

    2013.04 - 2015.03

    科学研究費補助金  特別研究員奨励費

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    Authorship:Principal investigator 

Other research activities 【 display / non-display

  • 東京工業大学フロンティア材料研究所共同研究員

    2020.04

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    東京工業大学フロンティア材料研究所の共同研究員として、東京工業大学安井助教と熱電材料に関する共同開発を継続中。

  • 九州大学応用力学研究所共同研究員

    2019.04

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    九州大学応用力学研究所共同研究員九州大学柿本教授と熱電材料に関する共同開発を継続中。

Available Technology 【 display / non-display