Synthesis of Ba3(VO4)2 :Sm3+ phosphor by molten salt method and its temperature sensing characteristics.

A series of Ba_3-x ( VO₄ )₂ : xSm³⁺ (x = 0.02-0.16) phosphors were synthesized using the molten salt method with KCl as the salt. The effects of synthesis conditions as well as Sm³⁺ doping concentration on the phase structure and luminescence properties of the sample were investigated in detail. The temperature sensing characteristics of the sample were also studied. The optimum reaction conditions for synthesizing the sample are calcination temperature of 900 °C, calcination time of 1h, and a mass ratio of raw materials to molten salt of 1 : 3. The obtained sample has high phase purity and crystallinity. The micromorphology of the sample is lamellar with a thickness of about 1.53 mm. Upon the ultraviolet excitation of 318 nm, the broad emission from the VO₄^3- groups and characteristic emissions from Sm³⁺ can be observed simultaneously in the emission spectra of Ba_3-x(VO₄)₂:xSm³⁺ phosphors, with the emission colors concentrated in the yellow-white light region. With the increase of Sm³⁺ doping concentration (x) from 0.02 to 0.16, the intensity of the characteristic emission peak of Sm³⁺ first increases and then decreases, reaching its maximum value when x =0.10. The dominant mechanism for the concentration quenching in Ba_3-x(VO₄)₂ :xSm³⁺ phosphors is attributed to the dipole-dipole (d-d) interaction. Moreover, for Ba_2.9 (VO₄ )₂ : 0.10Sm³⁺ phosphors, it is found that the fluorescence intensity ratio of Sm³⁺ (652 nm) and VO₄^3- groups (504 nm) shows a significant temperature dependence in the temperature range of 298-473 K. Its maximum absolute and relative temperature sensor sensitivities are 0.36/K and 1.99%/K, respectively. The results indicate that Sm³⁺ doped Ba₃(VO₄)₂ phosphors exhibit excellent temperature sensing performance and potential applications in non-contact optical thermometry. [ABSTRACT FROM AUTHOR]