CO4-1

Millimeter Wave Absorption Spectra of Ionic Liquids

EXPERIMENTS: A fixed amount of ionic liquids (Tokyo Chemical Industry Co., Ltd.) were spread into filter
paper. Transmission spectra of single and double papers
with ionic liquids were measured at room temperatureand low temperatures. Absorption spectra were obtainedby subtraction of them. To confirmation, measurements
were repeated two or three times for each IL. Molecular
dynamics simulation is executed by Gromacs 5.0.
RESULTS: Four types of the spectral change occurredat temperature above melting point or glass transition
temperature[7]. The intensities of the absorption bands in
the ILs which are crystal in the solid state showed rapid
decrease at their melting points[4,5]. On the other hand,those in ILs which are vitreous in the solid state weakened and shifted gradually. Some others showed complicated change. The other type showed no absorption bandin this spectral range. Figures 1.a-d show typical spectraof these four types. Origin of these difference is not clear
yet. To investigate these variety of spectra, molecular
dynamics simulation is underway.

28002

-1

[Empy][TFSI]

22C
-115C
-46C
-12C

0
4

6
8
10
WAVE NUMBER (cm -1)

12

14

-1

ABSORPTION COEFFICIENT (cm )

(a)

10

20

(b)

[Dmim][DmP]
22C
-115C
-46C

0

4

6
8
10
WAVE NUMBER (cm -1)

12-1

ABSORPTION COEFFICIENT (cm )

10

(c)
10

[Bmim][TFSI]
22C
-115C
-46C
19C

0

-10

-1

INTRODUCTION: We have observed millimeterwave absorption bands of AgI-superionic conductive
glasses in sub-terahertz region. We also observed theseabsorption bands in CuI-superionic conductive glasses[1-3]. These bands seem to be due to collective motionof the conductive ions because their frequencies are lower than those estimated from the ionic masses. However,the dynamics of the collective movement of ions is notclear yet.
Ionic liquids(ILs) are molten salts even at room temperature because of large and anisotropic radius of composing anions and cations. It is interesting to compare
ionic motion in the ILs with those in superionic conductor for making clear the effect of glass network structure
onto the collective movement of ions.
Recently, we have observed sub-terahertz absorption
bands of ILs[4-6]. These bands seem to be due to ionicmovement because of their temperature dependence. That
is to say, the absorption bands disappear at low temperatures at which the IL is solid. However, the thermalchange of absorption spectra of these ILs were in various
way. This difference seems to be due to the difference ofthe process of their phase transition to the solid states(crystal or glass).
In this study we have measured millimeter wave absorption spectra of 33 ILs to make clear the ionic movement from the temperature change of absorption spectra.

20

ABSORPTION COEFFICIENT (cm )Faculty of Engineering, Tohoku Gakuin University
1
Research Reactor Institute, Kyoto University

ABSORPTION COEFFICIENT (cm )T. Awano and T. Takahashi1

4

6
8
10
WAVE NUMBER (cm -1)

12

15

(d)

[Bmim][BF 4]

10

22C
-115C
-46C

5

0

4

6
8
10
WAVE NUMBER (cm -1)

12

Fig. 1. Typical temperature dependence of absorption
increment spectra of ionic liquids. The baseline is theabsorption spectrum at 88 K.
REFERENCES:[1] T. Awano and T. Takahashi, J. Phys. Conf., 148(2009) 012040/1-4.
[2] T. Awano and T. Takahashi, J. Phys. Soc. Jpn. 79
Suppl. A (2010) 118-121.
[3] T. Awano and T. Takahashi, Proceedings of the 13th
Asian Conference on Solid State Ionics, (2012) 569-576.
[4] T. Awano and T. Takahashi, KURRI Progress Report
2014, CO4-2.
[5] T. Awano , A. Shikoda and T. Takahashi, 20th International Conference on Solid State Ionics, (2015) D2.02.
[6] T. Awano and T. Takahashi, KURRI Progress Report
2015, CO4-1.
[7] T. Awano , A. Shikoda and T. Takahashi, 21th International Conference on Solid State Ionics, (2017) IV-6 P.

CO4-2Synthesis of Noble Metal Nanoparticles Supported on Graphene by
Irradiation Reduction Method

F.Hori, H.Nakanishi, A.Tokai, M.Tanaka, S.Toda, M.Tani,
A.Iwase, K.Okitsu, Y.Mizukoshi1 and Q.Xu2
Dept. of Mater. Sci., Osaka Prefecture University
Institute of Materials Research, Tohoku University
2
Research Reactor Institute, Kyoto University

1

INTRODUCTION: Metallic nanoparticles have somespecific properties, which are not appeared in bulk
materials such as catalytic activities, magnetic properties,
electro conductivity and light absorption. These
properties depend on its size, shape, structure, chemicalcomposition and so on. They have many possibilities toapplied for various industrial fields. However, it is noteasy to fabricate multi elemental alloy nanoparticles with
controlling their size, shape and structure. Generally,
many kinds of metal nanoparticles commercially aresynthesized by using chemical reaction method, which is
not necessarily in water solution. Recent years, some
reports show that it is possible to fabricate various metal
nanoparticles under irradiation reduction fields such as
ultrasonic, solution plasma, electron beam, ion beam andgamma-ray irradiation. So far, we have tried and reported
that synthesis of shape and size controlled Au, Ag, Pd, Pt,
Cu and their complex nanoparticles under irradiation
reduction fields. On the other hand, we have developed aone-step gamma-ray irradiation method to synthesize
nanocomposites composed of graphene and Pt
nanoparticles from aqueous solution containing graphene
and Pt ions in water [1]. In this study, we have tried tosynthesize nanocomposites composed of graphene (Gp)and Pd nanoparticles (NPs) in aqueous solution by
gamma-ray irradiation, electron beam irradiation.

