Effect of oxygen vacancies on the red emission of SrTiO3:Pr3+ phosphor films

Abstract

The red emission of the Pr3+ ions was very sensitive to the oxygen vacancies in the host of 300-nm-thick SrTiO3 films. Comparing with the air-annealed films, a significant enhancement of up to 400% was observed in the red photoluminescence intensity for the vacuum-annealed samples, and the valence state of the Pr ions was found to be changed little. Based on the fact of the obvious overlap between the excitation band of the Pr3+ ions and emission band of the oxygen vacancies, it was suggested that the oxygen vacancies act as a sensitizer for the effective energy transfer from SrTiO3 host to Pr3+ ions. This study demonstrated that the red emission from Pr3+ ions in SrTiO3 was closely related to the oxygen vacancies.

Large enhancement of photoluminescence in SrTiO3:Pr3+ powders by fluorhydric acid treatment

“…However, no significant changes were found in the red emission intensity between the as-prepared and the HF-treated CaTiO 3 samples. This result is totally the same as that found in vacuum-annealed Pr 3 + doped SrTiO 3 and CaTiO 3 films, where the increase of red PL was presented in STO instead of Pr 3 + doped CaTiO 3 [11]. Based on the above analysis, we believe that the effect of HF treatment on the PL of STO powders has the same mechanism with that of vacuum-annealing, that is, the oxygen vacancies play the essential role in enhancing the red emission.…”

“…It can be seen that the PL intensity at about 614 nm for the vacuumannealed sample increases nearly three times, compared with that of the as-prepared one. This result is close to that observed in the STO films where an enhancement of four times was obtained after the films were vacuum-annealed [11]. However, such enhancement is obviously less than the one (18 times) observed in the HF-STO sample, manifesting that HF etching is more effective to improve the red PL intensity than vacuum-annealing for the sol-gel-made STO powders.…”

“…Similar to the case of the film [11], the enhanced red emission has also been found in STO powders by vacuum-annealing. Fig.…”

“…It was also proposed that such defect level can be formed due to the formation of oxygen vacancies [10]. In our recent study, the effect of oxygen vacancies on the red emission of the Pr 3 + ions in SrTiO 3 film was checked directly through subjecting the film into vacuum for annealing [11]. Comparing with the air-annealed films, a significant enhancement of the red PL intensity up to 400% was observed in the vacuumannealed samples, demonstrating that the red emission from Pr 3 + ions to SrTiO 3 was closely related to the oxygen vacancies.…”

Strong green and red up-conversion emission in Ho3+, Yb3+ and Li+ co- or tri-doped SrAl2O4 ceramics

“…The (Ho Sr ) · can be neutralized by the negative charge (Li Sr ) when Li + substitutes for Sr 2+ site. Also, the negative charge (Li Sr ) is deduced to produce oxygen vacancies (V O ) ·· which may facilitate the ET from excited carrier in the SAO lattice to the Ho 3+ [23,24]. Moreover, the Li + ion may diffuse to the interstitial site in the SAO lattice.…”