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

Abstract

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(NO 3 ) 3 and NH 4 VO 3 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 TEM 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 nm, 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. Eu 3+ and Dy 3+ doped zircon type LnVO 4 (Ln = La, Gd, Lu) samples show the characteristic dominant emissions of Eu 3+ at 613 nm ( 5 D 0 - 7 F 2 ) and Dy 3+ at 572 nm ( 4 F 9/2 - 6 H 13/2 ), respectively, as a result of an energy transfer from the VO 4 3− to Eu 3+ (Dy 3+ ). The formation mechanism of the spindle-like LnVO 4 nanoparticles with ultrasonic irradiation is discussed in the context.