イルメナイト型LiNbO_3及びNaNbO_3の結晶構造

概要

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Crystal structures of ilmenite type NaNbO_3 and LiNbO_3 which were prepared by low temperature hydrothermal and ion-exchange reactions respectively, were refilled by the X-ray powder Rietveld method. Final R-factors were R_<wp> = 16. 9, R_p = 12 2, R_B = 6.1% for NaNbO_3 and R_<WP> = 13.9, R_P = 11.1, R_B = 5.7% for LiNbO_3. The mean Nb-O distances of both ilmenite type compounds agreed with those of their corresponding stable phases. The mean Na-O distance of the ilmenite type NaNbO_3 was as large as that of the spinel type Na_2WO_4 while, the mean Li-O distance in the ilmenite type LiNbO_3 was slightly larger than that of the LiNbO_3 type LiNbO_3 or other compounds containing Li06 octahedra. Structural refinement of other ilmenite type compounds of MgTiO_3, CdTiO_3, NaSbO_3, NaBiO_3 and KSbO_3 was also carried out by the X-ray powder Rietveld method. Stability field of ilmenite type compounds, ABO_3 was discussed on the basis of volumes of the AO_6 and BO_6 octahedra.
社団法人日本セラミックス協会の論文
1990-04-01