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 LnVO4(Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) nanoparticles from an aqueous solution of Ln(NO3)3and NH4VO3without 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 LnVO4nanoparticles. The SEM and TEM images illustrate that the as-formed LnVO4particles have a spindle-like shape with an equatorial diameter of 30−70 nm and a length of 100−200 nm, which are the aggregates of even smaller nanoparticles of 10−20 nm. The results of XRD confirm the formation of a well-crystallized LnVO4phase with a tetragonal zircon structure. Eu3+and Dy3+doped zircon type LnVO4(Ln = La, Gd, Lu) samples show the characteristic dominant emissions of Eu3+at 613 nm (5D0-7F2) and Dy3+at 572 nm (4F9/2-6H13/2), respectively, as a result of an energy transfer from the VO43−to Eu3+(Dy3+). The formation mechanism of the spindle-like LnVO4nanoparticles with ultrasonic irradiation is discussed in the context. [ABSTRACT FROM AUTHOR]