Raman and IR spectra of K₄Nb₆O₁₇and K₄Nb₆O₁₇·3H₂O single crystals

Abstract

Polarised Raman and IR spectra of K 4 Nb 6 O 17 and K 4 Nb 6 O 17 · 3H 2 O single crystals were measured. The obtained spectra are discussed using the factor group approach for the orthorhombic P2 1 nb space group and assignment of bands to the respective motions of atoms is proposed. In particular, we have shown that the bands above 770 cm −1 can be attributed to the stretching modes of short niobium-oxygen bonds, which are present in this material due to the pronounced layered structure, whereas the potassium atoms contribute to the bands observed below 180 cm −1 . Our studies have revealed that intercalation of water molecules leads to shifts, broadening and changes in intensity of some bands. These changes have been attributed to slight changes in the bond lengths and angles, interactions of the water molecules with K atoms and structural disorder introduced by the intercalated water molecules. However, the main structural framework was preserved.

Exploring optoelectronic properties and mechanisms of layered ferroelectric K4Nb6O17 nanocrystalline films and nanolaminas

“…The main reflection bands are marked in the IR spectra, which is in accordance with other studies 46, 48 . For comparison, Raman and IR active modes with the proposed assignments are plotted in Fig.…”

“…Theoretically, KN has an orthorhombic structure with space group P 2 1 nb . The unit cell contains four formulas that have 324 zone-centre degrees of freedom described by the irreducible representation 81 A 1  + 81 A 2  + 81 B 1  + 81 B 2 46 . The NbO 6 octahedra mainly gives rise to the stretching and bending vibrations modes.…”

“…The research results described in our work are in good agreement with the report by M. Maczka et al . 46 .

Figure 4( a ) Raman spectra of KN-Pt and KN-NL. The insets show the schematic illustrations of bending and stretching vibrational modes of NbO 6 octahedra.

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Growth of potassium niobate micro-hexagonal tablets with monoclinic phase and its excellent piezoelectric property

“…3 that the main Raman peaks are observed at 226, 283, 542, 837, and 900 cm À 1 . According to the results of previous studies on niobates materials [23][24], 226 cm À 1 can be assigned of the Nb-O framework. 283 cm À 1 can be associated with the deformation in the NbO 6 framework.…”

Selective Synthesis of Silver Nanoparticles onto Potassium Hexaniobate: Structural Organisation with Bactericidal Properties

“…(1)] produces a white powder (Figure 1 A), which is commonly referred to as potassium hexaniobate (K 4 Nb 6 O 17 ). [28] 2 K 2 CO 3ðsÞ þ 3 Nb 2 O 5ðsÞ ! K 4 Nb 6 O 17ðsÞ þ CO 2ðgÞ ð1Þ…”