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- Title
Crystal chemistry and the role of ionic radius in rare earth tetrasilicates: Ba<sub>2</sub>RE<sub>2</sub>Si<sub>4</sub>O<sub>12</sub>F<sub>2</sub> (RE = Er<sup>3+</sup>-Lu<sup>3+</sup>) and Ba<sub>2</sub>RE<sub>2</sub>Si<sub>4</sub>O<sub>13</sub> (RE = La<sup>3+</sup>-Ho<sup>3+</sup>)
- Authors
Fulle, Kyle; Sanjeewa, Liurukara D.; Mcmillen, Colin D.; Kolis, Joseph W.
- Abstract
Structural variations across a series of barium rare earth (RE) tetrasilicates are studied. Two different formulas are observed, namely those of a new cyclo-silicate fluoride, BaRE2Si4O12F2 (RE = Er3+-Lu3+) and new compounds in the Ba2RE2Si4O13 (RE = La3+-Ho3+) family, covering the whole range of ionic radii for the rare earth ions. The Ba2RE2Si4O13 series is further subdivided into two polymorphs, also showing a dependence on rare earth ionic radius (space group for La3+-Nd3+, and space group C2/ c for Sm3+-Ho3+). Two of the structure types identified are based on dinuclear rare earth units that differ in their crystal chemistries, particularly with respect to the role of fluorine as a structural director. The broad study of rare earth ions provides greater insight into understanding structural variations within silicate frameworks and the nature of f-block incorporation in oxyanion frameworks. The single crystals are grown from high-temperature ( ca 953 K) hydrothermal fluids, demonstrating the versatility of the technique to access new phases containing recalcitrant rare earth oxides, enabling the study of structural trends.
- Subjects
RARE earth oxides; SILICATE minerals; RARE earth fluorides
- Publication
Acta Crystallographica Section B: Structural Science, Crystal Engineering & Materials, 2017, Vol 73, Issue 5, p907
- ISSN
2052-5192
- Publication type
Article
- DOI
10.1107/S2052520617009544