Development of new elasticoluminescent material SrMg2(PO4)2:Eu

We have succeeded in developing a new elasticoluminescent (elastico-L) material SrMg2(PO4)2:Eu (SMPE), which emits purple light clearly observable with the naked eye. SMPE can be synthesized at a firing temperature, which is several hundred degrees Kelvin lower than that for other materials of this group. Based on a comparison between elastico-L emission spectrum and photoluminescence spectrum, the emission was identified to be due to electron transition from an excited state 4f65d1 to the ground state 4f7 in Eu2+ ions. While the emission gradually decayed as stress was applied repeatedly, it recovered completely upon irradiation with UV light (365 nm). This behavior, characteristic to elastico-L materials of the defect-controlled type, suggests that deep charge traps are involved in the emission process. In this paper, the elastico-L mechanism in SMPE is discussed in detail with reference to its thermoluminescence and electroluminescence spectra.