  The upcoming flexible ultra-thin glass for foldable displays has attracted
widespread attention as an alternative to rigid electronic smartphones.
However, the detailed compositional effect of the chemical strengthening of the
glass is not well understood. The spatially resolved chemistry and the depth of
compression layer of tempered glass is far from being clear. In this study,
commonly-used X-ray spectroscopy techniques and atom probe tomography (APT)
were used comparatively to investigate the distribution of constituent elements
in two representative smartphone glass samples: non-tempered and
chemically-tempered glasses. Using APT, analysing the alkalis (Li, Na, K, Ca)
that could impact the failure of the tempered glass was feasible at
sub-nanoscale resolution; demonstrating that APT can be regarded as an
alternative technique for imaging chemical distribution in glass for mobile
applications.
