ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Single crystals of the nitridosilicate Ca0.27La0.03Si11.38Al0.62N16 with a filled α-Si3N4-type structure were obtained when preparing lanthanum nitridosilicates in a graphite furnace accidentally containing calcium residues. The lithium α-SiAlON LiSi9Al3O2N14 was prepared using spark plasma sintering, with the sample containing in addition a β-SiAlON, LiAlSiO4, and a glass phase. The structure of Ca0.27La0.03Si11.38Al0.62N16 was refined using MoKα single-crystal data, in space group P31c with a= 7.838(1), c= 5.703(1) Å, V= 303.4 Å3, to a weighted R(Fobs2) = 6.0% for 475 unique reflections. The isotypic structure of LiSi9Al3O2N14 was refined with anisotropic thermal parameters and a= 7.8277(2), c= 5.6909(2) Å to RF= 0.63% for 849 reflections for d≥ 0.5 Å using time-of-flight (TOF) neutron powder diffraction (NPD) data. The SiX4 (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 2b 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.2003.tb03364.x
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