The
lattice constant, or
lattice parameter, refers to the physical dimension of
unit cells in a
crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as
a,
b, and
c. However, in the special case of
cubic crystal structures, all of the constants are equal and we only refer to
a. Similarly, in crystal structures, the
a and
b constants are equal, and we only refer to the
a and
c constants. A group of lattice constants could be referred to as
lattice parameters. However, the full set of lattice parameters consist of the three lattice constants and the three angles between them.