Hiroshi Mizuseki - Academia.edu (original) (raw)
Uploads
Papers by Hiroshi Mizuseki
Advances in Materials Research, 2008
To study thermodynamic properties of materials, lattice model simulation such as lattice Monte Ca... more To study thermodynamic properties of materials, lattice model simulation such as lattice Monte Carlo (MC) simulation is one of the simple and fast method. One advantage of the method is that it can treat larger systems both in time scale and in spatial size compared with atomic-scale molecular dynamics (MD) simulations so that it can treat thermodynamic equilibrium or diffusion phase transition phenomena. However, it has limitation in the description of disordered or liquid phases because displacement of atoms from regular lattice points that may be important at high temperatures could not be considered. That is, lattice models neglect the vibration entropy as well as the elastic energy. The shortcomings lead to overestimation of the phase transition temperatures and underestimation of the width of single-phase fields.
Journal of Applied Physics, Feb 1, 2011
We investigated impact of type of crystal defects in multicrystalline Si (mc-Si) on electrical pr... more We investigated impact of type of crystal defects in multicrystalline Si (mc-Si) on electrical properties and their change after gettering process of impurities. A bundle of dislocations gives negative impact on the gettering process, while Sigma3 grain boundaries does not affect at all. In addition, we categorized random grain boundaries in mc-Si by the contact angle between adjacent dendrite crystals to form the grain boundary. Change in the contrast of photoluminescence intensity around the grain boundary was found to systematically vary by the contact angle, which showed good correlation with calculated interface energy of the grain boundary. Grain boundaries with low interface energy are concluded to be preferable to weaken recombination activity by the gettering process and improvement of solar cell performance based on mc-Si.
![Research paper thumbnail of Theoretical insights into the formation, structure, and electronic properties of anticancer oxaliplatin drug and cucurbit[n]urils n = 5 to 8](https://attachments.academia-assets.com/49679623/thumbnails/1.jpg)
](Journal of Inclusion Phenomena and Molecular Recognition in Chemistry, 2010
Materials Transactions, 2013
Japanese Journal of Applied Physics, Apr 1, 2010
J Incl Phenom Macrocycl Chem, 2010
Mol Simulat, 2004
ABSTRACT
Scientific reports, 2016
We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes... more We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+sp(2) bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicate that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.
Extended Abstracts of the Conference on Solid State Devices and Materials, Sep 25, 2001
ABSTRACT
The critical behavior of percolation model does not depend on the detail of the embedding lattice... more The critical behavior of percolation model does not depend on the detail of the embedding lattice. This fact can be a hard obstacle when one attempt to modulate and control the characteristics of the composite materials because the limit of modulation is limited by the percolation threshold, as in the case of substitution of expensive conductor materials by inexpensive insulator materials. Many attempts to solve this problem by changing the sizes and aspect ratios of conductor particles, expecting their effect in enhancing conduction as a ``bridge'' is not working well. We report our attempt to realize the same goal by introducing size differences in the insulator particles, not conductor particles. The effective transition point observed is actually lowered to 0.52 by this modulation from about 0.59 of conventional site percolation model (2D). The statistical nature of this novel model, in particular the optimum design of insulator particle size distribution, is a completely new and interesting theoretical problem. Moreover, this is considered to be a promising technique to reduce the amount of expensive conductor, for example the Indium in typical transparent conductor film.
Mater Trans, 2001
ABSTRACT
Extended Abstracts of the Conference on Solid State Devices and Materials, Sep 15, 2004
Aps Meeting Abstracts, 2008
The concept of percolation plays an important role in explaining various important physical pheno... more The concept of percolation plays an important role in explaining various important physical phenomena, including transport, mechanical, and electromagnetic properties of disordered systems. To date, many percolation models have been developed. Contrary to the ordinary site percolation models with homogeneous particles, systems have a certain particle-size distribution. Such a distribution may affect the properties of the system in certain ways. In the present study, site-percolation models with two different sizes of particles are systematically introduced on a square lattice to understand the effect of nonhomogeneity of the particles in the system. To estimate the critical phenomena with high accuracy, a finite-size scaling analysis is performed with a Monte Carlo simulation. The critical coverage at the percolation threshold is examined as a function of the size distribution of elements in the system. Fractal dimension and the critical exponentials are also estimated.