EXPERIMENTS: Aqueous solutions with a given
concentration of Pd(II) (PdCl2 ・ 2NaCl ・ 3H2O) and2-propanol. Graphenepowder (6 - 8 nm thick x 5 μmwide) was added into this water solution. The solution
was argon gas purged and sealed into polystyrene vessels.
After dispersion by an ultrasonic cleaning bath, they
were irradiated at about 300 K with -rays from 60Co
radio active source at gamma irradiation facility in
KURRI, Kyoto University. The total dose was fixed to
10 kGy with dose rate of 13.6 kGy/h. After irradiation,
the products were separated by centrifugation, washedwith water and dried by freeze-drying. UV–vis
absorption spectra were measured and all products were28043

observed by conventional TEM. Infrared spectra andRaman spectra (RS) of the prepared samples werecollected
byaFourier-transform
infrared
spectro-photometer(FT-IR)
anda
Raman
spectrophotometer.
RESULTS:
Pd NPs supported on Gp (Pd/Gp) were formed in one-pot
aqueous solution containing Gp and Pd(II) complex ionsby gamma-ray or electron beam irradiation. As shown infigure 1, it was confirmed that gamma-ray and electron
beam irradiation provided carbonyl groups (C=O) on Gp
and Pd NPs formed from the radiolytic reduction ofPd(II) complex ions were supported on the carbonyl
modified Gp. Although there is no fundamental
difference in the reaction generated by gamma-ray andelectron beam irradiation, but the size of Pd NPs of Pd/G
was differed greatly between them. Furthermore, Pd NPs
supported on nitrogen-doped Gp (Pd/N-Gp) wereprepared by the same condition of gamma-ray andelectron beam irradiation. The size of the Pd NPs of
Pd/N-Gp was smaller than that of Pd/G because of theincreased number of adsorption sites of Pd NPs.

Fig. 1 TEM image and size distribution of Pd-NPs supported
on graphene synthesized under gamma-ray irradiation field.

Acknowledgement
This work was supported by JSPS KAKENHI Grant-in-Aid for
Scientific Research (A)-15H02342.

Reference[1] A.Tokai, K.Okitsu, F.Hori, Y.Mizukoshi, A.Iwase, Rad. Phys.
Chem. 123, (2016) 68-72

CO4-3

Electron Irradiation Induced Damage Structure in Intermetallic Alloys

F. Hori, Y. Ueno, Y. Sumikura, K. Kobayashi, A. Iwase,
K. Ohsawa1, Q. Xu2 and N. Abe2
Dept. of Mater. Sci., Osaka Prefecture University
1

Res. Inst. of Appl. Mech., Kyushu University
Res. Reactor Inst., Kyoto University

2

INTRODUCTION: Fe-Al compound alloys have good
properties such as specific strength to weight ratio,oxidation resistance and strength in elevated temperature.
It is well known that intermetallic compound alloys
possibly include more than two types of vacancies
basically, that is A-vacancy and B-vacancy in A-B
compound alloy. Thermally equilibrium defects andchemically deviated structural defects in these compoundalloys are very complicated. However, the amount ofdefect and the defect structure affects the various
characteristic features, such as strength and electronic
conductivity and so on. Moreover, first principle
calculation shows that different number of hydrogenatoms can be trapped by Al- or Fe-vacancy in B2 type
Fe-Al alloy. On the other hand, we have reported thatvacancies introduced by electron irradiation strongly
depend on electron energy because of their different
threshold energy of displacement for each elemental atom.
Then we supposed that radiation induced vacancy typedefects can be controlled by changing the energy ofelectron irradiation. In this study, we have performed
electron irradiation for Fe-Al alloys followed byhydrogen charging by electrochemical method and H+
ion implantation. After irradiation and hydrogen charging
into Fe-Al alloys, Thermal desorption spectrometry(TDS) and positron annihilation measurements werecarried out.
EXPERIMENTS: Fe-48%Al alloy specimens with B2
structure were prepared by arc melting method. Sliced
samples with the thickness of 0.5 mm were annealed at
973 K for 120 h followed by air-quenched in vacuum.
These specimens were irradiated with 2 MeV electron to
the fluence of 1×1017 and 1×1018 /cm2 at JAEA-Takasaki
and with 9 MeV electron to the fluence of 5×1017 and3×1018 /cm2 at KURRI, Kyoto University. In both cases,
irradiations were carried out at about 330 K controlled by

28044	
 	 water flow system. After electron irradiation, hydrogenatoms were cathodically charged in the sulfuric acidaqueous solution including NH4SCN as an additive. Also
1.5 MeV-H+ irradiation with the fluence of 1×1016
ions/cm2 have performed for these alloys at National
Institute for Quantum and Radiological Science andTechnology. After and before irradiation, samples were
examined by X-ray diffraction, positron annihilation
lifetime, coincidence Doppler broadening measurements
and TDS. The positron lifetime spectra were analyzed byusing POSITRONFIT program.
RESULTS: After electro-chemical charging andhydrogen implantation into Fe-Al alloys, some peaks
observed in TDS spectra representing emission of
decomposed hydrogen bounded by defects and grainboundary (Fig.1). It found that hydrogen released
temperature for electron irradiated sample followed byhydrogen charging is slightly higher than that forhydrogen charged sample without irradiation. This result
reveals that the introduced hydrogen atoms might betrapped by vacancy. On the other hand, positronannihilation Doppler broadening S parameter decreases
after hydrogen charging or H+ irradiation showing that
implanted hydrogen is trapped by vacancy. This result is
consistent with the results of TDS.

