MIS31-01

Room:102A

Time:May 27 09:00-09:30

Nanobubble formation in gas hydrate dissolution process and memory effect of gas hydrate recrystallization
UCHIDA, Tsutomu1∗ ; YAMAZAKI, Kenji1 ; GOHARA, Kazutoshi1
1Div. App. Phys., Fac. Eng., Hokkaido Univ.

Gas hydrate is the ice-like crystal formed by water molecules (host lattice) and gas molecules (guests in the cages). Usually
the initial nucleation of gas hydrate requires the large super saturation (or super cooling) conditions. However, the recrystallization from the solution dissociated the gas hydrate crystal requires the smaller super saturation compared to the initial one. Thisphenomenon is called ’memory effect’ of gas hydrate formation, which is expected to be used for the industrial utilization of gas
hydrates.
The mechanism of the memory effect has not been revealed yet, but several models have been proposed. One of them isconsidered that the cage-like structure is remaining in the dissolved solution even after the crystal dissociation. We consider that,in addition to the host lattice formation, the condensation process of guest molecules would be required for the recrystallizationof gas hydrates. It is because the guest molecule concentration in the crystal is much higher than the solubility in water. As oneof the possible idea of this gas condensation process, we consider that the nanobubbles would be formed when the gas hydrate
is dissolved. In the gas hydrate crystal, each guest molecule is encaged in the cage. When the gas hydrate crystal is dissolvedin the solution, guest molecule would be dissolved in the solution one-by-one. Thus the gas molecule aggregation formed in thesolution would be small, that is, becomes nanobubble.
The Nanobubble has several unique properties and been expected to apply to various industrial utilizations. The size of bubble
is so small that the nanobubble can be existed in the solution without floatation. Also the internal pressure of bubble is considered to be very large, a large amount of guest molecules is expected to exist in the area of dissociation although the bubble is
too small to be observed by an optical microscope. In the present study, we aim to confirm the existence of nanobubbles in thesolution after the gas hydrate dissolution. We used the transmission electron microscope to observe the nanobubbles by using thefreeze-fracture replica technique.

Keywords: nanobubble, gas hydrate, memory effect, freeze-fracture replica technique, transmission electron microscope

1/1

MIS31-02

Room:102A

Time:May 27 09:30-09:45

TEM observation of dissolution process of sodium chlorate nanocrystals
KIMURA, Yuki1∗ ; YAMAZAKI, Tomoya1 ; SATOH, Hisao2
1

Institute of Low Temperature Science, Hokkaido University, 2 Naka Energy Research Laboratory, Mitsubishi Materials Corporation
Recent years, we are focusing on nanometer scale live imaging of nucleation and dissolution of crystals in a solution usingtransmission electron microscope (TEM) to know the fundamental processes. Since, basically, high-vacuum environment has tobe maintained in the TEM during the observation, sample is limited. To overcome the difficulties to introduce a solution into a
TEM, very ingenious graphene cell or specially designed amorphous silicon nitride membrane has been established and achieved
in situ observation of nucleation [e.g., 1-4]. As the results, several new perspectives such as, non-classical nucleation pathway,
coalescence and oriented attachment, in the nucleation process have been reported. Against the use of liquid cell, we used ionicliquid as a solvent instead of water to avoid evaporation of a solvent in the high-vacuum of a TEM [5]. Ionic liquids have a great
properties for TEM observation, such as negligible vapor pressure and high electrical conductivity. As the result, following newconsequences were found after experiments of sodium chlorate nanocrystals.
1. Solubility-independent formation of polymorph.
2. Crystals do not dissolve smoothly but in a fluctuating manner.
3. New crystals form even in a totally dissolving system.
4. Ripening occurs but different from Ostwald ripening.
In case of Ostwald ripening, initially presenting larger particles grow as a result of dissolution of smaller particles. However,
our observation shows that ripening occurs with accompanying formation of new crystals, i.e., most of the initial crystals is
replaced by new crystals. In the presentation, we will show the difference of the dissolution process between in ionic liquid andwater solutions, which can be observed by a special holder having a liquid cell for TEM observation.
References[1] J. M. Yuk, J. Park, P. Ercius, K. Kim, D. J. Hellebusch, M. F. Crommie, J. Y. Lee, A Zettl, A. P. Alivisatos, High-resolution
EM of colloidal nanocrystal growth using grapheme liquid cells. Science , 336, (2012) 61-64.
[2] H.-G. Liao, L. Cui, S. Whitelam, H. Zheng, Real-time imaging of Pt3 Fe nanorod growth in solution. Science , 336 (2012)
1011-1014.
[3] D. Li, M. Michael, H. Nelsen, J. R. I. Lee, C. Frandsen, J. F. Banfield, J. J. De Yoreo, Direction-specific interactions control
crystal growth by oriented attachment. Science , 336 (2012) 1014.
[4] M. H. Nielsen, S. Aloni, J. J. De Yoreo, In-situ TEM imaging of CaCO3 nucleation reveals coexistence of direct and indirect pathways, Science , 345 (2014) 1158.
[5] Kimura, Y., Niinomi, H., Tsukamoto, K. & Garcia-Ruiz, J. M. In-situ live observation of nucleation and dissolution of
sodium chlorate nanoparticles by Transmission Electron Microscopy. J. Am. Chem. Soc. , 136 (2014) 1762-1765.
Keywords: TEM, dissolution, nano, in-situ observation

