Preparation of novel mesoporous GdVO4: Eu3+ crystals by CTAB-SDS micellar-assisted hydrothermal method in wide pH range

Using cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfonate (SDS) as a template, the novel mesoporous europium doped miro-/nano-crystalline gadolinium vanadate (GdVO4:Eu3+) crystals were controllably synthesized by a facile hydrothermal process over a wide adjustable pH range. The structure, morphology and luminescence properties of GdVO4:Eu3+ crystals were characterized and compared by X-ray power diffraction (XRD), scanning electron microscope (SEM) transmission electron microscopy (TEM), nitrogen absorption-desorption and photoluminescence spectroscopy (PL). The results revealed that the pH influenced the nucleation rate of GdVO4:Eu3+ crystals in the reaction solution, and the CTAB and SDS performed a pivotal function in the morphology of final products via forming micelles and transforming growth direction. When the reaction solution was pH = 14, the cationic surfactant CTAB and anionic surfactant SDS were successively added, and the finally obtained phase-pure tetragonal GdVO4:Eu3+ crystals exhibited a mesoporous structure with a BET surface area of 11.41 m2∕g and the average nanocrystalline size in the range of 40–60 nm. Additionally, the mesoporous GdVO4:Eu3+ crystals showed the strongest luminescence intensity among all the samples with different morphologies.