Intrinsic and extrinsic defects build a novel mechanoluminescent phosphor Na2MgGeO4:Mn2+

Abstract

Constructing suitable defects in lattice is of great significance for developing new elastic mechanoluminescent materials. Here, a series of novel mechanoluminescent phosphors Na₂Mg_1−xGeO₄:xMn²⁺ (0 ≤ x ≤ 0.025) were synthesized by a high-temperature solid-state reaction method in an ambient atmosphere. The defects in the crystal lattice and the mechanism of photoluminescence and mechanoluminescence were clarified through Rietveld refinement, X-ray photoelectron spectroscopy, electron spin resonance and thermoluminescence spectra. The intrinsic oxygen vacancy defects form a deeper trap level, which plays an important role in the photoluminescence of the host. The relatively shallow extrinsic cation substitution defect Mn_Mg is mainly responsible for the mechanoluminescence of doped samples. This study not only highlights the importance of defects to optical properties, but also broadens our insight into the development of novel functional materials by defect control.