Pressure-triggered enormous redshift and enhanced emission in Ca2Gd8Si6O26:Ce3+ phosphors: Ultrasensitive, thermally-stable and ultrafast response pressure monitoring

To overcome the challenges of pressure monitoring with high sensitivity, we have designed a series of Ce3(+)-activated Ca2Gd8Si6O26 phosphors with outstanding pressure sensing properties. Excited with UV light, the resultant phosphors can emit a blue-violet luminescence, originating from optically active Ce3(+) ions. The optimal doping content for Ce3(+) ions in the Ca2Gd8Si6O26 host lattices is 3 mol%, for which the concentration quenching mechanism is dominated by the electric dipole-dipole interaction. The thermal stability of the prepared phosphors was explored by measuring temperature-dependent emission spectra, and determining the activation energy, which is ~0.225 eV. Furthermore, in order to study the pressure sensing ability of the designed phosphors, their luminescence spectra were recorded as a function of pressure up to ~10 GPa. With increasing pressure, an abnormal enhancement of emission intensity was observed, with an enormous red-shift of the emission band of 3.00 nm/GPa, and a decreasing full width at half maximum (FWHM) of -2.45 nm/GPa for the synthesized phosphors. The determined performance of the sensors developed now classifies them as the most sensitive pressure gauges, i.e., the shift rate is approximately one order of magnitude higher than that of the commonly used ruby sensor. Importantly, the developed pressure sensor shows a negligible temperature dependence, i.e., 0.0023 nm/K for the line-shift and 0.0017 nm/K for the FWHM, and an ultrafast response due to the short emission lifetime of the Ce3(+) excited state of -20 ns. Additionally, the structural stability of the compounds under pressure is verified by Raman spectroscopy up to -11 GPa. These results make the Ce3(+)-activated Ca2Gd8Si6O26 phosphors a promising candidate for ultrasensitive manometry and provide some guidelines for the development of novel pressure sensors.