Fig. 1 Hydrogen emission behavior of before and after
irradiated Fe-Al alloys.

Acknowledgement
This work was supported by JSPS KAKENHI Grant-in-Aid for
Scientific Research (B)-26289365.

Observation of Transient Damage States in Materials under Ion Irradiation

H. Tsuchida1,2, H. Minagawa2, S. Nakanishi2 and Q. Xu3
1

Quantum Science and Engineering Center, Kyoto University
2
Department of Nuclear Engineering, Kyoto University
3
Research Reactor Institute, Kyoto University

INTRODUCTION: The effects of energetic-particle
irradiation on metallic materials have been extensively
studied in nuclear and radiation materials science. Ion
irradiation induces crystal lattice disorder following various dynamic relaxation processes including defect recombination and aggregation. During irradiation, damage
evolution proceeds by the reciprocal processes of defectproduction and relaxation, and then reaches a certain
equilibrium damage state. To date, experimental andcomputer simulation studies have focused on an understanding of a transient damage state under irradiation, anda new model calculation relevant to dynamic annealing
has recently been reported [1].
To understand transient damage states in materials underion irradiation, we performed in situ X-ray diffraction(XRD) study of lattice expansion associated with deformation of a thin Al foil under MeV-energy heavy-ion
irradiation [2]. The change in the lattice parameter during
irradiation and its ion-beam flux dependence were analyzed. We investigated the effect of defect production on
lattice expansion. Moreover, with the correlation between
lattice expansion and displacement damage, we considered a model for lattice expansion originating from theaccumulation of Frenkel defects. From the model, we
obtained the relationship between the relative change inlattice parameter and the value of displacement per atom(dpa) rate. A comparison of the results from model calculations and experiments shows that the dpa rate calculated from the model, which takes account of athermal defect-recombination, is strongly correlated with the change
on lattice parameter. This result suggests that the concentration of surviving defects under irradiation diminishes
because of spontaneous recombination of defect produced.

where a0 and aduring are the lattice constant observed
before and during irradiation, respectively. Fig. 1 shows
the dependence of dpa rate on the relative change in thelattice parameter. The dpa rate is given as σ darc × φ ,where σ darc is the displacement damage cross section
estimated using the athermal recombination-correlated(arc) model [3], and φ is the beam flux. The arc model
was developed to estimate the damage cross sections
taking account of athermal defect-recombination. This
enables the determination of the surviving fraction or therecombination fraction of defects produced during irradiation. The result indicates that the magnitude of the lattice expansion is correlated with the arc-dpa rate. Thus,
the present in situ XRD experiment affords a new method
to investigate transient damage states in materials underion irradiation.

8

6∆a/a [×10–3]

CO4-4

4

2

0

0

1

2

3

σarc
φ [×10–3 dpa/σ]d

EXPERIMENTS: A high-purity well-annealed aluminum foil with a thickness of 3 µm was used as a target
specimen. The free-standing target foil was irradiatedwith three different projectiles: specifically 2.5-MeV C,
3.0-MeV O and 4.3-MeV Si ions. We performed in situ
X-ray diffraction (XRD) analysis of the target specimen
under ion irradiation, and measured diffraction peak fromAl (200) plane before, during and after ion irradiation.

Fig. 1. Dependence of the relative change of thelattice parameter on the dpa rate. Symbols denotethe experimental data: □ for 2.5-MeV C ions, ▲for 3.0-MeV O ions, and ○ for 4.3-MeV Si ions.
Solid curve denotes a result of fitting the data.

RESULTS: During ion irradiation, the diffraction peak
position was sifted to a lower diffraction angle comparedwith that measured before irradiation, indicating an expansion of lattice. The relative change in lattice parameter,∆a a = (aduring − a0 ) a0 , increases as the beam flux increases,

REFERENCES:[1] X.M. Bai et al., Science, 327 (2010) 1631-1634.
[2] M. Minagawa et al., Nucl. Instr. and Meth. B, 372(2016) 38-43.
[3] K. Nordlund et al., Nucl. Sci. NEA/NSC/DOC (2015)
9.

28047

CO4-5

Trapping of Hydrogen Isotopes at Vacancy-Type Defects in Tungsten

Y. Hatano, K. Yumizuru1, T. Toyama2 and Q. Xu3
Hydrogen Isotope Research Center, Organization for
Promotion of Research, University of Toyama
1
Graduate School of Science and Engineering for Education, University of Toyama
2Institute for Materials Research, Tohoku University
3
Research Reactor Institute, Kyoto University
INTRODUCTION: Retention of hydrogen isotopes especially tritium in plasma facing materials is one of themost important issues in safety assessment of fusion reactors. It has been shown that neutron irradiation causes
significant increase in deuterium (D) retention in W, aleading candidate of plasma-facing material, due to trapping effects of radiation-induced defects [1]. Detailed
understanding of trapping mechanisms is necessary forthe mitigation of this undesirable irradiation effects.
To examine defect-hydrogen isotope interactions in W,
the authors irradiated samples of polycrystalline W withhigh energy electrons to 10−3 dpa to induce Frenkel pairs
uniformly throughout the bulk [2]. Then the irradiatedsamples were annealed at 573 K under vacuum or D2 gas
atmosphere, and clustering of vacancy-type defects and Dtrapping were examined using positron annihilation spectroscopy (PAS) and thermal desorption spectroscopy(TDS) [2]. Significant increase in positron lifetime accompanied with increase in D retention was observed
after electron irradiation and subsequent annealing due toformation of vacancies and their clustering. In addition,
positron lifetime for D-charged samples was shorter thanthat for D-free samples annealed in vacuum. This difference was ascribed to the presence of electrons of D atoms
in vacancies.
In this year, detailed coincidence Doppler broadening(CDB) measurements were performed for better understanding of D trapping at vacancy clusters. Samples irradiated to lower dose were also examined to clarify thethreshold damage level at which the irradiation effects onhydrogen isotope retention starts to appear.
EXPERIMENTS: Disk samples of W were irradiatedwith 8.5 MeV electrons to ~1×10−3 dpa at LINAC at
Kyoto University Research Reactor Institute (KURRI).
The irradiated samples were shipped to International Research Center for Nuclear Materials Science, Institute forMaterials Research (IMR-Oarai), Tohoku University. A
part of samples were sealed into quartz capsules undervacuum or D2 gas atmosphere (0.1 MPa) and heated at
573 K for 100 h. Then CDB measurements were performed using 22Na positron source.
Several W samples were irradiated with 5.5 MeV
electrons at LINAC at KURRI to ~5×10−4 dpa. Positron
lifetime and D retention after exposure to D plasma at
450 K were measured.
RESULTS AND DISCUSSION: Fig. 1 shows ratio

