Radiation Damage of Ni²⁺†Doped NH<inf>4</inf>MgPO<inf>4</inf> · 6 H<inf>2</inf>O

An optical absorption study of NH4MgPO4 · 6 H2O doped with Ni2+ shows that Ni2+ substitutes for Mg2+ in the lattice. This spectrum is fitted to the Liehr and Ballhausen scheme for a 3d8 ion in Oh surroundings. A correlated ESR and optical absorption study of these crystals on X‐ or γ‐irradiation at room temperature indicates the formation of Ni3+ and NH3+ radicals. The NH3+ center is found to have an isotropic g and AH and an anisotropic AN. This center is also produced in undoped crystals with lower yield. Ni3+ centers are found to be paramagnetic and exhibit their characteristic optical absorption bands. Copyright © 1982 WILEY‐VCH Verlag GmbH & Co. KGaA