THE CRYSTAL-STRUCTURE OF A NONSTOICHIOMETRIC NASICON
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The crystal structure of a nonstoichiometric NASICON prepared from a hydrothermally synthesized precursor phase was solved by means of X-ray powder and neutron powder diffraction methods. The NASICON phase is monoclinic with unit cell parameters, from Rietveld refinement of the neutron data, of a = 15.6209(8), b = 9.0326(5), c = 9.2172(5) A , = 123.67(1), V = 1082.5 A 3. The space group is C2/c with Z = 4. The structure is essentially that proposed earlier by Hong, but the nonstoichiometry results from replacement of part of the Zr4+ by Na+. Refinement of site occupancies coupled with the requirement of overall charge balance yields the formula Na2.88(Na0.32Zr1.68)Si1.84P1.16O11.54 which also agrees well with analytical data. Only 20% of the Na1 sites are occupied, but 80% of the Na3 sites are filled. This structure provides a framework from which to rationalize the many reports in the literature that NASICON can only be prepared with difficulty by high temperature solid state reactions. 1985.
MATERIALS RESEARCH BULLETIN
author list (cited authors)
RUDOLF, P. R., SUBRAMANIAN, M. A., CLEARFIELD, A., & JORGENSEN, J. D.
complete list of authors
RUDOLF, PR||SUBRAMANIAN, MA||CLEARFIELD, A||JORGENSEN, JD