Investigation of the cyan phosphor Ba2Zr2Si3O12:Eu2+, Dy3+: Mechanoluminescence properties and mechanism

In this paper, we have developed a cyan mechanoluminescence material Ba2Zr2Si3O12: Eu2+, Dy3+ via a solid-state reaction. The crystal structure, photoluminescence and mechanoluminescence (ML) of this phosphor have been systematically investigated. The results showed that the ML intensity increased with Dy3+ concentration from 0.5 to 3 at.% and then reduced following a further increase in Dy3+ content. In addition, the maximum ML intensity was obtained for Ba2Zr2Si3O12: 0.02Eu2+, 0.03Dy3+. In particular, the ML spectrum was similar to the PL and afterglow emission spectra with a slight red shift, showing a dominant peak at approximately 508 nm that was generated from the 5d-4f transition of Eu2+. Furthermore, when the decay time was less than 1 h, the ML intensity rapidly decreased following an increase in the load circle. Following an increase in decay time, the ML intensity was stable and was hardly affected by the load circles. The thermoluminescence (ThL) results have shown that the addition of Dy3+ can create three types of traps with trap depths of 0.682, 0.742 and 0.79 eV. Through combination of the ML and ThL results, the ML mechanism can be explained by the detrapping process of the electrons in shallow and deep traps that were induced by piezoelectricity. The relation between the ML intensity and compressive stress was nearly linear in the test range, indicating that the sample can be used as sensors to detect stress. Furthermore, a cyan ML light can clearly be observed by the naked eye in the dark, which suggested that Ba2Zr2Si3O12: Eu2+, Dy3+ can visualize the stress in an object.