28048

curves of CDB spectra obtained by normalizing each
CDB spectrum to that of well-annealed W sample. The
electron irradiation and subsequent annealing in vacuum
resulted in clear increase in the ratio values in the low
momentum region and decrease in the high momentum
region. This change indicates increase in the probabilityof positron annihilation with conduction electrons due toformation and clustering of vacancies. The presence of D
in the samples led to further increase in the ratio values in
the low momentum region and decrease in the high momentum region. The remarkable influence of D is explained by annihilation of positrons with valence electrons of D atoms in vacancies. In other words, the observed change in the ratio curve is one of the direct evidences of D trapping at vacancies.
The positron life time for W samples irradiated to~5×10−4 dpa was 117.9 ± 0.4 ps. This value is comparable with that for non-irradiated W (118 ps). No clear effects on D retention was observed. It was therefore concluded that irradiation effects on hydrogen isotope retention becomes significant at ~10–3 dpa.
CDB measurements were performed under theframework of Joint Research of IMR-Oarai.
1.3
1.2
1.1
W
k
l
u
b
o
t
o
i
t
a
R

1.0
0.9
0.8
0.7
0.6

Non-irradiated0.5

E-irradiatedAnnealed in vacuum

0.4
0.3

Annealed in D2 gas
0

5

10

15

20

25

Momentum (x10-3 m0c)

Fig. 1 Ratio curves of CDB spectra of non-irradiated W
and those after electron irradiation and subsequent annealing at 573 K under vacuum or D2 gas atmosphere(0.1 MPa). The curves were obtained by normalizing
each CDB spectrum to that of well-annealed W samples.
REFERENCES:[1] Y. Hatano et al., J. Nucl. Mater., 438 (2013)
S114–S119 and Nucl. Fusion 53 (2013) 07300[2] Y. Hatano et al., KURRI Progress Report 2015, 81

CO4-6Preliminary Study of Variation in Current-Voltage Characteristics
of Field Emitter Array Structure under Gamma-ray Irradiation

Y. Gotoh, T. Morito, M. Nagao1, N. Sato2, M. Akiyoshi3,
and I. Takagi
Graduate School of Engineering, Kyoto University
1
National Institute of Advanced Industrial Science andTechnology, AIST
2
Research Reactor Institute, Kyoto University
3
Radiation Research Center, Osaka Prefecture University

emitter current of about -4 nA was observed. While thegate and focus currents were about 1.5 nA and sum ofthese currents approximately coincides the value of theemitter current. The electric resistance was calculated to
be about 1 GΩ, which was approximately the same value
obtained in the previous measurement. The data acquiredat the distance of 40 cm showed similar values.
4

EXPERIMENTAL SETUP: The measurements of thecurrent-voltage characteristics were made in a small
vacuum vessel that was evacuated before the irradiation
experiments. The vacuum vessel was connected with aseparate vacuum pumping system via a 1/4” stainlesssteel tube. The vessel itself did not possessed a pumping
system. Therefore, the vessel was once evacuated by avacuum system connected to the vessel, and the vessel
was then encapsulated to be irradiated by γ-rays.
EXPERIMENTAL PROCEDURE: The FEAs were
fabricated at National Institute of Advanced Industrial
Science and Technology. Since the FEAs possessed threeelectrodes of emitter, gate and focus, the current thatflowed these electrodes were monitored with asource-measure units. In the previous measurement, irradiation of γ-ray was performed from the normal directionof the FEA surface. In the present study, irradiation was
performed from the side to observe the effect of the γ-ray
incidence. The measurements were done at two different
distances from the γ-ray source: 22 cm and 40 cm.
RESULTS: Figure 1 shows the current-voltage characteristics of the emitter, gate, and focus electrodes under
γ-ray irradiation, measured at 22 cm distant from theγ-ray source. When the emitter was biased to -5 V, the

28050

2

Current (nA)

INTRODUCTION: We have been investigating radiation tolerance of the components of a compact image
sensor based on field emitter array (FEA) and photoconductor [1,2]. The purpose of the development is to realize
a compact image sensor that can be used for the nuclear
decommissioning process for Fukushima Daiichi nuclear
power plant. By the last year, we have irradiated gamma-ray to the FEAs and cadmium telluride-based photodiodes to check the robustness of these devices. As a result, the properties of these devices were not deteriorated
with the γ-ray irradiation until the adsorbed dose reached
1.2 MGy [1]. Now the research phase is moved to thenext stage where in situ observation of the device performance under γ-ray irradiation. Last year, we havemade the first preliminary experiments of the in situ observation [3]. However, the method of the measurements
has not yet been established. In this study, we have performed a similar experiments, but irradiating the FEA
sample from oblique direction.