1/1

MIS31-03

Room:102A

Time:May 27 09:45-10:00

Dissolution behavior of compacted smectite clay
SATOH, Hisao1∗
1

Mitsubishi Materials Corporation

Smectite, a clay mineral forming natural bentonite widely exists in altered meteorite to sedimentary rock as micro to nanocrystal. Since smectite can appear in the various forms from as-grown {001} stacking to random-aggregate, its dissolution
behavior is poorly understood. For example, dissolution of colloidal suspension of smectite can be driven by solution pH,
undersaturation ∆G and temperature (Sato et al., 2005), while compacted smectite is stabilized (Nakayama et al., 2004).
Among many approaches for dissolution of smectite, AFM (atomic force microscopy) can directly measure dissolving nanodispersed particles, but high-densiry random aggregates. In order to improve AFM, we developed in-situ VSI (vertical scanninginterferometry) and auto-compaction cell. By this means, we conducted in-situ measurements of compacted smectite (Namontmorillonite) immersed in 0.3M NaOH at 70 ℃. This method can realize real-time measurements of decreasing material
volume of smectite under various densities. After measurements, recovered particles were measured by AFM to refine the stepedge surface area.
As the result of AFM-assisted VSI measurements, dissolution rates of compacted smectite vary from 2.9E-11 mol/m2 /s (density
0.001, Sato et al., 2005) to 2.6E-13 mol/m2 /s (density 1.64, compacted, Satoh et al., 2013). Most possible reason explaining thisbehavior is self-masking effect which nano-particulates mask step-edges each other (reduced dissolution). However, compaction
on random aggregates induces edge-dislocation that newly produces dissolution centers. This was well-recognized especially inthe early compaction stage (promoted dissolution).
Thus, high density clay as nano-stacked or aggregated particles always accompanies with dissolution, but it is not continued
by self-masking effect as a kind of negative-feedback mechanism. To investigate and understand such a complex behavior ofclay, computer simulation by Monte-Carlo calculation is needed.

Keywords: smectite, dissolution, compaction, AFM, VSI

1/1

MIS31-04

Room:102A

Time:May 27 10:00-10:15

Atomic scale in situ observation of cation exchange on montmorillonite surface
ARAKI, Yuki1∗ ; SATOH, Hisao2 ; ONISHI, Hiroshi1
1Graduate School of Science, Kobe Univ., 2 Mitsubishi Materials Corporation

The clay minerals are expected to apply for the assessment of radioactive waste due to their ion exchange property. While
the stoichiometry of the ion exchange has been understood well, the dynamics of the ions at the clay-solution interface, such as
the effect of topography of the clay surface on selectivity of the ion exchange and the surface diffusion of the ions, has not beenclarified.
We performed in situ observation of the ion exchange on the montmorillonite with atomic resolution in the 0.1 ∼ 1 M cesium
chloride solutions by the frequency modulation atomic force microscopy (FM-AFM). The montmorillonite is 100 nm plate-likecrystal whose interlayer cations are sodium and calcium ions. The replacement of the ions on the montmorillonite surface was
identified by the change of the configuration of the lattice of the montmorillonite surface in the cesium chloride solutions. We
introduce the result of the FM-AFM observations of the atomic-scale change of the montmorillonite surface depending on theconcentration of the cesium ions.

