InP lattice parameter as a function of rapid neutron fluence for crystals with different initial impurity content n, cm–3: (1) major carrier concentration (1.6–2.3)·1018 ; (2) 3.5·1016; (3) (3–4.1)·1016 ; (4) 2·1017 ; (5) (4.2–5.2)·1016 ; (6) 8·1017; (7) 3.9·1018.