Publication Date:
2015-05-20
Description:
Substitution is widely employed to design single-host phosphor with multiple sites for one activator, which could emit more than one band. BaSrMg(PO 4 ) 2 :Eu 2+ was reported as a potential single-host white light-emitting phosphor for white LEDs, possessing multiple sites for Eu 2+ doping. However, different emission spectra were observed in this paper for the sample with same nominal formula. Therefore, XRD and Rietveld refinements were employed to investigate the crystal structure in detail and the results indicated that the sample contains Sr 2 P 2 O 7 coexisting with the main phase BaSrMg(PO 4 ) 2 . Meanwhile, BaSrMg(PO 4 ) 2 phase was identified to be isostructural with Ba 2 Mg(PO 4 ) 2 and was confirmed by TEM. Photoluminescence of the phosphor sintered at 900°C shows two emission bands peaking at 424 and 585 nm. Hence, different from the literature, the blue band was assigned to the 4 f 6 5 d 1 4 f 7 transition of Eu 2+ occupying the Sr 2+ sites in Sr 2 P 2 O 7 and the yellow band to the Eu 2+ occupying Sr 2+ and Ba 2+ sites in BaSrMg(PO 4 ) 2 . The relative intensity ratio of yellow/blue bands is consistent with the content ratio of two phases in the samples with different synthesis temperatures, which is further proof for the original of the blue band. The results of the thermal quenching data demonstrated that the Sr 2+ -substituted phosphor was better than Ba 2 Mg(PO 4 ) 2 .
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Permalink