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The N-doped Sr 2.985 Mg 1-y Si 2 O 8 :0.005Eu2+,0.01Dy3+,yMn2+ (0 ≤ y ≤ 0.15) phosphors were designed to obtain long-persistent phosphors for white LEDs. All the samples were determined to be single-phase by XRD analysis. The particles show smooth surface with the help of the H 3 BO 3 flux. The energy-dispersive X-ray spectrum indicates the existence of N element. Various Eu2+ emission centers have been gained and verified by the photoluminescence spectra and long-persistent emission spectra, and a red-shift of the Eu2+ emission was observed in the N-doped samples due to the nephelauxetic effect. In Eu2+-Mn2+ co-activated phosphors, tunable emission has been realized and an efficient energy transfer from Eu2+ to Mn2+ was found, which could belong to the dipole-dipole interaction mechanism. The optimal afterglow time was obtained in the Sr 2.985 MgSi 2 O 7.76 N 0.16 :0.005Eu2+,0.01Dy3+ sample, but doping Mn2+ reduces the afterglow time largely. The mechanism for the increase of luminescence intensity and afterglow time with N present was interpreted. The temperature-dependent luminescence was also evaluated. [ABSTRACT FROM AUTHOR]

Luminescent ions doped lead free ferroelectric ceramics are the potential candidates to the widespread application of optoelectronic devices due to the coupling between their unique photoluminescence and inherent ferroelectric performance. In this work, the tunable photoluminescence response is successfully achieved in (1- x)Na 0·5 Bi 0·5 TiO 3 - x CaTiO 3 : Eu3+ (NBT- x CT: Eu3+, x =0.07, 0.1) via electric field poling. It is found that the enhancement of photoluminescence intensity became apparent for polarized NBT-0.07CT: Eu3+, wherein x =0.07 is near the morphotropic phase boundary region. However, for NBT-0.1CT: Eu3+ ceramic with a morphotropic phase boundary, the variation trend of the emission intensity after electric field poling is opposite. These results are ascribed to the lattice distortion and phase transition induced by an external field poling, which originates from ferroelectric and structural instability near and in the morphotropic phase boundary of NBT- x CT: Eu3+ (x =0.07, 0.1) ceramics. • The NBT- x CT: Eu3+ specimens exhibit strong prominent red emission. • The lattice distortion and phase transition are induced by an external field poling. • Electric-field-induced photoluminescence modulation is successfully achieved. • NBT-0.07CT: Eu3+ possesses more superior performance than NBT-0.1CT: Eu3+. [ABSTRACT FROM AUTHOR]

In this work, a series of Ca 9(1- m - n) La(PO 4) 5 SiO 4 F 2 : m Eu, n Mn (CLPS: m Eu, n Mn, 0 ≤ m ≤ 3%, 0 ≤ n ≤ 4%) phosphors were designed for multifunctional applications. The phase purity was evaluated by XRD technique, which revealed that the obtained samples were single-phase. When the Eu was doped, it was found that the emission spectra exhibited different characteristics depending on the excitation wavelength. More than one Eu2+ emission center was confirmed in the Eu-activated CLPS phosphors, and the optimal Eu2+ doping concentration was determined to be 1 mol%. To realize tunable emission, the Eu-Mn codoped CLPS phosphors were synthesized, in which the efficient energy transfer (ET) from Eu2+ to Mn2+ occurred. The corresponding ET mechanism was discussed by using the Dexter's ET formula. Upon 365 nm excitation, the thermal quenching properties of both Eu-single-doped and Eu-Mn-codoped CLPS phosphors were evaluated, and the spectral features were interpreted. Under 300 nm excitation, it was found that the CLPS:1%Eu sample showed different decay rates for the Eu2+ and Eu3+ emission intensities with temperature, which was considered to apply to optical thermometry. High sensitivity was obtained in the present phosphor. • The tunable emission was realized in the Eu-Mn codoped CLPS phosphors. • The different thermal quenching properties for different Eu2+ centers were found. • High sensitivity was obtained in the wide temperature range for optical thermometer. • The CLPS:Eu, Mn phosphors show potential applications in LEDs and optical thermometer. [ABSTRACT FROM AUTHOR]