Yasumasa Koyama - My portal

Profile Information

Affiliation: Professor, Faculty of Science and Engineering School of Fundamental Science and Engineering, Waseda University

Degree: 工学博士(東京工業大学)
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工学修士(東京工業大学)
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Researcher number: 20150295
J-GLOBAL ID: 200901026774614076
researchmap Member ID: 1000090718

External link: http://www.koyamalab.sci.waseda.ac.jp/

Research Interests

Solid-State Physics I (Optical Properties, Properties, Semiconductor & Dielectrics)

Research Areas

Research History

Apr, 1994

School of Science and Engineering, Waseda University
Apr, 1990

早稲田大学材料技術研究所兼任研究員
Apr, 1989

School of Science and Engineering, Waseda University
Apr, 1985 - Mar, 1987

（米国Purdue大学博士研究員）
Apr, 1981

School of Engineering, Tokyo Institute of Technology

Education

Awards

2008

平成20年度日本学術振興会日本学術振興会科学研究費補助金第1回審査員表彰
1996

日本金属学会功績賞
1990

村上記念研究奨励賞
1982

本多記念研究奨励賞
1982

日本金属学会論文賞
1981

手島記念研究奨励賞
1979

日本金属学会ジェフリース賞

Papers

108

Formation of the $alpha$-Mn and R structures from the $beta$-Mn structure in Mn-Si alloys

T. Doi, T. Kobayashi, M. Tanimura, Y. Koyama

Physical Reveiw B / The American Physical Society, 82 184205, Nov, 2010 Peer-reviewed
Crystallographic Features of Ferroelectric States around the Tetragonal/Rhombohedral Phase Boundary in Pb_1-xLa_x(Zr_1-yTi_y)O₃

M. Arao, Y. Inoue, R. Ando, Y. Koyama

Materials Science Forum, 638-642 1737-1742, Jan, 2010 Peer-reviewed
Stability of the orbital-modulated state in the layered perovskite manganite Sr_2-xR_xMnO₄ (R = Pr, Nd)xR_xMnO₄ (R = Pr, Nd)

Y. Inoue, M. Arao, G. Shindo, Y. Koyama

Materials Science Forum, 638-642 1760-1765, Jan, 2010 Peer-reviewed
Metastable dodecagonal-atomic-column state related to the formation of the σ structure in the Cr-Co alloy system

T. Doi, M. Tanimura, Y. Koyama

Physical Reveiw B / The American Physical Society, 79(13) 134204, Apr, 2009 Peer-reviewed
Phase transition with non-deterministic nature in the Ni(3)Al(0.45)V(0.50) alloy

M. Tanimura, T. Doi, Y. Koyama

EPL, 82(4) 40007, May, 2008 Peer-reviewed
Crystal-structure units of the R (Fe(3)Mo(2)) phase in the Fe-Mo alloy system

Toshihiro Doi, Makoto Tanimura, Yasumasa Koyama

PHYSICAL REVIEW B, 77(13) 134205, Apr, 2008
Crystallographic features of the orbital-ordered state in the layered perovskite manganite Sr2-xPrxMnO4

Wataru Norimatsu, Go Shindo, Yasumasa Koyama

PHYSICA B-CONDENSED MATTER, 403(5-9) 1585-1586, Apr, 2008
Role of the triclinic Al(2)Fe structure in the formation of the Al(5)Fe(2)-approximant

Akihiko Hirata, Yuichiro Mori, Manabu Ishimaru, Yasumasa Koyama

PHILOSOPHICAL MAGAZINE LETTERS, 88(7) 491-500, 2008 Peer-reviewed
Stability of electronic states in the layered perovskite Sr_2-xNd_xMnO₄

W. Norimatsu, Y. Koyama

Physica C, 463-465(1) 115-119, Oct, 2007 Peer-reviewed
Diffusion blocking, path variability, and bifurcation of the final state in the phase separation of Ni₃(Al,V)_1-δ alloys

Makoto Tanimura, Yasumasa Koyama

Physical Review B / The American Physical Society, 76(5) 54103, Aug, 2007 Peer-reviewed
Ferroelectric domain structures around the morphotropic phase boundary of the piezoelectric material PbZr_1-xTi_xO₃

T. Asada, Y. Koyama

Physical Review B / The American Physical Society, 75(21) 214111, Jun, 2007 Peer-reviewed
Crystallographic features of the orbital-ordered, and charge-and-orbital-ordered states in Sr_2-xNd_xMnO₄

