Primary- and upconverted emission in the glass and glass-ceramics doped with Er3+ ions in the context of maximum phonons

Highlights: • In case of photoemission of the Er³⁺-doped glass and glass-ceramics the usefulness of a simple three-level model is proven. • Analysis of the results shows maximum phonon energy decrease by several tens of cm^‐1 going from glass to glass-ceramics. • Three-level model provides good fits to the experimental data either for primary emission or for upconverted emission. -- Abstract: On the example of oxyfluoride glass and glass-ceramics doped with erbium ions we show how the process of phase transformation affects the maximum phonon energy value. Our analysis is based on temperature dependence of luminescence and on stationary solutions of kinetic equations describing the simplest possible model of the luminescence centrum and its dependence on temperature. It appears that this three-level model describes properly not only primary luminescence at ~1534 nm but also upconverted emissions at 519 nm, 538 nm and 649 nm, when the excitation is at ~980 nm.