Er 3+ -activated Ba 2 V 2 O 7 upconversion nanosheets for dual-mode temperature sensing.

So far, there has been substantial research on non-contact luminescence thermometry approaches that rely on luminescence intensity ratio (LIR) technology. However, there is limited availability of phosphors doped with Er 3+ ions that exhibit on-par luminescence and high sensitivity. In this work, samples of Ba 2 V 2 O 7 :Er 3+ were synthesized using a sol-gel method aided by citric acid. The luminescence properties of these samples, including upconversion and down-shifting, were investigated using both ultraviolet and 980 nm laser stimulation. When subjected to ultraviolet (UV) light, the sample exhibits a distinct broadband emission that appears pale green. This emission is a distinguishing property of the sample and is attributed to the presence of V 2 O 7 2- ions. Upon being stimulated by a 980 nm laser, the sample exhibits standard green up-conversion Er 3+ emission bands. Concurrently, an assessment was conducted on the phosphor's ability to measure temperature by analysing the LIR between the thermally coupled 2 H 11/2 , 4 S 3/2 energy levels (TCELs) and the non-thermally coupled 2 H 11/2 , 4 F 9/2 energy levels (NTCELs) of the Er 3+ ion. The corresponding highest sensitivity of temperature for TCELs and NTCELs can position Ba 2 V 2 O 7 :Er 3+ nanosheets as a capable option for materials utilized in temperature-sensing applications.