KARTIK SAU

Scopus Publications

Visualizing Concerted Ion Migration of Superionic Conductors via Directed Graphs
Ryuhei Sato, Yasunobu Ando, Kartik Sau, Yasushi Shibuta
Chemistry of Materials, 2026
Surface melting–driven hydrogen absorption for high-pressure polyhydride synthesis
Ryuhei Sato, Lewis J. Conway, Di Zhang, Chris J. Pickard, Kazuto Akagi, et al.
Proceedings of the National Academy of Sciences of the United States of America, 2025
The synthesis of new polyhydrides with high superconducting T c is challenging owing to the high pressures and temperatures required. In this study, we used machine-learning potential molecular dynamics simulations to investigate the initial stage of polyhydride formation in calcium hydrides. Upon contact with high-pressure H 2 , the surface of CaH 2 melts, leading to CaH 4 formation. This surface melting proceeds via CaH 4 liquid phase as an intermediate state. High pressure reduces not only the hydrogenation (CaH 2 (s) + H 2 (l) ↔ CaH 4 (s)) enthalpy but also the enthalpy for liquid polyhydride formation (CaH 2 (s) + H 2 (l) ↔ CaH 4 (l)). Consequently, this surface melting process becomes more favorable than the fusion of the polyhydride bulk. Thus, high pressure not only shifts the equilibrium toward the polyhydride product but also lowers the activation energy, thereby promoting the hydrogenation reaction. From these thermodynamic insights, we propose structure-search criteria for polyhydride synthesis that are both computationally effective and experimentally relevant. These criteria are based on bulk properties, such as polyhydride (product) melting temperature and pressure-dependent hydrogenation enthalpy, readily determined through supplementary calculations during structure prediction workflows.
Unlocking the secrets of ideal fast ion conductors for all-solid-state batteries
Kartik Sau, Shigeyuki Takagi, Tamio Ikeshoji, Kazuaki Kisu, Ryuhei Sato, et al.
Communications Materials, 2024
All-solid-state batteries (ASSBs) are promising alternatives to conventional lithium-ion batteries. ASSBs consist of solid-fast-ion-conducting electrolytes and electrodes that offer improved energy density, battery safety, specific power, and fast-charging capability. Despite decades of intensive research, only a few have high ionic conductivity at ambient temperature. Developing fast ion-conducting materials requires both synthesis of high-conducting materials and a fundamental understanding of ion transport mechanisms. However, this is challenging due to wide variations of the ionic conductivity, even within the same class of materials, indicating the strong influence of structural modifications on ion transport. This Review discusses three selected material classes, namely layered oxides, polyhedral connections, and cluster anion types, as promising fast ion conductors. Emphasis is placed on the inherent challenges and the role of the framework structure on mobile ion conduction. We elucidate strategies to address these challenges by leveraging theoretical frameworks and insights from materials science.
Colossal Reversible Barocaloric Effects in a Plastic Crystal Mediated by Lattice Vibrations and Ion Diffusion
Ming Zeng, Carlos Escorihuela‐Sayalero, Tamio Ikeshoji, Shigeyuki Takagi, Sangryun Kim, et al.
Advanced Science, 2024
