A TIME OF FLIGHT NEUTRON POWDER RIETVELD REFINEMENT STUDY AT ELEVATED-TEMPERATURE ON A MONOCLINIC NEAR-STOICHIOMETRIC NASICON
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Time of flight neutron powder data were collected at elevated temperatures on a sample of NASICON of composition Na3.17Zr1.93Si1.9P1.1O12. This sample, prepared by reheating a commerically available NASICON to minimize the ZrO2 impurity, has been previously structurally refined from room temperature neutron diffraction data collected at Argonne National Laboratory. Conductivity measurements show a cusp at ca. 170C attributed to the monoclinic-rhombohedral transition and the purpose of this work was to explore the nature of the transition. Data runs were made at 143, 173, 202, 300, and 391C. No evidence for a crystal system change was found. The highest temperature data sets could not be refined satisfactorily by the Rietveld method using a rhombohedral model, but rather required a monoclinic cell in space group C2 c to achieve convergence. An explanation for the conductivity cusp is given in terms of a disordering of the sodium ions and a change in conduction pathways which lowers the barriers to ion movement. 1988.
JOURNAL OF SOLID STATE CHEMISTRY
author list (cited authors)
RUDOLF, P. R., CLEARFIELD, A., & JORGENSEN, J. D.
complete list of authors
RUDOLF, PR||CLEARFIELD, A||JORGENSEN, JD