Pressure-driven configurational crossover between 4f7 and 4f65d1 States - Giant enhancement of narrow Eu2+ UV-Emission lines in SrB4O7 for luminescence manometry

Accurate, fast, and non-invasive methods for the determination of the local pressure magnitude are crucial for the investigation of the physical and chemical behavior of materials at the extreme conditions of high pressure. A promising method for remote operando pressure measurements is luminescence manometry. However, a limiting bottleneck for high-pressure readout is the usually occurring quenching of the emission signal of the luminescent sensor material upon compression. In this work, we reported for the first time the pressure-induced intensity enhancement (by 3 orders of magnitude) of the 4f(7)(P-6(7/2)) -> 4f(7) ( S-8(7/2) ) emission line of Eu2+ in the UV range due to pressure-induced configurational crossover between the excited (4)f(6)5d(1) and 4f(7) energy levels in SrB4O7 host. The peak centroid of the narrow 4f (7) -> 4f(7) transition exhibits a significant red-shift (similar to -12.84 cm(-1) GPa(-1); 0.17 nm GPa(-1)) with simultaneous tem-perature independence of the line position (4.8.10(-4) nm K-1). The pressure sensitivity of the proposed system is competitive to the so far well-established luminescent pressure sensors based on Al2O3:Cr3+ (ruby) and SrB4O7:Sm2+ with characteristic narrow line emission in the red range, and offers an alter-native spectral range in parallel with an intensity enhancement at higher pressures. This novel pressure gauge may significantly improve the accuracy of the remote pressure measurements and open up new horizons for materials science research at even higher pressures. (c) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study reports the pressure-induced intensity enhancement of the emission line of Eu2+ in SrB4O7 host. The pressure sensitivity of the proposed system is competitive to established luminescent pressure sensors and offers an alternative spectral range at higher pressures.