Designing a super broadband near infrared material Mg3Y2Ge3O12:Cr3+ using cation inversion for future light sources

Abstract

A series of broad emission band near infrared materials Mg₃Y₂Ge₃O₁₂:Cr³⁺ (650–1200 nm) was prepared based on cation inversion. For trivalent chromium ions (Cr³⁺), garnet structural components can provide conditions for the occurrence of cation inversion. With an increase in Cr³⁺ concentration, the Mg²⁺ and Ge⁴⁺ cations are inverted to ensure valence equilibrium, which was explained by recording the low temperature spectrum of the structure and carrying out structural refinement. As a result, this structure provides a new luminescent center [GeO₆] for Cr³⁺, leading to a secondary enhancement in emission intensity. The wavelength of the main peak was found to move from 771 to 811 nm, and the full width at half maximum (FWHM) was broadened from 180 to 226 nm. The lattice occupation, luminescence mechanism and the reasons behind the red-shift and broadening of the spectra were studied in detail. By analyzing the crystallinity and particle size distributions of the samples, as well as the Cr³⁺ ion energy level shift, it was determined that cation inversion is an effective method that can be used to tune the luminescence performance. Meanwhile, a super broad near infrared light emitting diode (LED) with a FWHM of 260 nm was obtained by combining a GaN chip with MYG:0.40Cr³⁺.