Solid‐state methods for cooling and heating promise a sustainable alternative to current compression cycles of greenhouse gases and inefficient fuel‐burning heaters. Barocaloric effects (BCE) driven by hydrostatic pressure (p) are especially encouraging in terms of large adiabatic temperature changes (|ΔT| ≈ 10 K) and isothermal entropy changes (|ΔS| ≈ 100 J K−1 kg−1). However, BCE typically require large pressure shifts due to irreversibility issues, and sizeable |ΔT| and |ΔS| seldom are realized in a same material. Here, the existence of colossal and reversible BCE in LiCB11H12 is demonstrated near its order‐disorder phase transition at ≈380 K. Specifically, for Δp ≈ 0.23 (0.10) GPa, |ΔSrev| = 280 (200) J K−1 kg−1 and |ΔTrev| = 32 (10) K are measured, which individually rival with state‐of‐the‐art BCE figures. Furthermore, pressure shifts of the order of 0.1 GPa yield huge reversible barocaloric strengths of ≈2 J K−1 kg−1 MPa−1. Molecular dynamics simulations are performed to quantify the role of lattice vibrations, molecular reorientations, and ion diffusion on the disclosed BCE. Interestingly, lattice vibrations are found to contribute the most to |ΔS| while the diffusion of lithium ions, despite adding up only slightly to the entropy change, is crucial in enabling the molecular order–disorder phase transition.
Explore the Ionic Conductivity Trends on B12H12 Divalent Closo-Type Complex Hydride Electrolytes
Egon Campos dos Santos, Ryuhei Sato, Kazuaki Kisu, Kartik Sau, Xue Jia, et al.
Chemistry of Materials, 2023
Topological Data analysis of Ion Migration Mechanism
Ryuhei Sato, Kazuto Akagi, Shigeyuki Takagi, Kartik Sau, Kazuaki Kisu, et al.
Journal of Chemical Physics, 2023
Topological data analysis based on persistent homology has been applied to the molecular dynamics simulation for the fast ion-conducting phase (α-phase) of AgI to show its effectiveness on the ion migration mechanism analysis. Time-averaged persistence diagrams of α-AgI, which quantitatively record the shape and size of the ring structures in the given atomic configurations, clearly showed the emergence of the four-membered rings formed by two Ag and two I ions at high temperatures. They were identified as common structures during the Ag ion migration. The averaged potential energy change due to the deformation of the four-membered ring during Ag migration agrees well with the activation energy calculated from the conductivity Arrhenius plot. The concerted motion of two Ag ions via the four-membered ring was also successfully extracted from molecular dynamics simulations by our approach, providing new insight into the specific mechanism of the concerted motion.
The role of cation size in the ordered-disordered phase transition temperature and cation hopping mechanism based on LiCB11H12
Kartik Sau, Shigeyuki Takagi, Tamio Ikeshoji, Kazuaki Kisu, Ryuhei Sato, et al.
Materials Advances, 2023
The ordered–disordered transition temperature is reduced significantly with increasing cationic sizes. A possible principle for creating better ion-conducting materials is to have smaller cations in a larger unit cell.
Enhanced thermophysical properties of water-based single and hybrid metallic nanofluids: Insights from Equilibrium Molecular Dynamics
Sakti Pada Shit, Sudipta Pal, N.K. Ghosh, Kartik Sau
