Acta Materialia (2012)

Mechanoluminescence in BaSi2O2N2:Eu
J. Botterman, K. Van den Eeckhout, I. De Baere, D. Poelman, P.F. Smet
Acta Materialia 60 (2012) 5494-5500

Abstract
Mechanoluminescence (ML), a general term for the phenomenon in which light emission occurs during any mechanical action on a solid, can be divided roughly into two classes: destructive ML and non-destructive ML. For practical use in high-end applications (e.g. pressure sensors), materials with non-destructive ML properties are preferred. This paper reports on the strong non-destructive ML in BaSi2O2N2:Eu. When irradiated in advance with ultraviolet or blue light, this phosphor shows intense blue-green light emission upon mechanical stimulation such as friction or pressure. The ML has an emission band peaking at 498 nm, which is 4 nm red-shifted compared to the steady-state photoluminescence. The origin of the ML is discussed and related to the persistent luminescence of BaSi2O2N2:Eu. The same traps are responsible for both phenomena. Based on the occurrence of ML in this phosphor, we were able to show that the predominant crystallographic structure of BaSi2O2N2:Eu belongs to space group Cmc21.

Keywords: Mechanoluminescence, Persistent phosphor, Charge trapping, Thermoluminescence, Piezoelectric materials

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