Luminescence and temperature-sensing properties of Y4GeO8:Bi3+,Eu3+ phosphor

In this paper, Y4GeO8:Bi3+,Eu3+ phosphor with dual emission centers was elaborated via conventional solid-state reaction technology. Thorough research on the structure, morphology, and luminous properties of Y4GeO8:Bi3+,Eu3+ phosphor, the potential applications in optical thermometry were investigated by means of fluorescence intensity ratio and thermochromic techniques. Under 290 and 347 nm excitation, Y4GeO8:Bi3+,Eu3+ phosphor presents broadband emission from P-3(1) -> S-1(0) transition of Bi3+ ions and characteristic emission peaks from 4f-4f transition of Eu3+ ions. Outstanding temperature-sensing capabilities are acquired from Y4GeO8:Bi3+,Eu3+ phosphor. The maximum relative sensitivity (S-r) can attain 1.51% K-1 (lambda(ex) = 290 nm). With temperature raising (303-513 K), the emitted color of Y4GeO8:Bi3+,Eu3+ phosphor (lambda(ex) = 290 nm) shifts from faint yellow to red with a high chromaticity shift (0.180), which can be distinguished by the unaided eye clearly. Our results indicate that Y4GeO8:Bi3+,Eu3+ phosphor has potential applications in optical temperature measurement and high-temperature safety marker.