Highly Sensitive Temperature Sensors Resulting from the Luminescent Behavior of Sm 3+ -Doped Ba 2 MgMoO 6 High-Symmetry Double-Perovskite Molybdate Phosphors.

We present double-perovskite molybdate with the formula of Ba 2 MgMoO 6 doped with Sm 3+ ions as a potential red phosphor to improve the color characteristics of white-light-emitting dioded (wLEDs). The new orange-red phosphor was synthesized using the co-precipitation (CP) method, and then its structural and spectroscopic properties were determined. Red emission at 642.6 nm dominates, which results from the electric dipole (ED) transition of the 4 G 5/2 → 6 H 9/2 type, and the materials are characterized by short luminescence decay times. BMM:Sm 3+ is, to our best knowledge, the clearest example of dominant red emission of Sm 3+ resulting from the location of the dopant in octahedral sites of high-symmetry cubic structure. In the sample containing 0.1% Sm 3+ , Sm 3+ ions are located in both Mg 2+ and Ba 2+ sites, while at higher concentrations the Ba 2+ site is less preferable for doping, as a result of which the emission becomes more uniform and single-site. The relative sensitivity calculated from FIR has a maximum of 2.7% K -1 at -30 °C and another local maximum of 1.6% K -1 at 75 °C. Such value is, to the best of our knowledge, one of the highest achieved for luminescent thermometry performed using only Sm 3+ ions. To sum up, the obtained materials are good candidates as red phosphor to improve the color characteristics of wLEDs, obtaining a color-rendering index (CRI) of 91 and coordinated color temperature (CCT) of 2943 K, constituting a warm white emission. In addition to this, a promising precedent for temperature sensing using high-symmetry perovskite materials is the high sensitivity achieved, which results from the high symmetry of the BMM host.