W. Norimatsu, Y. Koyama

Physical Review B / The American Physical Society, 75(23) 235121, Jun, 2007 Peer-reviewed
Orientation relationship between the bcc and σ phases in Cr-Co alloys

T. Doi, M. Tanimura, Y. Koyama

Materials Research Society Symposium Proceedings, 980, Apr, 2007 Peer-reviewed
Doping Effect on Ferroelectric Microstructure in YMn_1-xTi_xO₃

S. Mori, J. Tokunaga, Y. Horibe, T. Asada, Y. Koyama, T. Katsufuji

Ferroelectrics, 348 170, Mar, 2007 Peer-reviewed
Domain-structure relaxation in the tetragonal-to-orthorhombic phase transition of the layered perovskite Sr_1.8La_0.2Mn_1-yFe_yO₄

W. Norimatsu, Y. Koyama

Physical Review B / The American Physical Society, 75(10) 104416, Mar, 2007 Peer-reviewed
Ferroelectric Domain Structures Near the MPB in (1-x)Pb(Zn_1/3Nb_2/3)O₃-xPbTiO₃

T. Asada, T. Shibata, Y. Koyama

Ferroelectrics, 347 223, Feb, 2007 Peer-reviewed
The role of antiphase boundaries in the kinetic process of the L1(2) -> D0(22) structural change of an Ni3Al0.45V0.50 alloy

Makoto Tanimura, Yasumasa Koyama

ACTA MATERIALIA, 54(16) 4385-4391, Sep, 2006 Peer-reviewed
Characteristic features of the Fe₇Mo₆-type structure in a transition-metal alloy examined using transmission electron microscopy

A. Hirata, A. Iwai, Y. Koyama

Physical Review B / The American Physical Society, 74(5) 54204, Aug, 2006 Peer-reviewed
Evolution of orthorhombic domain structures during the tetragonal-to-orthorhombic phase transition in the layered perovskite Sr_2-xLa_xMnO₄

W. Norimatsu, Y. Koyama

Physical Review B / The American Physical Society, 74(8) 85113, Aug, 2006 Peer-reviewed
Influence of Si addition on microstructure evolution of Ni3Al0.50V0.50 alloy

Makoto Tanimura, Kei-ichi Kondo, Toshihiro Doi, Yasumasa Koyama

MATERIALS TRANSACTIONS, 47(7) 1755-1761, Jul, 2006 Peer-reviewed

Professional Memberships

Research Projects

Crystallographic relation between coordination-polyhedron structures involving dodecagonal atomic columns and approximant-phase structures related to the dodecagonal quasicrystal

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science, Apr, 2015 - Mar, 2018

Koyama Yasumasa, INOUE Yasuhide
12角形原子コラムを含む配位多面体構造および近似結晶構造の特徴

科学研究費助成事業(基盤研究(C)), 基盤研究(C), 科学研究費助成事業(早稲田大学), 2015 - 2017
Crystallographic relation between coordination-polyhedron structures involving dodecagonal atomic columns and approximant-phase structures related to the dodecagonal quasicrystal

2015 - 2017
Are higher order structures present in coordination-polyhedron structures of alloys, just like proteins?

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, 2006 - 2007

KOYAMA Yasumasa, HIROTSU Yoshihiko, HIRATA Akihiko
Are higher order structures present in coordination-polyhedron structures of alloys, just like proteins?

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, 2006 - 2007

KOYAMA Yasumasa, HIROTSU Yoshihiko, HIRATA Akihiko
ナノ粒子添加による超高度金属材料の創成

新技術開発研究（2003年〜2004年は産学連携、2005年からは社会連携に種別名称変更）, 文部科学省, 2000 - 2004
リラクサーの機能発現機構の解明と巨大誘電応答特性をもつ新リラクサーの開発

新技術開発研究（2003年〜2004年は産学連携、2005年からは社会連携に種別名称変更）, 文部科学省, 2000 - 2004
Piezoelectricity and hetero-structure fluctuations in ferroelectric materials having composition near a morphotropic phase boundary

Grants-in-Aid for Scientific Research, Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science, 2001 - 2003

KOYAMA Yasumasa
Structural phase transition in the heavy fermion system Cu_6Ce

Grants-in-Aid for Scientific Research, Grant-in-Aid for General Scientific Research (C), Japan Society for the Promotion of Science, 1990 - 1992

KOYAMA Yasumasa