Focus
Gate

0
−2

Emitter
−4
−6
−6

−4

−2

0

Emitter voltage (V)Fig. 1. Current-voltage characteristics of the emitter, gate, and focus electrodes under the γ-ray irradiation.
DISCUSSION: In the FEA, the emitter was common
and the upper electrode was either the gate or the focus
electrode. The ratio of the areas corresponding to the gate
and the focus is not unity, it was somewhat strange tohave similar currents between the gate and the focus. One
possible reason for this would be the effect of the leads
from the feedthrough to the device. Shielding the leadmay be necessary.
SUMMARY: The current-voltage characteristics of
FEAs under the γ-ray irradiation were measured. The
emitter current was larger than the gate and the focus
electrodes. Detailed analysis of these currents are now
underway.
ACKNOWLEDGMENTS: A part of this study was
supported by Japan Society for Promotion of Sciencethrough a Grant-in-Aid for Scientific Research No.
16H04631.
REFERENCES:[1] Y. Gotoh et al., Tech. Dig. of the 29th International
Vacuum Nanoelectronics Conference, IVNC2016,
Vancouver, July 8-10, 2016, p. 20.
[2] T. Okamoto et al., Physica Status Solidi (c) 13 (2016)635.
[3] Y. Gotoh et al., KURRI Progress Report 2015 (2016)
p. 73

CO4-7

Study of the Properties of Water and the Physiological Activation Phenomena byusing High-Intensity Pulsed Coherent Radiation

S. Okuda, Y. Tanaka, Y. Kida and T. Takahashi1during the CTR irradiation experiments is under preparation.

Graduate School of Engineering, Osaka Prefecture University
1
Research Reactor Institute, Kyoto University

Shielding wall
SampleMirror system

INTRODUCTION: The coherent transition radiation(CTR) from electron bunches of a linear accelerator (linac) has continuous spectra in a submillimeter to millimeter wavelength range corresponding to the terahertz(THz) frequency range. It is a picosecond pulsed lightand hence, has extremely high peak-intensities comparedwith the other THz light sources. The light source systemusing the CTR from the electron beams of the 45 MeV
L-band electron linac was established at Kyoto University Research Reactor Institute (KURRI) [1-3]. This CTR
light source developed has been applied to absorption
spectroscopy. Recently, the possibility of any nonlinear
effects was found in the measurement of the absorption
spectroscopy at KURRI.
The important application of the light source is the investigation of the biological effects of the CTR. The main
purpose of the present work is the investigation of thebiological effects of the high-intensity pulsed CTR.
EXPERIMENTAL METHOD: The electron linac at
KURRI was used in the experiments. In most experiments the beam energy, macropulse length and the repetition rate are 42 MeV, 47 ns and 60 Hz, respectively. The
experimental configurations for the absorption spectroscopy are schematically shown in Fig. 1. The output CTR
light from a light source chamber was transported out
from the accelerator room. The spectrum of the light after
passing through the sample was measured with a Martin-Puplett type interferometer and a liquid-He-cooledsilicon bolometer. The wavenumber resolution was 0.1
cm-1. The incident light was divided to two parts with thesame light intensity in the interferometer. In this system
the absorption spectroscopy and the irradiation were carried out at the same time.
In the absorption spectroscopy the sample was locatedon the light path between the interferometer and the detector. The thickness of the liquid sample was about 100
m, which was sandwiched with two anhydrous quartz
plates 3 mm thick. The light was focused at a light collimator 8 mm in diameter located before the sample. The
details of the methods for the measurements are described in ref. 2 and 3. The liquid samples used in theexperiments were water, aqueous solutions of NaCl forthe investigation of the basic behaviors of the absorbed
light in the analysis of the biological effects by the irradiation of CTR.
In the irradiation experiments of the CTR several kindsof bacillus, cell and microorganism were used. After theirradiation the physiological activation phenomena were
investigated. The new system for observing the sample

28052

Mirror system

Accelerator

Collimator

Detector

SampleLock-in Amp.

Light Source
Interferometer

Linac trigger

Experimental room

Linac room

Fig. 1. Schematic diagram showing the configurations
for absorption spectroscopy and irradiation experiments using the CTR
RESULTS AND DISCUSSION: The characteristics of
the CTR light source were investigated, and the electron
beam conditions and the experimental configurations
were optimized. The light spectrum was sufficiently stable during the measurements within ±2-3% in a wavenumber range of 4-13 cm-1. The spectrum had a peak at awavenumber of about 7 cm-1. If a band-pass light filter ora grating-type monochromator is used in order to avoid
the influence of the main part of the spectrum around thepeak the wavenumber range would be expanded to 2-35
cm-1, which is determined by the specification of the detector. The intensity of light was estimated to be about
10-7 W/0.1%b.w. and was found to be sufficiently higheven if it becomes 10-6 of the initial one after transmission through the sample due to absorption. The micropulse length of the CTR which corresponds to that of theelectron beam from the linac was evaluated by the interferogram to be about 3 ps. Such a relatively short pulse
length is due to the special bunching process in the optimized operational conditions of the linac. These results
indicate that the peak light intensity in the micropulse isabout 104 W. While the averaged CTR power is sufficiently low to induce thermal effects, the comparatively
high peak power might cause any nonlinear effects.
In the irradiation experiments of CTR to investigate
the biological effects the experimental conditions havebeen optimized. Preliminary results have been obtainedby the CTR irradiation so far.
REFERENCES:[1] T. Takahashi et al., Rev. Sci. Instrum. 69 (1998) 3770.
[2] S. Okuda and T. Takahashi, Infrared Phys. Technol.
51 (2008) 410.
[3] S. Okuda and T. Takahashi, J. Jpn. Soc. Infrared
Science & Technology 25 (2016) 49 (in Japanese).

