Blue-excitable orange-red-emitting M 3 Y(PO 4 ) 3 :Pr 3+ (M = Ba, Sr, Ca) phosphors for multifunctional applications

Research on multifunctional luminescent materials has become an emerging trend for new applications of optical sensing, monitoring, anticounterfeiting, lighting, etc. Herein, a library of Pr 3+ -doped M 3 Y(PO 4 ) 3 (M = Ba, Sr, Ca) phosphors was prepared for careful spectroscopic studies in potential lighting and optical temperature sensing applications. With the help of density functional theory calculation, diffuse reflectance spectra, and steady/dynamic photoluminescence spectra, the effects of alkaline earth metals on the fluorescence properties of M 3 Y(PO 4 ) 3 :Pr 3+ were studied systematically. Under the excitation of blue ∼ 445 nm, orangish-red fluorescence of approximately 602 nm was efficiently detected due to Pr 3+ 1 D 2 → 3 H 4 transition, which becomes stronger by regulating alkaline-earth elements from Ba to Sr and to Ca. An optimized Ca 3 Y(PO 4 ) 3 :0.7%Pr 3+ sample was validated with excellent thermal stability 89%@423 K and further applied to fabricate a white light emitting diode by combining with commercial YAG:Ce 3+ phosphors on a 445 nm blue chip. Specifically, CIE chromaticity coordinates (0.3510, 0.3650) and correlated color temperature (∼ 4838 K) were obtained for an obvious improvement. Moreover, optical thermometry properties of Ca 3 Y(PO 4 ) 3 :0.7%Pr 3+ were explored on basis of Pr 3+ 3 P 0 - 3 P 1 thermally coupled energy levels. Their fluorescence intensity ratios following the Boltzmann equation could be operated over 298-598 K with superior relative sensitivity ∼ 0.87% K -1 at 298 K. These interesting results for multifunctional luminescence will greatly promote the development of novel Pr 3+ -doped luminescent materials as well as the related photoelectric devices.