Molten salts synthesized L‐Ta 2 O 5 :Er 3+ /Yb 3+ with superior pure green upconversion luminescence

Abstract L‐Ta 2 O 5 :Er 3+ /Yb 3+ upconversion phosphors were synthesized by employing the molten salts method with B 2 O 3 as solvent. The optimal doping concentrations of Er 3+ and Yb 3+ are 0.2 and 2.5 mol%, respectively. The green upconversion luminescence (UCL) integral intensity of the acid‐pickling sample reached 40% of β‐NaYF 4 :Er 3+ /Yb 3+ under 980 nm laser excitation. Er 3+ /Yb 3+ may take the sites of Ta 5+ and insert into the interlayers of L‐Ta 2 O 5 . Using the luminescence intensity ratio (LIR) technique, the relative temperature sensitivity was obtained to be 0.95 %K −1 at 303 K. L‐Ta 2 O 5 :Er 3+ /Yb 3+ with outstanding pure green UCL intensity and high‐temperature sensitivity can be applied to luminescence display and temperature sensing.