Huge enhancement of Sm2+ emission via Eu2+ energy transfer in a SrB4O7 pressure sensor

Abstract

Taking advantage of the excellent pressure-sensing properties of the Sm²⁺ ion in the SrB₄O₇ crystal, we demonstrate an enormous enhancement of about 60 times in the emission intensity of Sm²⁺ ions when Eu²⁺ ions are also incorporated into the crystalline structure. This enhancement is induced by the energy transfer from Eu²⁺ to Sm²⁺ ions. The spectral position of the ultra-narrow and most intense ⁵D₀ → ⁷F₀ emission line in the material was correlated with pressure and successfully calibrated up to about 58 GPa. The material exhibits favorable pressure-sensing features, i.e. dλ/dp ≈ 0.29 nm GPa⁻¹, negligible temperature-dependent shift, narrow and well-separated emission lines, and a strong luminescence signal. The samples also exhibit multicolor tunable luminescence from orange-red to amaranth, and to warm-white light, depending on the excitation wavelength used and dopant content in the matrix, allowing their potential application in white light emitting diode (LED) devices.