A TEM of defect ordering in a calcium yttrium sulfide solid solution with an average NaCl-type structure

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1006/jssc.1994.1229· OSTI ID:508655

Withers, R L; Thompson, J G ^[1]; Otero-Diaz, L C ^[2]

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1. Australian National Univ., Canberra (Australia)
2. Universidad Complutense, Madrid (Spain)

A detailed transmission electron microscope and powder X-ray diffraction study has been made of Ca{sub 5}Y{sub 4}S{sub 11}, which is one limiting composition of the widely substoichiometric, NaCl-related, solid solution (1 - x)CaS + (x) Y{sub 2}S{sub 3}, 0 {le} x {le} 2/7, in the CaS-Y{sub 2}S{sub 3} system. Long-range vacancy ordering and associated structural relaxation characterized by the modulation wave vector q = {1/2}(111)* is shown to lower the space group symmetry from cubic to rhombohedral. Twinning between rhombohedral domains and antiphase boundaries within a particular rhombohedral domain are observed as well as spectacular diffuse intensity distribution which shows many similarities but also significant differences to that previously reported in substoichiometric transition metal carbides and nitrides.

• OSTI ID: 508655
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 2 Vol. 111; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
CALCIUM COMPOUNDS
CUBIC LATTICES
OXIDES
SOLID SOLUTIONS
STOICHIOMETRY
SULFIDES
TRANSMISSION ELECTRON MICROSCOPY
TRIGONAL LATTICES
VACANCIES
X-RAY DIFFRACTION
YTTRIUM COMPOUNDS