Spindle-like Lanthanide Orthovanadate Nanoparticles: Facile Synthesis by Ultrasonic Irradiation, Characterization, and Luminescent Properties

A general and facile ultrasonic irradiation method has been established for the synthesis of the lanthanide orthovanadate LnVO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) nanoparticles from an aqueous solution of Ln(NO3)(3) and NH4VO3 without any surfactant or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the as-prepared products. Ultrasonic irradiation has a strong effect on the morphology of the LnVO(4) nanoparticles. The SEM and TEEM images illustrate that the as-formed LnVO(4) particles have a spindle-like shape with an equatorial diameter of 30-70 nm and a length of 100-200 am, which are the aggregates of even. smaller nanoparticles of 10-20 nm. The results of XRD confirm the formation of a well-crystallized LnVO(4) phase with a tetragonal zircon structure. Eu3+ and Dy3+ doped zircon type LnVO(4) (Ln = La, Gd, Lu) samples show the characteristic dominant emissions of Eu3+ at 613 nm (D-5(0)-F-7(2)) and Dy3+ at 572 nm (F-4(9/2)-H-6(13/2)), respectively, as a result of an energy transfer from the VO43- to Eu3+ (Dy3+). The formation mechanism of the spindle-like LnVO(4) nanoparticles with ultrasonic irradiation is discussed in the context.