Keywords: clay, montmorillonite, ion exchange, frequency modulation AFM

1/1

MIS31-05

Room:102A

Time:May 27 10:15-10:30

Surface Free Energy of Fluorite and Apatite Crystals
TSUKAGOSHI, Ayano1∗
1

Tsukagpshi Ayano, 2 Suzuki Takaomi

Specific surface free energy (SSFE) is significant value to explain the morphology of crystal. The relationship between SSFEand growth length of crystal face is considered to be proportional, which is known as Wulff’s relationship, and well accepted
for thermodynamic interpretation of crystal growth theoretically. Though Wulff’s relationship is well accepted for theoreticalanalysis, experimental measurement of SSFE for crystal face is very few. According to Young’s equation, SSFE of solid face canbe introduced from contact angle of liquid on the solid face, and we observed SSFE of some crystals, for example, apatite[1],ruby[2], and quartz[3]. However, the SSFEs of crystal face have wide distribution even for a flat face of the crystal. Suchwide distribution of observed SSFE was considered to result from steps on the crystal face. In this work, we observed SSFE ofnatural fluorite crystal. Natural fluorite crystal was cut and polished for (100), (110), and (111) faces. SSFE can be separated
to dispersion component which results from van der Waals force and polar components which results from interaction between
permanent dipole moments. The polar component of SSFEs on (100) and (111) faces were smaller then have large rate ofdispersion component of than that on (110) face, because (100) and (111) faces are polarized face. Although the SSFE of real
crystal is calculated from macroscopic value such as contact angles of liquid droplets, the SSFE reflects microscopic surface
structure such as steps and the ionic morphology of the crystal face. We also observed SSFEs of apatite and fluorite crystals inorder to demonstrate the effect of steps on the SSFE. Contact angle of water and formamide droplet on crystal face was observed
using digital camera. SSFE was calculated using Fowkes approximation and Wu’s harmonic mean equations. Though the crystals
we experimentally obtained were growth form, the relationship between SSFE and the growth rate was almost proportional, whichlooks to satisfy Wulff’s relationship qualitatively.
Keywords: Surface free energy, apatite, fluorite

1/1

MIS31-06

Room:102A

Time:May 27 10:30-10:45

Numerical simulation of step dynamics: Quantitative formulation based on a phase-field
methodMIURA, Hitoshi1∗
1

Nagoya City University

Step dynamics on a crystal surface is one of the fundamental processes of crystal growth. Growth units such as atoms andmolecules in the ambient phase are incorporated into kink sites at the step front, and the step then spreads along the crystal
surface, resulting in the growth of the crystal in the vertical direction (layer-by-layer growth mechanism). Therefore, the physics
of supply and advancement of steps should be clarified for understanding the crystal growth mechanism.
In 1949 a spiral growth mechanism was proposed to explain non-negligible growth of crystals at low supersaturation [1]. If
a screw dislocation emerges normally at the crystal surface, it acts as an eternal step source and forms a spiral hillock with thedislocation outcrop as the top. The normal growth rate is given by an analytic formula as a function of supersaturation [2,3]. A
formula giving the hillock slope versus supersaturation plus the measurement of the slope as a function of supersaturation allows
us to determine the free surface energy of the step riser and the Burgers vector of the step sources [4,5]. However, these analytic
formulas do not describe the dynamics of individual steps. Actual growing crystal surface shows complex step behaviors, forexample, emergence of a closed-loop step between two dislocations with opposite signs, and formation of new step islands dueto two-dimensional nucleation [6]. In order to investigate the effect of the complex step behaviors on the crystal growth, analternative method that can treat the dynamics of numerous steps simultaneously is required.
In this study, we proposed a new numerical scheme to calculate the dynamics of numerous steps quantitatively based on aphase-field (PF) method. The PF method has been developed as a numerical technique for simulating the step dynamics on crystal
surface [7]. In this method, two-dimensional height profile on the crystal surface is expressed by an order parameter termed
phase , which takes a constant value between steps (terrace) and bridges between two different-height terraces continuously within
a finite width. We newly defined a free energy functional including a supersaturation term explicitly and derived a governing
equation for the phase field (PF equation) based on the minimum free energy principle. We also formulated the PF equation sothat the advancing rate of a straight step corresponds to that determined by the direct integration hypothesis (exact solution) [3] ata small supersaturation limit. We applied this scheme to some step dynamics problems to check the validity. We confirmed thatthe advancing rate of a straight step could be calculated accurately with optimized computational parameters. We examined thegrowth and dissolution of a two-dimensional island in supersaturation condition and found that the time evolution of its radius
agrees with the analytic solution including the Gibbs-Thomson effect. We also introduced screw dislocations according to [7]to calculate the normal growth rate of the spiral growth mechanism. Our numerical results agreed with the analytic formulas[2,3] in various cases: a single dislocation, a pair of dislocations with opposite/like signs, and an array of dislocations with equalinterval.
Note that our simple formulation requires only a single parabolic partial differential equation to be solved numerically. Our
scheme would provide a new approach for the study of crystal growth.
References: [1] F. C. Frank, 1949, Disc. Faraday Soc. 5, 48. [2] Burton et al., 1951, Phil. Trans. Roy. Soc. A 243, 866. [3] A.
A. Chernov, 1984, Modern Crystallography, Vol. III (Springer-Verlag: Berlin). [4] A. A. Chernov et al., 1986, J. Crys. Growth74, 101. [5] P. G. Vekilov et al., 1992, J. Crys. Growth 121, 44. [6] K. Maiwa et al. 1998, J. Crys. Growth 186, 214. [7] R.
Kobayashi, 2010, in Selected Topics on Crystal Growth (American Institute of Physics), pp. 282.
Keywords: Crystal growth, Step dynamics, Numerical simulation, Phase field method

