Rare-earth and transition metal ion single-/co-doped double-perovskite tantalate phosphors: Validation of suitability for versatile applications

Novel rare-earth (RE;e.g., europium (Eu^(3+)), samarium (Sm^(3+)), and praseodymium (Pr^(3+))) and transition metal (TM^(4+);e.g., manganese (Mn^(4+))) ion single-/co-doped double-perovskite Ca2InTaO6 (CITO) phosphors were prepared and investigated with respect to their crystal structure and photoluminescence (PL) properties. Among them, the CITO:Eu^(3+) phosphors were found to exhibit an ultra-high internal PL quantum yield (89.1%) and good thermal stability (78.7% at 423 K relative to the initial value at 303 K). As such, the corresponding packaged white light-emitting diode (LED) was able to display a remarkable color rendering index (CRI;= 91.51@10 mA). Besides, the potential in applications of anti-counterfeiting fields and a novel LED structure based on flexible phosphor-converted films was also studied. Moreover, due to their different thermal quenching, trivalent lanthanide (Ln^(3+))/Mn^(4+) co-doped CITO phosphors were designed for optical thermometry based on the luminescence intensity ratio (LIR) between different 4f transitions of various Ln^(3+) ions and ^(2)Eg → ^(4)A_(2g) (Mn^(4+)) transition. Particularly, the LIR between the ^(4)G_(5/2) → ^(6)H_(9/2) and ^(2)Eg → ^(4)A_(2g) peaks of the CITO activated with 5 mol% Sm^(3+) and 0.3 mol% Mn^(4+) exhibited the most excellent relative sensitivity (Sr;= 3.80 %·K^(−1)) with beneficial temperature uncertainty of 0.0648 K. Overall, these results are of significance to offer valuable databases for constructing multifunctional high-performance optical platforms using single-/co-doped double-perovskite tantalates.