Chemical Thermodynamics and Thermal Analysis, 2022
Particle size and temperature effects on thermal conductivity of aqueous Ag nanofluids: modelling and simulations using classical molecular dynamics
Sakti Pada Shit, N. K. Ghosh, Sudipta Pal, Kartik Sau
European Physical Journal D, 2022
Fast divalent conduction in MB12H12·12H2O (M = Zn, Mg) complex hydrides: effects of rapid crystal water exchange and application for solid-state electrolytes
Kazuaki Kisu, Arunkumar Dorai, Sangryun Kim, Riku Hamada, Akichika Kumatani, et al.
Journal of Materials Chemistry A, 2022
Water molecules are exchanged in the crystal structure, which imparts a high divalent conductivity to hydrated complex hydrides. MB12H12·12H2O (M = Zn or Mg) exhibits exceptional conductivities higher than those of less-hydrated complex hydrides.
Insights of cationic diffusion in nickel-based honeycomb layered tellurates using molecular dynamics simulation
Kartik Sau, Tamio Ikeshoji
Solid State Ionics, 2022
Ring mechanism of fast Na+ ion transport in Na2LiFeTeO6: Insight from molecular dynamics simulation
Kartik Sau, Tamio Ikeshoji
Physical Review Materials, 2022
Colossal barocaloric effects in the complex hydride Li 2 B 12 H 12
Kartik Sau, Tamio Ikeshoji, Shigeyuki Takagi, Shin-ichi Orimo, Daniel Errandonea, et al.
Scientific Reports, 2021
Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi2TeO6
Titus Masese, Yoshinobu Miyazaki, Josef Rizell, Godwill Mbiti Kanyolo, Chih-Yao Chen, et al.
Nature Communications, 2021
Thermophysical properties of graphene and hexagonal boron nitride nanofluids: A comparative study by molecular dynamics
Sakti Pada Shit, Sudipta Pal, N.K. Ghosh, Kartik Sau
Journal of Molecular Structure, 2021
Comparative Molecular Dynamics Study of the Roles of Anion-Cation and Cation-Cation Correlation in Cation Diffusion in Li2B12H12and LiCB11H12
Kartik Sau, Tamio Ikeshoji, Sangryun Kim, Shigeyuki Takagi, Shin-ichi Orimo
Chemistry of Materials, 2021
Origin of fast ion conduction in Na3PS4: Insight from molecular dynamics study
Kartik Sau, Tamio Ikeshoji
Journal of Physical Chemistry C, 2020
Role of divalent cation (Ba) substitution in the Li+ion conductor LiTi2(PO4)3: A molecular dynamics study
Kartik Sau, Tamio Ikeshoji, Supriya Roy
Physical Chemistry Chemical Physics, 2020
Role of Framework Flexibility in Ion Transport: A Molecular Dynamics Study of LiM2 IV(PO4)3
Krishnanjan Pramanik, Kartik Sau, P. Padma Kumar
Journal of Physical Chemistry C, 2020
Reorientational motion and Li+ -ion transport in Li2 B12 H12 system: Molecular dynamics study
Kartik Sau, Tamio Ikeshoji, Sangryun Kim, Shigeyuki Takagi, Kazuto Akagi, et al.
Physical Review Materials, 2019
Influence of ion–ion correlation on Na+ transport in Na2Ni2TeO6: molecular dynamics study
Kartik Sau
Ionics, 2016
Ion-ion repulsion and entropic effects on Na+ transport in Na2Ni2TeO6: Molecular dynamics study
Kartik Sau
Aip Conference Proceedings, 2016
Role of Ion-Ion Correlations on Fast Ion Transport: Molecular Dynamics Simulation of Na2Ni2TeO6
Kartik Sau, P. Padma Kumar
Journal of Physical Chemistry C, 2015
Ion transport in Na2M2TeO6: Insights from molecular dynamics simulation
Kartik Sau, P. Padma Kumar
Journal of Physical Chemistry C, 2015
Molecular dynamics investigation of Na+ in Na2Ni 2TeO6
Kartik Sau, P. Padma Kumar
Aip Conference Proceedings, 2014

