Super-sensitive multi-modal optical manometer based on huge pressure-induced spectral red-shift and broadening of Mn2+ emission band in green-emitting Zn2GeO4 phosphors

To overcome the small sensitivities of luminescent manometers, Mn2+-activated Zn2GeO4 green-emitting phosphors with admirable manometric characteristics were synthesized. The structural stability of the studied samples is theoretically and experimentally investigated. Moreover, as pressure elevates, a huge spectral red-shift and a broadening of the emission band are observed in studied samples, contributing to color-tunable luminescence, i.e. from green to yellow, and ultimately to orange-red. Specifically, when pressure increases to 6.76 GPa, the emission band centroid shifts from 535.9 to 634.9 nm, leading to a superior sensitivity of dλ/dp = 21.3 nm/GPa. Whereas, in the same operating pressure range, the full width at half maximum (FWHM) of the emission band rises from 32.3 to 102.9 nm, resulting in unprecedentedly high sensitivity of dFWHM/dp = 17.0 nm/GPa. Furthermore, through analyzing the pressure-dependent color coordinates, a maximum sensitivity of 29.43% GPa-1 is achieved, when x-coordinate is adopted. Additionally, the applicability of the developed manometer is confirmed by a simple uniaxial pressure experiments to showcase its practical use in industrial and daily-life purposes. Notably, the designed sensor exhibits the highest pressure sensitivities reported to date in different modes, namely, emission band centroid, FWHM and color coordinate, making supersensitive multimodal optical manometry a reality.