Spectrum of Amino Acid in the Sub-THz region using Coherent TR
RESULTS: Measured spectra of some kinds of aminoacid, e.g., Phenylalanine, α-Alanine, and Tryptophan, areshown in Figs. 2. Difference between L and D forms has
been observed. The identification of observed absorption
is now in progress.

T. Takahashi
Research Reactor Institute, Kyoto University

REFERENCES:[1] T. Takahashi, et al., KURRI-PR 2015 CO4-7.
[2] T. Takahashi et al., Rev. Sci. Instrum. 69 (1998)
3770.

L-Phenylalanine

D-Phenylalanine
2

TRANSMITTANCE

TRANSMITTANCE

2

1.5

1

0.5

0

0

1.5

1

0.5

0

10
20
-1
WAVENUMBER (cm )02TRANSMITTANCE

TRANSMITTANCE

1.5

1

0.5

0

0

1.5

1

0.5

0

10
20
-1
WAVENUMBER (cm )0L-Tryptophane

10
20
-1
WAVENUMBER (cm )D-Tryptophane

2

2

1.5

1

0.5

0

10
20
-1
WAVENUMBER (cm )L-a-Alanine

D-a-Alanine
2

TRANSMITTANCEINTRODUCTION: In recent years various types ofcoherent radiation emitted from a short bunch of
relativistic electrons have attracted a considerable
attention as a bright light source in the THz-wave andmillimeter wave regions for the spectroscopic purpose.
Coherent transition radiation (CTR), which is emitted
from a boundary between two media, is one of such a
coherent light source. CTR is usually utilized as a
non-polarized light source, because the electric vector oftransition radiation (TR) emitted from a metallic screen isaxially symmetric with respect to the trajectory of anelectron beam. In my previous reports [1] the circularly
polarized CTR using a pair of wire-grid radiators with thedifferent polarization has been developed with a new idea.
The significant point of my new technique is the use of
linearly polarized CTR with the wire-grid radiator. With
this technique the polarization degree is able to becontrolled precisely. Circularly polarized light has been
useful in the circular dichroism spectroscopy. In thisreport spectra of some kinds of amino acid have beenmeasured using linearly polarized CTR.
EXPERIMENTAL PROCEDURES: The experiment
was performed at the coherent radiation beamline [2] at
the L-band linac of the Research Reactor Institute, Kyoto
University. The energy, the width of the macro pulse, andthe repetition rate of the electron beam were 42 MeV, 47
ns, and 60 Hz, respectively. The average current of theelectron beam was 2.3 A. The spectrum of CTR was
measured by a Martin-Puplett type interferometer and a liquid-helium-cooled Si bolometer.
The schematic diagram of the experiment was
shown in Fig.1.

TRANSMITTANCE

CO4-8

1.5

1

0.5

0

0

10
20
-1
WAVENUMBER (cm )

0

10
20
-1
WAVENUMBER (cm )Fig. 2 Spectra of some kinds of amino acid.

Fig. 1 The schematic diagram of the experiment.

28058

CO4-9Complex Structure of Ions Coordinated with Hydrophilic Polymer. 17.
Inner Precipitation of Inorganic Salt as Fillers and Their Dissolution.

A. Kawaguchi and Y. Morimoto
Research Reactor Institute, Kyoto University
INTRODUCTION: We have reported interacted structures between iodine (polyiodide ions, Inm-, m, n: integer,n ≠ 1 ) and polymers.[1] Even if polyiodide ions areprepared as solutes in aqueous solution, they can be diffused into various polymeric matrix, both to hydrophilicpolymers and to hydrophobic ones through easy operation at room temperature. Such preparation is expected
to introduce novel functionality and wide applications topolymeric materials with easy operation.[2]On the other hand, results applied with "inner precipitation" can not be easily controlled in some cases. As one
reason, it is due to spontaneous ionic diffusion from outersolution of free transfer of ions into polymeric environment with restriction on ionic diffusion and due to inner
ionic diffusion under hierarchic structure of polymers anduncertainty of polyiodide ions. Under such complication and diversity, posterior ionic diffusion represented as"secondary doping" of Ag+ ion or other metallic ions is
expected to indicate different scheme of ionic diffusion or
their reaction different from ones in solution.
And, for precipitation or production of AgI, which ishardly soluble inorganic salt in water, it also shows unusual behavior against independent ordinary powder of thesalt.
EXPERIMENTS: Sample preparation for hydrophilicpolymer (PA6, polyamide-6, NylonTM-6, TORAY) andhydrophobic matrix (“SEBS”- elastomer, ARON-KASEI
Co.Ltd.) was mentioned before.[3,4]"Rayfan #1401" in thickness of 0.1mm was used as
non-doped PA6. A strip cut from a PA6 sheet werestretched (x3-4) and was annealed at 210˚C in vacuum.
This strip was doped with I2-KI(aq) (0.2N) at 5˚C for
more than 5days and this process (iodine-doping) was
terminated by rinsing with water. After drying in vacuum at R.T.(25˚C) for 3 weeks, the sample was immersed
in AgNO3(aq) (2M) at R.T. for more than 24hrs.
As hydrophobic materials as matrix, commercial"SEBS"-elastomer, AR-770C and AR-830C were used ashydrophobic matrixes, which are composed of both polystyrene (hard segment) and polyethylene-polybutylene
co-polymer (soft segment). Iodine doping for these hydrophobic matrixes was achieved with I2-KI(aq)/3.0N(for 22 hrs., at R.T.) and secondary doping of Ag+ ion
was done with AgNO3(aq)/0.25M (for 30min., at R.T.).
RESULTS: Iodine (I2) is insoluble to water. Therefore,
for preparation of aqueous solution of I3-, which is thesmallest polyiodide ion, mono-iodide ion (I-) is required

