Improved calibtration curve for the Sm²⁺:BaFCl pressure sensor

The pressure sensor proposed by Shen, Gregorian & Holzapfel [High Press. Res. (1991), 7, 73–75], based on the pressure-dependent shift of the luminescence line due to the ⁵D₀−⁷F₀ electronic transition of Sm²⁺ in a matrix of BaFCl, has been tested in a diamond-anvil cell and calibrated against the R₁−R₂ doublet shift of ruby and the known NaCl equation of state, in the pressure range between 0.0001 and 4.3 GPa. The parabolic dependence of the shift from the pressure can be approximated by the equation Δ(nm) = 1.46P − 0.047P², where the shift, Δ, is in nm and the pressure, P, in GPa. The estimated error in the pressure measurements is 5%. The Sm²⁺: BaFCl luminescence sensor can be advantageously used in the low to moderate pressure range (0.0001–5 GPa or more).