Synthesis and optical properties of efficient orange emitting GdB5O9:Sm3+ phosphors
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In the present study the single phase polycrystalline GdB5O9:Sm3+ target materials were prepared by aqueous sol–gel method. The powder X-ray diffraction was used to monitor the crystal phase formation. Samples doped with 1 and 2.5% Sm3+ showed bright orange–red emission upon excitation with near-UV radiation. The emission possessed excellent colour saturation and good colour coordinate stability. Emission spectra recorded at different temperatures showed that the thermal quenching activation energy is around 35 meV. Moreover, the temperature dependent photoluminescence (PL) decay measurements revealed that PL lifetime values barely change in the temperature range of 77–500 K showing that the external quantum yield decreases much faster than the internal one. The highest quantum yield of ca. 60% was obtained for the sample doped with 1% Sm3+ ions. Further increase of Sm3+ content resulted in concentration quenching as a consequence of increased probability of cross-relaxation. Rather high quantum yield and well resolved sharp emission lines makes these phosphors suitable for application as an orange–red component in near-UV LEDs, on the one hand, and the luminescent security pigments, on the other hand.
GdB5O9:1% Sm3+ possesses 60% quantum yield.
GdB5O9:1% Sm3+ at 500 K loses only 40% of efficiency.
GdB5O9:Sm3+ phosphors possess high colour saturation.
KeywordsGadolinium, pentaborates Thermal quenching Colour coordinates Quantum efficiency Sm3+
This research was funded by a grant (No. S-MIP-17-48) from the Research Council of Lithuania.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
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