The increase in threats from global warming due to the consumption of fossil fuels requires our p... more The increase in threats from global warming due to the consumption of fossil fuels requires our planet to adopt new strategies to harness the inexhaustible sources of energy. Hydrogen is an energy carrier which holds tremendous promise as a new renewable and clean energy option. Hydrogen is a convenient, safe, versatile fuel source that can be easily converted to a desired form of energy without releasing harmful emissions. However, no materials was found satisfy the desired goals and hence there is hunt for new materials that can store hydrogen reversibly at ambient conditions. In this chapter, we discuss and compare various nanofullerene materials proposed theoretically as storage medium for hydrogen. Doping of transition elements leads to clustering which reduces the gravimetric density of hydrogen, while doping of alkali and alkali-earth metals on the nanocage materials, such as carborides, boronitride, and boron cages, were stabilized by the charger transfer from the dopant to the nanocage. Further, the alkali or alkali-earth elements exist with a charge, which are found to be responsible for the higher uptake of hydrogen, through a dipole- dipole and change-induced dipole interaction. The binding energies of hydrogen on these systems were found to be in the range of 0.1 eV to 0.2 eV, which are ideal for the practical applications in a reversible system.
Materials Transactions, Dec 1, 2011
Phys. Chem. Chem. Phys., 2016
Synthesis of pristine MXene sheets from MAX phase is one of the foremost challenges in getting a ... more Synthesis of pristine MXene sheets from MAX phase is one of the foremost challenges in getting a complete understanding of the properties of this new technologically important 2D-material. Efforts to exfoliate Nb4AlC3 MAX phase always lead to Nb4C3 MXene sheets, which are functionalized and have several Al atoms attached. Using the first-principles calculations, we perform an intensive study on the chemical transformation of MAX phase into MXene sheets by inserting HF, alkali atoms and LiF in Nb4AlC3 MAX phase. Calculated bond-dissociation energy (BDE) shows that the presence of HF in MAX phase always results in functionalized MXene, as the binding of H with MXene is quite strong while that with F is weak. Insertion of alkali atoms does not facilitate pristine MXene isolation due to the presence of chemical bonds of almost equal strength. In contrast, weak Li-MXene and strong Li-F bonding in Nb4AlC3 with LiF ensured strong anisotropy in BDE, which will result in the dissociation of the Li-MXene bond. Ab initio molecular dynamics calculations capture these features and show that at 500-650 K, the Li-MXene bond indeed breaks leaving a pristine MXene sheet behind. The approach and insights developed here for chemical exfoliation of layered materials bonded by chemical bonds instead of van der Waals can promote their experimental realization.
By combining empirical potential approach with first-principles calculations, we investigate the ... more By combining empirical potential approach with first-principles calculations, we investigate the atomic and electronic structures of grain boundary in silicon to estimate the deleterious effect on photovoltaic properties. Optimized geometries of several boundary structures are obtained by using a Tersoff potential. Moreover, the electronic structures of boundary have been examined using the density-functional theory with the plane-wave pseudopotential method. Calculations show that the electronic properties depend strongly on the atomistic structures, their properties are corresponding to efficiency of photovoltaic cell. This work was supported by the New Energy and Industrial Technology Development Organization (NEDO)
Materials Transactions, Jul 1, 2012
Advances in Materials Research, 2008
To study thermodynamic properties of materials, lattice model simulation such as lattice Monte Ca... more To study thermodynamic properties of materials, lattice model simulation such as lattice Monte Carlo (MC) simulation is one of the simple and fast method. One advantage of the method is that it can treat larger systems both in time scale and in spatial size compared with atomic-scale molecular dynamics (MD) simulations so that it can treat thermodynamic equilibrium or diffusion phase transition phenomena. However, it has limitation in the description of disordered or liquid phases because displacement of atoms from regular lattice points that may be important at high temperatures could not be considered. That is, lattice models neglect the vibration entropy as well as the elastic energy. The shortcomings lead to overestimation of the phase transition temperatures and underestimation of the width of single-phase fields.
