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Green-emitting phosphor Eu 2+ doped NaBaScSi 2 O 7 was synthesized by a solid-state reaction, and the photoluminescence properties were investigated in conjunction with a structural analysis. The crystallographic occupancy of Eu 2+ in the Sc silicate NaBaScSi 2 O 7 matrix was studied based on the Rietveld refinements results and the crystal chemistry rules. The optimum concentration of Eu 2+ in the NaBaScSi 2 O 7 phosphor was about 10 mol%, and the concentration quenching mechanism was verified to be the dipole-dipole interaction. Upon excitation at 365 nm, the composition-optimized NaBaScSi 2 O 7 :Eu 2+ exhibited strong green light peaking at 501 nm with the CIE chromaticity (0.0706, 0.5540) and a high internal quantum efficiency of about 65%. The thermally stable luminescence properties were also studied and compared with those of the commercial green phosphors. A white light emitting diode (w-LED) lamp was finally fabricated by using the present green phosphor and the commercial blue and red phosphors, which exhibited a high color rendering index (R a ) of 86.5 at a correlated color temperature of 2528 K with CIE coordinates of x ¼ 0.353, y ¼ 0.324. These results suggest that NaBaScSi 2 O 7 :Eu 2+ is a potential green phosphor candidate for near-UV-pumped w-LEDs.

[1] The rotation pattern and fault activity in the southeast margin of the Tibetan Plateau (SEMTP) provide meaningful constraints on the geodynamic evolution of the plateau. However, the lack of Cenozoic paleomagnetic studies and accurate age constraints on Neogene sediments prevents a better understanding of the late Cenozoic tectonic activity in this area. To clarify the tectonic rotation pattern and deformation history of the SEMTP, we report new magnetostratigraphic data from a late Neogene sedimentary sequence in the Dali Basin, northwestern Yunnan Province, China. Rock magnetic analyses indicate that both magnetite and hematite are the main carriers of the characteristic remanent magnetizations (ChRMs). Magnetostratigraphic results show that the sedimentary profile spans from Chron C4n.1r to Chron C2n. The age of the sedimentary sequence in the Dali Basin can thus be paleomagnetically constrained to an interval from late Miocene to early Pleistocene. The basal age of the sediments is~7.6 Ma, which indicates that the unroofing of Diancang Shan and activation of the Dali fault system were initiated at this time. The appearance of conglomerates and syntectonic sediments suggests the reactivation of the Dali fault system at 2.5 Ma. Moreover, the overall mean ChRM direction suggests that the Dali Basin experienced significant (4.4 AE 2.5), but minor post-late Miocene rotation. This indicates that most of the clockwise rotation demonstrated by previous paleomagnetic studies in the SEMTP occurred prior to late Miocene and may be concentrated between Eocene and Miocene, which is contemporaneous with the sinistral slip of the Ailao Shan-Red River fault.

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