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Targeting Vacancies in Nitridosilicates: Aliovalent Substitution of M 2+ (M=Ca, Sr) by Sc 3+ and U 3+
Author(s) -
Bielec Philipp,
Eisenburger Lucien,
Deubner H. Lars,
Günther Daniel,
Kraus Florian,
Oeckler Oliver,
Schnick Wolfgang
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201812460
Subject(s) - vacancy defect , crystallography , divalent , crystal structure , actinide , chemistry , x ray crystallography , chemical stability , ion exchange , ion , materials science , diffraction , nuclear chemistry , physics , organic chemistry , optics
Based on the known linking options of their fundamental building unit, that is the SiN 4 tetrahedron, nitridosilicates belong to the inorganic compound classes with the greatest structural variability. Although facilitating the discovery of novel Si–N networks, this variability represents a challenge when targeting non‐stoichometric compounds. Meeting this challenge, a strategy for targeted creation of vacancies in highly condensed nitridosilicates by exchanging divalent M 2+ for trivalent M 3+ using the ion exchange approach is reported. As proof of concept, the first Sc and U nitridosilicates were prepared from α‐Ca 2 Si 5 N 8 and Sr 2 Si 5 N 8 . Powder X‐ray diffraction (XRD) and synchrotron single‐crystal XRD showed random vacancy distribution in Sc 0.2 Ca 1.7 Si 5 N 8 , and partial vacancy ordering in U 0.5 x Sr 2−0.75 x Si 5 N 8 with x ≈1.05. The high chemical stability of U nitridosilicates makes them interesting candidates for immobilization of actinides.