The preparation, structure, and conductivity of scandium-substituted NASICONs

Journal Article · Thu Nov 14 23:00:00 EST 1985 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(85)90109-4· OSTI ID:5954961

Subramanian, M A; Clearfield, A; Rudolf, P R

A series of NASICON type compounds was prepared in which Sc(III) partially replaced Zr(IV). By simultaneously correlating the extent of this substitution with the amount of Si(IV) replacement o P(V) it was possible to obtain a series with a constant amount (3 mole) of sodium ion. All of the rhombohedral members of this series exhibited similar conductivities and activation energies over the temperature range 30-350/sup 0/C. Transformation to the monoclinic phase occurred at a composition of Na/sub 3/ Sc /SUB 0.5/ Zr /SUB 1.5/ Si /SUB 1.5/ P /SUB 1.5/ O/sub 12/ and was accompanied by a threefold increase in conductivity. Activation energies of the monoclinic (room temperature) phases in the temperature range 200-300/sup 0/C were 0.2-0.23 eV. Crystal structures of the rhombohedral phase of composition Na/sub 3/ScZrSiP/sub 2/O/sub 12/ and the monoclinic phase, Na/sub 3/ Sc /SUB 0.5/ Zr /SUB 1.5/ Si /SUB 1.5/ P /SUB 1.5/ O/sub 12/, were carried out by Rietveld refinement of their X-ray powder patterns. The structures confirmed those presented by Hong, and also confirmed the stoichiometry of these phases as evidenced from site occupancy refinement. These results were compared with the structure of a nonstoichiometric phase, Na /SUB 3.20/ Zr /SUB 1.68/ Si /SUB 1.84/ P /SUB 1.16/ O /SUB 11.54/ , prepared by hydrothermal route. In the latter case it was shown that the low Zr content is due to Na/sup +/ substitution for Zr/sup 4 +/. No such substitution occurred in the scandium containing phases, and it is suggested that when Sc/sup 3 +/ substitution for zirconium takes place it prevents the sodium ion from occupying these sites.

• Research Organization: Department of Chemistry, Texas AandM University, College Station, Texas
• OSTI ID: 5954961
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 60:2; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACTIVATION ENERGY
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ENERGY
HYDROTHERMAL SYNTHESIS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHOSPHORUS COMPOUNDS
PHOSPHORUS OXIDES
PHYSICAL PROPERTIES
SCANDIUM COMPOUNDS
SCANDIUM OXIDES
SILICON COMPOUNDS
SILICON OXIDES
SODIUM COMPOUNDS
SODIUM OXIDES
STOICHIOMETRY
SYNTHESIS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES