Faculty Profiles - KANDA Hideki

Papers - KANDA Hideki

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Molecular Simulation Study on Freezing in Nano-Pores Reviewed

Minoru Miyahara*, Hideki Kanda, Ko Higashitani and Keith E. Gubbins

Studies in Surface Science and Catalysis Vol. 128 page： 31 2000.12

Solidification of LJ Fluid in Cylindrical Nano-Pores and Its Geometrical Hindrance Effect: A Monte Carlo Study Reviewed

Hideki Kanda, Minoru Miyahara*, and Ko Higashitani

Langmuir Vol. 16 ( 22 ) page： 8529 2000.10

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Grand canonical Monte Carlo (GCMC) simulations have been conducted to investigate freezing phenomena of Lennard-Jones (LJ) methane confined in cylindrical nanopores of reduced pore diameter ranging from 4.5 to 9.5 with saturated vapor as equilibrium bulk condition. The arrangement of the LJ particles in frozen state is found to form a hexagonal array within each concentric circular layer. Nonmonotonic dependence of freezing point against pore diameter, which is observed in strongly attractive pore made of carbon, is interpreted as a result of competition between geometrical hindrance effect of a wall's shape and compression effect of a wall's attractive potential. Geometrical hindrance effect, which originates from excess energy of cylindrical frozen state relative to the fcc lattice state, is clarified to become stronger for smaller pore size. The latent heat is also smaller for smaller pore size. We model the shift of freezing point in cylindrical pore considering the geometrical hindrance effect, and its reliability is verified successfully through comparison with the GCMC results.

DOI： 10.1021/la991659p

制限空間内相転移モデルの構築とナノ細孔特性評価法への応用

神田英輝

粉体工学会誌 Vol. 37 ( 10 ) page： 761-762 2000.10

Verification of Condensation Model for Cylindrical Nano-Pores : Analysis of Nitrogen Isotherm for FSM-16 Reviewed

Hideki Kanda, Minoru Miyahara*, Tomohisa Yoshioka and Morio Okazaki

Langmuir Vol. 16 ( 16 ) page： 6622 2000.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

An improved condensation model for the estimation of pore-size distribution in the range of nanometers is examined. In the authors' previous paper, the model proved its reliability in computer experiments employing the molecular dynamics technique. The model is tested here in a real experimental system with a MCM-41-like ordered mesoporous silicate, FSM-16. The study includes how to find the adsorbate-solid interaction strength, which is taken into account as an additional contribution for condensation other than the Kelvin effect. The true pore size of the material is separately determined to be 3.2 ± 0.2 nm by high-resolution transmission electron microscopy observation, and by a colloidal particle adsorption method. The conventional model for condensation, the Kelvin model, underestimates the pore size of FSM-16 to be 2.5 nm from the nitrogen isotherm. The present model successfully predicts the pore size to be 3.4 nm, and proves its reliability in the real experimental system. The effect of the pore wall's potential on the capillary coexistence relation is further discussed comparing ordered mesoporous silicates and the usual silica materials.

DOI： 10.1021/la991575g

Condensation Model for Cylindrical Nano-Pores Applied to Realistic Porous Glass Generated by Molecular Simulation Reviewed

Hideki Kanda, Minoru Miyahara* and Ko Higashitani

Langmuir Vol. 16 ( 14 ) page： 6064 2000.6

Solid-Liquid Phase Transition of Lennard-Jones Fluid in Slit Pores under Tensile Condition Reviewed

Minoru Miyahara*, Hideki Kanda, Mutsumi Shibao, and Ko Higashitani

The Journal of Chemical Physics Vol. 112 ( 22 ) page： 9909-9916 2000.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The effect of equilibrium vapor-phase pressure onto freezing of a simple fluid in a nanopore is examined. We employ a molecular dynamics (MD) technique in a unit cell with imaginary gas phase, which has the benefit of easy determination of equilibrium vapor pressure. The method is shown to give consistent results with those by the grand canonical Monte Carlo (GCMC) method, and to have better feature of smaller degree of hysteresis between freezing and melting. The MD simulations showed liquid?solid phase transitions, at a constant temperature, with the variation in the equilibrium vapor-phase pressure below the saturated one. Thus-determined solid?liquid coexistence lines exhibited significant dependence of the freezing point against small changes in the bulk?phase vapor pressure, which implies the importance of tensile effect on freezing in nanopores. The capillary effect on the shift in freezing point was successfully described by a simple model based on continuum and isotropic assumption, even in a pore as small as 2 nm in width.

