Low-temperature wet chemical synthesis and photoluminescence properties of YVO4: Bi3+, Eu3+ nanophosphors

YVO4: Bi3+, Eu3+nanophosphors are prepared by the citrate-assisted low-temperature wet chemical synthesis. When the colloidal solution is aged at 60 °C, the crystalline YVO4: Bi3+, Eu3+ nanorods are formed from the amorphous gel precursors, as confirmed by transmission electron microscopy and X-ray diffractometry (XRD). YVO4: Bi3+, Eu3+ nanophosphors emit red through energy transfer from Bi3+ to Eu3+ under near-UV-light excitation. The emission intensity increases with increasing the fraction of the crystalline phase during aging. The excitation peak corresponding to Bi3+-V5+ charge transfer relative to those of O2−-V5+ and O2−-Eu3+ charge transfers gradually becomes strong until the completion of the crystallization, although the contents of individual Bi3+ and Eu3+ ions incorporated into YVO4 keep constant. When the aging is continued after the completion of the crystallization, the content of incorporated Bi3+ gradually increases, and hence the emission intensity decreases as a result of the energy migration among Bi3+ ions. These results suggest that in addition to the fraction of the crystalline phase and the contents of incorporated Bi3+ and Eu3+ ions, the local chemical states around Bi3+ play significant roles in photoluminescence properties.