Our Research Objective = “Paving the way for Materials Design through a deep understanding of chemical bonding ”

Enormous time and effort have been devoted to material development. However, as society continues to change dynamically and rapidly, more accurate and swift material development is now required than ever before. If we can realize material design by understanding the correlation between atomic/electronic structures and functional expression, we can significantly accelerate material development. To achieve such material design, it is essential to elucidate the atomic and electronic structures in the local regions responsible for functional expression, and further understand the mechanisms and laws governing functional expression from the obtained results. The Mizoguchi Laboratory aims to achieve 'Material Design Realization' through research using first-principles calculations, informatics methods, and atomic-resolution measurements (STEM-EELS).
The Mizoguchi Laboratory is engaged in the following research themes:

Materials Informatics for materials developments　

In recent years, data science has been attracting attention as the fourth paradigm, and "Materials Informatics," which uses data science in material research, is advancing globally and rapidly. In our group, we are tackling the following research subjects by constructing artificial intelligence (AI) based on the informatics science.
1) Determination and prediction of structures and properties of lattice defects
2) New analytical methods combining spectral analysis with machine learning
3) AI for fast materiasl simulations
4) Generative AI for materials development
For example, using our methods, it is possible to complete calculations that would normally take 22 years in just 3 hours. Additionally, by utilizing AI technology, we have succeeded in gaining new insights that even specialized researchers could not obtain before.

Keywords:Materials Informatics, Data-Driven, Artificial Intelligence, Generative AI, Material Exploration, Spectral Analysis, Autonomous & Automated Analysis, Lattice Defects, Physics Extraction

“Prediction of the Ground State Electronic Structure from Core-loss Spectra of Organic Molecules by Machine Learning” PY. Chen, K. Shibata, K. Hagita, T. Miyata, and T. Mizoguchi J. Phys. Chem. Lett., 14 (2023) 4858-4865.
“Learning excited states from ground states by using an artificial neural network S. Kiyohara, M. Tsubaki, and T. Mizoguchi, npj Comp. Mater., 6 (2020) 68-1-6. here
“Machine learning applications for ELNES/XANES “ T. Mizoguchi and S. Kiyohara, Microscopy 69 (2020) 92-109. here
“Prediction of interface structures and energies via virtual screening” S. Kiyohara, H. Oda, T. Miyata, and T. Mizoguchi, Science Adv., 2 (2016) e1600746-1-7. here

Understanding the Structure-Function Correlation in Energy-Related Materials　　

Developing high-performance power generation materials and storage materials is essential for achieving carbon neutrality. Our laboratory is conducting research aiming to understand the correlation between structure and function by analyzing the atomic and electronic structures near lattice defects such as interfaces and dopants, targeting energy-related materials like solar cell materials, secondary battery materials, ion conductors, and superconductors, using first-principles calculations, machine learning, and atomic-level analysis.

Keywords: Solar Cell Materials, Fuel Cell Materials, Ion Conductors, Superconductors

“Possible New Graphite Intercalation Compounds for Superconductors and Charge Density Wave Materials: Systematic Simulations with Various Intercalants Using a van der Waals Density Functional Method” N. Kawaguchi, K. Shibata, and T. Mizoguchi, J. Phys. Chem. C, 127 (2023) 9833-9843.
“A valence state evaluation of a positive electrode material in a Li-ion battery with first-principles K- and L-edge XANES spectral simulations and resonance photoelectron spectroscopy” K. Kubobuchi, M. Mogi, M. Matsumoto, T. Baba, C. Sato, T. Yamamoto, T. Mizoguchi, H. Imai, J. Appl. Phys., 120, 142125-1-13 (2016)
“The atomic structure, band gap, and electrostatic potential at the (112)[1-10] twin grain boundary of CuInSe2” H. Yamaguchi, H. Hiramatsu, H. Hosono, and T. Mizoguchi, Appl. Phys. Lett., 104, 153904-1-5 (2014).

Lattice Defect Formation and Dynamics in Semiconductors and Two-Dimensional Materials　

With the dramatic improvement in computing speed in recent years, it is becoming possible to perform electronic state calculations for systems consisting of hundreds of atoms using parameter-free first-principles methods. Additionally, the environment for "Universal" machine learning potentials has improved, making it possible to optimize the structure of models with thousands of atoms with high precision on a laptop-level computer. Our laboratory is utilizing such cutting-edge simulation methods to conduct research on lattice defects, dopants, surfaces, and interfaces in advanced materials such as semiconductors, ceramics, two-dimensional compounds, and layered compounds, focusing on their formation behavior and dynamics.

Keywords:Semiconductors, Ceramics, Two-Dimensional Compounds, Moire materials

“Unraveling the Stability of Layered Intercalation Compounds through First-Principles Calculations: Establishing a Linear Free Energy Relationship with Aqueous Ions” N. Kawaguchi, K. Shibata, and T. Mizoguchi, ACS phys. Chem. Au, 4 (2024) 281-291.
“A defect formation mechanism induced by structural reconstruction of a well-known silicon grain boundary” YS. Xie, K. Shibata, and T. Mizoguchi, Acta Mater., 250 (2023) 118827-1-11.
“The influence of neighboring vacancies and their charge state on the atomic migration of LaAlO3” T. Yamamoto and T. Mizoguchi , Appl. Phys. Lett., 102 (2013) 211910-1-4.
“Defect energetics in LaAlO3 polymorphs: A first principles study” T. Yamamoto and T. Mizoguchi , Phys. Rev. B, 86 (2012) 094117.

