Synthesis and phonon properties of nanosized Aurivillius phase of Bi₂MoO₆

Abstract

MoO 6 of a platelet shape were synthesized by a mild hydrothermal crystallization process. The effect of particle size on the structure and properties of Bi 2 MoO 6 was studied by X-ray diffraction, transmission electron microscopy, as well as Raman and infrared (IR) spectroscopies. Moreover, temperature-dependent Raman spectra were collected for bulk and nanocrystalline Bi 2 MoO 6 . These studies showed that the thickness of the smallest crystallites is about 8-11 nm. Raman and IR studies have revealed that the damping and the intensity of Raman and IR bands are significantly modified with decreasing particle size and temperature. Moreover, some bands experience significant shifts both towards lower and higher wavenumbers. The obtained results indicate that, similar to the isostructural Bi 2 WO 6 , the orthorhombic distortion decreases with decreasing particle size. However, the structure of nanocrystalline Bi 2 MoO 6 remains orthorhombic and noncentrosymmetric, and the structural changes are not the same as those observed in Bi 2 WO 6 .

Hydrothermal Synthesis, Characterization, and Optical Properties of Ce Doped Bi2MoO6 Nanoplates

“…The band at 841 cm −1 was assigned as the A 2 symmetric and asymmetric stretching vibrations of the MoO 6 octahedrons, relating to the motion of the apical oxygen atoms normal to the layers. When the Ce was doped into the samples, the strong bands at 792 cm −1 and two shoulder peaks at 715 and 840 cm −1 also slightly shifted to 713, 791, and 838 cm −1 , confirming an effective substitution of Bi 3+ ions by Ce 3+ ions in the as-prepared nanocrystals, as also revealed by the XRD analysis [23][24][25][26]. FTIR spectra of the samples (Figure 6) show the band in the 400-900 cm −1 range, corresponding to Bi-O stretching and bending, Mo-O stretching, and Mo-O-Mo bridging stretching modes of Bi 2 MoO 6 .…”

“…Additional weak spin-orbit doublet peaks with binding energy of 157.92 eV for Bi 4f 7/2 and 163.40 eV for Bi 4f 5/2 are also detected, suggesting that some of bismuth exist as the (+3 − ) valence state [16]. Probably, the Bi (+3− ) formal oxidation state could be attributed to the substoichiometric phase within the microsized plates [16] [23][24][25].…”

Recent advances in linear and nonlinear Raman spectroscopy. Part V

“…Nanosized crystallites Bi 2 MoO 6 of a platelet shape were synthesized by Maczka et al . by a mild hydrothermal crystallization process . The effect of particle size on the structure and properties of Bi 2 MoO 6 was studied by XRD, TEM, as well as Raman and IR spectroscopies.…”

One-dimensional Bi2MoO6 nanotubes: controllable synthesis by electrospinning and enhanced simulated sunlight photocatalytic degradation performances

“…The peak at 803 cm -1 (A 1g mode) could be assigned to the symmetric stretch of a MoO 6 octahedron, while the peaks at 714 and 839 cm -1 (A 2u mode) showed the characteristics of orthorhombic distortions of the MoO 6 octahedron in Bi 2 MoO 6 with Aurivillius structure of layered slabs (Bi 2 O 2 2? ) connected through the corner sharing of distorted MoO 6 octahedra (Maczka et al 2010;Gruar et al 2010). The bands below 400 cm -1 were originated from the bending modes of the MoO 6 octahedra coupled with stretching and bending modes of the Bi-O polyhedra (Miao et al 2013).…”