Intense green/blue light emission of Zn2GeO4 nanophosphors doped Tb3+ ions under 265-nm excitation

A series of Zn2GeO4:Tb3+ nanophosphors have been prepared by the high temperature solid state method. The XRD patterns of samples are basically consistent with Zn2GeO4 standard card and the influence of Tb3+ ion on the peak shift is discussed detailedly. The SEM results show that the average sizes of all nanophosphors, whether undoped or doped, are about 50 nm except that some particles in Zn2GeO4 nanophosphor doped with 0.7 mol% terbium take on the cubic structure and the maximum size are about 130 nm. Under 265 nm excitation, there exists a broad blue emission belonging to Zn2GeO4 host. Moreover, the intense photoluminescence peaks at 490, 550 nm and weak peaks at 585, 622 nm of Tb3+ ions are obtained, and optimum Tb3+ doping concentration is 0.7 mol%. The decay curves of host emissions with the varied Tb3+ concentrations are measured, and the mechanisms of photoluminescence and energy transfer from Zn2GeO4 host to Tb3+ ions are analyzed systematically.