Highly Pressure-Responsive Dual-Mode Optical Manometer Based on Mn2+-activated Ca2Gd8(SiO4)6O2 Phosphors

To address the low pressure sensitivity of optical manometers, a series of Mn2+-activated Ca2Gd8(SiO4)6O2 phosphors was developed. The synthesized phosphors exhibit an intense and broad emission band, and their luminescence behaviors are dependent on Mn2+ content. By combining the theoretical and experimental approaches, the structural stability of resulting phosphors at elevated pressure was investigated. Besides, with increasing the pressure, an enormous spectral red-shift was detected in the studied samples, leading to pressuremodulated multi-color emissions. Specifically, as pressure rises from 0.38 to 13.66 GPa, the emission band centroid shifts from 592.2 to 661.2 nm, resulting in a high sensitivity (d lambda/dp) of 7.25 nm/GPa. Furthermore, according to the color coordinates of the developed sensor, its optical manometric characteristics were also investigated, revealing its maximum sensitivities 12.64 % and 3.25 % GPa- 1, when x-coordinate and y-coordinate are adopted, respectively. Additionally, the emission band centroid is slightly impacted by temperature, resulting in a high thermal invariability manometric factor of 181.25 K/GPa. These achievements reveal that the Mn2+-activated Ca2Gd8(SiO4)6O2 phosphors are good candidates for the temperature-invariant, dual-mode optical manometry, and our findings may also provide some guidelines for further development of high-sensitivity optical manometers.