Dopant concentration-dependent morphological evolution of Zn2GeO4:Mn2+/Eu3+ phosphor and optical temperature sensing performance

Self-calibrated optical luminescent thermometers were prepared based on Eu 3+ /Mn 2+ co-doped Zn 2 GeO 4 phosphors with controllable morphology via a facile hydrothermal synthesis process. The co-doped concentration of Eu 3+ ions in Zn 2 GeO 4 :Mn 2+ played important roles in the evolution of the morphology and the formation of the dual luminescent emission mode. Depending on different excitation wavelengths ranging from 260 to 360 nm, the dual emission centers located at about 534 nm and 612 nm were ascribed to d - d transition derived from 4 T 1 - 6 A 1 of Mn 2+ ions and f - f transition originated from 5 D 0 - 7 F 2 of Eu 3+ ions, respectively, which gave rise to the excellent self-calibrating temperature sensing functions. The related luminescent and sensing mechanism of the Eu 3+ /Mn 2+ co-doped Zn 2 GeO 4 phosphors are also proposed. The as-obtained Eu 3+ /Mn 2+ co-doped Zn 2 GeO 4 phosphors had a high relative sensitivity ( S r ) of 1.96% ºC −1 between 20 and 80 °C, as well as stable reusability, demonstrating its superiority as a ratiometric luminescent thermometer for temperature sensing applications.