title: The series RE5Li2Sn7 (RE = Ce, Pr, Nd, Sm) revisited: crystal structure of RE5Li2-xSn7+x [0 ≤ x ≤ 0.03 (1)].
abstract: The series of RE5Li2Sn7 (RE = Ce-Sm) compounds were synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. The compounds are pentacerium dilithium heptastannide, Ce5Li1.97Sn7.03, pentapreseodymium dilithium heptastannide, Pr5Li1.98Sn7.02, pentaneodymium dilithium heptastannide, Nd5Li1.99Sn7.01, and pentasamarium dilithium heptastannide, Sm5Li2Sn7. All five compounds crystallize in the chiral orthorhombic space group P212121 (No. 19), which is relatively uncommon among intermetallic phases. The structure belongs to the Ce5Li2Sn7 structure type (Pearson symbol oP56), with 14 unique atoms in the asymmetric unit. Minor compositional variations exist, due to the mixed occupancy of Li and Sn atoms at one of the Li sites. The small occupational disorder is most evident for RE5Li2-xSn7+x (RE = Ce, Pr; x ≃ 0.03), while the structure of Nd5Li2Sn7 and Sm5Li2Sn7 show no apparent disorder.
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Julien P A
authors.initials: JP
authors.lastname: Makongo
authors.affiliation: Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
authors.forename: Svilen
authors.initials: S
authors.lastname: Bobev
keywords: Ce5Li2Sn7 structure type; crystal structure; lithium; polar intermetallic phases