In this paper, a large enhancement of red elastico-mechanoluminescence (EML) intensity has been observed in piezoelectric semiconducting CaZnOS: Mn²⁺ phosphors via the co-doping of Nd³⁺ ions. The optimal EML intensity of CaZnOS: 1%Mn²⁺, 1.2%Nd³⁺ was about ten times than that of CaZnOS: 1%Mn²⁺. In addition, the relationship between the EML intensity and the applied load was almost linear and the phosphor exhibited recoverable performance under ultraviolet (UV) (254？nm) excitation, which is a potential candidate for pressure sensing sensor applications. The thermoluminescence (TL) results indicated the co-doping of Nd³⁺ ions not only increased the concentration of traps but also introduced two new types traps. Further investigations revealed that the shallow trap contributed the most to the long afterglow and two deep traps were mainly responsible for the EML performance. Based on the piezoelectricity-induced detrapping model, all the results suggested the enhanced EML intensity of CaZnOS: Mn²⁺ can attribute to the increased trap quantity and regulated trap concentration generated by the co-doping of Nd³⁺ ions.

SEM images of the CaZnOS: Mn²⁺, 1.2%Nd³⁺ (a), (b) and related EDS elemental mapping images of Ca (c), Zn (d), O (e), S (f), Mn (g) and Nd (h).