1/1

MIS31-07

Room:102A

Time:May 27 11:00-11:15

Controlling surface tunneling reactions of solid benzene via surface structure
HAMA, Tetsuya1∗ ; UETA, Hirokazu1 ; KOUCHI, Akira1 ; WATANABE, Naoki1 ; TACHIKAWA, Hiroto2
1

Institute of Low Temperature Science, Hokkaido University, 2 Division of Materials Chemistry, Graduate School of Engineering, Hokkaido University
Organic molecular solids including thin films and fine particles generally exhibit a range of crystalline phases as well as anamorphous state. The dependence of chemical reactivities on their surface structure has attracted considerable attention because
they play a crucial role in an almost limitless amount of research fields, ranging from atmospheric and interstellar chemistry
to biological and material sciences. However, despite the rapid accumulation of structural information about organic materials,
the correlation between the surface structure of these materials and their chemical properties is not fully understood. Here, we
demonstrate that the surface structure of an organic molecular solid determines its chemical reactivity toward an adsorbate. We
investigated the following sequential hydrogen (H) atom addition to amorphous and crystalline benzene (C6 H6 )C6 H6 + H → C6 H7 E a = 18.2 kJ mol−1 , [R1]C6 H7 + H → C6 H8 , [R2]C6 H8 + H → C6 H9 E a = 6.3 kJ mol−1 , [R3]C6 H9 + H → C6 H10 , [R4]C6 H10 + H → C6 H11 E a = 10.5 kJ mol−1 , [R5]C6 H11 + H → C6 H12 . [R6]E a is the activation barrier for H-atom addition in the gas phase. The radical recombination reactions R2, R4, and R6 are barrierless on the surface. In situ infrared spectroscopy revealed that cold H atoms can add to the amorphous benzene surface at 20
K to form cyclohexane (C6 H12 ) by tunneling. However, hydrogenation of crystalline benzene is greatly suppressed. We suggestthat the origin of the high selectivity of hydrogenation by tunneling is the difference of geometric constraints; that is, the presenceof reactive dangling C6 H6 molecules that lacks near neighbors on the amorphous C6 H6 surface and the strong intermolecularsteric hindrance on the crystalline C6 H6 . The present findings can lead us to a better understanding of heterogeneous reaction
systems involving tunneling, and also provide the possibility of nonenergetic surface chemical modification without undesiredside reactions or physical processes.
Keywords: Aromatic hydrocarbons, hydrogenation, amorphous structure, crystalline structure, quantum tunneling, reaction control

1/1

MIS31-08

Room:102A

Time:May 27 11:15-11:30

Large molecular dynamics simulations of the vapor-to-liquid nucleation of water
TANAKA, Kyoko1∗ ; TANAKA, Hidekazu1 ; DIEMAND, Juerg2 ; ANGELIL, Raymond2
1

