Er3+ concentration-dependent microstructural and upconversion luminescence process of transparent perfluoride composite glass

The phase compositions of the samples were identified using an Xray diffractometer (PANalytical X′ Pert Pro Empyrean) with Cu-Kα irradiation. The crystal morphology and elemental distribution characterization of the samples were performed using a field-emission scanning electron microscope equipped with EDS (FESEM, HitachiS-4800).

The thermal behavior of the samples was investigated by the thermogravimetric analyzer (EXSTAR SII:TG/DTA7300) at a heating rate of 10 K/min. The mid-infrared transmission spectra of samples with a thickness of 1 mm were obtained using a Fourier transform spectrometer (Nicolet). The UC spectra and time-resolved curves were measured using the instrument FLSP 920 (Edinburgh Instruments Ltd.).