28079

for polyiodide ions tosolve in aqueous solution. On theother hand, prior existence of I- ion produces precipitation of silver iodide (AgI) salt on posterior addition of
Ag+ ion. (Ag+ + I- → AgI↓) In the case of aqueous solution of polyiodide ion or "(1st) iodine-doped" hydrophilicpolymers (for example, I2-KI(aq) or "iodine-doped" PA6or "iodine-doped" PVA, etc.), posterior addition of Ag+
ion forms precipitation of AgI nano-grains; inner diffusion of Ag+ ion ("secondary doping") into "iodine doped"hydrophilic polymers can realize "as-shaped" hybrid
composite where fillers of inorganic salt grains are dispersed in hydrophilic matrixes.[5]However, while independent AgI grains are stable atroom temperature and show very low solubility in water,
AgI precipitates dispersed in polymeric matrixes which
are prepared as "as-shaped" composite are not always
stable nor unchanged. Inner precipitation of AgI grains
in PA6 matrix also shows activity to swelling; dissolutionof the "hardly soluble" salt by water swelling is observedin SANS profiles.[6] And even for as hydrophobic matrix, such as "SEBS"-elastomer, inner dispersion of Ag+
ion and dissolution of AgI or polyiodide ions are also
observed.[7] Generally, there is tendency that excessive"secondary doping" induces dissolution of AgI precipitates.
It is one evidence to indicate that Ag+ ion can be posteriorly diffused into hydrophobic matrixes from aqueous
solution, and that inner precipitation of AgI which temporally formed in the matrixes can be easily dissolved orreleased with advance of "secondary doping". On considering application or functionality on surface of polymeric materials applied with "iodine-doping", suggested
as metallic plating for example, such antinomic process
should be also considered.

REFERENCES:[1] A. Kawaguchi, Polymer, 35, 3797-3798. (1994)[2] patent. JPN-5444559 (2014).
[3] A. Kawaguchi, et.al., KURRI Prog. Rep. 2010,
218-218. (2011)[4] A. Kawaguchi, et.al., KURRI Prog. Rep. 2014,
114-114. (2015)[5] A. Kawaguchi, et.al., Polym. Prep. Jpn., 56, 769-769.
(2007)[6] A. Kawaguchi, et.al., KURRI Prog. Rep. 2002,
20-20. (2003)[7] A. Kawaguchi, Polym. Prep. Jpn., 60, 630-630.
(2011)

Hydrogen Retention on plasma Facing Material Irradiated byHigh Energy Particle BeamResearch Institute for Applied Mechanics, Kyushu
University
1
Hydrogen Isotope Research Center, University of
Toyama2
Research Reactor Institute, Kyoto University
INTRODUCTION: It is of importance to clarify phenomena of implantation, retention, diffusion and permeation of tritium on surface of the armor materials of thefirst wall/blanket and the divertor on fusion device from aviewpoint of precise control of fuel particles, reduction oftritium inventory and safe waste management of materials contaminated with tritium (T). Refractory metals suchas tungsten (W) is potential candidate for an armor of thefirst wall and the divertor plate of the fusion reactor because of its low erosion yield and good thermal properties.
The armor material will be subjected to heavy thermalloads in the steady state or transient mode combined withhigh energy neutron irradiation that will cause serious
material degradation. In addition, high energy runaway
electrons would bombard the armor materials along theequatorial plane in fusion device. It is considered thatthese cause radiation damage and enhance tritium retention. In the present works, T exposure experiments havebeen carried out on W samples which were irradiated byhigh energy electrons using LINAC in KURRI of Research Reactor Institute, Kyoto University to investigate
effects of high energy electrons irradiation and microstructure on tritium retention of W. In this fiscal year,
pure W and recrystallized W were irradiated by high energy electron beam. After that, positron annihilation experiment was carried out to identify the radiation defect.
In addition, tritium exposure experiments have been carried out using a tritium (T) exposure device.
EXPERIMENTS: W samples used were ITER grade
W (IG-W) and recrystallized W. In the case of IG-W, one
was W sample (ITER grade W(1)) which the surface
were manufactured to be oriented parallel to the rollingsurface and rolling direction. The other W sample (ITER
grade W(3)) which the surface were manufactured to beoriented perpendicular to the rolling surface and rolling
direction. On the other hand, heat treatment was performed at 1800 oC for 1h at high vacuum to recrystallize
IG-W. The sizes of W samples were 10mm x 10mm x
1mm. The surface of the both samples were polished tobe mirrored． High energy electrons irradiation has been
carried out using LINAC in KURRI of Research Reactor
Institute, Kyoto University. An energy of electron irradiated was 10 MeV and DPA was 2.8 x 10-3. Temperatureduring the irradiation was measured by thermocouples
which was contacted with a backside of the W samples.
After the electron beam irradiation, positron annihilation

28082

experiment was carried out. In addition, T exposure experiments have been carried out using a T exposure device in University of Toyama. Pressure of the T gas was
1.3 kPa and T exposure was kept for 4 h. T concentrationin the gas was about 5 %. Temperatures of pre-heating
and T exposures were 100 oC. After the exposure to T gas,
T amount retained in surface layers of the sample was
evaluated by β-ray-induced X-ray spectrometry (BIXS)
and imaging plate (IP) measurements.
RESULTS: As shown in Fig. 1, there is little difference
between results from W(1) and W(3). On the other hand,
after the recrystallization, lifetime from defect (τ2) increased and intensity of I2 decreased. This result indicatesthat defects of the small number with large clusters wereformed by the recrystallization. The electron irradiation
made life time of τ2 small. In addition, intensity of I2
increased. These indicate that small defects were induced
and concentration of the defects increased both of pure W
and recrystallized W by the electron irradiation. T exposure experiments have been carried out and impact on theelectron beam irradiation of T retention is under investigation.

