Highly uniform NaLa(MoO4)2:Eu3+ microspheres: microwave-assisted hydrothermal synthesis, growth mechanism and enhanced luminescent properties

Uniform and well-crystallized NaLa(MoO4)(2) microspheres were prepared by a facile microwave-assisted hydrothermal method at low temperature without any surfactants or templates. The as-prepared products were systematically characterized by powder X-ray diffractometer, scanning electron microscope, high resolution transmission electron microscope (HRTEM) and photoluminescence (PL) spectrometer. The results indicate that the phase, morphology, and size of the products can be tuned by altering reaction temperature and time. A possible formation mechanism of the microspheres was proposed based on the time-dependent experiments and HRTEM results, which contained an oriented attachment and Ostwald ripening process. Under ultraviolet excitation, the NaLa(MoO4)(2):Eu3+ microcrystals exhibit strong red luminescence at 613 nm which attributes to D-5(0) -> F-7(2) transition of Eu3+. The dependence of NaLa(MoO4)(2):Eu3+ PL intensity on different morphologies have been investigated in detail. The results revealed that the PL intensity of NaLa(MoO4)(2):Eu3+ microspheres is higher than that of polyhedrons and dendrites particles, and proved that the microspheres might have potential application in solid lighting technology.