interstice; space between lattice points
Technical term in physics referring to the space or gap between points in a crystal lattice or similar grid.
Impurities can enter the interstices of a crystal lattice.
格子点 refers to a lattice point itself, while 格子点間 refers to the space between such points.
格子間 is a more general term for interstitial spaces in a lattice, while 格子点間 specifically emphasizes the space between lattice points.
Compound of 格子点 (lattice point) + 間 (interval, space). The exact historical derivation is uncertain, but the term is a straightforward technical coinage.