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Structures of Filled α‐Si 3 N 4 ‐Type Ca 0.27 La 0.03 Si 11.38 Al 0.62 N 16 and LiSi 9 Al 3 O 2 N 14
Author(s) -
Grins Jekabs,
Esmaeilzadeh Saeid,
Shen Zhijian
Publication year - 2003
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2003.tb03364.x
Subject(s) - crystallography , spark plasma sintering , lanthanum , crystal structure , lithium (medication) , materials science , neutron diffraction , boron , mineralogy , analytical chemistry (journal) , chemistry , inorganic chemistry , microstructure , medicine , organic chemistry , endocrinology , chromatography
Single crystals of the nitridosilicate Ca 0.27 La 0.03 Si 11.38 Al 0.62 N 16 with a filled α‐Si 3 N 4 ‐type structure were obtained when preparing lanthanum nitridosilicates in a graphite furnace accidentally containing calcium residues. The lithium α‐SiAlON LiSi 9 Al 3 O 2 N 14 was prepared using spark plasma sintering, with the sample containing in addition a β‐SiAlON, LiAlSiO 4 , and a glass phase. The structure of Ca 0.27 La 0.03 Si 11.38 Al 0.62 N 16 was refined using Mo K α single‐crystal data, in space group P 31 c with a = 7.838(1), c = 5.703(1) Å, V = 303.4 Å 3 , to a weighted R ( F obs 2 ) = 6.0% for 475 unique reflections. The isotypic structure of LiSi 9 Al 3 O 2 N 14 was refined with anisotropic thermal parameters and a = 7.8277(2), c = 5.6909(2) Å to R F = 0.63% for 849 reflections for d ≥ 0.5 Å using time‐of‐flight (TOF) neutron powder diffraction (NPD) data. The SiX 4 (X = N or N/O) tetrahedra are regular in both structures, with Si‐N distances of 1.745(1) − 1.785(3) Å for the calcium‐lanthanum compound and 1.741(1) − 1.765(1) Å for the lithium compound. The Ca/La and lithium atoms are located on the 2 b position, (1/3, 2/3, z ), coordinated by seven anions with the shortest metal‐anion distances of 2.38(1) and 2.05(2) Å, respectively. The lithium atoms are displaced ∼0.28 Å relative to the position of the Ca/La atoms, and the lithium atoms can alternatively be described as tetrahedrally coordinated.