LAUSR

Abstract Well-crystallized NaGd(MoO 4 ) 2 :Sm 3+ microcrystals with different morphologies were successfully prepared via a facile hydrothermal method without any additives and characterized by an X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectroscopy. The morphologies of the samples evolved from truncated octahedrons, through tetragonal plates and square sandwiches without filling, to elongated bipyramids by simply altering pH values from 3.5 to 7.0. According to the time-dependent experiments, a possible formation mechanism of the tetragonal plate was proposed. Moreover, the luminescent properties of NaGd(MoO 4 ) 2 :Sm 3+ phosphors with different morphologies and Sm 3+ concentrations were investigated. The sample with the morphology of tetragonal plates obtained under the pH value of 4.5 presented the stronger red-emitting than others. Moreover, the optimal concentration ( x ) of Sm 3+ was confirmed to 0.03. The concentration quenching of Sm 3+ was mainly attributed to dipole-dipole interaction.