Hokkaido University, 2 University of Zurich

Phase transitions play important roles in many areas of science and technology. The classical nucleation theory (CNT) is themost widely used model for describing homogeneous nucleation and provides the nucleation rate as a function of the supersaturation ratio and the surface tension of a condensed phase. However, many studies have reported that the CNT fails to describe
experimentally obtained results. In the case of water, the deviations between the nucleation rates predicted by the classical nucleation theory and the experimental values are several order of magnitude.
Molecular dynamics (MD) simulations are able to directly resolve details of the nucleation process, and provide useful test
cases for nucleation models. Until now, many MD simulations examining the nucleation process of water molecules have been
carried out [1-3]. Tanaka et al. [3] performed MD simulations of the nucleation of water vapor in order to test nucleation theories
with 4000 water molecules. The results showed that the classical nucleation theory (CNT) and the modified classical nucleation
theory (MCNT) overestimate the nucleation rates in all cases. On the other hand, the semi-phenomenological model, which corrects the CNT prediction using the second virial coefficient of a vapor, reproduced the formation free energy of a cluster within
10% and the nucleation rate J within one order of magnitude. The sticking probability of the vapor molecules to the clusters was
also determined from the growth rates of the clusters. The sticking probability rapidly increases with the supersaturation ratio S,
which is similar to the Lennard-Jones system. For such low-S cases, we must estimate the sticking probability precisely for theevaluation of J.
Previous typical MD simulations of homogeneous nucleation use 103 -104 atoms. At low vapor densities, and therefore low
supersaturations, a single nucleation event becomes unlikely to occur within reasonable computational timeframes. Simulations
with larger number of molecules allow for the occurrence of such rare nucleation events, and enable us to measure these low rates.
Recently, we started the large-scale MD simulations the SPC/E rigid water model with LAMMPS (Large-scale Atomic/Molecular
Massively Parallel Simulator). In the simulations, the particle numbers are 1 to 120 million atoms (324000-4116000 molecules).
We assumed NVT (constant volume and temperature) ensembles and used a three-dimensional periodic boundary condition withdifferent parameters of temperature T and initial supersaturation ratio S. Here, first results for the large-scale simulations arepresented. We obtained the smaller nucleation rates by 4-5 order of magnutude than the previous studies.
[1]K. Yasuoka and M. Matsumoto, J. Chem. Phys. 109, 8463 (1998).
[2]H. Matsubara, T. Koishi, T. Ebisuzaki, and K. Yasuoka, J. Chem. Phys. 127, 214507 (2007).
[3]K. K. Tanaka, A. Kawano, and H. Tanaka J. Chem. Phys. 140, 114302 (2014).

Keywords: nucleation, vapor to liquid transition, molecular dynamics simulation, water

1/1

MIS31-09

Room:102A

Time:May 27 11:30-11:45

Homogeneous Nucleation of Nanoparticles from Supersaturated Vapor Investigated by
In-situ IR Measurement Experiment
ISHIZUKA, Shinnosuke1∗ ; KIMURA, Yuki1
1

Institute of Low Temperature Science, Hokkaido University

When we evaporate experimental materials in the atmosphere, nanoparticles condense from highly supersaturated vapor via
homogeneous nucleation. This technique is known as the Gas Evaporation method. Nuclei must overcome energetic disadvantage
of surface by making chemical bonds to form particles. Since energetic barrier for homogeneous nucleation is excessively high,homogeneous nucleation occurs from highly supersaturated vapor [1-3]. In such conditions, precursors should grow following
kinetically feasible reaction path, which is deviated from equilibrium condensation. Furthermore, the size of nuclei is so smallthat they show quite different physical and chemical properties from that of bulk material. Therefore, chemical reaction processes
and its properties during transition state of homogenous nucleation are still unrevealed.
For the purpose of examination of condensation sequences of nanoparticles, we investigated by a new experimental apparatus
named Free-flying In-situ infrared measurement of Nucleating nanoparticles Experimental (FINE) system [4]. FINE system
is for gas evaporation method combined with FT-IR and enables direct in-situ IR measurement of condensation of 10-100 nm
nanoparticles via homogeneous nucleation from vapor.
We applied FINE system for silicate and titanium oxides and revealed that condensation proceeds through metastable phaseswith non-crystalline IR feature, which is known as Ostwald’s step rule. Just condensed nanoparticles would be liquid droplet andcrystallization proceeded subsequently. In previous study, we succeed in measurement of IR evolution after nucleation. However,
the information about precursors is still lack to understand condensation mechanism. We are now developing a new experimental
set up for FINE system and going to talk about future work.
References[1] Kimura, Y., Miura, H., Tsukamoto, K., Li, C. et al., 2011, J. Cryst. Growth., 316, 196.
[2] Kimura, Y., Tanaka, K. K., Miura, H., & Tsukamoto, K., 2012, Crystal Growth & Design., 12, 3278.
[3] Kimura, Y., Tanaka, K. K., Sakon, I., Nozawa, T. et al., 2014, Int. J. Microgravity Sci. Appl., 31, 130.
[4] Ishizuka, S., Kimura, Y. & Sakon, I., 2015, The Astrophysical Journal, in press.
Keywords: Homogeneous Nucleation, Vapor Growth, in-situ, Nanoparticles