Journal of Applied Physics, Feb 1, 2011
We investigated impact of type of crystal defects in multicrystalline Si (mc-Si) on electrical pr... more We investigated impact of type of crystal defects in multicrystalline Si (mc-Si) on electrical properties and their change after gettering process of impurities. A bundle of dislocations gives negative impact on the gettering process, while Sigma3 grain boundaries does not affect at all. In addition, we categorized random grain boundaries in mc-Si by the contact angle between adjacent dendrite crystals to form the grain boundary. Change in the contrast of photoluminescence intensity around the grain boundary was found to systematically vary by the contact angle, which showed good correlation with calculated interface energy of the grain boundary. Grain boundaries with low interface energy are concluded to be preferable to weaken recombination activity by the gettering process and improvement of solar cell performance based on mc-Si.
Journal of Inclusion Phenomena and Molecular Recognition in Chemistry, 2010
Materials Transactions, 2013
Japanese Journal of Applied Physics, Apr 1, 2010
J Incl Phenom Macrocycl Chem, 2010
Mol Simulat, 2004
ABSTRACT
Scientific reports, 2016
We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes... more We here identify by ab initio calculations a new type of three-dimensional (3D) carbon allotropes that consist of phenyl rings connected by linear acetylenic chains in sp+sp(2) bonding networks. These structures are constructed by inserting acetylenic or diacetylenic bonds into an all sp(2)-hybridized rhombohedral polybenzene lattice, and the resulting 3D phenylacetylene and phenyldiacetylene nets comprise a 12-atom and 18-atom rhombohedral primitive unit cells in the symmetry, which are characterized as the 3D chiral crystalline modification of 2D graphyne and graphdiyne, respectively. Simulated phonon spectra reveal that these structures are dynamically stable. Electronic band calculations indicate that phenylacetylene is metallic, while phenyldiacetylene is a semiconductor with an indirect band gap of 0.58 eV. The present results establish a new type of carbon phases and offer insights into their outstanding structural and electronic properties.
Extended Abstracts of the Conference on Solid State Devices and Materials, Sep 25, 2001
ABSTRACT
The critical behavior of percolation model does not depend on the detail of the embedding lattice... more The critical behavior of percolation model does not depend on the detail of the embedding lattice. This fact can be a hard obstacle when one attempt to modulate and control the characteristics of the composite materials because the limit of modulation is limited by the percolation threshold, as in the case of substitution of expensive conductor materials by inexpensive insulator materials. Many attempts to solve this problem by changing the sizes and aspect ratios of conductor particles, expecting their effect in enhancing conduction as a ``bridge'' is not working well. We report our attempt to realize the same goal by introducing size differences in the insulator particles, not conductor particles. The effective transition point observed is actually lowered to 0.52 by this modulation from about 0.59 of conventional site percolation model (2D). The statistical nature of this novel model, in particular the optimum design of insulator particle size distribution, is a completely new and interesting theoretical problem. Moreover, this is considered to be a promising technique to reduce the amount of expensive conductor, for example the Indium in typical transparent conductor film.