Material Design of Glasses, Liquids, and Soft Materials Utilizing Atomic-Resolution Measurements　　

Glasses, liquids, gases, and soft materials are widely used in daily life and industrial activities. The properties of these materials are often determined by local atomic structure disorder and dynamic behavior changes, but local structure analysis is challenging due to their complexity. Our laboratory is developing methods to analyze glasses, liquids, gases, and soft materials with high spatial resolution using transmission electron microscopy and is applying these methods to actual materials. We have successfully observed the behavior of individual atoms in liquids in real space, observed dynamic behavior of gas molecules with high spatial resolution, and quantitatively elucidated high-temperature phase separation phenomena in glasses in real space and real-time.


Keywords:Glass, Ionic Liquids, Electrolytes, Fuel Cells, Surfactants, Soft Materials, Gases

“Revealing Spatial Distribution of Al-Coordinated Species in a Phase-Separated Aluminosilicate Glass by STEM-EELS” K. Liao, A. Masuno, A. Taguchi, H. Moriwake, H. Inoue, and T. Mizoguchi, J. Phys. Chem. Lett., 11 (2020) 9637–9642. here
“In situ observation of the dynamics in the middle stage of spinodal decomposition of a silicate glass via scanning transmission electron microscopy”K. Nakazawa, S. Amma, and T. Mizoguchi, Acta Mater. 200 (2020) 720-726. here
“Real-space analysis of diffusion behavior and activation energy of individual monatomic ions in a liquid” T. Miyata, F. Uesugi, and T. Mizoguchi, Science Advances, 3 (2017) e1701546-1-5. here
“Estimation of the molecular vibration of gases using electron microscopy” H. Katsukura, T. Miyata, M. Shirai, H. Matsumoto, and T. Mizoguchi, Scientific Reports, 7 (2017), 16434-1-9. here
“An estimation of molecular dynamic behaviour in a liquid using core-loss spectroscopy” Y. Matsui, K. Seki, A. Hibara, T. Mizoguchi, Scientific Reports, 3 (2013) 3503-1-7. here

Atomic-Resolution Material Analysis by “The Ultimate Analysis”　　

By combining spherical aberration-corrected scanning transmission electron microscopy (STEM) with electron energy loss spectroscopy (EELS), it is possible to obtain atomic-resolution information on the atomic and electronic structures of materials. This method is so powerful that it is referred to as "The Ultimate Analysis." Our laboratory is applying this "Ultimate Analysis" to advanced materials such as artificial superlattices and optical fibers, aiming to establish material design.

Keywords:Amorphous Materials, Artificial Superlattices, Li-Ion Battery Cathode Materials, Solar Cell Materials

“Nanoscale Investigation of Local Thermal Expansion at SrTiO3 Grain Boundaries by Electron Energy Loss Spectroscopy” K. Liao, K. Shibata,and T. Mizoguchi, Nano Letters, 21 (2021) 10416-10422
“Controlling interface intermixing and property of SrTiO3 based superlattices” T. Mizoguchi, H. Ohta et al., Adv. Funct. Mater. 21, (2011) 2258–2263.
“Atomic Scale Identification of Individual Lanthanide Dopants in Optical Glass Fiber” T. Mizoguchi et al., ACS Nano, 7 (2013) 5058-5063.
“Site dependence and Peak assignment of YBa2Cu3O7 O-K ELNES” T. Mizoguchi et al.,Phys. Rev. B, 77 (2008) 024504-1-5.

First-Principles Computational Methods for Core-Level Excitation Spectra　　

Electron energy-loss near-edge structure (ELNES) and X-ray absorption near-edge structure (XANES) are both core-level excitation spectra that occur when core electrons transition to unoccupied orbitals. ELNES and XANES are powerful material analysis techniques with high spatial resolution, time resolution, and detection sensitivity. However, interpreting these spectra requires theoretical calculations based on first-principles methods. Our laboratory is working on developing theoretical computational methods for ELNES/XANES and is currently engaged in research aimed at establishing comprehensive computational methods for all structures, all elements, and all absorption edges. Futhermore, based on the spectrum database through the simulations, we have attempted to extract new insight and physics from the spectrum via machine learning.

Keywords:Core-Level Excitation Spectroscopy, ELNES, XANES, Single Particle, Exciton, Multi-Electron, spectrum database, new physics for spectrum

“Basics and Applications of ELNES calculation” [Invited Review] H. Ikeno and T. Mizoguchi, Microscopy, 66 (2017) 305–327.
“Excitonic, vibrational, and van der Waals interactions in electron energy loss spectroscopy”[Invited Manuscript] T. Mizoguchi, T. Miyata, and W. Olovsson, Ultramicroscopy, 180 (2017) 93-103.
“Strong excitonic interactions in the oxygen K-edge of perovskite oxides” K. Tomita, T. Miyata, W. Olovsson, and T. Mizoguchi, Ultramicroscopy, 178 (2017) 105-111.
“Core–Excitonic Interaction in Sodium L2,3 Edge Structure Investigated Using the Bethe-Salpeter Equation” K. Tomita, T. Miyata, W. Olovsson, and T. Mizoguchi, J. Phys. Chem. C, 120 (2016) 9036-9042.
“Theoretical ELNES: one particle and many particle calculations”[Invited Review] T. Mizoguchi, W. Olovsson, H. Ikeno, and I. Tanaka, Micron 41 (2010) 695–709