1/1

MIS31-10

Room:102A

Time:May 27 11:45-12:00

Application of the transmission electron microscopy to the study of the crystallization
process in a solution
YAMAZAKI, Tomoya1∗ ; KIMURA, Yuki1
1

Institute of Low Temperature Science, Hokkaido University

One of the powerful methods to demonstrate the crystal growth and dissolution processes is in situ observation using a microscope, because it can directly visualize these processes in real time. The crystal growth and dissolution processes in a solution
have been studied mainly using various optical microscopies as a noninvasive technique. Some high resolution optical microscopies is able to visualize the molecular-level structure on a crystal surface [1-3]. However, the lateral resolution of optical
microscopy is sub-micron because it is limited by the wavelength of a light source [1]. To resolve the crystallization processes
more clearly, the transmission electron microscopy (TEM), which has the nano-order resolution, is a strong method for in situ
observation. Recently, in situ observations of the crystallization processes in solutions under TEM have been energetically performed using the liquid cells or an ionic liquid to adapt to the high-vacuum environment [4-6]. These observations allow us to
see the behavior of nano-particles and crystallization process of inorganic materials in a solution. Here, using the liquid cell, we
have performed in situ observation of the crystallization of a lysozyme protein, which is used to study the crystallization process
in a solution as a model material, by the TEM for understanding the processes of crystallization.
We used two TEMs with LaB6 filament at an acceleration voltage of 200 kV (Hitachi H-8100) and with field-emission gun
at an acceleration voltage of 300 kV (Hitachi HF-3300). For the observation of crystals in a solution, we used a “Poseidon”
TEM holder (Protochip, Inc.) combined with a liquid cell. The liquid cell consists of a pair of semiconductor-based plates with
an amorphous silicon nitride window and 150 or 500-nm-thick spacer to form the flow path of the crystallization solution. The
lysozyme was crystallized using NaCl as a precipitant in a sodium acetate buffer solution at pH = 4.5.
As a result, we succeeded in observing the crystals and amorphous particles of lysozyme protein using the TEM and the liquidcell holder. In this presentation, we report the recent results of in situ observation of its crystallization process including the
growth and dissolution.
Acknowledgement
We thank M. Shirai and H. Matsumoto of Hitachi High-Technologies Corporation for their help with the TEM observation using HF-3300. The authors acknowledge supports from a Grant-in-Aid for Research Activity Start-up from KAKENHI(26887001) and for a grant for Young Scientists (A) from KAKENHI (24684033).
References[1] G. Sazaki et al ., J. Cryst. Growth 262 (2004), 536.
[2] P. Dold et al ., J. Cryst. Growth 293 (2006), 102.
[3] A. E. S. Van Driessche et al ., Cryst. Growth & Des. 7 (2007), 1980.
[4] J. M. Yuk et al ., Science 336 (2012), 61.
[5] Y. Kimura et al ., J. Am. Chem. Soc. 136 (2014), 1762.
[6] M. H. Nielsen et al ., Science 345 (2014), 1158.
Keywords: in situ observation, transmission electron microscopy, crystallization, solution growth, lysozyme

1/1

MIS31-11

Room:102A

Time:May 27 12:00-12:30

Growth and dissolution of the hydrogel-grown lysozyme crystals
MARUYAMA, Mihoko1∗ ; HAYASHI, Yuki1 ; SUGIYAMA, Shigeru2 ; ADACHI, Hiroaki3 ; YOSHIMURA, Masashi1 ;MORI, Yusuke1
1

Grad. School. Eng. Osaka Univ., 2 Grad. School. Sci. Osaka Univ., 3 SOSHO Inc.

