Er ³⁺ -Activated NaLaMgWO ₆ double perovskite phosphors and their bifunctional application in solid-state lighting and non-contact optical thermometry

Herein, Er ³⁺ -activated NaLaMgWO ₆ phosphors were prepared by a traditional high-temperature solid-state method. Based on the double perovskite structure of the NaLaMgWO ₆ host, we observe the desirable PL properties of Er ³⁺ . When excited at about 378 nm, the as-obtained materials can emit strong green light. When applied to a temperature sensor based on the fluorescence intensity ratio (FIR) principle, the prepared phosphors show excellent sensitivity ranging from 303 to 483 K. With elevated operation temperature, the sensitivity is about 2.23% K ^-1 at 483 K, resulting from the sensitive thermally coupled levels ( ² H _11/2 and ⁴ S _3/2 ) of Er ³⁺ ions in the double perovskite structure. The calculated relative sensitivity of the temperature sensor was 1.04% K ^-1 at 303 K. In particular, besides high sensitivity, its superior water resistance is an equally thrilling discovery. Therefore, it is demonstrated that the as-prepared Er ³⁺ -activated NaLaMgWO ₆ phosphors have promising potential applications in both near-UV solid-state lighting and non-contact optical thermometry.