Structure and thermal stability of δ-Bi₂O₃thin films deposited by reactive sputtering

Abstract

Nanocrystalline δ-Bi2O3 thin films have been deposited onto Si (100) and quartz substrates by reactive sputtering. The structural characteristics and thermal stability of the thin films have been investigated by x-ray diffraction and Raman spectra. It was found that the δ-Bi2O3 thin films could exist stably below 200 °C and undergo a phase transition sequence δ → β → α with increasing annealing temperature beyond 200 °C. These phase transitions were further confirmed by optical constant and optical band gap studies.

Comparative study on photocatalytic performances of crystalline α- and β-Bi2O3 nanoparticles under visible light

“…The frequency peaks at 142 and 158 cm À1 , as shown in Fig. 2B, are associated obviously with the Raman spectrum of b-Bi 2 O 3 similar to the data reported by Fan et al [44]. The other Raman shifts at 210, 386, and 632 cm À1 in Fig.…”

“…The other Raman shifts at 210, 386, and 632 cm À1 in Fig. 2B are approximately similar to the Raman data: 218, 365, and 631 cm À1 [44]. The peak at 1042 cm À1 , which is shown in Fig.…”

Laser irradiation-induced α to δ phase transformation in Bi2O3 ceramics and nanowires

“…Moreover, the size of the laser spot is much smaller than the size of the polycrystalline samples, which is not the case for the irradiated nanowires. This may explain the occasional appearance of a Raman peak at about 656 cm À1 only in spectra from irradiated ceramics, in agreement with Raman observations reported by Fan et al 18 in annealed d-Bi 2 O 3 . These authors tentatively attributed a Raman peak centered at 655 cm À1 to the metastable c-Bi 2 O 3 phase by comparison of XRD and Raman measurements.…”

“…Raman spectra of the dBi 2 O 3 phase usually show a wide and asymmetric band centered between 610 and 640 cm À1 . 7,8,18,19 In the present case, the band characteristic of the d phase appears centered between 619 and 625 cm À1 in Raman spectra of the nanowires and between 624 and 628 cm À1 in those measured in ceramic samples. d-Bi 2 O 3 may be regarded as an anion deficient fluorite structure, where Bi occupies the fcc sites, having a defect oxygen sublattice the structure of which is still under discussion.…”

Enhanced photoelectrochemical activity of electro-synthesized CdS–Bi2S3 composite films grown with self-designed cross-linked structure

“…Shen et al [27] in an earlier work. There are several other small peaks located on the spectra of composite films, may be ascribed to the trace amount of different oxide phases Bi 2 O 3 [28,29] and CdO present as impurity in the matrices.…”