RECENT SCHOLAR PUBLICATIONS

Hybrid sampling approach to machine-learning potentials for gas adsorption: Hydrogen adsorption in MOF-303
K Sau, I Hamada, T Ikeshoji, Y Lu, S Roy, S Furukawa, L Zhang, HB Tran, ...
ChemRxiv , 2026
2026
Visualizing Concerted Ion Migration of Superionic Conductors via Directed Graphs
R Sato, Y Ando, K Sau, Y Shibuta
Chemistry of Materials 38 (1), 287-295 , 2025
2025
Citations: 1
Surface melting–driven hydrogen absorption for high-pressure polyhydride synthesis
R Sato, LJ Conway, D Zhang, CJ Pickard, K Akagi, K Sau, H Li, S Orimo
Proceedings of the National Academy of Sciences 122 (22), e2413480122 , 2025
2025
Citations: 4
Hydrogen Absorption Promoted by Surface Melting: Guidelines for High-Pressure Superhydride Synthesis
R Sato, L Conway, D Zhang, C Pickard, K Akagi, K Sau, L Hao, S Orimo
ChemRxiv 2024 (0917) , 2024
2024
Citations: 1
Unlocking the secrets of ideal fast ion conductors for all-solid-state batteries
K Sau, S Takagi, T Ikeshoji, K Kisu, R Sato, EC dos Santos, H Li, ...
https://www.nature.com/articles/s43246-024-00550-z.epdf?sharing_token … , 2024
2024
Citations: 71
Colossal reversible barocaloric effects in a plastic crystal mediated by lattice vibrations and ion diffusion
M Zeng, C Escorihuela‐Sayalero, T Ikeshoji, S Takagi, S Kim, S Orimo, ...
Advanced Science 11 (26), 2306488 , 2024
2024
Citations: 26
Landscape-Sketch-Step: An AI/ML-Based Metaheuristic for Surrogate Optimization Problems
R Monteiro, K Sau
arXiv preprint arXiv:2309.07936 , 2023
2023
Citations: 2
Explore the Ionic Conductivity Trends on B 12 H 12 Divalent Closo -Type Complex Hydride Electrolytes
E Campos dos Santos, R Sato, K Kisu, K Sau, X Jia, F Yang, S Orimo, H Li
Chemistry of Materials 35 (15), 5996-6004 , 2023
2023
Citations: 16
Materials Advances
K Sau, S Orimo
2023
Topological data analysis of ion migration mechanism
R Sato, K Akagi, S Takagi, K Sau, K Kisu, H Li, S Orimo
The Journal of Chemical Physics 158 (14) , 2023
2023
Citations: 11
The role of cation size in the ordered–disordered phase transition temperature and cation hopping mechanism based on LiCB 11 H 12
K Sau, S Takagi, T Ikeshoji, K Kisu, R Sato, S Orimo
Materials Advances 4 (10), 2269-2280 , 2023
2023
Citations: 3
Particle size and temperature effects on thermal conductivity of aqueous Ag nanofluids: modelling and simulations using classical molecular dynamics
SP Shit, NK Ghosh, S Pal, K Sau
The European Physical Journal D 76 (12), 238 , 2022
2022
Citations: 5
Enhanced thermophysical properties of water-based single and hybrid metallic nanofluids: insights from equilibrium molecular dynamics
SP Shit, S Pal, NK Ghosh, K Sau
Chemical Thermodynamics and Thermal Analysis 8, 100096 , 2022
2022
Citations: 13
Insights of cationic diffusion in nickel-based honeycomb layered tellurates using molecular dynamics simulation
K Sau, T Ikeshoji
Solid State Ionics 383 (1), 115982 , 2022
2022
Citations: 5
Ring mechanism of fast ion transport in : Insight from molecular dynamics simulation
K Sau, T Ikeshoji
Physical Review Materials 6 (4), 045406 , 2022
2022
Citations: 9
Fast divalent conduction in MB 12 H 12· 12H 2 O (M= Zn, Mg) complex hydrides: effects of rapid crystal water exchange and application for solid-state electrolytes
K Kisu, A Dorai, S Kim, R Hamada, A Kumatani, Y Horiguchi, R Sato, ...
Journal of Materials Chemistry A 10 (46), 24877-24887 , 2022
2022
Citations: 25
Thermophysical properties of graphene and hexagonal boron nitride nanofluids: a comparative study by molecular dynamics
SP Shit, S Pal, NK Ghosh, K Sau
Journal of Molecular Structure 1239, 130525 , 2021
2021
Citations: 29
Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi 2 TeO 6
T Masese, Y Miyazaki, J Rizell, GM Kanyolo, CY Chen, H Ubukata, ...
Nature communications 12 (1), 4660 , 2021
2021
Citations: 40
Colossal barocaloric effects in the complex hydride Li B H
K Sau, T Ikeshoji, S Takagi, S Orimo, D Errandonea, D Chu, C Cazorla
Scientific reports 11 (1), 1-9 , 2021
2021
Citations: 30
Comparative Molecular Dynamics Study of the Roles of Anion–Cation and Cation–Cation Correlation in Cation Diffusion in Li 2 B 12 H 12 and LiCB 11 H 12
K Sau, T Ikeshoji, S Kim, S Takagi, S Orimo
Chemistry of Materials 33 (7), 2357-2369 , 2021
2021
Citations: 36