We recently developed a new method for growing protein crystals in a high-concentration hydrogel. Using the method we cancrystallize protein crystals with increased mechanical stability, as a result the crystals give us high resolution of X-ray diffraction
pattern. On the other hand the crystals contain the hydrgel fragments and the effects on crystal defects such as dislocations were
unknown. In this study, we slightly etched the crystal surface and estimated the dislocation density.
Hydrogel-grown and solution-grown LZM crystals were slightly dissolved by increasing the temperature, and their surface
morphologies were observed by laser confocal microscopy. The solution-grown crystals exhibited deep etch pits at 303 K, while
the hydrogel-grown crystals exhibited etch pits at a higher temperature (305 K). In addition, the density of the etch pits on thesolutiongrown crystals at 305 K was significantly higher than that on the hydrogel-grown crystals at the same temperature. These
results demonstrate that the hydrogel-grown crystals are more tolerant of temperature changes than those grown in solution.

1/1

MIS31-P01

Room:Convention Hall

Time:May 27 18:15-19:30

Specific Surface Free Energy of Celestine
NAKAGURO, Kie1∗ ; SUZUKI, Takaomi1
1

Facluty of engineering, Shinshu University

The morphology of crystal is determined by the stability of each crystal face. Especially, Wulffs relationship is well known:
growth length of the crystal face is proportional to the specific surface free energy (SSFE) of the crystal face. Though SSFE
is theoretically discussed, experimental determination of SSFE is very few. We calculated the SSFE of some single crystals
using contact angle of liquid droplets. We observed some sulfates such as, gypsum, anhydrite, and barite. This time we observed
celestine (SrSO4), and determined the SSFE of natural and polished face in order to discuss stability of each face. Though naturalcelestine crystal do not have (001) face, the natural celestine crystal was cut and polished in order to produce (001) face. SSFEof (210) and (001) faces were 25.3 and 51.2 mN/m. SSFE of (210) face was much smaller than that of (001) face, indicating that(210) face is more stable than (001) face. Dispersion component which causes van der Waals force and polar component whichcauses permanent dipole moment interaction of SSFE were obtained separately. Dispersion and poplar component for SSFEof (001) face was 47.9 and 3.3 mN/m, respectively. On the other hand, they were 13.0 and 12.3 mN/m for the SSFE of (210)
face. (001) face of celestine is considered to be neutral face and the dispersion component for the interaction between liquid andsolid is dominant. Though contact angle of liquid is macroscopic value, we can discuss microscopic, as atomic scale structure of
crystal face.
Keywords: celestine, surface free energy

1/1

MIS31-P02

Room:Convention Hall

Time:May 27 18:15-19:30

On the relation between the origins of aragonite and transition temperatures to calcite
YOSHIMURA, Masahiro1∗ ; SUZUKI, Michio2 ; SASAKI, Takenori3 ; KOGURE, Toshihiro1
1

Graduate School of Science, Univ. Tokyo, 2 Graduate School of Agriculture, Univ. Tokyo, 3 The University Museum, Univ.
Tokyo
Aragonite, a polymorph of CaCO3 , is less stable than calcite in the ambient condition, but commonly forms with both biological and geological origins. In particular, aragonite as the biominerals seems important in the geoscience fields because it
constitutes the fossils of hard tissues or becomes a carbon reservoir in the carbon cycle near the surface of the earth. Hence, it
is interesting to know how the mineralogical stability is different between aragonites with different origins. For this purpose, wehave investigated the transition temperatures of various biogenic aragonite to calcite by heating, using high-temperature XRD, as
well as geological and synthetic ones. Among 21 specimens, almost biotic aragonites showed a transition temperature 60-100C
lower than geological and synthetic ones. However, the shells of land snails (three species were examined) showed almost thesame transition temperature as abiotic aragonites. Accordingly, it cannot be concluded that the biotic aragonite is always lessstable than geological ones. Besides, aragonite of a coral showed an onset temperature of the transition around 40C lower thanthe other biotic aragonites.
Keywords: aragonite, calcite, phase transition, biomineral, X-ray diffraction

1/1

MIS31-P03

Room:Convention Hall

Time:May 27 18:15-19:30

In situ AFM study on crystal growth of barite
KUWAHARA, Yoshihiro1∗ ; MAKIO, Masato2
1

Faculty of Soc. Cul. Studies, Kyushu Univ., 2 Grad. School Soc. Cul. Studies, Kyushu Univ.

