Samples of Cu2+-doped material, grown in acidic solutions (pH ≈ 0), were studied by using electron paramagnetic resonance techniques at 294 to 77K. A Cu2+ center was found, with spin Hamiltonian parameters that were almost constant with temperature. At 294K, gx = 2.313, gy = 2.144, gz = 2.046, Ax = 162, Ay = 0, Az = 13, A′x = 0 and A′y = 78 (A-values in units of 10−4/cm). A model was proposed, with a Cu2+ ion at the center of a Br− square, and with 2 adjacent vacancies at NH4+ sites.

EPR of Cu2+ Doped in NH4Br - Orthorhombic Center. W.Sano, E.Di Mauro: Journal of Physics and Chemistry of Solids, 1997, 58[3], 391-2