30aB05
セラミックス中におけるトリチウムの拡散と捕捉	 
Tritium diffusion and trapping in various ceramics	 
大矢恭久1、田口僚久1、宮原祐人1、波多野雄治2、原正憲2、松山政夫2、奥野健二1
Yasuhisa Oya1, Tomohisa Taguchi2, Yuto Miyahara3, Yuji Hatano4, Masanori Hara2,Masao Matsuyama1 and Kenji Okuno1
1

静岡大理放射研、2富山大水素研
Shizuoka Univ., 2Univ. of Toyama

1-1

Figure shows D2 TDS spectra for the D2+
implanted SiC, Si3N4 and SiO2 samples. These TDS
specta consisted of four desorption stages at 450 K,650 K, 800 K and 1000 K, attributing to thedesoprtion of deuterium trapped on surface,retained in the interstitial site, trapped as Si-D bondand trapped as C/N/O-bonds, respectively. The
deuterium retentions by surface adsorption andSi-D bond were increased in the orders of
SiO2>Si3N4>SiC and SiC>Si3N4>SiO2, respectively,
showing that the retention of deuterium bound to Si
as Si-D bond was increased with the increase ofcovalent characteristics of the ceramics. The XPS
analyses showed that the positive peak shift of
Si-2p was observed for SiC after deuterium
implantation, indicating the formation of Si-D bondfor covalent ceramics.	  However, the amount ofdeuterium adsorbed on the surface was opposite
trend, leading to the ionic characteristics would
control the deuterium adsorption. It can be said thatelectrostatic interaction with deuterium on thesurface would have a large contribution on theamount of deuterium adsorbed on the surface andthe adsorption on the surface would be major
trapping site of hydrogen isotope for the ionicceramics.
10.0
8.0

Peak 1

Peak 2	 Peak 3

Peak 4

SiC
Si3N4
SiO2

6.0	 

17-2

Desorption rate / 10 D m sCeramics have many advantages for the usage ascomponent materials in fusion devices. One ofcritical issues for the assessment of utilization ofceramics for fusion devices is the evaluation oftritium retention and its trapping characteristics. In
our previous studies, the deuterium retention
behaviors for SiC and SiO2 were studied and it was
found that the deuterium trapping process was quite
different among these samples. However,systematic understanding for hydrogen isotope
retention and trapping behaviors is not enough. The
nature of bond in ceramics, which can be
categorized into covalent bond and ionic bond,would be one of the key parameters for controlling
the retention and desorption behaviors of hydrogenisotope in/from ceramics. In this study, thecorrelation between the hydrogen isotope retention
and desorption behaviors and the nature of bond ofceramics was discussed.
The plate or disk types of SiC, Si3N4 and SiO2
were used as samples. The sizes of plate samples
were 10×10 mm and 0.5 mm thickness for Si3N4,and SiO2, although that for SiC was 10 mmdiameter and 0.5 mm thickness disk. The
differences of electronegativity of constituent
elements for SiC, Si3N4 and SiO2 were 0.7, 1.2 and1.7, respectively. These samples were preheated at1173 K for 1 hour under vacuum with the pressureof less than 10-5 Pa. Then, the 0.2 keV deuteriumion (D2+) implantation and TDS measurement wereperformed to elucidate the deuterium retention anddesorption behaviors. The D+ flux and fluence were
set to be 1.0 × 1017 D+ m-2 s-1 and 1.0 × 1022 D+ m-2,respectively. The TDS measurements were carriedout from room temperature to 1173 K with aheating rate of 0.5 K s-1. In addition, the chemical
states of constituent atoms before and after D2+
implantation were evaluated by XPS to clarify thedeuterium trapping characteristics.

4.02.00.0300

6009001200
Temperature / K
Fig. TDS spectra for each D2+ implanted ceramics