Energy transfer has been generally utilized for the sensitization of luminescence in phosphors. It is common that excitation of donor can be transferred efficiently to acceptor. However, energy transfer should be investigated in association with the transfer efficiency from donors to activators. To accomplish this, energy transfer from Gd3+ to Eu3+ and Tb3+ was investigated. It was found that the transfer efficiency from Gd3+ to Eu3+ is higher than that from Gd3+ to Tb3+ because there are less energy mismatches between the emission of Gd3+ and the absorption of Eu3+ than that between Gd3+ and Tb3+ in the host NaGd(PO3)(4). (C) 2013 Elsevier B.V. All rights reserved.