Mechanoluminescence of a Ba ₄ Si ₆ O ₁₆ :Eu ²⁺ , Ho ³⁺ ‐Containing Glass‐Ceramic: Experiments Under Different Loading Modes and Modeling

A bulk (cm 3 ‐large) and homogeneous Ba 4 Si 6 O 16 :Eu 2+ , Ho 3+ ‐containing glass‐ceramic was previously obtained from the congruent crystallization of an oxynitride glass. We show in the present work that the europium oxidation state can be controlled by the incorporation of silicon nitride (<6 mol. %). The elastico‐mechanoluminescence (EML) is investigated by means of experiments involving different mechanical loading modes, including pure hydrostatic loading, uniaxial compression, torsion, three‐point bending and dynamic loading (ball drop). The effect of the loading parameters on the EML response is examined, both during the loading and the unloading stages. A model is proposed, which is based on thermoluminescence investigations and on the physics of persistent luminescence. An optimal fitting of the EML intensity is obtained under the assumption of a linear dependence of the depth of the energy level on the applied stress. A value of 1.37·10 –3 eV·MPa –1 is determined from uniaxial compression experiments. The EML phenomenon is found to chiefly stem from the hydrostatic part of the stress. Unlike the SrAl 2 O 4 :Eu 2+ , Dy 3+ crystal, (i) there is no EML signal under pure shear (torsion experiments) for the studied active phase and (ii) the EML intensity weakens upon unloading in uniaxial compression.