Optical Pressure Sensor Based on the Emission and Excitation Band Width (fwhm) and Luminescence Shift of Ce3+-Doped Fluorapatite—High-Pressure Sensing

A novel, contactless optical sensor of pressure based on the luminescence red-shift and bandwidth (full width at half-maximum, fwhm) of the Ce³⁺-doped fluorapatite-Y₆Ba₄(SiO₄)₆F₂ powder has been successfully synthesized via a facile solid-state method. The obtained material exhibits a bright blue emission under UV light excitation. It was characterized using powder X-ray diffraction, scanning electron microscopy and luminescence spectroscopy, including high-pressure measurements of excitation and emission spectra, up to above ∼30 GPa. Compression of the material resulted in a significant red-shift of the allowed 4f → 5d and 5d → 4f transitions of Ce³⁺ in the excitation and emission spectra, respectively. The pressure-induced monotonic shift of the emission band, as well as changes in the excitation/emission band widths, have been correlated with pressure for sensing purposes. The material exhibits a high pressure sensitivity (dλ/d P ≈ 0.63 nm/GPa) and outstanding signal intensity at high-pressure conditions (∼90% of the initial intensity at around 20 GPa) with minimal pressure-induced quenching of luminescence.