Yellow, orange and red emission generated from Yb, Er doping strontium gadolinium oxide under multi-mode excitation

The development of multimode excited up-conversion (UC) luminescent materials is of great significance for information multi-encryption and anti-counterfeiting technology upgrade. In this work, SrGd2O4:Yb3+, Er3+ phosphors were synthesized by solid-state reaction method. SrGd2O4:Yb3+, Er3+ was proved to be Orthorhombic system by XRD diffraction experiments. The SEM analysis revealed that the average grain size of the samples ranged from 1 to 2 μm. The UC luminescence properties of samples were studied when excited at 915 nm, 980 nm, and 1550 nm. CIE color coordinates showed that the color of SrGd2O4:Yb3+, Er3+ phosphors can be tuned by different laser excitation. Specifically, the sample emitted yellow light under 915 nm excitation, orange-red light under 980 nm excitation, and pure red light under 1550 nm excitation. The mechanism of energy level transitions revealed that the luminescence under 915 nm and 980 nm excitation originated from a two-photon process, while the luminescence under 1550 nm excitation originated from three-photon absorption. The UC-QY of SrGd2O4: Yb3+, Er3+ dispersion was investigated by a reference method, and their values were 2.7% (915 nm), 4.3% (980 nm), and 6.4% (1550 nm) when excited by different lasers, respectively. The results laid a foundation for the research of the material in the field of anti-counterfeiting. •The luminescence characteristics of SrGd2O4:Yb3+, Er3+ phosphors excited at multi-wavelength were studied for the first time.•The UC-QY of SrGd2O4:Yb3+, Er3+ dispersion under multi-wavelength were studied.•The work lays a foundation for the research in the field of anti-counterfeiting.