Susumu Fujii

Quantifying the dependence of thermal conductivity on grain boundary (GB) structure is critical for controlling nanoscale thermal transport in many technologically important materials. A major obstacle to determining such a relationship is the lack of a robust and physically intuitive structure descriptor capable of distinguishing between disparate GB structures. We demonstrate that a microscopic structure metric, the local distortion factor, correlates well with atomically decomposed thermal co

To improve ionic conductivity, solid-state electrolytes with polarizable anions that weakly interact with mobile ions have received much attention, a recent example being lithium/sodium-rich antiperovskite M₃HCh (M = Li, Na; Ch = S, Se, Te). Herein, in order to clarify the role of anions in antiperovskites, the M₃FCh family, in which the polarizable H^- anion at the octahedral center is replaced by the ionic F^- anion, is investigated theoretically and e

In silicon, lattice thermal conductivity plays an important role in a wide range of applications such as thermoelectric and microelectronic devices. Grain boundaries (GBs) in polycrystalline silicon can significantly reduce lattice thermal conductivity, but the impact of GB atomic structures on it remains to be elucidated. This study demonstrates accurate predictions of the GB structures, GB energies, and GB phonon properties in silicon using machine learning potentials (MLPs). The results indic

Yttria stabilized zirconia (YSZ) ceramics have been used for various engineering applications including structural ceramics, biomedical materials, and thermal barrier coatings. The versatile and excellent properties of YSZ stem from its unique microstructure consisting of monoclinic, tetragonal, and cubic phases, whose stability depends on yttria concentration and temperature. However, there are no empirical interatomic potentials (EIPs) that can reproduce the structures and energies of ZrO2 and

Optimizing multiple materials properties which are simultaneously in competition with each other is one of the chief challenges in thermoelectric materials research. Introducing greater anharmonicity to vibrational modes is one strategy for suppressing phonon thermal transport in crystalline oxides without detrimentally affecting electronic conductivity, so that the overall thermoelectric efficiency can be improved. Based on perturbed molecular dynamics and associated numerical analyses, we show

We proposed on-demand spectrum and core allocation method which constructs virtual grid for space division multiplexed elastic optical network. Virtual grid requires relatively simple switch configuration. Simulation result demonstrates that virtual grid can improve both blocking probability and inter-core crosstalk.

Controlling thermal conductivity in nanocrystalline materials is of great interest in various fields such as thermoelectrics. However, its reduction mechanism has not been fully given due to the difficulty to assess local thermal conduction at grain boundaries (GBs) and grain interiors. Here, we calculated spatially decomposed thermal conductivities across and along MgO symmetric GBs using perturbed molecular dynamics, varying the GB separation from 2.1 to 20.0 nm. This reveals the different len

Yttria stabilized zirconia (YSZ) is an important engineering ceramic oxide used for various applications, including solid electrolytes in solid oxide fuel cells due to its high ionic conductivity. Accurate and computationally inexpensive interatomic potentials for cubic ZrO2 and YSZ are required to accommodate the large number of defect configurations originating from high concentrations of Y and oxygen vacancies and to statistically understand their properties in realistic time. In this study,

The tetrahedral distortion of iron(ii) centres in the cyanide-bridged framework FePd(CN)4 was recently demonstrated experimentally. Here, we theoretically confirmed the electronically driven tetrahedral distortion of iron(ii) by comparing the density of states and total energies of FePd(CN)4 (d6) and ZnPd(CN)4 (d10). The calculation results suggested that a Jahn-Teller-like effect is caused on the tetrahedral geometry by the electronic effect of unequally occupied non-bonding 3d orbitals in the

Abstract Phosphatidylcholine (PC) vesicle was quantitatively flocculated with trimethylammonium glycol chitosan iodide (MGCH) over the pH region of 3 – 12. The results obtained by IR analysis of the aggregate and by turbidity titration in the presence of metal cations, suggested that the flocculation would be based on the salt-linkage formation between phosphate group of PC and trimethylammonium group in MGCH.

SrTiO 3 is a typical cubic perovskite and serves as a candidate for thermoelectric materials. To improve the performance, it is necessary to reduce its inherently high lattice thermal conductivity by introducing lattice defects such as grain boundaries. However, the atomic structures and compositions of grain boundaries that effectively suppress thermal conduction in SrTiO 3 have not been elucidated. Here, we have systematically calculated the thermal conductivity of 88 SrTiO 3 symmetric tilt gr

Abstract Effect of pH on the flocculation of phosphatidylcholine vesicle with trimethylammonium glycol chitosan iodide (MGCH) was investigated over the pH region of 3–12. The flocculation based on the salt-linkage formation between phosphate group on the vesicle surface and trimethylammonium group in MGCH is affected by pH of bulk-phase.