Synthesis, microstructure, and photoluminescence properties of thornlike SiC:Tb nanostructures

Abstract

Thornlike Tb-doped SiC (SiC:Tb) nanostructures were synthesized through a carbothermal reduction of electrospun Tb-doped SiO 2 nanofibers (SiO 2 :Tb). The synthesized SiC nanostructures annealed at a high temperature of 1300 C displayed a unique morphology and a high crystalline quality with the b-SiC phase. Strong green-light emissions were detected from the SiC:Tb samples. Photoluminescence excitation results show that, besides a small amount of energy coming from the SiC cores (464 nm), most of the energy needed for the excitation of Tb 3þ ions comes from the light absorption of the SiO 2 -Tb surface layers (295 nm) and near-interface regions in the samples (388 nm). Transmission electron microscopy, energy dispersive spectrometry, and Raman analyses suggested that the formations of Tb clusters and SiO 2 surface layers are very important to the enhancement of the luminescence behaviors of Tb 3þ ions. Finally, we have constructed an excitation model and further proposed an energy transfer mechanism for these thornlike SiC:Tb nanostructures.

Microstructural and photoluminescent properties of terbium-doped SiC nanotubes prepared by sputtering using electrospun polymer templates

“…From the above XRD results, it can be seen that the a-SiC gradually transforms into a crystalline one via a high-temperature annealing. Referred to the previous results [17], the Tb 3 þ ions will be forced out of SiC nanotubes to their surface due to their large ionic diameter. When a certain amount of Tb 3 þ ions are separated out from the tube walls, they can usually cluster together, react with Si, and form many SiTb x nanoclusters on the surface of the tubes, which can work not only as the luminescence centers but also the energy absorbers.…”

“…Recently, Zhou et al [16] studied the PL properties of SiC nanotube prepared by electrospun polymer templates, and found that the PL performances have greatly improved due to their high surface defect states. And from the previous results, RE doping into nanoscale semiconductors can greatly improve their PL performances [17,18], which will have potential applications in light emitting diodes or diode lasers. Therefore, it is important and instructive to study RE doped SiC nanostructures and further explore the energy transfer mechanism.…”

“…The 500 1C annealed samples exhibit a blue-green broad band overlapping the whole [8,14,26], and the low 456-nm PL peak can be attributed to a-SiC in the sputtered films [27]. Four characteristic PL peaks of Tb 3 þ ions are located at $ 493, 549, 592, and 617 nm, which correspond to their intra-4f 5 D 4 -7 F 6 , 5 D 4 -7 F 5 , 5 D 4 -7 F 4 , and 5 D 4 -7 F 3 transitions, respectively [17,28]. From the above results, it is clear that much energy has been captured by the Si-C-O related defects, which exhibit a light emission centered at $ 430 nm.…”

“…From the enlarged TEM image shown in Fig. 4(c) and (d), it is seen that many SiTb x nanoclusters are formed on the surface of the tubes [17]. And the outer diameter of the nanotubes is about 200-300 nm, the wall thickness increases up to about 100 nm, which may be caused by the catalytic growth of SiC nanocrystals by Tb elements.…”

Tunable white light emission by variation of composition and defects of electrospun Al2O3–SiO2 nanofibers

“…The PLE spectrum monitored at 420 nm is a broad absorbance band centered at around 346 nm, while the PLE spectrum monitored at 520 nm shows a 275 nm absorption peak (4.51 eV), together with a broad shoulder around 300–400 nm. According to the previous results, the 275 nm absorption peak might be attributed to the absorption of mullite components formed in the samples [ 38 ], and the broad band around 300–400 nm to the absorption by the near-interface regions between the SiO 2 and mullite crystals [ 39 ]. Moreover, the 550 nm emission has a similar PLE spectrum to that of the 610 nm, indicating a similar origin of the light absorbance.…”