Abstract
The structure of Bi5Nb3O15 was investigated by refinement of the powder neutron diffraction pattern as well as by structural change through acid treatment and subsequent treatments of an acid-treated product with n-alkylamines. Rietveld refinement suggests that Bi5Nb3O15 adopts a mixed-layer Aurivillius-related phase structure, [Bi2O2]+[NbO4]+[Bi2O2]+[BiNb2O7] [Pnc2 (space group No. 30)] with a = 2.1011 (4), b = 0.5473 (1) and c = 0.5463 (1) nm. After the acid treatment of Bi5Nb3O15 with 3 mol/L HCl, a new reflection (at 2.25 nm after drying at room temperature or at 1.89 nm after drying at 120 °C) appeared in the X-ray diffraction (XRD) pattern in addition to the reflections due to Bi5Nb3O15. Upon acid treatment, a part of the Bi ions were lost and essentially no Nb ions were dissolved during acid treatment to give a Bi/Nb molar ratio of 1.4. The TG curves of the acid-treated product showed mass loss (ca. 4 mass%) in the range of 300-600 °C. It was also demonstrated that the particle shapes did not change upon acid treatment. The reaction of the acid-treated product (after drying at room temperature) with n-alkylamines led to a shift of the newly appearing reflection to a lower angle, and the d-value of the low-angle reflection increased linearly in accordance with the increment of the number of carbon atoms in n-alkylamines. These results indicate that the [Bi2O2] sheet in Bi5Nb3O15 was partially leached by acid treatment to form a layered compound H4BiNb3O11·xH2O, capable of accommodating n-alkylamines in the interlayer space, and its anhydrous form, H4BiNb3O11, upon drying. Based on the variation in the interlayer distance upon intercalation of n-alkylamines into the acid-treated product, the structure of the acid-treated product can be suggested to comprise alternately stacked protonated [BiNb2O7] and [NbO4] sheets, a result consistent with the Rietveld refinement of Bi5Nb3O15.
Original language | English |
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Pages (from-to) | 2517-2524 |
Number of pages | 8 |
Journal | Journal of Solid State Chemistry |
Volume | 180 |
Issue number | 9 |
DOIs | |
Publication status | Published - 2007 Sep |
Keywords
- Acid treatment
- Aurivillius phase
- Crystal structure
- Intercalation
- Intergrowth
- Ion exchange
- Layered perovskite
- Neutron diffraction
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry