The YbVO4 micro-doughnuts were successfully fabricated by a facile hydrothermal method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) were used to characterize the resulting samples. The diameter and thickness of YbVO4 micro-doughnuts are around 750 nm and 480 nm, respectively. It is found that trisodium citrate (Na3Cit) is essential for obtaining YbVO4 microdoughnuts. Moreover, the crystal growth process was thoroughly discussed through a series of time-dependent experiments and a possible formation mechanism was proposed. Furthermore, the up-conversion (UC) luminescent properties as well as the emission mechanisms of YbVO4:Ln3+ (Ln3+ = Er3+, Tm3+ and Ho3+) microcrystals were systematically investigated.
