Hydrothermal synthesis and photoluminescent properties of hierarchical GdPO 4 •H 2 O:Ln 3+ (Ln 3+ = Eu 3+ , Ce 3+ , Tb 3+ ) flower-like clusters

Abstract 3D hierarchical GdPO 4 ·H 2 O:Ln 3+ (Ln 3+  = Eu 3+ , Ce 3+ , Tb 3+ ) flower clusters were successfully prepared on glass slide substrate by a simple, economical hydrothermal process with the assistance of disodium ethylenediaminetetraacetic acid (Na 2 H 2 L, where L 4−  = (CH 2 COO) 2 N(CH 2 ) 2 N(CH 2 COO) 2 4− ). In this process, Na 2 H 2 L was used as both a chelating agent and a structure-director. The hierarchical flower clusters have an average diameter of 7–12 μm and are composed of well-aligned microrods. The influence of the molar ratio of Na 2 H 2 L/Gd 3+ and reaction time on the morphology was systematically studied. A possible crystal growth and formation mechanism of hierarchical flower clusters is proposed based on the evolution of morphology as a function of reaction time. The self-assembled GdPO 4 ·H 2 O:Ln 3+ superstructures exhibit strong orange-red (Eu 3+ , 5 D 0  →  7 F 1 ), green (Tb 3+ , 5 D 4  →  7 F 5 ) and near ultraviolet emissions (Ce 3+ , 5d →  7 F 5/2 ) under ultraviolet excitation, respectively. This study may provide a new channel for building hierarchically superstructued oxide micro/nanomaterials with optical and new properties.