Structure and conductivity of the NASICON analog Na/sub 3/SC/sub 2/(PO/sub 4/)/sub 3/
Neutron and x-ray diffraction data of Na/sub 3/SC/sub 2/(PO/sub 4/)/sub 3/ are presented that show the transition from an ordinary-conducting, high temperature phase to a still higher temperature, superionic conducting phase. There are at least four polymorphic modifications. At room temperature, the refined neutron diffraction data confirm the Cc space group reported by Efremov and Kalinin but with a = 16.0449(24), b = 8.9225(15), c = 9.0656(13)A, ..beta.. = 126.918(21), R/sub weighted pattern/ = 17.5%, and R/sub expected/ = 7%. Between 25/sup 0/C and 64/sup 0/C, a second polymorph appears. The structure is monoclinic but has not yet been refined. At 64/sup 0/C, a third polymorph C appears. It is rhombohedral R3c. Using hexagonal axes, a = 8.9273(2), c = 22.3668A, R/sub wp/ = 6.28% and R/sub e/ = 3.83% at 100/sup 0/C. At 166/sup 0/C, the high temperature polymorph D appears. It is the superconducting phase of NASICON(Sc). It, too, is rhombohedral R3c with a = 8.9274(1), c = 22.5493(6)A, R/sub wp/ = 5.81% and R/sub e/ = 3.87% at 225/sup 0/C. The diffraction data are correlated with ionic conductivity measurements as a function of temperature.
- Research Organization:
- Argonne National Lab., IL (USA); National Measurement Lab. (NBS), Washington, DC (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 6183137
- Report Number(s):
- CONF-820508-8; ON: DE83007670
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPOUNDS
COHERENT SCATTERING
CORRELATIONS
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DATA
DIFFRACTION
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
EXPERIMENTAL DATA
HEXAGONAL LATTICES
HIGH TEMPERATURE
INFORMATION
MEDIUM TEMPERATURE
MONOCLINIC LATTICES
NEUTRON DIFFRACTION
NUMERICAL DATA
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
SCANDIUM COMPOUNDS
SCANDIUM PHOSPHATES
SCATTERING
SODIUM COMPOUNDS
SODIUM PHOSPHATES
TRANSITION ELEMENT COMPOUNDS
X-RAY DIFFRACTION