October 2025

Journal

Non-linear elastic-plastic behavior of the invert glass lithium phosphorous oxynitride (LiPON)

By:
Kalnaus, Sergiy ; Westover, Andrew S; Veith, Gabriel M; Owensby, Kyra D; Tsai, Wan-Yu; Egami, Takeshi
Journal Name:
Journal of Non-Crystalline Solids
Page Number:
123793
Volume:
669
Publication Date:
October 6, 2025
View DOI Listing:
https://doi.org/10.1016/j.jnoncrysol.2025.123793

Abstract

Micro and nano-scale mechanical behavior of network/ionic glasses is dictated by their composition and the number of constraints per structural unit. From this perspective, the glass LiPON presents the opportunity for enhancement of the microscale ductility due to its rather unconstrained orthophosphate structure. We use instrumented nanoindentation with different tip geometries to investigate the mechanical response of LiPON glass. The results reveal that the elastic modulus of LiPON is not constant and depends on pressure. With the method utilizing spherical nanoindentation and continuous stiffness measurement (CSM) we determine the yield point of LiPON. We propose the Drucker-Prager type of yield criterion for LiPON and estimate its yield stress in compression as 2.4 GPa. There exists another stress threshold, however, around 490 MPa, at which the elastic deformation becomes non-linear, and this can be mistaken for the yield stress.