Barite (BaSO4 ) is the most abundant mineral of barium and occurs in a wide variety of geologic environments that spangeologic time from the Early Archean to the present. Because of its low solubility (K sp = 10−9.99 at 25C) in water, the dissolution
and precipitation of barite control the concentration and mobility of Ba in ground and surface water. Barite is also a common
scale mineral, and its formation, with its low solubility in water, is almost inevitable in industrial water, oil, and gas-production
systems. Because Ra2+ and Ba2+ are of similar ionic radius and electronegativity, some Ra2+ is incorporated into the barite
crystal structure during its precipitation. Therefore, water including radioactive Ra ions produced from oil, gas, and geothermal
wells or from U mine wastes, which contain an array of radioactive nuclides, including 226 Ra, may precipitate radioactive barite.
Many in situ and ex situ AFM studies on the dissolution reactions of the barite (001) surface have been conducted to elucidate
the processes involved and problems mentioned above. However, information on microscopic growth reactions of barite inaqueous solutions is sparse. Here we report the results of a preliminary experiment performed by in situ AFM observations of
the growth behavior on the (001) surface of barite in supersaturated BaSO4 solutions at 25C.
The barite sample was obtained from the Stonehem Barite Deposit in Colorado, USA in the form of a single optically clear
crystal. The barite crystal was cleaved parallel to the (001) cleavage plane with a sharp knife blade immediately before the AFM
observations. The BaSO4 aqueous solution was prepared by mixing Na2 SO4 and Ba(NO3 )2 solutions consisting of analyticalgrade chemicals and deionized water immediately before the AFM observations. The degree of supersaturation and ionic strength
were calculated using the program PHREEQC. In situ observations of the barite growth were performed by a Nanoscope III witha Multimode SPM unit (Digital Instruments) operating in contact-mode AFM (CMAFM) on a vibration isolation platform in atemperature- and humidity-controlled room. The cleaved barite crystals were first reacted with deionized water at 25C to ensurestable AFM scanning conditions and obtain reliable AFM images. We then replaced the water with BaSO4 solution in the fluid
cell and began observing the growth process on the barite (001) surface at 25C. Deionized water and BaSO4 solution flowed
through the fluid cell at a constant rate of 0.6 ml/h, controlled by a syringe pump.
The growth behavior on the barite (001) surface at 25C appeared to begin with the advancement of the initial step edges andfilling in of the etch pits formed in the water before the BaSO4 solution was injected. The advancing fronts of the steps were
not angular but rather irregular, wavy, or rounded. Under higher supersaturation conditions (>S = 13), circular sector-shaped
two-dimensional (2D) nuclei were observed slightly later than the advancement of the initial step edges. These sector-shaped
islands are defined by half-layer steps (3.6 A) parallel to [120], [1-20] and a curved step edge tangent to [010]. The advance rateof the curved step was approximately 5 times that of the [120] step.
Other growth behavior observed on the barite (001) surface included the formation of prismatic or bladed growth ledges andgrowth hillocks and spirals. The prismatic growth ledges were formed at kinks or faults at multi-layer steps and were elongatedalong the [010] direction with curved edges. The growth hillocks and spirals were also elongated along the [010] direction anddisplayed a bow-shaped form. The morphology of the growth hillocks and spirals was very similar to that of the deep etch pits
formed in NaCl solutions at room temperature or in water at 60C, that is, under the conditions that promote barite dissolution.
Keywords: crystal growth, barite, atomic force microscopy, two-dimensional nucleus, spiral growth

1/1

MIS31-P04

Room:Convention Hall

Time:May 27 18:15-19:30

Dissolution Rate of Crystals in Solution
TSUKAMOTO, Katsuo1∗ ; SATOH, Hisao2
1

Graduate School of Engineering, Osaka University, 2 Mitsubishi Materials

Compared to growth mechanism of crystals, dissolution mechanism has not been studied so well because the phenomena has
been regarded as the reverse process of crystal growth. However the phenomena is not so simple as often has been observedin coupled-dissolution and precipitation. This mechanism has been applied to the interpretation of natural mineral dissolution
or replacement, it would be important for the selection of polymorphs or chirality during dissolution of medicine or someother materials, as well as natural minerals. Some examples will be shown based on the precise dissolution rate of crystals byinterferometry for discussion.
Keywords: crystal growth, dissolution mechanism, sprial growth, nucleation, crystallization, phase-shift interferometry

1/1