Effects of Mn substitution on the structure and properties of chalcopyrite-type CuInSe2

Mn-doped CuInSe2 compounds(CuIn1-xMnxSe2, x = 0.0125-0.20 and Cu(1-y)In(1-y)Mn(2)ySe(2), 2y = 0.0125 - 0.60) were synthesized by high-temperature solid-state reactions. Single phase materials with chalcopyrite structure persist upto 0.10 and 0.20 doping for CuIn1-xMnxSe2 and Cu1-yIn1-yMn2ySe2, respectively. The chalcopyrite and sphalerite phases co-exist in the Cu(1-y)In(1-y)Mn(2)ySe(2) system for 2y = 0.25-0.50. At tempts to introduce greater manganese content, x = 0.15 - 0.20 for Cu1-xIn1-xMn2xSe2 and 2y = 0.60 for Cu(1-y)In(1-y)Mn(2)ySe(2), result in partial phase segregation. For the single-phase samples, the lattice parameters of both systems increase linearly with manganese concentration and thus follow Vegard's law. The temperature of the chalcopyrite - sphalerite phase transition is decreased by manganese substitution for all single-phase samples. The band gap of the materials remains around 0.9eV. Additionally, the Mn-doped CuInSe2 compounds display paramagnetic behavior, where as pure CuInSe2 is diamagnetic at 5-300K. All the CuIn1-xMnxSe2 and Cu(1-y)In(1-y)Mn(2)ySe(2) compounds with chalcopyrite structure show antiferromagnetic coupling and measured effective magnetic moments upto 5.8mB/Mn. (C) 2009 Elsevier Inc. All rights reserved.