Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Alonso, M. C.*; Garc
a Calvo, J. L.*; Pettersson, S.*; Cu
ado, M.*; Vuorio, M.*; Weber, H.*; Ueda, Hiroyoshi*; Naito, Morimasa; Walker, C.
Proceedings of 13th International Congress on the Chemistry of Cement (13th ICCC) (CD-ROM), 7 Pages, 2011/07
Low pH cementitious (LopHC) materials are expected to be used in the construction of an underground repository for the geological disposal of high level radioactive waste (HLW). A fundamental aspect of the development of LopHC is the accurate and reliable measurement of the pore fluid pH in order to qualify and help quantify mix designs to achieve specific pH targets. The main objective of the current research is the development of an agreed protocol for measuring the pH value of LopHC. There are four different methods described in the literature for characterizing the pore solution of cementitious materials: (1) Pore fluid expression; (2) Leaching methods, including both in-situ and ex-situ techniques); (3) Percolation methods; and (4) Embedded pH sensors. In a first step, different parameters that may affect the measured pH values were evaluated, including the solid/liquid ratio, fineness, carbonation, time, and the results obtained from a pH meter in comparison with an OH titration. Based on the results obtained from the first step, selected protocols were proposed and tested for reproducibility and repeatability in 8 laboratories of 7 countries using the same LopHC sample. The proposed methodologies showed very promising results with low deviation and high reproducibility and have allowed the development of an agreed set of simple protocols for the determination of pH in LopHC.
Allelein, H.-J.*; Auvinen, A.*; Ball, J.*; G
ntay, S.*; Herranz, L. E.*; Hidaka, Akihide; Jones, A. V.*; Kissane, M.*; Powers, D.*; Weber, G.*
NEA/CSNI/R(2009)5, 388 Pages, 2009/12
Pensl, G.*; Schmid, F.*; Reshanov, S.*; Weber, H. B.*; Bockstedte, M.*; Mattausch, A.*; Pankratov, O.*; Oshima, Takeshi; Ito, Hisayoshi
Materials Science Forum, 556-557, p.307 - 312, 2007/00
no abstracts in English
Schmid, F.*; Reshanov, S. A.*; Weber, H. B.*; Pensl, G.*; Bockstedte, M.*; Mattausch, A.*; Pankratov, O.*; Oshima, Takeshi; Ito, Hisayoshi
Physical Review B, 74(24), p.245212_1 - 245212_11, 2006/12
Times Cited Count：11 Percentile：47.25(Materials Science, Multidisciplinary)Hexagonal SiC is co-implanted with silicon Si
, carbon C, or neon Ne ions along with nitrogen N ions. Also hexagonal SiC irradiated with electrons e
of 200 keV energy. During the subsequent annealing step at temperatures above 1450 
C a deactivation of N donors and a reduction of the compensation are observed in the case of the Si/N co-implantation and e irradiation. Using Hall measurement, the N donor deactivation is studied as a function of the concentration of the co-implanted species and the annealing temperature. The formation of energetically deep defects is analyzed with deep level transient spectroscopy. A detailed theoretical analysis based on the density functional theory is conducted; it takes into account the kinetic mechanisms for the formation of N interstitial clusters and N-vacancy complexes. In accordance with all the experimental results, this analysis distinctly indicates that the (N
)
-V
complex, which is thermally stable at high temperatures, is responsible for the N donor deactivation.