500
Positron lifetime (ps)K. Tokunaga, M. Matsuyama1, K. Araki, M. Hasegawa,K. Nakamura and Q. Xu2

400

t-mean
τ1
τ2

(a)

300
200
100
0

W(1)

W(3)

W_an

W_e_irr W_an_e_irr

10080Intensity, I2(%)

CO4-10

I2

(b)

60
40
20
0

W(1)

W(3)

W_an W_e_irr W_an_irr

Fig. 1. Positron life time(a) and intensity of I2 (b).
W_an is the sample which was recrystallized.
W_e_irr and W_an_ii are electron irradiated samplesof pure W and recrystallized W, respectively.

CO4-11 Presence of Diluted High-valence Fe and Sn Ions in Layered Rock-salt Structure
M. Tabuchi and Y. Kobayashi1
National Institute of Advanced Industrial Science andTechnology (AIST)
1
Research Reactor Institute, Kyoto University
INTRODUCTION: Although the Fe ion in iron oxides
has 2+ and/or 3+ states, tetravalent and pentavalent Fe
ion can be stabilized in Perovskite structure. Tabuchi et al.
found tetravalent Fe ion in LiFeO2-Li2MnO3 solid solution with layered rock-salt structure (R-3m) at 15 years
ago [1] using 57Fe Mössbauer spectroscopy. He detectalso pentavalent Fe ion in the solid solution below 10K[2]. Through long-term efforts to brush-up synthetic
method, this material is now attractive one as
high-capacity positive electrode material [3, 4].
In this work, 0.2LiFeO2-0.8Li2MnO3 solid solution
was selected using different synthetic procedure. We
succeeded to find hexavalent iron by low-temperature
57
Fe Mössbauer measurements. Although the hexavalentiron can be stabilized at only tetrahedral site, X-ray
Rietveld analysis was done.
EXPERIMENTS: The 0.2LiFeO2-0.8Li2MnO3 sample
was prepared by coprecipitation-calcination method.
Fe(NO3)3 ·9H2O and MnCl2 ·4H2O reagents dissolved
with distilled water. The Fe-Mn aq. soln. (Fe:Mn molar
ratio=2:8) was dripped into NaOH solution at 20 °C for
2-3 h. The Fe-Mn coprecipitate was oxidized by bubblingwith oxygen for 2 days. After washing and filtration, aged
Fe-Mn coprecipitate was dispersed into LiOH soln.
(Li/(Fe+Mn)=2.00). The slurry was dried at 50 °C for 2days and then the dried mixture was pulverized for calcination. The mixture was firstly calcined at 500°C for 20h
under O2 flow and then fired at 700 or 750 °C for 20h in
O2 or N2 flow. All products were washed with distilledwater, filtered and dried at 100 °C for above characterization.
RESULTS: Fig. 1 shows 57Fe Mössbauer spectra at 3 K
for two samples calcined at different temperature in O2
flow. The spectra were analyzed by same fitting model:
three sextets and one symmetric doublet with different
isomer shifts (IS). A sextet with the largest internal field(Hi=45-46 T) is assigned as high-spin trivalent iron because of its IS value (+0.42-+0.43 mm/s). Other two sextets have almost the same IS value (+0.20-+0.21 mm/s)
and different Hi values (12 and 22T). These parametersindicated that tetravalent irons with two kinds of local
structure existed. The origin is still unknown. Surprisingly, the IS value for the doublet (IS=-0.73 mm/s) was quite
small, which can be assigned as hexavalent iron like
BaFeO4. To the best of our knowledge, this is the firsttime to detect hexavalent Fe in complex oxides. Since thehexavalent iron can be stabilized at tetrahedral site, careful X-ray Rietveld analysis was performed.
The analysis showed that transition metals existed not
only typical four octahedral 4g, 2b, 2c and 4h sites but

28084

also tetrahedral 8j one (5-7 % in occupancy) in monoclinic layered rock-salt structure (C2/m). As shown in Fig.
2, the M8jO4 tetrahedron adjacent to M4gO6 octahedron
was highly distorted; they consisted of three short M8j-O
distances and one long M8j-O one. In addition to theabove analysis, low-temperature XRD data have to betaken, because the hexavalent iron cannot be detected at
300 K.
After finishing the above analysis, Sn doped samples
will be prepared, because tin doped sample is attractive toimprove the electrochemical cycle performance.

Fig. 1 57Fe Mössbauer spectra at 3 K for two samples
calcined at 700 (upper) or 750 ºC (lower part) in O2
flow.

Fig. 2 Applied cation distribution model for X-ray
Rietveld analysis. Gray circles correspond to cation on
tetrahedral 8j site.
REFERENCES:[1] M. Tabuchi et al., J. Electrochem. Soc., 149 (2002)
A509-A524.
[2] M. Tabuchi et al., J. Appl. Phys., 104 (2008)
043909-1-10.
[3] M. Tabuchi et al., J. Power Sources, 318 (2016)18-25.
[4] M. Tabuchi et al., J. Power Sources, 195 (2010)
834-844.