Surfactant-free sacrificial template synthesis of submicrometer-sized YVO4:Eu3+ hierarchical hollow spheres with tunable textual parameters and luminescent properties.

For the first time, well-dispersed submicrometer-sized YVO4:Eu3+ hollow spheres were successfully synthesized though a surfactant-free method by employing Y(OH)CO3:Eu3+ colloidal spheres as a sacrificial template and NH4VO3 as a vanadium source. The synthetic process mainly consists of two steps, i.e., hydrothermal reaction and acid erosion. By simply changing the amount of NH4VO3 added, the textural parameters of the as-obtained hollow spheres, such as the inner diameter and shell-thickness, can be easily tuned. Moreover, double-shelled hollow spheres could also be obtained when the amount of NH4VO3 was increased to a certain extent. Particularly, the amorphous colloidal spheres of the template could be completely consumed when the amount of NH4VO3 was in large excess, giving rise to the direct formation of uniform hollow spheres without acid erosion. The possible formation process is discussed in detail. Under ultraviolet excitation, the obtained hollow YVO4:Eu3+ phosphors showed strong red emissions, and the Commission Internationale d'Eclairage (CIE) coordinates of the YVO4:Eu3+ phosphors were closely related with the textural parameters such as the inner diameter, shell-thickness and number of shells, indicating a size-dependent characteristic.