TY - JOUR
T1 - Origin of the mixed alkali effect in silicate glass
AU - Onodera, Yohei
AU - Takimoto, Yasuyuki
AU - Hijiya, Hiroyuki
AU - Taniguchi, Taketoshi
AU - Urata, Shingo
AU - Inaba, Seiji
AU - Fujita, Sanae
AU - Obayashi, Ippei
AU - Hiraoka, Yasuaki
AU - Kohara, Shinji
N1 - Funding Information:
This work was partially supported by JST-PRESTO ‘Advanced Materials Informatics through Comprehensive Integration among Theoretical, Experimental, Computational and Data-Centric Sciences’, Japan Grant Number JPMJPR15N4 (to S.K.); the ‘Materials Research by Information Integration’ Initiative (MI2I) project of the Support Program for Starting Up Innovation Hub from JST (To Y.O., S.K., and Y. H.); JST CREST 15656429 (to Y.H.); and JSPS KAKENHI Grant Number JP19K05648 (to Y.O.). The synchrotron radiation experiments were performed at BL04B2 of SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI; Proposal Nos. 2016A1499 and 2017B0134). The neutron experiment at the Materials and Life Science Experimental Facility of the J-PARC was performed under a user program (Proposal No. 2017A0146). We acknowledge Dr. Toshiya Otomo and Dr. Kazutaka Ikeda for their help in the neutron diffraction measurement using the spectrometer NOVA at J-PARC. Dr. Hirokazu Masai is gratefully appreciated for helpful discussions.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Abstract: Silicate glasses have evolved from basic structural materials to enabling materials for advanced applications. In this article, we unravel the origin of the mixed alkali effect for alkali silicate 22.7R2O–77.3SiO2 glasses (R = Na and/or K) by identifying the variation in the alkali ion location around the non-bridging oxygen atoms. To do so, we constructed a state-of-the art structural model, which reproduces both diffraction and NMR data with a particular focus on the behavior of the alkali ions. A novel topological analysis using persistent homology found that sodium-potassium silicate glass shows a significant reduction in large cavities as a result of the mixed alkali effect. Furthermore, a highly correlated pair arrangement between sodium and potassium ions around non-bridging oxygen atoms was identified. The potassium ions can be trapped in K–O polyhedra due to the increased bridging oxygen coordination; therefore, the correlated pair arrangement is likely the intrinsic origin of the mixed alkali effect.
AB - Abstract: Silicate glasses have evolved from basic structural materials to enabling materials for advanced applications. In this article, we unravel the origin of the mixed alkali effect for alkali silicate 22.7R2O–77.3SiO2 glasses (R = Na and/or K) by identifying the variation in the alkali ion location around the non-bridging oxygen atoms. To do so, we constructed a state-of-the art structural model, which reproduces both diffraction and NMR data with a particular focus on the behavior of the alkali ions. A novel topological analysis using persistent homology found that sodium-potassium silicate glass shows a significant reduction in large cavities as a result of the mixed alkali effect. Furthermore, a highly correlated pair arrangement between sodium and potassium ions around non-bridging oxygen atoms was identified. The potassium ions can be trapped in K–O polyhedra due to the increased bridging oxygen coordination; therefore, the correlated pair arrangement is likely the intrinsic origin of the mixed alkali effect.
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U2 - 10.1038/s41427-019-0180-4
DO - 10.1038/s41427-019-0180-4
M3 - Article
AN - SCOPUS:85076165688
SN - 1884-4049
VL - 11
JO - NPG Asia Materials
JF - NPG Asia Materials
IS - 1
M1 - 75
ER -