TY - JOUR
T1 - Charge states of Ca atoms in β-dicalcium silicate
AU - Mori, Kazuhiro
AU - Kiyanagi, Ryoji
AU - Yonemura, Masao
AU - Iwase, Kenji
AU - Sato, Takashi
AU - Itoh, Keiji
AU - Sugiyama, Masaaki
AU - Kamiyama, Takashi
AU - Fukunaga, Toshiharu
N1 - Funding Information:
We wish to acknowledge several useful discussions with Dr. K. Oishi of Shimizu Corporation and Prof. M. Kawai of KENS at KEK. Many thanks are given to Dr. J. Fieramosca and Prof. J.W. Richardson of IPNS at ANL for valuable technical supports of TOF-NPD experiments. This work was supported by a Grant-in-Aid for Creative Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan.
PY - 2006/11
Y1 - 2006/11
N2 - In order to study the crystal structure of β - Ca2 SiO4, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600 °C. Rietveld refinement at RT has shown that β - Ca2 SiO4 is monoclinic based on P21/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3 Å were calculated, with the valences of Ca(1) with seven Ca{single bond}O bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen-Brown-Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in β - Ca2 SiO4 are [Ca(1)SiO4]2- and Ca(2)2+, respectively. Furthermore, the [Ca(1)SiO4]2- unit has the shortest Ca-O distance, and its length kept constant at 2.23 Å at all temperatures. In the short-range structure analysis at RT, the shortest Ca-O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO4]2- unit has covalency on the shortest Ca-O in addition to Si-O.
AB - In order to study the crystal structure of β - Ca2 SiO4, time-of-flight neutron powder diffraction experiments were carried out at temperatures between room temperature (RT) and 600 °C. Rietveld refinement at RT has shown that β - Ca2 SiO4 is monoclinic based on P21/n symmetry and two different types of Ca sites, Ca(1) and Ca(2). All interatomic distances within 3 Å were calculated, with the valences of Ca(1) with seven Ca{single bond}O bonds and Ca(2) with eight were estimated to be 1.87+ and 2+ by the Zachariasen-Brown-Altermatt formula (bond valence sum). Applying charge neutrality the two charge states of Ca in β - Ca2 SiO4 are [Ca(1)SiO4]2- and Ca(2)2+, respectively. Furthermore, the [Ca(1)SiO4]2- unit has the shortest Ca-O distance, and its length kept constant at 2.23 Å at all temperatures. In the short-range structure analysis at RT, the shortest Ca-O bond was also observed in a radial distribution function. These results imply that the [Ca(1)SiO4]2- unit has covalency on the shortest Ca-O in addition to Si-O.
KW - Bond valence sum
KW - Crystal structure
KW - Neutron powder diffraction
KW - Radial distribution function
KW - Rietveld analysis
KW - Short-range structure
KW - β - Ca SiO
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U2 - 10.1016/j.jssc.2006.06.018
DO - 10.1016/j.jssc.2006.06.018
M3 - Article
AN - SCOPUS:33748573991
SN - 0022-4596
VL - 179
SP - 3286
EP - 3294
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 11
ER -