Extraordinary Skewed Solid-Liquid Coexistence for Tensile Fluid in Nanopores and Its Origin: A Molecular Simulation Study Reviewed

Minoru Miyahara*, Hideki Kanda, Mutsumi Shibao and Ko Higashitani

Peer reviewed Proceedings of The 2nd Pacific Basin Conference on Adsorption Science and Technology page： 431 2000.5

Modeling Capillary Condensation in Cylindrical Nano-Pores: Molecular Dynamics Study Reviewed

Minoru Miyahara*, Hideki Kanda, Tomohisa Yoshioka and Morio Okazaki

Langmuir Vol. 16 ( 9 ) page： 4293 2000.3

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We modeled condensation phenomena within cylindrical nanopores as a possible replacement for the Kelvin model that underestimates nanometer order pore sizes. The proposed model follows the simple concept of a continuum assumption similar to that for the Kelvin model. The difference was in the introduction of the contribution of the pore-wall potential and the curvature-dependent surface tension in our model. A molecular dynamics (MD) technique developed by the authors for isotherm determination was employed to test the concept and the model. Several isotherms for N2-like Lennard-Jones (LJ) particles in a silicate-like cylindrical pore with various diameters from 2 to 4 nm were obtained through MD simulations, and a relation between pore diameter and critical condensation pressure was determined. The present model successfully described the relation to demonstrate its reliability. The validity of the proposed model was examined also from the aspect of the shape of the meniscus and the pressure profile in the condensed phase, and gave fairly good agreement.

DOI： 10.1021/la991227e

Condensation Model for Cylindrical Nano-Pores Applied to Mesoporous Silicate FSM-16 Reviewed

Hideki Kanda, Minoru Miyahara*, Tomohisa Yoshioka and Morio Okazaki

Peer reviewed Proceedings of Fundamentals of Adsorption 6 page： 321 1998.5

Molecular Dynamics Study on Condensation in Cylindrical Nano-pores -Modeling and Verification- Reviewed

Minoru Miyahara*, Hideki Kanda, Tomohisa Yoshioka and Morio Okazaki

Peer reviewed Proceedings of Fundamentals of Adsorption 6 page： 249 1998.5

シリンダ状ナノ細孔内凝縮モデルとナノ細孔径評価－ＭＤ法およびメソポーラスシリカを用いた検証－

神田英輝、宮原稔、吉岡朋久、岡崎守男

Adsorption News Vol. 12 ( 1 ) page： 20-21 1998.4

Single-Electrode Transient Behavior for Electric Double Layer Capacitor Composed of Nano-Porous Carbon Electrode. Reviewed

Satoshi Iwasaki, Hideki Kanda, Minoru Miyahara* and Morio Okazaki

Kagaku Kogaku Ronbunshuu Vol. 23 ( 4 ) page： 519 1997.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Single-electrode transient behavior was measured mainly during the discharging process for a model cell of electric double layer capacitor with nano-porous carbon electrodes and reference electrode. Apparent conductivity in the cell, which we call " effective conductivity," is determined with approximation of current in transient behavior to a one-dimensional electrophoretic model. A comparison of effective conductivity with conductivity of bulk solution suggests an interesting mechanism of transfer of electrolyte ions. The difference in transient behavior between various electrolyte ions was not conspicuous in spite of distinctive differences in conductivity of each bulk solution. The large pore diameter of the carbon electrode results in rapid transient behavior and such an electrode should be suitable for rapid charge and discharge. The effect of origin of carbon electrode is found to be significant to bring considerable differences in discharge rate. However, the difference in transient behavior that was caused by materials for carbon electrode becomes smaller for lower concentrations of electrolyte solution. Effective conductivities for all experiments do not directly reflect conductivities of bulk solution of each electrolyte. This implies that electrolyte ions are transported based not only on the electrophoretic effect, but also on a mechanism similar to surface diffusion.

DOI： 10.1252/kakoronbunshu.23.519

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