MOST CITED SCHOLAR PUBLICATIONS

Unlocking the secrets of ideal fast ion conductors for all-solid-state batteries
K Sau, S Takagi, T Ikeshoji, K Kisu, R Sato, EC dos Santos, H Li, ...
https://www.nature.com/articles/s43246-024-00550-z.epdf?sharing_token … , 2024
2024
Citations: 71
Role of Ion–Ion Correlations on Fast Ion Transport: Molecular Dynamics Simulation of Na 2 Ni 2 TeO 6
K Sau, PP Kumar
The Journal of Physical Chemistry C 119 (32), 18030-18037 , 2015
2015
Citations: 47
Ion Transport in Na2M2TeO6: Insights from Molecular Dynamics Simulation
K Sau, PK Padmanabhan
The Journal of Physical Chemistry C , 2015
2015
Citations: 43
Mixed alkali-ion transport and storage in atomic-disordered honeycomb layered NaKNi 2 TeO 6
T Masese, Y Miyazaki, J Rizell, GM Kanyolo, CY Chen, H Ubukata, ...
Nature communications 12 (1), 4660 , 2021
2021
Citations: 40
Comparative Molecular Dynamics Study of the Roles of Anion–Cation and Cation–Cation Correlation in Cation Diffusion in Li 2 B 12 H 12 and LiCB 11 H 12
K Sau, T Ikeshoji, S Kim, S Takagi, S Orimo
Chemistry of Materials 33 (7), 2357-2369 , 2021
2021
Citations: 36
Colossal barocaloric effects in the complex hydride Li B H
K Sau, T Ikeshoji, S Takagi, S Orimo, D Errandonea, D Chu, C Cazorla
Scientific reports 11 (1), 1-9 , 2021
2021
Citations: 30
Thermophysical properties of graphene and hexagonal boron nitride nanofluids: a comparative study by molecular dynamics
SP Shit, S Pal, NK Ghosh, K Sau
Journal of Molecular Structure 1239, 130525 , 2021
2021
Citations: 29
Influence of ion–ion correlation on Na+ transport in Na2Ni2TeO6: molecular dynamics study
K Sau
Ionics 22 (12), 2379-2385 , 2016
2016
Citations: 28
Reorientational motion and Li+ -ion transport in Li2B12H12 system: Molecular dynamics study
K Sau, T Ikeshoji, S Kim, S Takagi, K Akagi, S Orimo
Phys. Rev. Materials 3 (7), 075402 , 2019
2019
Citations: 27
Colossal reversible barocaloric effects in a plastic crystal mediated by lattice vibrations and ion diffusion
M Zeng, C Escorihuela‐Sayalero, T Ikeshoji, S Takagi, S Kim, S Orimo, ...
Advanced Science 11 (26), 2306488 , 2024
2024
Citations: 26
Fast divalent conduction in MB 12 H 12· 12H 2 O (M= Zn, Mg) complex hydrides: effects of rapid crystal water exchange and application for solid-state electrolytes
K Kisu, A Dorai, S Kim, R Hamada, A Kumatani, Y Horiguchi, R Sato, ...
Journal of Materials Chemistry A 10 (46), 24877-24887 , 2022
2022
Citations: 25
Origin of Fast Ion Conduction in Na3PS4: Insight from Molecular Dynamics Study
K Sau, T Ikeshoji
The Journal of Physical Chemistry C , 2020
2020
Citations: 24
Role of Framework Flexibility in Ion Transport: A Molecular Dynamics Study of LiM 2 IV (PO 4 ) 3
K Pramanik, K Sau, PP Kumar
The Journal of Physical Chemistry C 124 (7), 4001-4009 , 2020
2020
Citations: 23
Explore the Ionic Conductivity Trends on B 12 H 12 Divalent Closo -Type Complex Hydride Electrolytes
E Campos dos Santos, R Sato, K Kisu, K Sau, X Jia, F Yang, S Orimo, H Li
Chemistry of Materials 35 (15), 5996-6004 , 2023
2023
Citations: 16
Enhanced thermophysical properties of water-based single and hybrid metallic nanofluids: insights from equilibrium molecular dynamics
SP Shit, S Pal, NK Ghosh, K Sau
Chemical Thermodynamics and Thermal Analysis 8, 100096 , 2022
2022
Citations: 13
Topological data analysis of ion migration mechanism
R Sato, K Akagi, S Takagi, K Sau, K Kisu, H Li, S Orimo
The Journal of Chemical Physics 158 (14) , 2023
2023
Citations: 11
Role of divalent cation (Ba) substitution in the Li+ ion conductor LiTi 2 (PO 4) 3: a molecular dynamics study
K Sau, T Ikeshoji, S Roy
Physical Chemistry Chemical Physics 22 (26), 14471-14479 , 2020
2020
Citations: 10
Ring mechanism of fast ion transport in : Insight from molecular dynamics simulation
K Sau, T Ikeshoji
Physical Review Materials 6 (4), 045406 , 2022
2022
Citations: 9
Particle size and temperature effects on thermal conductivity of aqueous Ag nanofluids: modelling and simulations using classical molecular dynamics
SP Shit, NK Ghosh, S Pal, K Sau
The European Physical Journal D 76 (12), 238 , 2022
2022
Citations: 5
Insights of cationic diffusion in nickel-based honeycomb layered tellurates using molecular dynamics simulation
K Sau, T Ikeshoji
Solid State Ionics 383 (1), 115982 , 2022
2022
Citations: 5

KARTIK SAU

RESEARCH, TEACHING, or OTHER INTERESTS

Scopus Publications

RECENT SCHOLAR PUBLICATIONS

MOST CITED SCHOLAR PUBLICATIONS