Mater Trans, 2001
ABSTRACT
Extended Abstracts of the Conference on Solid State Devices and Materials, Sep 15, 2004
Aps Meeting Abstracts, 2008
The concept of percolation plays an important role in explaining various important physical pheno... more The concept of percolation plays an important role in explaining various important physical phenomena, including transport, mechanical, and electromagnetic properties of disordered systems. To date, many percolation models have been developed. Contrary to the ordinary site percolation models with homogeneous particles, systems have a certain particle-size distribution. Such a distribution may affect the properties of the system in certain ways. In the present study, site-percolation models with two different sizes of particles are systematically introduced on a square lattice to understand the effect of nonhomogeneity of the particles in the system. To estimate the critical phenomena with high accuracy, a finite-size scaling analysis is performed with a Monte Carlo simulation. The critical coverage at the percolation threshold is examined as a function of the size distribution of elements in the system. Fractal dimension and the critical exponentials are also estimated.
The increase in threats from global warming due to the consumption of fossil fuels requires our p... more The increase in threats from global warming due to the consumption of fossil fuels requires our planet to adopt new strategies to harness the inexhaustible sources of energy. Hydrogen is an energy carrier which holds tremendous promise as a new renewable and clean energy option. Hydrogen is a convenient, safe, versatile fuel source that can be easily converted to a desired form of energy without releasing harmful emissions. However, no materials was found satisfy the desired goals and hence there is hunt for new materials that can store hydrogen reversibly at ambient conditions. In this chapter, we discuss and compare various nanofullerene materials proposed theoretically as storage medium for hydrogen. Doping of transition elements leads to clustering which reduces the gravimetric density of hydrogen, while doping of alkali and alkali-earth metals on the nanocage materials, such as carborides, boronitride, and boron cages, were stabilized by the charger transfer from the dopant to the nanocage. Further, the alkali or alkali-earth elements exist with a charge, which are found to be responsible for the higher uptake of hydrogen, through a dipole- dipole and change-induced dipole interaction. The binding energies of hydrogen on these systems were found to be in the range of 0.1 eV to 0.2 eV, which are ideal for the practical applications in a reversible system.
Materials Transactions, Dec 1, 2011
Phys. Chem. Chem. Phys., 2016
Synthesis of pristine MXene sheets from MAX phase is one of the foremost challenges in getting a ... more Synthesis of pristine MXene sheets from MAX phase is one of the foremost challenges in getting a complete understanding of the properties of this new technologically important 2D-material. Efforts to exfoliate Nb4AlC3 MAX phase always lead to Nb4C3 MXene sheets, which are functionalized and have several Al atoms attached. Using the first-principles calculations, we perform an intensive study on the chemical transformation of MAX phase into MXene sheets by inserting HF, alkali atoms and LiF in Nb4AlC3 MAX phase. Calculated bond-dissociation energy (BDE) shows that the presence of HF in MAX phase always results in functionalized MXene, as the binding of H with MXene is quite strong while that with F is weak. Insertion of alkali atoms does not facilitate pristine MXene isolation due to the presence of chemical bonds of almost equal strength. In contrast, weak Li-MXene and strong Li-F bonding in Nb4AlC3 with LiF ensured strong anisotropy in BDE, which will result in the dissociation of the Li-MXene bond. Ab initio molecular dynamics calculations capture these features and show that at 500-650 K, the Li-MXene bond indeed breaks leaving a pristine MXene sheet behind. The approach and insights developed here for chemical exfoliation of layered materials bonded by chemical bonds instead of van der Waals can promote their experimental realization.
By combining empirical potential approach with first-principles calculations, we investigate the ... more By combining empirical potential approach with first-principles calculations, we investigate the atomic and electronic structures of grain boundary in silicon to estimate the deleterious effect on photovoltaic properties. Optimized geometries of several boundary structures are obtained by using a Tersoff potential. Moreover, the electronic structures of boundary have been examined using the density-functional theory with the plane-wave pseudopotential method. Calculations show that the electronic properties depend strongly on the atomistic structures, their properties are corresponding to efficiency of photovoltaic cell. This work was supported by the New Energy and Industrial Technology Development Organization (NEDO)
Materials Transactions, Jul 1, 2012