Excitation spectra of GdNb04: 0.2 Eu3 + and GdNbO4: 0.2 Eu3 + 0.03Bi3 + phosphors. Spectra of wavelength less than 357 nm belong to NB. ←_ + 02- and Eu3. →02-charge transfer band (CTB). Compared with the phosphors without Bi, when Bi and EU are present in gan bO, the excitation spectra of CTB in the matrix are widened. The existing literatures show that in CdNbO4: Eutnta-Bi lattice, there is a charge transfer transition in the region of 300-360nm wavelength (Bi-Nb 6s-4d), which leads to the emission of charge transfer.
Status. Bi+ absorbs ultraviolet light and NB to 0 °charge migration, which makes the ultraviolet band wider peak. In addition, some characteristic transitions of EU are also found in the excitation spectra, such as the results of electron migration at 395m.
The transition intensity of UV is decreased, which indicates that the addition of Bi is beneficial to the electromigration band of phosphors, which is relatively unfavorable to the f-f transition of EU, so the excitation peak of UV excitation wavelength of phosphors becomes wider and the peak intensity increases. However, it is shown that Bi is beneficial to the substrate in absorbing more energy, and the synthesized phosphors can be excited by two kinds of LED chips, near ultraviolet light and blue light.
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In order to analyze the influence of Bi on the emission spectrum and emission intensity of phosphor, the emission spectra of different Bi contents excited by 395 nm near ultraviolet light are shown in figure 7-7. Bi. ↑The content has little effect on the peak position and the shape of emission peak. From the illustrations in Fig. 7-7, it can be seen that the luminescence intensity of the phosphor with Bi content of Imol% is lower than that of the phosphor with Bi content of 2 μ mol%, which is higher than that of the GdNbO4: Eu' phosphor without the addition of Bi, and with the increase of the concentration of Bi, the luminescence intensity of the phosphor is higher than that of the GdNbO4: Eu' phosphor. The luminescence intensity of the phosphor increased, and when the concentration of Bi was 3 mol%, the luminescence intensity reached the maximum and then decreased. This can be attributed to the existence of too much B around the luminescent ion EU, which increases the probability of radiation-free transition, which leads to the concentration quenching. Therefore, the optimum Bi doping concentration is 3mol / cm, and the emission intensity at 612nm is almost twice that of GdNbO.EU3 + phosphors, which indicates that Bi'plays a good role in sensitizing EU.
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